If the Nest doesn't have a common wire connection it will power steal from the other connections, but only when it's not running. So on a really cold night its internal battery can deplete and then it shuts down. After a few hours the internal battery recharges and then it starts working again. I'm a Nest certified pro. I've installed thousands of them. 90% of service calls are related to the C wire not being connected.
Ted, I had the same problem in my house with a way oversized unit that would hit high limit. Trane XV90 to be exact. They changed out the burner orfiaces to a small size which helped some, lowered the gas pressure, increased the fan speed.... finally they soldered the orifaces shut and drilled them to a small size and it stopped hitting high limit. Ran close to it, but, didnt trip it out anymore. We also went to a less restrictive filter. It ran for years, but in the end, ended up cracking the heat exchanger after 19 years..... guess i cant complain on that one.
I am not in the business. I like watching your problem solving and the way you talk yourself through each of the scenarios. Great logic ( at least to me) is used.
I'm in Michigan and had a 2 stage furnace 125K/ 84K BTU, 1985 vintage. Since I had upgraded the windows and added insulation, I found that the 125K was oversized. I permanently hardwired the thermostat to the 84K setting and never had any problem with ignition and always had nice blue flames. Even on the coldest day in winter, the furnace was adequate to meet the task. More recently, I had Carrier 2 stage furnaces (2000 vintage) and the control board managed which stage was in use. It could also be wired so a 2 stage thermostat would determine which stage to use based on whatever logic existed in the thermostat. I don't know anything about those Nest t'stats, but maybe they're 2 stage capable. I know this video is old, so you probably solved the problem long ago. I like your videos and your calm, no nonsense approach to problem solving.
Hi Ted, I wanted to add my thoughts about Total Static Pressure Test that may be of use to you and your readers. With the test, the probes are positioned in the recommended places on the equipment as indicated and a measurement is taken. So, if high, you might look for restrictions closed baffles, dirty filters, undersized ducts, etc.... One thing to remember along with the usual suspects is don't forget restrictions in the return portion of the systems when doing total pressure. Inadequate return flow between rooms can affect it. I open all doors in the home to take my first measurement , and then take a second with all doors closed to see the change. There could be significant static pressure in the room its self. You could check using the manometer as well. If you are on the edge adding an additional return to a room may keep you in the limit.
Another great video Ted. In most furnaces you can see the speed taps on the diagram sticker inside one of the furnace doors. I ran into this issue once on an oversized Trane XB90 furnace and I did exactly what you did here in this video. But I also made a small opening on the supply duct right above the furnace to heat the furnace room in the basement. Customer called me back a year after for furnace cleaning and said everything was good after I made the change. ( upflow furnace; no flex ducting)
Anti DIY, I had a similar situation once and had more time to find a solution. I used the manometer to check static pressure on the supply and return ducts/plenium. I found the return side fine (.23 wc) but supply side high (.75 wc). Customer didn't not want to spend money for me to install more supply ducts or redo ducts at the time, but agreed that she would have me install whole new system in the summer It was easier for me to install a bypass 6" duct between supply and return duct with a manual damper in the middle. I was able to decrease supply side and increase return air, which was not ideal but stopped the high limit from going off.
One day problem on this was ceiling return and supplies. I've seen this before return air temperature was 82 and climbing. Too much heat is being sucked into the return from the supplies. When way around it and I've done is the supply grills the Vans the point straight down don't have the heat go across the ceiling have it goes straight down to the floor. That's why it would go off on a long cycle furnishes aren't made to be running with 80 + degree return air temperatures
If you're supply was 130 mixing at the register it was probably 135 at the takeoff. Return temp was perty high too I think in about of the manuals it tells you not to run a higher return temp then 80. Most furnaces i see are anywhere from 25 at the lowest and 80 at the highest which is way high in my opinion on the temp rise. I think 40-45 is good most the time, leaves room for a dirty filter or shut registers. Only think you really can do is derate gas, increase Airflow at blower tap,check shut registers or add ductwork if issue persists. Ultimately go in with smaller furnace as last resort. Nice video
For me its weird to see an upflow in an attic, I'm from Illinois where alot of houses have basements. I've dealt with horizontals only in attics here. Mostly air-handlers too. Crawlspace installs are BS also.
12” only handles 500 cfm 10” 300. Bumping up blower speed may help high limit but it also may over amp the blower motor if the return is also undersized. Why do some people think you can only draw return from one side of the furnace?? I often used the back or the opposite side to draw RA along with the main. That’s one of the best looking attic installs I’ve seen on your videos. I would make it mandatory for your installers to do a start up before they leave the job!!! I never left a job with/out a start up unless it was new con with no power Never never a change out !!!
"Bumping up blower speed may help high limit but it also may over amp the blower motor if the return is also undersized." Not true. Restricting air flow causes the static pressure to go up and lowers blower current.
This is a good tip for remembering fan speed: black is high, its the coldest color if you think about it. Blue would be med high because it would be the next coolest color, followed by yellow being med low, the color is getting warmer with red being low speed. The lower your fan speed the higher your temp rise. So low speed would have the highest temp rise. Make sense? Purple is usually med on 5 speed motors.
Hi Ted: I had a similar issue with a furnace and had to add a return duct and to get more air flow. Also turned down gas valve but furnace did not light well after that, so had to increase a little to get a good light without a bang. Also filter size was small and recommended to increase the size in the return and use a low flow air (cheap) for better flow. Thanks for fixing that hard to fix problem.
Furnace Skematic usually shows fan speed on icp but that works 2. Looks way short on return. Carrier has 90k btu 3ton furnaces. That's prob a 4 ton drive. Need to check the drive if 3 or 4 ton. Supply is 3 1/2 ton so seems fine 2 me.
I had one the other day that was going into setback, to 45 when it didn't detect any motion, and they were waking up cold, fixed the setback and it was fine after that.
I would recommend : 1. Static presure test than compare to the blower chart . Check pressure between the coil also 2. duct calculation to see if you can move 1170 cfm with current ductwork . ( that's what's needed for 90k) Just going of the experience to me its undersized - I usually run 2x14" returns on 75k furnace-3 ton set up 3. Add 4" filter( get rid of 1") 4. Maybe even increase motor speed to high if needed , ( rheem has tap that you can share same speed cool/ heat) not sure about carrier Hope this helps!
Agree. I feel it would have been more accurate to say that the ducting is potentially undersized as opposed to the furnace being oversize.. ultimately potato potatoes :)
If its oversized furnace, make sure that ductwork is properly sized . In this case ductwork should be sized for cooling 400-350- 450 cfm per ton( depends on the area). After ductwork is fixe, furnace will work ok, comfort will be affected due to short cycles on warmer days, set point will be reached much faster but it will not go of high limit. On cold days will have longer cycle. My rough guess 18"-20" minimum return, same to supply ( it all depends depending on friction rate/ velocity per manual D )
Check static pressure, Return, supply and drop across coil. Remove high limit and put inspection camera up into coil to see if it’s dirty. Check all supply registers to make sure they are open, adjust if needed. Open all bedroom doors, if there are no returns in the bedrooms they will over pressurize and choke off the supply air.
A big problem in that house is as the furnace is running the return air is sucking in a lot of the heat from the registers. Your return error was 82 degrees and I'm sure it would go higher as the furnace runs longer. Because you have ceiling Supply and returns one way I've been able to get around that is going to the supply grills bending the veins downward. Make the Heat come down as much as possible. And if you're by Windows you can make it come straight down. That's one of the problems at that place you're sucking in heat from the supplies heat stratification is happening. Furnaces are not designed to run with 80 + degree return air temperature. You'll trip a limit every time
I've used Klein probes. Nice and robust. The ones I've had were previous versions that didn't have the magnet. Now that I've seen this new version I may get one because that was my only gripe.
I know that this is how it is done all over the United States (you don't have to tell me that) but having ceiling returns and ceiling supplies only works efficiently for "cooling" where you are taking the hottest air in the room back to the air handler to have the heat removed. Having high wall/ceiling returns for heat simply takes out the nice warm air and leaves the cold air in the room. It is a little more complicated than that. For my own personal use I use a high-low wall return set up that is dampered so that it can be changed with the seasons. Makes a world of difference.
I seemed to find The 1” pleated filters always have a restriction,, plus flex duct move a bit less air as metal , so we always ran the next size up on flex , okla.state Lic.# xxxx
I think it's really interesting how it heated from 71 to 80 degrees in 10 minutes with the vents being on the ceiling. Heat usually does better coming from the floor.
I have ran into same problems before. Customer says well we planned on adding on to house but never did at least they were honest. I never go below 3.1- 3.0 high fire. Speaking of high fire you pulled that monometer hose off gas valve I was tensed up untill you put cap back on lol think you did that on purpose. Great video I would add to do quick CFM check on all supply vents before you leave especially since they had manuel dampers. Also while you have that fancy monometer check duct static pressure see if you have any insulation gremlins on your coil. Thanks for videos we appreciate you :)
You may have to remove the first orifice and cap it and run only 3 tubes instead of 4... And recalibrate to get the proper heat rise temp. Heat rise should be taken at the furnace suppy and return. TSTAT may make temp before High limit at 160 degrees trips.. What you did may work depending on run time...
Maybe check the static pressure and see just how restricted it is ? Add some duct work and correctly solve the problem ? And why now is it shutting off on high limit ? Unless it’s been doing since installed ? I think more investigation needed to be done !
Hi Ted. Thanks for all you do. Love your work! Learn a lot from you. Just a suggestion, but, my thoughts are to run a total static pressure test when changing fan speed along with gas pressure that you did. Also temp rise...you also confirmed restricted airflow. Curious, did you check filter in the home? I'm pretty sure you did, but just didn't mention it on video. Thanks Ted!
I’ve never seen a regulator needed on internal distribution lines, only at the meter or in certain appliances. Does SC not put regulators on the meter outside the house?
To anyone that watches Mr cook videos your watching a true old school pro that cares about his family people I think there people he loves and cares about I know you say what there clients no your wrong he loves what he does gods work going we get to witness when people really care for each other I think it's really not about money it's what God sees in use love you Mr Cook
We just replaced a perfectly good Keeprite , trouble was previous company installed a 100 k 2 stage in a 1500 square foot side split . They only thing we could do was install the right size 60 k . In Canada we are not allowed to modify furnaces by plugging burners , nor would I. The only solution Ted is a new 60 2 stage
I’m not sure why it’s called Anti-DIY as he seems to encounter an endless array of hack jobs. There is not much integrity any more. Ted does a great job and always seems to do right by his customers.
How do you like your 2 stage. I had one installed 11 months ago . I would never buy one again. Was sold it mine went out in Feb last year, couldn't get bids, needed heat then. Mine takes about 2 hours to go from 69 to 72 when it is 3e0 out. Sometimes stage 2 comes on sometimes it doesn't, seems like furnace runs 1/3 of the time.
Thank for the video. I had my furnace replaced 3 years ago and it was oversized. It countinued to over heat and shut off and turn back on right away. Ive had the technician out 7x now though out the install to try to fix. I was told by a different hvac tech that the has was tuned down to temporarily fix the over heating. Well now its in the negative cold snap here in Chicago and my heat cant keep up with the -10s and 20+degree windshield. Runs all night for few days stright sometimes dosent shut off. We went to bed and it was 74 degrees woke up and it was reading 68 degrees in the home. Had to buy a space heater to make it though last few days. Different techs who came out said the furnace installed was to large for my home. Also the return air duck was to small. They said the downstairs area could use a return because it dosen't have one. My question is, is this issue fixable and is the contract responsible for rectifying this problem with the correct size furnace. I have a warranty company that i use and they now said they aren't going to replace it, even though they admited to the contractor they used said the new units to big. My old furnace never had that problem before. Any recourse you can recommend be greatly appreciated.
Nice video. I would have done exactly what you did but left customer with option of a dump zone or replace furnace. You have to have more airflow for 90 btus. Thanks for sharing
The biggest problem or one of them on this was heat stratification. Return air supply boats on ceilings they're returning her temperature was getting into the mid-80s. Furnace is aren't designed for that warm of a return air temperature. One way around it is to take the supply Grill veins and aim the heat to go down straight down instead of across the ceiling. Return air air temperature is getting too warm
As another put it. It's all in the engineering. Thought I was watching myself work, only I'm not as good looking as you. What I do is tell the customer he the unit is oversized, and re-engineering the ducts are required. This includes possible return additions, larger ducts, replacement of all stamped registers. In addition to what you did, add drops, and dump into coldest room or unused room if possible. Get the external static down, kill the high fire if possible. It can be done, but I don't re-engineer the units themselves, as far as jets go for legal reasons, only on cars. Others may be more daring then a old timer like me. I have pulled a duct off a plenum to get them by until a reduct could be done. Temp rise was still high after what you did. One old timer to another.
What gets me is that he checked the gas pressure but never checked the static pressure. The supply ducting looks 'ok', but the return duct looks small, what size is it? Also, didn't he notice all the oil leaking from the blower motor for a 2016 model, defiantly says that the static pressure is way high and the motor is overworking trying to move air. May be a oversized furnace, but I suspect the return duct was too small.
After all that, my next operation, and I have done this when I had no choice is to block the orifice on the last burner, the one with the flame sensor, disabling it, then moving the sensor over one burner. As long as there isn't a thermal limit in that exchanger tube, it won't hurt a thing. Then adjust gas psi if needed. I have gone as low as 3.2" or as the manufacture suggests. Of course the best thing to do is install the properly sized equipment.
with icp furnaces previous they had smart valve pilot in middle which seemed much safer to plug one of the outside orfices still static pressure could be high with blower tonnage it was much easier in old days to make something work than now now with everyone knowing more than the one that was called nice presentation
Do a static pressure test to see where you are running also could do a combustion test when adjusting gas valve to make sure that your ppm is not above 100 there are combustionVariables for different types of gas units you can look on Testo or Bacharach website for that information
had the same issue in our home for 12 years. 80,000btu in a roughly 1,200sqt home. For the first few years the company could not figure it out, so they say, they were just trying to brush us aside. What helped which was not ideal, in the winter remove the air filter, open up a second return air and open up another exhaust. This helped but on really cold days it still tripped the high limit and we had no heat until we turned the furnace off and on. We finally replaced the furnace a few months ago and got a good HVAC company to come in and we currently have a 2 stage 40,000btu & so far for the past 4 months no issues. Makes a big difference when the company knows what the hell they are doing lol
I had 2 companies that wanted to put an 80K BTU furnace in my 1100sq/ft ranch, neither seemed to care about the size of the house and based the sizing off the duct work. 3rd company wanted to know the size of the house and insulation it had, they recommended a 60K BTU. They were also unfortunately the most expensive, their 60K BTU single stage single speed furnace was the same or more than the others wanted for an 80K BTU 2 stage with ECM motor. I ended up going with them anyway and fortunately haven't had any issues.
I’ve seen where technicians have moved the flame sensor over and plugged one of the orfices to bring the output down, I’ve never done it, but I’ve seen it work.
I'm wondering about the moisture/rain/condensation stains on the exhaust flue and below that on the manifold, which also looks to be getting onto the flame sense wire/part. I wonder if it's condensing on real cold nights and wetting the flame sensor/wire causing a lockout :)
Wow, I'm up in MN and I have a 60K BTU output for a 4K+ sq ft house. 98% efficient. Works great because when it is very cold it runs all the time - which is what it is supposed to do. I also have smooth metal ducts which are much larger than this system. Another case of over sizing the system, which seems all too common.
@22:17 😱: Two sets of solid double yellow lines that are two or more feet apart sometimes appear as a road marking. Such lines stand for a solid wall. Don't drive on or over these road markings. You may not make a left turn or U-turn across it.
Sensible load means nothing if you cannot move the right amount of air. Little more return and supply would be great. Does anybody ever do combustion analysis anymore? Most important test on a gas furnace. And it can give you signs of overheating problems.
Couple things I have done with this type of problem is 1st I have removed one of the orfice and put in a plug and relocated the flame sensor, 2nd I have removed some of the vents say a 6” and made them 8” to get rid of more air 3rd would be to add more vents to different parts of the house or garage
I'm thinking that eliminating one of those jet burners would be helpful in this situation and capping off the Spud for that unit. But that's an idea to try. I would likely do a center jet burner if it didn't rely on the wings to ignite the next one, so, your probably going to do the end. Would also turn the pressure back up to 3.5.
Note fan speed on wiring diagram. Check static pressures. Compare to fan chart. Should be easy to find online being a 2016 model. Check temperature rise and gas pressure. Good chance that evaporator coil has gotten more restricted over time and is just now starting to impact the heat exchanger. Check the static pressure differential between the outlet of the furnace and the outlet of the evaporator if you get a “call back”. I agree it is too big but they may not pay you for a new furnace and just live with the problem but they may pay for a coil cleaning and a larger return duct or two. Give them both options. A band aid solution and a few permanent solutions. The customer has to own the decision.
I would have pulled the black "HI" for heat, put the yellow or blue on cooling for a lower fan speed to help with humidity control, was the ac oversized as well?!? If so humidity control will be an issue with a higher speed, if the fan speed is too high in cooling, it can literally yank the condensation off the coil blowing through the duct, rusting and prematurley making any metal duct rot quick.... Lower fan speed allows coil to get colder, drain out properly while helping humidity also.
@@henryjonswift6997 The plenum wont be imbalanced its mixing just fine. you cant even cap the center off anyway, how will the crossover work>? it was a nice thought though.
Fixing other peoples oversizing mistakes, I have several times filled the last jet with solder, then moved the flame sensor over 1 burner. Never had an issue and works great.
had a 100k 80% gas furnace . was way to big. blocked one of the four burner jets and worked much better for 10 years until I put in a 56k 92% rheem in last fall.
Isn't the required airlfow for the 90k furnace 1200 cfm. Are the runs long and just to cocked up. Or does round flex have a different flow rate than round metal. Don't really work with flex much. Because on 2 10's and 1 12 metal duct you should be able to flow right around 1400 cfm depending on static pressure. Cause I've run into oversized units and I mean they are typically obvious as In The supply and return ducts are just way to small. I mean like ducts sized for 2 ton ac with 100k furnace
I'd put a temperature controller like a Ranco sensing the discharge air temperature on one of the main branches set to cycle in series the white thermostat wire from the thermostat to the circuit board of the furnace to shut off the burners when the discharge air get too hot and under the high limit temperature limit. The the burners will short cycle on long runs but the furnace would operate as close to normal as possible and the home owners most likely would never know the difference.
I'm not big heat specialist so your videos are very educating for me. Thank you. I'm little bit crazy about duckt sizing. My solution here will be add extra return and extra supply register. At least 350 CFM . Will it help?
Another great video! I also have an oversized furnace & inadequate ducting, but the tech actually set the fan to spin at the same speed throughout the cycle. It no longer hits that second stage where it spins faster. Is he wrong?
I'm a plumbing contractor, not HVAC, but I feel like I do a pretty good job researching how to do things before I dive into unfamiliar waters. About 22 years ago when I put our furnace in, I was told I could put in a bigger furnace than our house needed (we were considering adding on) and just derate it by pulling out one of the four orifices and plugging it off. It sounded like a good idea at the time and it was easy enough to do. With 4 orifices it would have been 100K, so pulling one out I suppose put it at around 75K. I've got a few more years experience behind me now and I'm curious if experienced HVAC pro's would think that doing that would possibly increase the risk of un-even heating and possibly cracking the heat exchanger. When watching your video I was saying to myself "just pull one of the orifices out, that'll knock the temp down a bit w/o lowering pressure too far" but now when I consider the possible risk of damaging the heat exchanger, I realize that maybe I should have checked a few more sources to see if pulling and plugging an orifice maybe wasn't that great of an idea after all.
90K BTU, 17" Wide, 1400 CFM. Furnace being fed from the side with that small pipe (likely a pleated filter too). Yes the furnace is suffocating and the limit is tripping. Have seen it with other ICP brands as well. Likely a 70,000 would have been more appropriate. The 90s can be finicky with overheating.
A 12” return isn’t enough. Static pressure across the unit would have removed the guess work. Adding a 12” return and an 8” supply spill duct/register in a hallway would help immensely. Kicking up the blower speed could be objectionable noise and drafty
Ted, could you have sealed one of the burners closed and only lit 3 instead of 4? I realize you don't want to rig it, but was wondering if that would effectively make it a 3 ton. Not a HVAC guy but am learning
Pretty sure if I seen that right the black fan speed wire should have been on the heat tap , where I work we never chang the heat tap , just change for the a/c size
Wire diagram is right on blower access panel or main panel. Carrier , bryant, payne all have wire schematics to motor wire tap. If you have an ANDROID phone there is a great app for almost ALL makes and models with all install manuals available called FURNACE CODES AND DIAGNOSTICS by Fire-n-ice on google play store. excellent tool to have as well as the carrier service tech app for all replacement components
You recommended 60,000 btu on a 1800 sq foot house with 20 degrees for a low that night. Looking at the variables. It would have to be zone 1 (the south) A 60,000 btu with 80% efficiency is 48,000btu output. An 1800 sq foot house would require 54,000. I know there can be a lot of variables. Can you shed some light on this? Please
50F temp rise sounds pretty decent unless it has a low range like 25 to 50 vs the normal 40 to 60 - or it would be if the return wasn't pulling in such warm air due to location. Why not put both heating and cooling on high? Just need a jumper wire and Y connection/splitter. No pro, but i've observed going up only one speed doesn't drop the rise very much on undersized ducts.
Does installing a 2-stage furnace pretty much make the problem go away, other than having over payed for a too big furnace and not making use of the high-stage?
WOW great video, had the same problem and my guy did just that , lower gas pressure and fan speed medium high and problem were fixed, and yes my furnace was to big for the house
Return air on the ceiling for heat .....yuk, needs the floor, should have duel more supply runs and return would help. Short fix Ceiling fan's a must to move the hot air off the ceiling
If the Nest doesn't have a common wire connection it will power steal from the other connections, but only when it's not running. So on a really cold night its internal battery can deplete and then it shuts down. After a few hours the internal battery recharges and then it starts working again. I'm a Nest certified pro. I've installed thousands of them. 90% of service calls are related to the C wire not being connected.
Ted, I had the same problem in my house with a way oversized unit that would hit high limit. Trane XV90 to be exact. They changed out the burner orfiaces to a small size which helped some, lowered the gas pressure, increased the fan speed.... finally they soldered the orifaces shut and drilled them to a small size and it stopped hitting high limit. Ran close to it, but, didnt trip it out anymore. We also went to a less restrictive filter. It ran for years, but in the end, ended up cracking the heat exchanger after 19 years..... guess i cant complain on that one.
I am not in the business. I like watching your problem solving and the way you talk yourself through each of the scenarios. Great logic ( at least to me) is used.
I'm in Michigan and had a 2 stage furnace 125K/ 84K BTU, 1985 vintage. Since I had upgraded the windows and added insulation, I found that the 125K was oversized. I permanently hardwired the thermostat to the 84K setting and never had any problem with ignition and always had nice blue flames. Even on the coldest day in winter, the furnace was adequate to meet the task. More recently, I had Carrier 2 stage furnaces (2000 vintage) and the control board managed which stage was in use. It could also be wired so a 2 stage thermostat would determine which stage to use based on whatever logic existed in the thermostat. I don't know anything about those Nest t'stats, but maybe they're 2 stage capable. I know this video is old, so you probably solved the problem long ago. I like your videos and your calm, no nonsense approach to problem solving.
Hi Ted, I wanted to add my thoughts about Total Static Pressure Test that may be of use to you and your readers. With the test, the probes are positioned in the recommended places on the equipment as indicated and a measurement is taken. So, if high, you might look for restrictions closed baffles, dirty filters, undersized ducts, etc.... One thing to remember along with the usual suspects is don't forget restrictions in the return portion of the systems when doing total pressure. Inadequate return flow between rooms can affect it. I open all doors in the home to take my first measurement , and then take a second with all doors closed to see the change. There could be significant static pressure in the room its self. You could check using the manometer as well. If you are on the edge adding an additional return to a room may keep you in the limit.
Another great video Ted. In most furnaces you can see the speed taps on the diagram sticker inside one of the furnace doors.
I ran into this issue once on an oversized Trane XB90 furnace and I did exactly what you did here in this video. But I also made a small opening on the supply duct right above the furnace to heat the furnace room in the basement. Customer called me back a year after for furnace cleaning and said everything was good after I made the change. ( upflow furnace; no flex ducting)
Anti DIY, I had a similar situation once and had more time to find a solution.
I used the manometer to check static pressure on the supply and return ducts/plenium.
I found the return side fine (.23 wc) but supply side high (.75 wc).
Customer didn't not want to spend money for me to install more supply ducts or redo ducts at the time, but agreed that she would have me install whole new system in the summer
It was easier for me to install a bypass 6" duct between supply and return duct with a manual damper in the middle. I was able to decrease supply side and increase return air, which was not ideal but stopped the high limit from going off.
One day problem on this was ceiling return and supplies. I've seen this before return air temperature was 82 and climbing. Too much heat is being sucked into the return from the supplies. When way around it and I've done is the supply grills the Vans the point straight down don't have the heat go across the ceiling have it goes straight down to the floor. That's why it would go off on a long cycle furnishes aren't made to be running with 80 + degree return air temperatures
If you're supply was 130 mixing at the register it was probably 135 at the takeoff. Return temp was perty high too I think in about of the manuals it tells you not to run a higher return temp then 80. Most furnaces i see are anywhere from 25 at the lowest and 80 at the highest which is way high in my opinion on the temp rise. I think 40-45 is good most the time, leaves room for a dirty filter or shut registers. Only think you really can do is derate gas, increase Airflow at blower tap,check shut registers or add ductwork if issue persists. Ultimately go in with smaller furnace as last resort. Nice video
up next, the husband is turning it off at night to keep the wife from chewing up all the gas and cooking him out LOL
What my dad does but with our electric heat.
Ted needs a service man for his van, "tire pressure monitor", "change engine oil soon". His van has 235,432 miles already...
poor guy running his vehicle to the last leg of life just like me.
For me its weird to see an upflow in an attic, I'm from Illinois where alot of houses have basements. I've dealt with horizontals only in attics here. Mostly air-handlers too. Crawlspace installs are BS also.
We up north call southern attic systems hillbilly heaters...
No one knows aggravation until you lay in a wet crawlspace on a cold night working on a sooted up horizontal oil furnace lol
12” only handles 500 cfm 10” 300. Bumping up blower speed may help high limit but it also may over amp the blower motor if the return is also undersized. Why do some people think you can only draw return from one side of the furnace?? I often used the back or the opposite side to draw RA along with the main. That’s one of the best looking attic installs I’ve seen on your videos. I would make it mandatory for your installers to do a start up before they leave the job!!! I never left a job with/out a start up unless it was new con with no power
Never never a change out !!!
"Bumping up blower speed may help high limit but it also may over amp the blower motor if the return is also undersized."
Not true. Restricting air flow causes the static pressure to go up and lowers blower current.
This is a good tip for remembering fan speed: black is high, its the coldest color if you think about it. Blue would be med high because it would be the next coolest color, followed by yellow being med low, the color is getting warmer with red being low speed. The lower your fan speed the higher your temp rise. So low speed would have the highest temp rise. Make sense? Purple is usually med on 5 speed motors.
Hi Ted: I had a similar issue with a furnace and had to add a return duct and to get more air flow. Also turned down gas valve but furnace did not light well after that, so had to increase a little to get a good light without a bang. Also filter size was small and recommended to increase the size in the return and use a low flow air (cheap) for better flow. Thanks for fixing that hard to fix problem.
Furnace Skematic usually shows fan speed on icp but that works 2. Looks way short on return. Carrier has 90k btu 3ton furnaces. That's prob a 4 ton drive. Need to check the drive if 3 or 4 ton. Supply is 3 1/2 ton so seems fine 2 me.
I would have just taken the easy route and blamed it on the Nest thermostat. 😂
thats some funny stuff right there
I had one the other day that was going into setback, to 45 when it didn't detect any motion, and they were waking up cold, fixed the setback and it was fine after that.
@@denverlewis5087 good find Denver. the old nest has a mind of its own. The machines are watching us 👀
Lol. Great comment
If the return air was lower in the side wall or in the floor would be better for the air flow
blower speeds and full wiring diagrams are usually available on the furnace doors.
I would recommend :
1. Static presure test than compare to the blower chart . Check pressure between the coil also
2. duct calculation to see if you can move 1170 cfm with current ductwork . ( that's what's needed for 90k) Just going of the experience to me its undersized - I usually run 2x14" returns on 75k furnace-3 ton set up
3. Add 4" filter( get rid of 1")
4. Maybe even increase motor speed to high if needed , ( rheem has tap that you can share same speed cool/ heat) not sure about carrier
Hope this helps!
Agree. I feel it would have been more accurate to say that the ducting is potentially undersized as opposed to the furnace being oversize.. ultimately potato potatoes :)
If its oversized furnace, make sure that ductwork is properly sized . In this case ductwork should be sized for cooling 400-350- 450 cfm per ton( depends on the area). After ductwork is fixe, furnace will work ok, comfort will be affected due to short cycles on warmer days, set point will be reached much faster but it will not go of high limit. On cold days will have longer cycle. My rough guess 18"-20" minimum return, same to supply ( it all depends depending on friction rate/ velocity per manual D )
You can increase motor speed to high by making a "Y"connector to connect Cool and Heat tap to high motor lead... this works fine .
Static pressure definitely important to determine actual system airflow output. Thanks for sharing DT, solid advice.
Check static pressure, Return, supply and drop across coil. Remove high limit and put inspection camera up into coil to see if it’s dirty. Check all supply registers to make sure they are open, adjust if needed. Open all bedroom doors, if there are no returns in the bedrooms they will over pressurize and choke off the supply air.
Those white rodger valves come set high like that from the factory on Carrier products. The installers did not even check the gas pressure and left.
A big problem in that house is as the furnace is running the return air is sucking in a lot of the heat from the registers. Your return error was 82 degrees and I'm sure it would go higher as the furnace runs longer. Because you have ceiling Supply and returns one way I've been able to get around that is going to the supply grills bending the veins downward. Make the Heat come down as much as possible. And if you're by Windows you can make it come straight down. That's one of the problems at that place you're sucking in heat from the supplies heat stratification is happening. Furnaces are not designed to run with 80 + degree return air temperature. You'll trip a limit every time
Nice job Ted, I always look forward to your videos.
Ted is a good technician with top notch troubleshooting skills. I learned from his videos.
I've used Klein probes. Nice and robust. The ones I've had were previous versions that didn't have the magnet. Now that I've seen this new version I may get one because that was my only gripe.
You can buy really strong magnets on Amazon that come with double sided tape.
I know that this is how it is done all over the United States (you don't have to tell me that) but having ceiling returns and ceiling supplies only works efficiently for "cooling" where you are taking the hottest air in the room back to the air handler to have the heat removed. Having high wall/ceiling returns for heat simply takes out the nice warm air and leaves the cold air in the room. It is a little more complicated than that. For my own personal use I use a high-low wall return set up that is dampered so that it can be changed with the seasons. Makes a world of difference.
I seemed to find The 1” pleated filters always have a restriction,, plus flex duct move a bit less air as metal , so we always ran the next size up on flex , okla.state Lic.# xxxx
I think it's really interesting how it heated from 71 to 80 degrees in 10 minutes with the vents being on the ceiling. Heat usually does better coming from the floor.
Circulation. Its all about the ductwork
I have ran into same problems before. Customer says well we planned on adding on to house but never did at least they were honest. I never go below 3.1- 3.0 high fire. Speaking of high fire you pulled that monometer hose off gas valve I was tensed up untill you put cap back on lol think you did that on purpose. Great video I would add to do quick CFM check on all supply vents before you leave especially since they had manuel dampers. Also while you have that fancy monometer check duct static pressure see if you have any insulation gremlins on your coil. Thanks for videos we appreciate you :)
Knowing that homes are built with inadequate duct systems. Do you do static pressure testing, for situations such as this....
That is a good point. Thanks
@22:52 You have LIDL grocery down there too now.... What do you think of it?
Produce and bakery is mainly what I will go in there for.
You may have to remove the first orifice and cap it and run only 3 tubes instead of 4... And recalibrate to get the proper heat rise temp. Heat rise should be taken at the furnace suppy and return. TSTAT may make temp before High limit at 160 degrees trips.. What you did may work depending on run time...
Downsize oriiface. Or block off burner but looked like you would have to relocate flame sense
Maybe check the static pressure and see just how restricted it is ? Add some duct work and correctly solve the problem ? And why now is it shutting off on high limit ? Unless it’s been doing since installed ? I think more investigation needed to be done !
Hi Ted. Thanks for all you do. Love your work! Learn a lot from you. Just a suggestion, but, my thoughts are to run a total static pressure test when changing fan speed along with gas pressure that you did. Also temp rise...you also confirmed restricted airflow. Curious, did you check filter in the home? I'm pretty sure you did, but just didn't mention it on video. Thanks Ted!
I’ve never seen a regulator needed on internal distribution lines, only at the meter or in certain appliances. Does SC not put regulators on the meter outside the house?
i would just plug the last burner away from the flame sensor,that will decrease the temperature rise and it's safe to do it
To anyone that watches Mr cook videos your watching a true old school pro that cares about his family people I think there people he loves and cares about I know you say what there clients no your wrong he loves what he does gods work going we get to witness when people really care for each other I think it's really not about money it's what God sees in use love you Mr Cook
We just replaced a perfectly good Keeprite , trouble was previous company installed a 100 k 2 stage in a 1500 square foot side split .
They only thing we could do was install the right size 60 k . In Canada we are not allowed to modify furnaces by plugging burners , nor would I.
The only solution Ted is a new 60 2 stage
Lloyd Young Finally someone who knows wtf they are talking about
I’m not sure why it’s called Anti-DIY as he seems to encounter an endless array of hack jobs. There is not much integrity any more. Ted does a great job and always seems to do right by his customers.
How do you like your 2 stage. I had one installed 11 months ago . I would never buy one again. Was sold it mine went out in Feb last year, couldn't get bids, needed heat then. Mine takes about 2 hours to go from 69 to 72 when it is 3e0 out. Sometimes stage 2 comes on sometimes it doesn't, seems like furnace runs 1/3 of the time.
Been watching alot of your videos lately before subscribing and can't believe the number of shoddy installs in your area
Thank for the video. I had my furnace replaced 3 years ago and it was oversized. It countinued to over heat and shut off and turn back on right away. Ive had the technician out 7x now though out the install to try to fix. I was told by a different hvac tech that the has was tuned down to temporarily fix the over heating. Well now its in the negative cold snap here in Chicago and my heat cant keep up with the -10s and 20+degree windshield. Runs all night for few days stright sometimes dosent shut off. We went to bed and it was 74 degrees woke up and it was reading 68 degrees in the home. Had to buy a space heater to make it though last few days. Different techs who came out said the furnace installed was to large for my home. Also the return air duck was to small. They said the downstairs area could use a return because it dosen't have one. My question is, is this issue fixable and is the contract responsible for rectifying this problem with the correct size furnace. I have a warranty company that i use and they now said they aren't going to replace it, even though they admited to the contractor they used said the new units to big. My old furnace never had that problem before. Any recourse you can recommend be greatly appreciated.
Nice video. I would have done exactly what you did but left customer with option of a dump zone or replace furnace. You have to have more airflow for 90 btus. Thanks for sharing
Add 1 8" inch duct anywhere in the house that customer prefers and you'll be set👍
The biggest problem or one of them on this was heat stratification. Return air supply boats on ceilings they're returning her temperature was getting into the mid-80s. Furnace is aren't designed for that warm of a return air temperature. One way around it is to take the supply Grill veins and aim the heat to go down straight down instead of across the ceiling. Return air air temperature is getting too warm
20 seconds in and see it doesn't have enough return !
To my knowledge yellow is a medium low speed where blue is a medium high speed.
Low - red
Medium low - yellow
Medium high - blue
High - black
This is correct. Fan speed was already higher before messing around with it.
Plus he could of just check the wiring diagram... it’s on there
Yellow is medium high
Amprobe will tell you
As another put it. It's all in the engineering. Thought I was watching myself work, only I'm not as good looking as you. What I do is tell the customer he the unit is oversized, and re-engineering the ducts are required. This includes possible return additions, larger ducts, replacement of all stamped registers. In addition to what you did, add drops, and dump into coldest room or unused room if possible. Get the external static down, kill the high fire if possible. It can be done, but I don't re-engineer the units themselves, as far as jets go for legal reasons, only on cars. Others may be more daring then a old timer like me. I have pulled a duct off a plenum to get them by until a reduct could be done. Temp rise was still high after what you did. One old timer to another.
What gets me is that he checked the gas pressure but never checked the static pressure. The supply ducting looks 'ok', but the return duct looks small, what size is it? Also, didn't he notice all the oil leaking from the blower motor for a 2016 model, defiantly says that the static pressure is way high and the motor is overworking trying to move air. May be a oversized furnace, but I suspect the return duct was too small.
Nice observation sir.
Could you not take out one of the burners in the heat exchanger and just run 3 not 4 and take 25% off of the btu? I’m not a hvac guy just a thought.
After all that, my next operation, and I have done this when I had no choice is to block the orifice on the last burner, the one with the flame sensor, disabling it, then moving the sensor over one burner. As long as there isn't a thermal limit in that exchanger tube, it won't hurt a thing. Then adjust gas psi if needed. I have gone as low as 3.2" or as the manufacture suggests.
Of course the best thing to do is install the properly sized equipment.
Did you check the coil, and see if it's dirty.?
I can almost guarantee that coil was not dirty
with icp furnaces previous they had smart valve pilot in middle which seemed much safer to plug one of the outside orfices still static pressure could be high with blower tonnage it was much easier in old days to make something work than now now with everyone knowing more than the one that was called nice presentation
Do a static pressure test to see where you are running also could do a combustion test when adjusting gas valve to make sure that your ppm is not above 100 there are combustionVariables for different types of gas units you can look on Testo or Bacharach website for that information
had the same issue in our home for 12 years. 80,000btu in a roughly 1,200sqt home. For the first few years the company could not figure it out, so they say, they were just trying to brush us aside. What helped which was not ideal, in the winter remove the air filter, open up a second return air and open up another exhaust. This helped but on really cold days it still tripped the high limit and we had no heat until we turned the furnace off and on.
We finally replaced the furnace a few months ago and got a good HVAC company to come in and we currently have a 2 stage 40,000btu & so far for the past 4 months no issues. Makes a big difference when the company knows what the hell they are doing lol
I had 2 companies that wanted to put an 80K BTU furnace in my 1100sq/ft ranch, neither seemed to care about the size of the house and based the sizing off the duct work. 3rd company wanted to know the size of the house and insulation it had, they recommended a 60K BTU. They were also unfortunately the most expensive, their 60K BTU single stage single speed furnace was the same or more than the others wanted for an 80K BTU 2 stage with ECM motor. I ended up going with them anyway and fortunately haven't had any issues.
madmatt2024 cheaper is never better when it comes to your hvac
experience is the best tool,just watching u work tell,s me u got lot,s of it!!!
I’ve seen where technicians have moved the flame sensor over and plugged one of the orfices to bring the output down, I’ve never done it, but I’ve seen it work.
No... just no.
Way too dangerous to do. You don't wanna play with someone's life.
Are you kidding?
Hi there HVAC guy. Good job of one handed repair and diagnostics!
I'm wondering about the moisture/rain/condensation stains on the exhaust flue and below that on the manifold, which also looks to be getting onto the flame sense wire/part. I wonder if it's condensing on real cold nights and wetting the flame sensor/wire causing a lockout :)
Wow, I'm up in MN and I have a 60K BTU output for a 4K+ sq ft house. 98% efficient. Works great because when it is very cold it runs all the time - which is what it is supposed to do. I also have smooth metal ducts which are much larger than this system. Another case of over sizing the system, which seems all too common.
@22:17 😱:
Two sets of solid double yellow lines that are two or more feet apart sometimes appear as a road marking. Such lines stand for a solid wall. Don't drive on or over these road markings. You may not make a left turn or U-turn across it.
You are a professional thank you for your videos
Sensible load means nothing if you cannot move the right amount of air. Little more return and supply would be great. Does anybody ever do combustion analysis anymore? Most important test on a gas furnace. And it can give you signs of overheating problems.
Couple things I have done with this type of problem is 1st I have removed one of the orfice and put in a plug and relocated the flame sensor, 2nd I have removed some of the vents say a 6” and made them 8” to get rid of more air 3rd would be to add more vents to different parts of the house or garage
I'm thinking that eliminating one of those jet burners would be helpful in this situation and capping off the Spud for that unit. But that's an idea to try.
I would likely do a center jet burner if it didn't rely on the wings to ignite the next one, so, your probably going to do the end.
Would also turn the pressure back up to 3.5.
Every time I hear that phone ring I think about $$$$$$. 🤣😂 That's MONEY calling you!!!
Note fan speed on wiring diagram. Check static pressures. Compare to fan chart. Should be easy to find online being a 2016 model. Check temperature rise and gas pressure. Good chance that evaporator coil has gotten more restricted over time and is just now starting to impact the heat exchanger. Check the static pressure differential between the outlet of the furnace and the outlet of the evaporator if you get a “call back”. I agree it is too big but they may not pay you for a new furnace and just live with the problem but they may pay for a coil cleaning and a larger return duct or two. Give them both options. A band aid solution and a few permanent solutions. The customer has to own the decision.
I would have pulled the black "HI" for heat, put the yellow or blue on cooling for a lower fan speed to help with humidity control, was the ac oversized as well?!?
If so humidity control will be an issue with a higher speed, if the fan speed is too high in cooling, it can literally yank the condensation off the coil blowing through the duct, rusting and prematurley making any metal duct rot quick.... Lower fan speed allows coil to get colder, drain out properly while helping humidity also.
if its to big for the house then cap off one jet to make it smaller
I'd only recommend that on odd number burners. 3 or 5. Cap center jet to keep balance heating of plenum.
@@henryjonswift6997 Hell, why not block the flue to slow down the combustion and reduce heat output? (this is sarcasm just to clarify)
@@henryjonswift6997 The plenum wont be imbalanced its mixing just fine. you cant even cap the center off anyway, how will the crossover work>?
it was a nice thought though.
Fixing other peoples oversizing mistakes, I have several times filled the last jet with solder, then moved the flame sensor over 1 burner. Never had an issue and works great.
whats the delta T across the heat exchanger? Is the gas valve a 2 stage valve?
I've often thought about shutting down one burner and dropping back the gas pressure. Not sure if it would work or not but it's a thought.
I capped the last jet moved over the flam flame sensor everything was a okay give that a shot nice video thank you
I thought about capping one of the jets but I wasn't sure about it since I no longer do HVAC. It still seems like kind of a hack to do that though.
had a 100k 80% gas furnace . was way to big. blocked one of the four burner jets and worked much better for 10 years until I put in a 56k 92% rheem in last fall.
It’s all in the duct work
Exactly! I would have liked to see a static pressure reading on the return side (as well as a total static pressure).
Yes sir!
Why no Manual J load calc to get the correct sizing?
Isn't the required airlfow for the 90k furnace 1200 cfm. Are the runs long and just to cocked up. Or does round flex have a different flow rate than round metal. Don't really work with flex much. Because on 2 10's and 1 12 metal duct you should be able to flow right around 1400 cfm depending on static pressure. Cause I've run into oversized units and I mean they are typically obvious as In The supply and return ducts are just way to small. I mean like ducts sized for 2 ton ac with 100k furnace
I'd put a temperature controller like a Ranco sensing the discharge air temperature on one of the main branches set to cycle in series the white thermostat wire from the thermostat to the circuit board of the furnace to shut off the burners when the discharge air get too hot and under the high limit temperature limit. The the burners will short cycle on long runs but the furnace would operate as close to normal as possible and the home owners most likely would never know the difference.
I'm not big heat specialist so your videos are very educating for me. Thank you. I'm little bit crazy about duckt sizing. My solution here will be add extra return and extra supply register. At least 350 CFM . Will it help?
Check the CFM chart for Med High and see if that will work for 3.5 ton. If it does, put the heat in High set cooling to med high.
John Ashworth or use a jumper and run both on high
Another great video! I also have an oversized furnace & inadequate ducting, but the tech actually set the fan to spin at the same speed throughout the cycle. It no longer hits that second stage where it spins faster. Is he wrong?
Do you ever get your instruments calibrated? (gauges, manometer, IR thermometers, etc)
ever since intercity was bought out by icp It basically looks just like a carrier inside even a similar inducer
I'm a plumbing contractor, not HVAC, but I feel like I do a pretty good job researching how to do things before I dive into unfamiliar waters. About 22 years ago when I put our furnace in, I was told I could put in a bigger furnace than our house needed (we were considering adding on) and just derate it by pulling out one of the four orifices and plugging it off. It sounded like a good idea at the time and it was easy enough to do. With 4 orifices it would have been 100K, so pulling one out I suppose put it at around 75K. I've got a few more years experience behind me now and I'm curious if experienced HVAC pro's would think that doing that would possibly increase the risk of un-even heating and possibly cracking the heat exchanger. When watching your video I was saying to myself "just pull one of the orifices out, that'll knock the temp down a bit w/o lowering pressure too far" but now when I consider the possible risk of damaging the heat exchanger, I realize that maybe I should have checked a few more sources to see if pulling and plugging an orifice maybe wasn't that great of an idea after all.
Voids any remaining warranty. If there ever was a fire in the attic, you would wear all the blame
How did the customer react? Are they considering replacement?
Thx. Something to watch instead of tv. I suppose raising fan speed will shorten the run cycle unfortunately.
90K BTU, 17" Wide, 1400 CFM. Furnace being fed from the side with that small pipe (likely a pleated filter too). Yes the furnace is suffocating and the limit is tripping. Have seen it with other ICP brands as well. Likely a 70,000 would have been more appropriate. The 90s can be finicky with overheating.
A 12” return isn’t enough. Static pressure across the unit would have removed the guess work. Adding a 12” return and an 8” supply spill duct/register in a hallway would help immensely. Kicking up the blower speed could be objectionable noise and drafty
Ted, could you have sealed one of the burners closed and only lit 3 instead of 4? I realize you don't want to rig it, but was wondering if that would effectively make it a 3 ton. Not a HVAC guy but am learning
Pretty sure if I seen that right the black fan speed wire should have been on the heat tap , where I work we never chang the heat tap , just change for the a/c size
I like that case for your manometer has everything in it nice
Wire diagram is right on blower access panel or main panel. Carrier , bryant, payne all have wire schematics to motor wire tap. If you have an ANDROID phone there is a great app for almost ALL makes and models with all install manuals available called FURNACE CODES AND DIAGNOSTICS by Fire-n-ice on google play store. excellent tool to have as well as the carrier service tech app for all replacement components
You recommended 60,000 btu on a 1800 sq foot house with 20 degrees for a low that night. Looking at the variables. It would have to be zone 1 (the south) A 60,000 btu with 80% efficiency is 48,000btu output. An 1800 sq foot house would require 54,000. I know there can be a lot of variables. Can you shed some light on this? Please
Great video, thanks for all the detailed explanation too.
50F temp rise sounds pretty decent unless it has a low range like 25 to 50 vs the normal 40 to 60 - or it would be if the return wasn't pulling in such warm air due to location.
Why not put both heating and cooling on high? Just need a jumper wire and Y connection/splitter. No pro, but i've observed going up only one speed doesn't drop the rise very much on undersized ducts.
After watching this again, would it be possible to plug one of the burners, so only three are going?
Does installing a 2-stage furnace pretty much make the problem go away, other than having over payed for a too big furnace and not making use of the high-stage?
Well you can always under fire it like you said. Never over fire. Is there no filter on the return?! Maybe the Acoil is filthy?
Plus put a relay in there that makes the fan run on high in both heating and cooling
Love the channel, as a mechanic I hate seeing "Change oil" Tire monitor system lights on! Look after the Van please.
On a Standard Stactic Pressure at 3.5 they have 1400 in Duct which is what a 3.5 calls for js
WOW great video, had the same problem and my guy did just that , lower gas pressure and fan speed medium high and problem were fixed, and yes my furnace was to big for the house
Setting the manifold gas pressure low has other sets of problems. You should stick to the manufacturer recommendations.
Curious if you use a flat rate system and if so which system?
Thanks
Nice clean and logical approach and comments!
Return air on the ceiling for heat .....yuk, needs the floor, should have duel more supply runs and return would help. Short fix Ceiling fan's a must to move the hot air off the ceiling