Electric Heat Troubleshooting, Service, and Math Class
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- Опубліковано 27 лип 2024
- In this class Bryan teaches the Kalos technicians Electric Heat Troubleshooting, Service, and Math. This includes electric heat, often used supplementary in heat pumps and furnaces. He also shares stories from the field.
Heat strips are one form of electric heat. It would stand to reason that taking a bit of heat strip off wouldn't hurt anything, but the electric heat would be less effective. However, when you factor Ohm's law into the equation, you'd be taking off part of the heat strip and reducing the resistance, meaning that the amps will increase. Heat strips also burn out when they touch another piece of metal, like the casing around it, as the amp draw becomes much higher.
Electric heat has some benefits, including its consistent BTU output (3.41 BTUs per watt); regardless of the outdoor temperature, you can expect the same BTU output all the time. It is also reliable and usually easy to work on. However, it is inefficient. Electric heat is the baseline of COP (coefficient of performance), and a pool heat pump that has a COP of 3 is three times more efficient than just the electric heat.
Electric heat has other issues, including odors or smoke when it first starts after a long time of inactivity. (It's easy to burn off the heat strips on a PM, especially if you jumper W to R or use the thermostat to burn off the heat strips.) Electric heat also causes high bills when it runs too much and causes stress on the electrical service. Electric heat elements also draw very high current, so you have to manage your wire sizing and electrical connections. You can also encounter mistakes with blower interlock; you don't want to run the heat strips without the blower running.
In a 4.6-kilowatt (5kW) heater, you would divide 4,600 by the unit's rated voltage to get the amps of electric heat. The wattage decreases when the voltage decreases because of Watt's law. When you put more voltage (electrical pressure) on the circuit, you get more current. So, the total watts would decrease if volts or amps were to decrease. If you divide the watts by voltage, you can find out your amps. To find the BTU output, take the watts (volts x amps) and multiply them by 3.41. You can also use Ohm's law to find the resistance. Take the voltage and divide it by the amps to get the resistance (ohms). The voltage is a moving target, but resistance stays constant for the most part.
The data tag should tell you the proper wire size to feed the air handler; look for the MCA (minimum circuit ampacity) to help you make your decision. Keep in mind that 5-kW heaters are not necessarily 5 kilowatts.
When it comes to terminals, you have W, W1, W2, W3, and E. W is just heat; it is usually just for a single stage of heat. W1 means first-stage heat; it indicates the compressor with the reversing valve de-energized. W2 means second-stage heat and can refer to electric heat. W3 is the next stage of heat, and E is just for emergency heat. We used to have to jumper Y1 and W1 and a few other terminals together on older thermostats; they perform similar functions, but the reversing valve would distinguish heating from cooling.
When testing heat strips, you can usually (but not always) expect 5kW heaters to draw 20 amps and 10kW to draw 40 amps but still 20 amps per strip. However, the way you read the amps can change based on the voltage (230v vs. 208v). Commercial buildings often have 208 volts supplied to them because they are hooked up to two of three power legs.
Heat strips also have thermal limits; therm-o-discs can be found on the high and low sides for extra protection. These discs also have temperature ratings on them. You can tell if the thermal limits are open by ohming them. If they are open, you'll measure OL or infinite ohms. If they are closed, the ohms will be low.
To control the electric heat, a unit will have either a contactor or a sequencing relay. Sequencers have contacts that close at different times. You don't want to use a 90-340 relay, but we sometimes use those for a fan interlock.
When using a 90-340 for the fan interlock, you must set it up correctly as not to melt the relay; the current from the heat strips should not go through the relay at all. To avoid confusion as much as possible, follow the wiring diagram and think of the relay as upside down.
We can also stage heat strips if we have more than one. Staging makes the unit draw lower inrush current and use less electric heat (the less you use, the better).
When testing heat strips, you can use three methods: measure the heat strip amps, test on and test off, and force the system into defrost to test the heat strip amps.
Heat pumps with supplementary heat may have special code considerations when wiring to the outdoor thermostat, which you must keep in mind.
Read all the tech tips, take the quizzes, and find our handy calculators at www.hvacrschool.com/.
Learn more about the 2022 HVACR Training Symposium at hvacrschool.com/symposium/.
Aonther reason I love hvac school your stories add some dad jokes next time lol
I regret not going to a trade school. I used my GI bill to go to college and get a useless degree that put me in a cubicle for the past 10 years, and here I am at 35 watching youtube videos and hunting for an apprenticeship to replace the trade school I should have gone to in the first place. These videos are a HUGE help to get me ready though, and there are things about this style of learning that are not all that bad. I can pause this lecture several times to take sidebar research and clarify things he brings up that may be a term I don't know or concept I am not familiar with yet, whereas in the classroom I just have to make a not to look something up later.
Thank you for your service
Don't beat yourself up, for one, least you had a G.I. bill and used it, also you had the guts to stand up for all our freedom so your a hero(never forget that). Then with your training on top your degree your discipline and work ethic rank you supreme so whatever it is you do in that cubicle your most likely a quantum leap ahead everyone else at that company well on your way over the top because you are a winner. Besides it's never too late to do whatever you want. Good luck and God bless you and. Thanks for your service. Keep your head up.
I respect the fact that you admit to your past mistakes. Lot's of seasoned techs pretend they have never made a mistake to the newer techs.. Good deal!!!!
Good point
YES, It's a shame when a new tech let's the smoke outta a compressor. It's critically charged smoke after-all. :-D
Man this brought back some many cool memories… Having a laid back / chill teacher is what makes this trade the best. Learning and having a laugh here and there is what I looked forward in class in my days of learning. I notice early there was never a dumb question because it always had an answer lol.
I'm not an HVAC tech, i just like to watch random classes on Wednesday nights. Great show!
Thank you so much for sharing these and willing to be vulnerable. You guys are a blessing to techs that are seeking to better themselves.
This guy is good and he's such a great teacher I've been doing HVAC for 20 years and this guy still always teaches me something
Im completing electrical engineering programs in school right now and these lessons are way better to learn and understand what's actually going on. Great lessons keep up the great work!
Its good to look at what field techs see. We often hate engineers, because you guys often put things in awkward places. 👍
WOW! Your video is the first time in 50 years I have seen ohm's and watt's law displayed in the circle format in the way I learned way back in the late 1960's. You're even using the letters I learned. I've always had difficulty in remembering the formulas as written. The circle form I can see in my head. Good job. I think that is the easiest way to remember them.
Your slide about W, W1, W2, W3, E is the best explanation I’ve seen. I live in Houston and even thought it’s prime climate for heat pumps they are extremely rare. With all this electrification shit coming out we’re trying to start pushing them to be ahead of the curve. Well, my first install with a Honeywell T6 thermostat kicked my ass trying to figure out what terminals to use. This would have saved me a lot of frustration! Thanks!
I happened on to this class. Before retirement, I was an automotive electrician with auto/truck HVAC experience. This class is great for commercial HVAC, and some of it makes sense to me. I would need to obviously go through the beginning or entry level training to understand the whole picture.
I love the honesty, we've all been there, made mistakes, learning process.
Love your lessons, Bryan. Would be great to see ways to test voltage in the ciruit. What you read on each side/across relays when they break one or both legs of power, etc.
I think the math used to figure out factory specifics for resistance is vital.
I am working on an old univent and will be using some info from here.
Alway great content!
Great class Bryan. Thanks for your time.
You also need to add the amperage of the blower motor to the supply of your heat strips since it will be powering both of them. It will also be an inductive load unlike the heat strips so it will draw more amperage than usual when first turned on.
Amazing how smart you are and keep it up for newbies.
Great man Love your training method !!!! going to take some classes and i watch your videos for i go take school. So that I'm not completely lost.... awesome keep up the good work.
I enjoy watching your videos. Very helpful
Really enjoyed this video, please keep providing more
Bryan: another good, informative video!
It's good to know the ohms of what you are working on since you can't always jump red to white...the reason is in some old buildings they have used whatever color wire they had on hand to wire a thermostat and you have to know the ohms of what you are working on and then ohm out the circuit to the common wire until you find the right circuit. It is not a perfect world like in a classroom when you get out in public! They jump stuff and then you have go in and try to figure what they did so you can get to the root cause to begin with.
Very informational, learned a lot about heat strip safety operation.
Good class Bryan. Gonna have to re-use for my group.
As a courtesy thermostat heating adjustment at a sister building, who’s heating elements were packed with dirt, I emptied out a four story office building when energizing the heater contactor.
I wanna work at Kalos an have these classes. Awesome video
Amazing content!
Great class
Great lesson. Got a question on those same heaters in the box there's the small sticker u showed in the video and then there's 2 big stickers with the different model of AH on the big stickers it will be 208/240 volts and the MOCP is different compare to the smaller sticker that rating is at 208/230 volts so my question is should we used the MOCP from the big sticker? as its 208/240 since when we measure voltage its usually a little over 240v.
It is not surprising this pops up as unemployed hvac tech I watch lots of hvac videos but I remember sun trust bank
Interesting class 👍
Great videos 👌
I only use 10 ga THHN wire, quality 10 ga terminals and a ratcheting crimper. Most of those electrical compartments do not have enough air movement to keep wires and terminals cool. No more overheating issues near the terminals.
MTW or bust lol!
@@jonnymac31 I use TGGT at the elements and MTW on the controls
We use to have installers leave the instruction manuels inside the heat strip section of Air Handlers. First time the heat strips came on, instant fire, smoke and plastic melting.
I heard from an installer that dropped a piece of tape,(1402) and the unit it started to smoke. he quickly shut off the unit and removed it.
Great channel
Great we need this
You can measure Voltage across those switches with power on. If you see “0” you’ll know it’s good. Be careful not to short out and burn up your test leads. 🤚
True but for the younger guys I would recommend turning power off because most packages are very small and tight
I like to install electrical tape so only 1/8" of tip is exposed. Had a coworker arc over 24 volt control circuit to 480 volt. Blew up a board.
Infinity does certainly have a ambient temperature sensor on the condenser
Thanks for school though. I needed a refresher
I don’t work on a lot of heat pumps I saw a unit today that had a B terminal and an O terminal, my guess would be that one is to energize cooling, the other to energize heat pump mode? Someone let me know? He wanted to install a smart Honeywell thermostat and that stat only had a O/B terminal on it, is there anyway to wire this stat??
On a 208Y/120 volt system (the wimpy Wye system) your heat strips will only put out 75% of their rated BTU output. So if you wanted the same output of a 5KW heat at 208 volts, you would have to install the next higher level of heat strip, which would be a 7.5KW heat strip. That would be at 240 volts. That would be 5.6KW at 208 volts.
Is it best to have the blower on low speed or medium speed for electric heat? Would that depend on the size of the heat kit?
I don't have any specific numbers on cfm and how much air you need to be moving based on size of electric heater but in personal experience working on mostly 15 and 20kw electric furnaces I would say medium at the least or high. You need to move a lot of air over electric heat to avoid problems and it all needs to be tied together with properly sized ductwork. I have seen many 20kw systems with wire removed from one element turning it to a 15kw system just because the ductwork was not big enough to move enough air over the elements without cycling limits.
You need 80 CFM per 1 KW
What is the power per kw down in Florida where in Winnipeg Canada and I use only a 15kw furnace set to 5kw for an 800 sq shop. And its really not that bad. O and it'd minus 36 Celsius here.
I had a call for a Trane air handler recently. Fan wouldn’t shut off. Turned out the 90-340 relay was stuck closed under load, but would open when the circuit breaker was turned off then on again. Any idea why? This one still puzzles me. I verified 0 volts to the coil, but it was still closed.
31:20 was that a mis-speak? 20 amps #20?
Hey just wondering if I can be there for your class? I'm old and just love your class. I'm in Milwaukee Wisconsin so let me know?
🔰🇺🇸 You’ll probably get a direct answer if you comment to them with the
@HVAC School
Do you have a video on troubleshooting strips?
This might not be the best place to ask this question but here goes anyway. I'm an automotive mechanic and I've noticed that the heater works pretty well the way it's designed in every car manufacturer. I'm in the south. My question is would using your water heater with a circulation pump not be more efficient than electric strip or heat pump? I just assume there is people here watching this that would know the answer to this question.
Pass it around dude. I need to see it .
In the old days if you jumped r to w you could burn up the heater anticipatory
May I make one suggestion: 1 Watt=3.41 BTU/H or 1 Watt x 1hour=3.41 BTU.
is this a separate school or is this just for the HVAC company Kalos? Either way its cool what youre doing.
I think it's boogie, woogie, woogie... Not woogie³ lol All bs aside tho, thanks for the info and advice in all your videos. Very helpful.
Scott (adult student/technician in training)
Re. your first chart: Another benefit of electric heat is the fact that it's efficiency is 100 % from the standpoint of energy conversion from electric to thermal energy. (You can probably win a few "Bar Bets" on this one)
Up here in Canada that point is sometimes hard to explain. Natural gas is more cost effective in most provinces but electric heat is more efficient. This leads to confusion over energy rebates. People will remove their old electric hot water tanks and install natural gas tanks and expect refunds for effeciency. Unfortunately for them the gas is more cost effective but less energy efficient. Good point to understand
@@adamradley4407 Absolutely correct Sir. The confusion arises from the fact that cost effectiveness is not equivalent to thermodynamic efficiency. The issue with which you in Canada are dealing is quite similar to that for most of us in northern New Hampshire. I can remember 25 or 30 years ago, following my retirement from Lockheed, explaining points like this to some of our community college students.
You should have measured the ohms on the piece of strip you cut off and then added a resistor to make up for it. lol...so easy!
I’m watching and I think “Hey, I bank with with suntrust” then a few seconds later “Hey I live in Clermont” small world
Thanks again for the videos!
🥃🥃🍺🍺🍺🍿🎯
Stay safe.
Retired (werk'n)keyboard super tech. Wear your safety glasses!
Perfect
They call the fire dept and say they smell smoke sometime!
Y is going to be first stage of heat in a heat pump W1 would be second stage
Very good video...
Hybrid heat is actually called Dual Fuel ... This is important cause you CAN NOT use a heat pump compatible thermostat.. It must have a Dual Fuel compatible thermostat to run a dual fuel system which utilizes a outdoor temperature sensor for you switch over ( balance point).....
Any hp stat I’ve used asks what kinda fuel you’re using
@@drodriguez394 usually the stat says dual fuel compatible... can't use heat pump only Stat. It will run heat pump with the furnace at same time and cause HP to trip on high pressure...
@@pineychristian we can also install a snap switch in the supply plenum that opens when temperature goes above say 115 F, that will open the “Y” circuit going to heat pump. Lots of ways to accomplish the same end result. Then you could use a standard hp thermostat.
@@USA-GreedyMenOfNoIntegrity absolutely that's old way of doing it. Duel fuel tstat have been out now for a while so just easier to buy one.
@@pineychristian dude the Bosch system we've been using is cold climate rated. Variable speed compressor. It can stage the elements 5kw at a time until we are -5f outside and then the heatpump will turn off and we rely on emergency heat strip. Only done on homes with PV systems.
So the heatpump at 10f drops from say 50k btu to 20k btu, and along that curve to its shutoff point, the electric heat is supplementary.
The coil is before the heat strip in a conventional AHU and electric setup
So my relay is bad bc my fan won’t come on but my heat strips come on
Your water heater and dryer both pull over 20A at 240V.
Both have resistive heat
Water heater is 4500w dryer is 5400w both are element @240v
If you do work , you're going to make mistakes ,if you sit on the desk you just going to get the mistakes the service person did you will never get feed back for the good service .
If resistance doesn't change you don't need to calculate it. The new value for watts is (240/230) * (old power value).
Wrong. It's 240 (squared)/230(squared) * old power value.. You do need to recalculate to make sure you include the new amperage reflected in the new voltage.
Best intro ever 🤣
Heat strips are no bueno amigo makes bills 💵 too high great video hefe
Electric stoves, and spas draw 50 amps on 220.
Both are worth it lol
You'd be hard pressed to actually draw 50A from a range. The burners and oven element click on and off to maintain the temp set, so they rarely crank 100% all at the same time. It was common to put 40A breakers on range circuits in the past even though modern ones state they need 50A, and I've never seen those trip.
@@bnasty267 the point was made that there are other appliances in a house that draw 50.
most ppl who vape got to learn ohms law and how to figure all that even more so if u make your own coils
The 208Y/120 volt system otherwise known as the wimpy Wye system. Give me a 240 delta high leg system anytime.
Thank you
For sharing.
Interesting
Bruh, the jokes are gold (😶or am i getting old...)
I don’t like using the word “inefficient” for electric heat. It’s actually 100% efficient, buts not very cost effective because the “fuel” (electricity) is more expensive than gas. Buildings downtown actually qualify for being “green” if they have electric heat because of its efficiency rating. This can be confusing as your heat pump can produce more btus than running electricity through heater but they use the same “fuel”. As a tech who does not work on a lot of air heat pumps, I wonder at what point, if there is one, in which elec heaters vs gas vs heat pump is more effective at BTU output. So I wish there was a more clear way of explaining this. It’s more about cost effectiveness. A class on this topic would be cool. This was a great class though.
As a home owner with a hydro heat pump in basement here in michigan I wish someone could tell me how to shut off my elec heat or aux I mostly heat with my wood fireplace. I'm sure it can be done because i read it somewhere just can't remember where.
@@Gods-Elect it’s not on a breaker?
@@murkyturkey5238 I don't think so.
@@murkyturkey5238 To my understanding the elec heat kick in when it thinks the heat pump can't keep up or do the job. I also think the reason some on here will not offer info is because i'm just a home owner.
On average heat pumps pull up even with electric heaters at about 5 degrees Fahrenheit. That is, though the heat pump is still transferring heat it's running very hard to do so and drawing the same electricity that an electric heater would to produce the same heat ( BTUs). This is why in colder climates a secondary heating source is necessary, unfortunately many people are unaware of this and are shocked when their electric bill skyrockets in the winter.
Great
😁 thank you
Show a video on fan poeer box
I learnt ohms law and power and current amps voltage all that when I started vaping and now I see so many things that apply to that same hms law. theory
You still have an issue with the defrost thermostat as wired.
If you do not run a wire to the air handler, how does "E" work on its own?
Maybe in FL is is not an issue, but in the northern climates and the customer has a heat pump issue, how would the "E" be energized?
We have that code for any energy rebate from the power company. If they come out to check on their random inspection, it will not pass and the owner won't get the rebate until it is fixed.
As a home owner with a hydro heat pump in basement here in michigan I wish someone could tell me how to shut off my elec heat or aux I mostly heat with my wood fireplace. I'm sure it can be done because i read it somewhere just can't remember where.
@@Gods-Elect I'm no expert but I would think you could just disconnect the wires that power the heat strip. Then when the heat strip is invoked, power will not be supplied bc the connection is broken. No power consumed and no heat produced.
If there is a manual that tells you a prescribed way to do this, it should be easy to find.
@@realSamAndrew Thanks I'll have to check that out good point you have there. I'll let you know what happens
@@Gods-Elect that's a deal! I would like to know. Please be safe and be sure to disable the house power and double check it's off before you touch anything. Some of these videos even show the pros forgetting sometimes. Don't be that guy!
Where are you located?
1 common reason commercial buildings use 3 phase is 3 phase has better characteristics for electric motors which are more common in commercial applications
🫵👍
One watt does NOT equal 3.41 BTU.
It equals 3.41 BTU/hr!
One watt-hour = 3.41 BTU.
I mean, nothing wrong with size 12 wire. But why even bother. Just grab some 10. It's like the most common wire, 30 amps, no biggie. Just in case too, I mean sometimes a heat strip may pull just over 20 amps. Find some melty wires in an electric heat area, grab the good stuff. And that reminds me....I need to pick up some NoAlOx for those unfortunate people that still have aluminum wire set ups.
And there is a huge push to bring in copper clad back into residential...we have forgotten about mobile home fires?? Afci won't let that happen? I'll watch from my phone, yee who forgets history... should be a hell of a show.
Boogie-woogie-woogie lmao
Hello sir, do you have any videos on air curtains?
3 phase heat strips are a way different animal. I cant wrap my mind around how their wired.
It can be little confusing.
Just worked on one the other day, my boss came by and showed me how they work and how to check them
Just think of the elements being wired with 3 separate 208 volt supplies.....each element is being independently energized by a single phase voltage of 208 volts. AB, BC, CA
Time delay usually takes 5 minutes..
I think it normally has a 90 to 120 seconds delay before blowing motor starts
Great instructor! HVAC school is full of last chance delinquents. Just wonder how that set-up would allow the emergency heat to work in the event the condenser unit failed to run. Isn't the call from the stat the same for emergency heat as the heat pump with strips, minus the Y(and O if say a Ruud/Rheem)? Meaning it's just a W2 call with G, and that circuit has now been interrupted by the high ambient lock out.
Remember folks this is not plumbing one mistake with electrical system you could be dead or not knowing what your doing you could burn your home down or someone else’s
Never liked electric heating since I wired in a baseboard 240 volt heater and room filled with smoke. That was back in 1970.It was just burning off oil left from manufacturing. Its convient if you only have say a small room or addition added on. Would love it when old apartment houses with no insulation had me install electric heaters in each unit. Told owners that renters would be paying an arm and a leg but they did not care because they were saving money by not running a large boiler. Had one guy in the top floor always kept windows open a little to get fresh air. After he got his first electric bill he taped windows installed plastic film and still had high electric bill. Won a couple of free lunches about the wattage of any heater of you valve the voltage say run a 240 volt baseboard heater in 120 volts. But output is reduced by 75% not 50% what some fellow dumb sparkies insisted
I don't the smart guy from class, OMG
You didn’t once mention air outlet temperature which customers complain it’s blowing cold air (it isn’t) with heat pumps not shutting off till 5 degrees so staging a heat strip to temper duct outlet temperatures is critical.
Why aren’t any of these electric heat videos talking about the main reason they are used in heat pump markets. It’s the most often time they are used also. Defrost. You the reason for the white wire on the condenser. Keeps you from getting calls saying my heat pump is blowing cold air.
No, you did not know ohms law. You memorized the formula.
Why don't hvac just run a click plc and program all these steps the trouble shooting becomes so easy
I know relays have been the normal forever it just seems so much easier I know the mill industry is way way better with the advancement of plc and drives
Because they are smarter than that, they want to challange unlike other fields.
Not sure how that makes them smarter. I mean everybody doing electrical work should know how to work with relays yes but plc just makes life allot easier and can do way more
@@josephjorgensen3282 Plc, simplify and take away most of the challange that is involved in old-fashion wiring.
In school to be a electrician we learned relay logic but now that I work in the field computers have taken almost 90 precent of the trade and it just looks like it would simplifie allot of there work
how you got your hair back?????????
God bless america bald eagle
The "not my yob" line was kinda low key racist lol
I like to watch his videos, so I can find the errors.
Houses have 208 too. Please consider replacing this instructor. He’s a clown 🤡!
Another instructor teaching Ohm's law in the wrong manner