I've seen a lot of discussion on whether a positive pressure evaporator (like one on top of an upflow furnace) needs a trap or not. While it doesn't cause the drain issue like a negative pressure, it does eliminate air leakage. Please share your opinion on this. I am a HS HVAC teacher and I'd love to know your thoughts.
No matter how many times this is explained verbally, the phenomenon of negative pressure is not usually well understood to most until they see it in real time. This is a terrific demonstration!
@@thejohnbeck lol first its funny seeing such a recent comment to an older video, right in line to what I was thinking as well. But I found the answer. When the system is running and sealed, and the fan in the system is moving air, it is on the input side (in this setup). Meaning its a vacuum, or under negative pressure. The drain is like a straw, so while the fan is on, the drain is sucking in air. (I wrongly assumed in the video that "system running" was focusing more on the temperature of the evap coil since he focused on it). When the fan stops, there's no sucking, and the pressure inside that area and outside are equal so the water is free to move via gravity. The trap on the drain needs to be filled with water or it doesn't work, because the weight of the water is more heavy than the sucking vacuum of the blower motor in that small area, so air cannot come up inside, so the water can move under gravitational forces, without being pulled back into the pan. Real world example. You get a fresh frosty milkshake from wendy's and go to suck on the straw. It's too thick but you kinda try again, but as you give up, the negative pressure in the straw makes your spit backwash into the straw.
My Carrier Infinity runs all day long here in FL and your video carefully explains why my pan holds water and I get the “stinky sock” smell. Thank you for the video.
When we moved into our new house in North Florida about 8-years ago, we soon started to have filter failures from moisture. This was happening every 1-2 months, and at times the failed/wet filter media would get blown up into the underside of the coils. It was quite maddening. After considerable research, I found a similar video and installed the clear trap you've shown in your video. After that, no more issues. I'm a bit confused why something so critical can be missed by the Building Inspector, and the private Home Inspector that I contracted to check the house out before we purchased it. You've done the best job explaining why the trap is needed, that I've ever seen. Great work!
Ha ha ha. Inspectors. That's a good one. They nitpick little things that don't mean a bit of difference, but anything important they forgot to mention in inspector school. Here's 10 pages of bullcrap that needs to be fixed. Give me my check.
Keep in mind this is for an air handler and not a coil on top of a furnace. The coil on top of the furnace has positive pressure so you dont need a trap.
The Delta p is small, very little air escapes. You can test this just by running the fan or furnace and very little air comes out of the drain hole, even less if you have a drain hose on it.
I am HVAC contractor with ~10 years of experience. I think that this video is the best explanation why do you install that p-trap on the condensate line so far. :) Thank you!
During home inspections I would talk about the vacuum effect when there is no trap. If the unit is in the garage or close to where there might b some chemicals, fumes can be sucked up into the air flow going to the home and if that happens because there is no trap at the condensate line no one will know where the Oder is coming from. So the trap here is rather important!
Good video. And this ONLY applies when the blower motor is on the supply side of the evaporator causing a negative pressure which sucks air into the condensate pan from the drain. When the blower motor is on the return side of the evap coil, you will have a positive pressure pushing air out of the drain hole and you won't need a p-trap for this
Great demonstration. But this only happens with the coil before the blower. When the coil is after the blower air comes out of the drain pipe and you need a trap to stop the air from escaping. I learned a lot from your channel thanks for the tips!
Again, well done! Getting this point across to installers that are trying to “just get the job done “is critical. No excuses for not having a trap installed.
Never realized while the air flowing through the evap is on its way to the cold outlets, it will pull air back through the drain tubing---perfectly logical. The back pull would be untreated air as well. We had our system changed in 2015 and they installed a trap. I thought it was silly. Now I know!!! Thanks for making the video.
Great visual for evaporators on the negative pressure side of the blower. You should explain that not all are on the negative side. An explanation of where to put the vent would also be helpful. In my neck of the woods most residential evaps are on the positive side of the blower.
My exact thought. The plus side of adding a trap on a push coil is you don’t lose some of the efficiency of air being leaked out of the drain, but it’s not critical to have one as it is on a pull coil.
Brilliant. I noticed last year when I happenned to look inside my furnace that the condensor pan was completely full and not draining. I could tell there was negative pressure so I openenned the filter area and sure enough it drained immediately. The system was installed by the previous homeonwer so I have no idea of the experience of the originall installer but they clearly didn’t understand this issue. Great explanation and video.
I just had my unit serviced. Guy at ACE told me I needed a trap (retired HVAC) guy who serviced unit did not install one. I have an identically appearing unit as the one pictured. Anyways guy called days later and now he said he “forgot to install” and is coming back to place one. Just trying to understand the process and this video was awesome! Thanks
@@acservicetechchannel could you tell me why water in the drain tray or pan starts flowing out when the pvc pipe system with water filled trap is attached?
Thank you very much for clueing me in. That solved the problem of condensate build up in the bottom of my A/C unit. I cut a hole in the piping for easy trap cleaning; I did not realize it receives an internal negative air pressure. I thought it only trapped debris. HAGO; Thanks again!
Thank you !!!! I felt dumb when I first saw a video of someone really cocky because he did understand it. I wasnt dumber i just had to take the time to educate myself. I hope when I go to school my teachers are as good as you.
Thanks so much Luis and make sure to check out the video I just published on does a minisplit need a condensate trap. I get into more detail there, thanks!
I've serviced a package unit witch had a zone board installed (left) inside the blower cabint wich burned out twice .I was ther on the second call, Noticed it was a little damp and the zone board had moister on it, and that they had short 4" pvc pipe off the drain pan. I added a p-trap, installed new zone board called back a month later to make sure clients system was working. Problem solved . Many techs even some hvac business iv talked to think these ptraps are unnecessary but I beg to differ .NICE DEMO CRAIG!
Thank you for posting. My apartment AC unit was leajing water all over the drip pan,and the EZ trap was bone dry. After watching your video, I opened the trap and filled the curve with water - hopefully this fixes the issue.
Unions in condensate lines aren’t necessary,a simple tee with a cap or a modern float switch has what you need to disassemble without any problems to clean………or best thing I’ve found after over 20years of doing it is a simple shop vac,connect it outside and it will suck all the bs out and then put the cleaning tabs in the evaporator coil pan and your g2g……..or your nitrogen tank with a simple Freon line hose will blow everything out from the inside out.
Wow! This is what is wrong with my AC! The person who installed my AC kept saying he had no idea what was wrong with my system and HE INSTALLED it. Thanks! Hopefully my hubby can fix it.
Literally could not understand why my furnace was filling up with water until I watched this video. Thank you so much you saved me an expensive service call.
That trap is not always necessary and the reason is that here in Florida, and other areas, houses are built on slabs. The condensate pipe runs down into/below the slab, then runs back up above ground level, usually about 6 to 8 inches high, where the water exits. This causes the "below ground" level of the pipe to fill with water, in effect automatically creating a very long "p-trap".
AC Contractor here in Florida lack great amount of critical knowledge The same way they do not use Nitrogen when soldering cooper lines and not even sanding cooper lines-You always need a condensate P trap -It is in the HVAC exam
@@user-hu4hx6bm6m Yes, but where is it located? The point was if it exits ground level, a p-trap at the air handler/furnace is where you'll see it. If it goes underground and returns to ground level, it's there, but you won't see it as it's formed under the slab, contains several inches of condensate, and prevents airflow from exiting the air handler.
I love those clear EZ trap! Don't like the shallow trap, they dry up in winter, first summer cooling = leak! In that case I make a deep one that can never dry out. Btw In case of positive pressure unit, no trap is required
@@abnergarcia6252 He means that if the blower pushes the air through the coil and not pulls..Blower is beneath the coil. in the video the blower is above the coil.
eddman32 thank you! So in the video the unit is a “negative” pressure unit? Anytime the blower “pulls” from the coil is a negative unit? Very interesting. After this video I found another video on “Expert Express Plumbing Heating....” where he shows the effect of high static in a zone system. And it was a horizontal left unit, but the water was being pushed out of the secondary drain plug.
Abner Garcia. The vast majority of units the blower "sucks" the air across the coil. In the minority are units that are either "ambient" pressure; or blower is upstream so that the air is "blown" ie positive pressure
Some Carrier AC’s have a built in trap in the Drain Pan, so you need to look and/or check the units literature. It you can’t see directly thru the opening to the drain pan, or from inside the drain pan to the pipe. Then check the literature.
Mine drips the entire time its on...doesn't speed up when the blower shuts down...My tech added a "chimney" to the "T" that exits the side of the A coil drip pan.. It sucks air over the draining water...
While that is a true point, however, a trap still serves a purpose in a positively pressurized cabinet (or unit), as it prevents the conditioned air from escaping. In terms of wasteful energy, can be compared to why they seal all the seams in the ducting.
Best ever demonstration! I don't think mine is linked into a trap but it I think the broken humidifier and furnace are linked into the line too. Furnace is under ac unit and has some sort of black box cleanout
Now I know why there’s a P-trap before the condensate pump. Thank you. It didn’t make any sense why a trap was necessary when no sewer gases would get through the condensate pump.
Have you ever seen a blocked drain line affect a TXV Craig? I was on a call once where the evap coil kept frosting over until the abnormally long, mostly flat, drain line was blown clear. The very moment the drain cleared the frosting stopped.
Frosting would only occur if the sat temp of the vapor line was below 32 degrees. Even if the bulb was submerged in the water, the temp of the water would not restrict the flow of the refrigerant into the evap coil. Very odd. I feel like I am missing some other part or detail, odd, thanks Tom!
The frosting happens because your A/C is constantly pulling moisture out of the air and returning it to that evaporator pan and if the water can’t drain the moisture doesn’t collect in the evaporator pan and then causes it to freeze because all excess moisture is not transferring
Great video! There should also be a vent pipe on the left (output) side of the trap you show in the beginning of the video. I remove the red cap on the trap and put the tube there.
Love the video, but one clarification. You only need a trap if the coil is on the negative pressure side of the fan. In the North, most of what we install are a gas furnace with the evaporator coil on top of the furnace. No trap is needed because the force of the blower is positive.
I’ve always puts traps because all the debris that will eventually get clogged will get clogged there and not in the wall or somewhere that is harder to get and then when it clogs a pipe cleaner and bleach is all you need 👏
This can happen on positive pressure units aswell, altough probably not as common. If the drainpan outlet is connected with a hose that is way thinner then the drainpan outlet pipe diameter, the velocity of the air passning makes drainage impossible, at least as long as fanspeed is high.
I don't have a trap on my system, but the drain runs well for a 4 ton unit. I suspect when I install this same trap tomorrow I'll pull even more condensate from the unit! And I thought my AC man was top notch... apparently not.
Good video but the placement of the blower in relation to the coil determines if the condensate drain has a negative or positive pressure. Most systems I have worked on have a positive pressure. A untrapped positive pressure system will blow air out the condensate line and I have had customers on occasion hear a bubbling sound in the walls from this. I experienced a job where an untrapped negative pressure condensate line was hooked up to the houses sewer drain line and without the trap it pulled sewer gas smell into the house. Also an explanation of the secondary drain should be given. When the primary drain becomes clogged, the water will then drain out the secondary instead of leaking into the house. It is code here in California on two story houses to have this secondary drain run outside over a window so the homeowner can visually see this problem. You could also install a condensate float switch in the secondary drain to catch this problem before water damage occurs.
I have a goodman furnace with the blower at the bottom and the ac lines and I'm assuming the coils on the top. My drain plug is on top half way point of the furnace. Will that make my system positive pressure. Because I don't have a p trap.
Right, most systems I've seen are that way also. With the blower below the coil and blowing upward into it, it will create positive pressure - not negative. My system blows air/water out the condensate port - not taking air in. Hence no trap required nor present. This is only an issue if the blower is after the a-coil in the system.
Okay so first time start up there are many instances where the traps are not prefilled but they don't overflow. Every residential and commercial product doesn't get pre-filled for the summer startup. I would assume at startup and an empty trap and the unit never shut off it would in fact overflow. Since it eventually cycles off whatever's in the pan winds up flowing into the trap that's how it gets filled.
The evaporator on my system is after the fan so no p-trap is necessary. But it does drain into the sanitary sewer so there is a p-trap where the tube drains into the sanitary sewer.
Occasionally I see condensate tubing left unglued, I suspect to allow for easy cleaning. What are you thoughts on not gluing a couple strategically selected fittings?
Thanks for such grt explaination, it's very rare that we can see a demo, which you have provided. Requesting if you'll can also provide the maths related to p trap..or thump rule... thanking you.
A B, the higher the static pressure in the system, the more need for a trap there is. You can't go wrong with a deep U trap but in most cases a p-trap will suffice. The biggest thing is making sure that a PM includes the cleaning of the trap or that the building owner is aware to clean the trap one to two times a year, thanks!
I am in mobile home, down flow furnace. no trap. I have no room for one without a huge ugly hole in the front Entrance. 5 years now no issues. Drain just goes out side of trailer through belly insulation
I have some conflicting issues. Company says its not necessary, systems run well without, all due to static pressure. They also say it leads to more service calls and possibly damage if customer doesn't get that service done leading to premature failure due to water damage on circuit boards and such. They mentioned with high static pressure issues such as roof top units, they use p traps.
This is a great demonstration. But isn't negative pressure only a thing on draw-through units (aka negative pressure system)? If it is a blow-through or positive pressure system, isn't there positive pressure where the coils are?
In this application the air is being pulled through the evap coil rather than being pushed. Does the same apply when the air is pushed over the coil rather than pulled?
Very Valuable Information that I was looking for I bought your AC book And I learned A lot, I can't wait Tell I see your book on Furnaces trouble shooting Specially on high efficiencies. On the market.
Two new carrier air conditioning systems. In two years, the condensate shallow traps, fungus slime blocked one and partially blocked the other. Water overflowed on one pan and was about to do the same on the other. The traps were removed, both drains went to down to a floor drain. No problem in six years, they both drain while the system is operating. How enough air from a fan could develop enough vacuum and stop water draining into a pipe, that drops down to the floor defies physics. If you drain is shallow, that may pose an issue, however, the traps should be clear so the home owner can check it.
I was always taught the need for a trap only applies in negative pressure systems. And have seen first hand this exact problem happen when one wasn't put in. But I've never had a problem running a positive pressure system w/o trap.
normally gravity is dragging the condensate water to drain, vacuum effect in the drain hole is a caused by a dirty evaporator and air filter..even of you dont loop the drain line the water can still flow, the good thing is looped drain line can make a barrier from outside air..
you only need a trap in 2 cases, when the evaporator is on the negative side of the furnace , and when the condensate is tapped into a house vent, alot of times we drain it into a soil stack. in pittsburgh we have basements. sometimes that's the only way.
I've got a condensate drain going from my downstairs AC unit, behind my hot water heater, and draining directly into the tub of my laundry sink four feet away. No trap. Ive never had any issues and it's been running for three years in a high humidity area.
Absolutely! We put 8 months of work into fine tuning those questions and they are the very ones I would like every tech to know pertaining to the book, thanks!
My coil is is under positive pressure from the furnace air flow . The airflow that comes out the drain at the coil i would say is significant to warrant a trap but by the time the air flow gets to the outside drain point ( about 30 feet away ) it is less air flow than a human breath. So i did not use a trap . That been 21 years with no stopped up drain pipe.
While that is a true point, however, a trap still serves a purpose in a positively pressurized cabinet (or unit), as it prevents the conditioned air from escaping. In terms of wasteful energy, can be compared to why they seal all the seams in the ducting.
Does all A/C require a trap? My A/C never had one. My vertical A/C unit flow sequence is 1) Filter on bottom, 2) Blower, 3) Furnace, 4) Drain tube/pan/evap coils.
so if youre not sure if you have a positive or negative pressure system, installing a p-trap would work on either one, correct? Positive would just blow the water out while running, while a negative needs the p-trap to allow water to drain while running. Do you recommend a vent AFTER the p-trap in both situations? And a T connection b4 the p-trap to allow for cleaning in the future?
Yes but a trap would stop low temp air from leaving the system and the building to go negative pressure while the system is running by blowing the low temp air outside. Also a trap will stop any gases in the area from making its way into the system especially if the drain is hooked to the septic line, thanks!
NEVER EVER attach hard condensate pipes to a septic vent(can create disease or sickness) use a condensate pump with the 3/8 poly tube in the septic vent... always install a trap in the positive or negative side of the ac... (basic ac 101)
The trap is not "required" on a positive pressure system. Any system where the blower is pushing air across the evaporator is a positive pressure system. If the evaporator is being pulled on by the blower, thats where your negative pressure situation comes in to play. The drawbacks of having a trap on a positive pressure system outweigh its benefits as the amount of cold air loss through a 3\4" pipe are insignificant and the traps will eventually plug up and cause an overflow/shutdown scenario. Should you be concerned about a positive pressure system allowing odors from your drain, there is a fundamental flaw there... The unit is pushing air out of the drain pipe. If you ever do have a smell being picked up and drawn into the ductwork when the blower is off you should consult a plumber about why that drain is so gross to begin with.
@@whitewigglesworth this is what happens on my system with the trap. The drain plugs every year. I now blow it out before the season. I was wondering if I should eliminate it. My evaporator is on the positive side. I thought the trap was there because they ran the drain to the septic pump cover in the basement to stop the gases. I rerouted the drain and installed an ejector pump but left the trap. I hate that it plugs every year.
I’m just an ignorant home owner do I have an ignorant question. Would a typical cooling cycle actually condense enough water to overflow the pan in Arizona even n the monsoon time? If not, would the pan holding the condensate simply fill, drain, fill, etc? It seems to me that the trap also provides a service escape every year. Please don’t misunderstand my questions. I’m trying to learn pros & cons in Arizona.
I would say that the accumulated water would drain out when the ac turns off. It would also be the reason the trap is self priming. As he said with high volume units or units that run continuously, the pan would run over or trip the safety switch.
The Venturi effect. Something that I thought was cool when I was learning the trade , mite sound stupid. When most people see temperature they think hot and cold. °F and C° is a measurement of heat , you're still measuring heat at -22 or the lack there of .
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Good berthed sher thankyou gues ok
That covers everything ,nice share , practical demo on point.,, Clean out cap for vent.,👍💪🤔🙏🖖✌️
I've seen a lot of discussion on whether a positive pressure evaporator (like one on top of an upflow furnace) needs a trap or not. While it doesn't cause the drain issue like a negative pressure, it does eliminate air leakage. Please share your opinion on this. I am a HS HVAC teacher and I'd love to know your thoughts.
No matter how many times this is explained verbally, the phenomenon of negative pressure is not usually well understood to most until they see it in real time. This is a terrific demonstration!
I still don't get it. I see that it works but no clue why. Thanks for saying negative pressure so I know what to search for!
@@thejohnbeck lol first its funny seeing such a recent comment to an older video, right in line to what I was thinking as well. But I found the answer. When the system is running and sealed, and the fan in the system is moving air, it is on the input side (in this setup). Meaning its a vacuum, or under negative pressure. The drain is like a straw, so while the fan is on, the drain is sucking in air. (I wrongly assumed in the video that "system running" was focusing more on the temperature of the evap coil since he focused on it). When the fan stops, there's no sucking, and the pressure inside that area and outside are equal so the water is free to move via gravity. The trap on the drain needs to be filled with water or it doesn't work, because the weight of the water is more heavy than the sucking vacuum of the blower motor in that small area, so air cannot come up inside, so the water can move under gravitational forces, without being pulled back into the pan. Real world example. You get a fresh frosty milkshake from wendy's and go to suck on the straw. It's too thick but you kinda try again, but as you give up, the negative pressure in the straw makes your spit backwash into the straw.
@@nikolaoslouvros3618 the spit explanation did it for me
I still don't get it =(
No ok. I get it. It's just sucking air in through the drain line. The P trap basically plugs it so it's harder for air to be sucked in that way.
My Carrier Infinity runs all day long here in FL and your video carefully explains why my pan holds water and I get the “stinky sock” smell. Thank you for the video.
When we moved into our new house in North Florida about 8-years ago, we soon started to have filter failures from moisture. This was happening every 1-2 months, and at times the failed/wet filter media would get blown up into the underside of the coils. It was quite maddening. After considerable research, I found a similar video and installed the clear trap you've shown in your video. After that, no more issues.
I'm a bit confused why something so critical can be missed by the Building Inspector, and the private Home Inspector that I contracted to check the house out before we purchased it.
You've done the best job explaining why the trap is needed, that I've ever seen. Great work!
Thanks a lot Terry!
Ha ha ha. Inspectors. That's a good one. They nitpick little things that don't mean a bit of difference, but anything important they forgot to mention in inspector school. Here's 10 pages of bullcrap that needs to be fixed. Give me my check.
Keep in mind this is for an air handler and not a coil on top of a furnace. The coil on top of the furnace has positive pressure so you dont need a trap.
That makes sense why my unit doesn't have a condensate trap
Trap will keep cool air from escaping though right?
The Delta p is small, very little air escapes. You can test this just by running the fan or furnace and very little air comes out of the drain hole, even less if you have a drain hose on it.
I am HVAC contractor with ~10 years of experience. I think that this video is the best explanation why do you install that p-trap on the condensate line so far. :) Thank you!
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During home inspections I would talk about the vacuum effect when there is no trap. If the unit is in the garage or close to where there might b some chemicals, fumes can be sucked up into the air flow going to the home and if that happens because there is no trap at the condensate line no one will know where the Oder is coming from. So the trap here is rather important!
Wouldn't the Trap as he has it here, be more likely to suck in the chemical smells? It is sucking in air right where the AC unit is.
I have been doing HVAC 8 years and never had such a good example of condensate traps.
Good video. And this ONLY applies when the blower motor is on the supply side of the evaporator causing a negative pressure which sucks air into the condensate pan from the drain. When the blower motor is on the return side of the evap coil, you will have a positive pressure pushing air out of the drain hole and you won't need a p-trap for this
great point! i was left wondering why my system continues to perform fine without a trap, but you've answered it!
You still need it, that's air loss going out of the condensate line.
Same here. Works fine. I lose very little air with my design
Great demonstration. But this only happens with the coil before the blower. When the coil is after the blower air comes out of the drain pipe and you need a trap to stop the air from escaping.
I learned a lot from your channel thanks for the tips!
Great point. This something missed in the video
how would a trap stop the air from escaping if there wasn't water in it first
This is the best video I found to fix the problem I have with my air handle thank you so much
Again, well done! Getting this point across to installers that are trying to “just get the job done “is critical. No excuses for not having a trap installed.
Never realized while the air flowing through the evap is on its way to the cold outlets, it will pull air back through the drain tubing---perfectly logical. The back pull would be untreated air as well. We had our system changed in 2015 and they installed a trap. I thought it was silly. Now I know!!! Thanks for making the video.
Great visual for evaporators on the negative pressure side of the blower. You should explain that not all are on the negative side. An explanation of where to put the vent would also be helpful. In my neck of the woods most residential evaps are on the positive side of the blower.
You are right
My exact thought. The plus side of adding a trap on a push coil is you don’t lose some of the efficiency of air being leaked out of the drain, but it’s not critical to have one as it is on a pull coil.
I like this man, every time see his video learn new things.
Thank you so much for all the videos.
You are good teacher :)
Glad to help Latif!
Next level cool deal.👍✌️🙏
Brilliant. I noticed last year when I happenned to look inside my furnace that the condensor pan was completely full and not draining. I could tell there was negative pressure so I openenned the filter area and sure enough it drained immediately. The system was installed by the previous homeonwer so I have no idea of the experience of the originall installer but they clearly didn’t understand this issue. Great explanation and video.
I just had my unit serviced. Guy at ACE told me I needed a trap (retired HVAC) guy who serviced unit did not install one. I have an identically appearing unit as the one pictured. Anyways guy called days later and now he said he “forgot to install” and is coming back to place one. Just trying to understand the process and this video was awesome! Thanks
thank you, one of the best explanation. very professional
Glad it was helpful!
@@acservicetechchannel could you tell me why water in the drain tray or pan starts flowing out when the pvc pipe system with water filled trap is attached?
@@sujithsurendran7672 Yeah, how exactly does the trap with water counteract the negative pressure of the flowing air?
Thank you very much for clueing me in. That solved the problem of condensate build up in the bottom of my A/C unit. I cut a hole in the piping for easy trap cleaning; I did not realize it receives an internal negative air pressure. I thought it only trapped debris. HAGO; Thanks again!
Thank you !!!! I felt dumb when I first saw a video of someone really cocky because he did understand it. I wasnt dumber i just had to take the time to educate myself. I hope when I go to school my teachers are as good as you.
Thanks so much Luis and make sure to check out the video I just published on does a minisplit need a condensate trap. I get into more detail there, thanks!
I've serviced a package unit witch had a zone board installed (left) inside the blower cabint wich burned out twice .I was ther on the second call, Noticed it was a little damp and the zone board had moister on it, and that they had short 4" pvc pipe off the drain pan. I added a p-trap, installed new zone board called back a month later to make sure clients system was working. Problem solved . Many techs even some hvac business iv talked to think these ptraps are unnecessary but I beg to differ .NICE DEMO CRAIG!
And I thought traps were for catching wedding bands only.
You guy's are a class act. Ty for sharing. Definitely looking into your E book.
Awesome, thanks!!
Thank you for posting. My apartment AC unit was leajing water all over the drip pan,and the EZ trap was bone dry.
After watching your video, I opened the trap and filled the curve with water - hopefully this fixes the issue.
good idea to put a union or slip compression fitting near the between trap and the unit ...easier to clean out the slime and crud ..
Unions in condensate lines aren’t necessary,a simple tee with a cap or a modern float switch has what you need to disassemble without any problems to clean………or best thing I’ve found after over 20years of doing it is a simple shop vac,connect it outside and it will suck all the bs out and then put the cleaning tabs in the evaporator coil pan and your g2g……..or your nitrogen tank with a simple Freon line hose will blow everything out from the inside out.
Wow! This is what is wrong with my AC! The person who installed my AC kept saying he had no idea what was wrong with my system and HE INSTALLED it. Thanks! Hopefully my hubby can fix it.
Literally could not understand why my furnace was filling up with water until I watched this video. Thank you so much you saved me an expensive service call.
That trap is not always necessary and the reason is that here in Florida, and other areas, houses are built on slabs. The condensate pipe runs down into/below the slab, then runs back up above ground level, usually about 6 to 8 inches high, where the water exits. This causes the "below ground" level of the pipe to fill with water, in effect automatically creating a very long "p-trap".
AC Contractor here in Florida lack great amount of critical knowledge The same way they do not use Nitrogen when soldering cooper lines and not even sanding cooper lines-You always need a condensate P trap -It is in the HVAC exam
@@user-hu4hx6bm6m Yes, but where is it located? The point was if it exits ground level, a p-trap at the air handler/furnace is where you'll see it. If it goes underground and returns to ground level, it's there, but you won't see it as it's formed under the slab, contains several inches of condensate, and prevents airflow from exiting the air handler.
I love those clear EZ trap! Don't like the shallow trap, they dry up in winter, first summer cooling = leak!
In that case I make a deep one that can never dry out.
Btw In case of positive pressure unit, no trap is required
Nathan what do you mean in case of a positive pressure unit a trap is not required?
@@abnergarcia6252 He means that if the blower pushes the air through the coil and not pulls..Blower is beneath the coil. in the video the blower is above the coil.
eddman32 thank you! So in the video the unit is a “negative” pressure unit? Anytime the blower “pulls” from the coil is a negative unit?
Very interesting.
After this video I found another video on “Expert Express Plumbing Heating....” where he shows the effect of high static in a zone system. And it was a horizontal left unit, but the water was being pushed out of the secondary drain plug.
Abner Garcia.
The vast majority of units the blower "sucks" the air across the coil.
In the minority are units that are either "ambient" pressure; or blower is upstream so that the air is "blown" ie positive pressure
@@abnergarcia6252 A fur down unit is a positive pressure unit(apt complexes).
Very informative. As a plumber this broadens my knowledge. Thanks
Glad it was helpful!
Very good. Thank you for your service to the industry!
Thanks a lot Chip!
I don't like ptrap dust build up in it
Some Carrier AC’s have a built in trap in the Drain Pan, so you need to look and/or check the units literature. It you can’t see directly thru the opening to the drain pan, or from inside the drain pan to the pipe. Then check the literature.
WOW 😮👍😅 I'm glad i Stumbled on this video 👍
Thank you Teacher Craig. That's Why I Always follow his videos teachings ❤️
Thank you for watching!
Ahhh makes sense. The blower creates a Venturi effect on the trap drawing air in when not primed. Thanks.
This was the best visual example I’ve ever seen thank you so much.
Mine drips the entire time its on...doesn't speed up when the blower shuts down...My tech added a "chimney" to the "T" that exits the side of the A coil drip pan.. It sucks air over the draining water...
Definitely every air handler needs a trap, but in some cases ac and furnace don't require. But it's good practice to just use one
What is the other plug for? I have water dripping out of the plug but very little coming out of the water line tubing. No trap either.
Amazing Explanation, but should have mentioned negative pressure with a trap and Positive pressure without!
While that is a true point, however, a trap still serves a purpose in a positively pressurized cabinet (or unit), as it prevents the conditioned air from escaping. In terms of wasteful energy, can be compared to why they seal all the seams in the ducting.
I am in HVACR school and I was just asking my teacher this same question the other day in class
Awesome, thanks HVAC with Greg!
I was wondering why there is a trap on my system. You learn new stuff every day
Best ever demonstration! I don't think mine is linked into a trap but it I think the broken humidifier and furnace are linked into the line too. Furnace is under ac unit and has some sort of black box cleanout
Your a dynamic instructor in all facets of AC Thank You.
I appreciate that!
Got you’re book last year and it’s nice to have. I didn’t not know about the trap for the drain on the coil. Good stiff
Thanks a lot Martin!
Now I know why there’s a P-trap before the condensate pump. Thank you. It didn’t make any sense why a trap was necessary when no sewer gases would get through the condensate pump.
Simple, but excellent demonstration!!
Glad you liked it!
Have you ever seen a blocked drain line affect a TXV Craig?
I was on a call once where the evap coil kept frosting over until the abnormally long, mostly flat, drain line was blown clear.
The very moment the drain cleared the frosting stopped.
Frosting would only occur if the sat temp of the vapor line was below 32 degrees. Even if the bulb was submerged in the water, the temp of the water would not restrict the flow of the refrigerant into the evap coil. Very odd. I feel like I am missing some other part or detail, odd, thanks Tom!
The frosting happens because your A/C is constantly pulling moisture out of the air and returning it to that evaporator pan and if the water can’t drain the moisture doesn’t collect in the evaporator pan and then causes it to freeze because all excess moisture is not transferring
Great video! There should also be a vent pipe on the left (output) side of the trap you show in the beginning of the video. I remove the red cap on the trap and put the tube there.
Thanks
Glad to help Jamal!
Love the video, but one clarification. You only need a trap if the coil is on the negative pressure side of the fan. In the North, most of what we install are a gas furnace with the evaporator coil on top of the furnace. No trap is needed because the force of the blower is positive.
I’ve always puts traps because all the debris that will eventually get clogged will get clogged there and not in the wall or somewhere that is harder to get and then when it clogs a pipe cleaner and bleach is all you need 👏
This can happen on positive pressure units aswell, altough probably not as common. If the drainpan outlet is connected with a hose that is way thinner then the drainpan outlet pipe diameter, the velocity of the air passning makes drainage impossible, at least as long as fanspeed is high.
I often see one of the p trap risers uncapped. In your video you have both of them capped. Can you please elaborate. Thank you for great videos.
I will be buying your book, workbook and charts very soon. I’m a maintenance man in an apartment complex and I’m finding your videos invaluable.
Thank you very much! We do try to provide information, methods, and procedures in layman's terms so that they are easily understandable, thanks!
I don't have a trap on my system, but the drain runs well for a 4 ton unit. I suspect when I install this same trap tomorrow I'll pull even more condensate from the unit! And I thought my AC man was top notch... apparently not.
Thank you for the explanantion. I’m glad I put the ez trap on my new AC last month.
Absolutely, nice cleanouts!
Thankyou gues
Good video but the placement of the blower in relation to the coil determines if the condensate drain has a negative or positive pressure. Most systems I have worked on have a positive pressure. A untrapped positive pressure system will blow air out the condensate line and I have had customers on occasion hear a bubbling sound in the walls from this. I experienced a job where an untrapped negative pressure condensate line was hooked up to the houses sewer drain line and without the trap it pulled sewer gas smell into the house. Also an explanation of the secondary drain should be given. When the primary drain becomes clogged, the water will then drain out the secondary instead of leaking into the house. It is code here in California on two story houses to have this secondary drain run outside over a window so the homeowner can visually see this problem. You could also install a condensate float switch in the secondary drain to catch this problem before water damage occurs.
We also require a secondary containment pan, and drain, on any unit installed over a finished ceiling.
Excellent explanation. Better than the OP.
I have a goodman furnace with the blower at the bottom and the ac lines and I'm assuming the coils on the top. My drain plug is on top half way point of the furnace. Will that make my system positive pressure. Because I don't have a p trap.
Right, most systems I've seen are that way also. With the blower below the coil and blowing upward into it, it will create positive pressure - not negative. My system blows air/water out the condensate port - not taking air in. Hence no trap required nor present. This is only an issue if the blower is after the a-coil in the system.
Learned this by experience....
Wondered why the condensation was not drawing whilst on! This is a great channel to learn! I have learned so much since I found this channel .thanks .
Okay so first time start up there are many instances where the traps are not prefilled but they don't overflow. Every residential and commercial product doesn't get pre-filled for the summer startup. I would assume at startup and an empty trap and the unit never shut off it would in fact overflow. Since it eventually cycles off whatever's in the pan winds up flowing into the trap that's how it gets filled.
The evaporator on my system is after the fan so no p-trap is necessary. But it does drain into the sanitary sewer so there is a p-trap where the tube drains into the sanitary sewer.
Occasionally I see condensate tubing left unglued, I suspect to allow for easy cleaning. What are you thoughts on not gluing a couple strategically selected fittings?
Thanks for such grt explaination, it's very rare that we can see a demo, which you have provided. Requesting if you'll can also provide the maths related to p trap..or thump rule... thanking you.
A B, the higher the static pressure in the system, the more need for a trap there is. You can't go wrong with a deep U trap but in most cases a p-trap will suffice. The biggest thing is making sure that a PM includes the cleaning of the trap or that the building owner is aware to clean the trap one to two times a year, thanks!
@@acservicetechchannel thanks alot
I am in mobile home, down flow furnace. no trap. I have no room for one without a huge ugly hole in the front Entrance. 5 years now no issues. Drain just goes out side of trailer through belly insulation
Mine blows air out of the evaporator if there's no water in it, so not always true.
It’s rare that you need a trap
clear concise explanation...
ps... not only blocks air, but also insects
Thanks for sharing. Something this smart and inexpensive seems like it should be a standard.
Never too old to learn! Thanks
You got that right!
I have some conflicting issues. Company says its not necessary, systems run well without, all due to static pressure. They also say it leads to more service calls and possibly damage if customer doesn't get that service done leading to premature failure due to water damage on circuit boards and such. They mentioned with high static pressure issues such as roof top units, they use p traps.
This is a great demonstration. But isn't negative pressure only a thing on draw-through units (aka negative pressure system)? If it is a blow-through or positive pressure system, isn't there positive pressure where the coils are?
Excellent explanation, as always. Thank you Craig. Stay safe!
Thanks a lot Ma ma!
What if it’s a positive pressure system?
In this application the air is being pulled through the evap coil rather than being pushed. Does the same apply when the air is pushed over the coil rather than pulled?
thanks for that demo! I recently encountered this at work.
Glad I could help!
It helps keep out bugs also add for some vacuum relief it needs to be cleaned per season
Always wondered why a trap? Thanks
Very happy you made this one
Hope you enjoyed it!
Thank you for getting straight to the point skipping all the BS.
I couldn’t see the top of the torso. Do you cap it or not?
Very Valuable Information that I was looking for I bought your AC book And I learned A lot, I can't wait Tell I see your book on Furnaces trouble shooting Specially on high efficiencies. On the market.
i use a tablespoon of bleach once a month when I use my ac, but my unit is smaller 2t. but this is good info, good job.
Two new carrier air conditioning systems. In two years, the condensate shallow traps, fungus slime blocked one and partially blocked the other. Water overflowed on one pan and was about to do the same on the other. The traps were removed, both drains went to down to a floor drain. No problem in six years, they both drain while the system is operating. How enough air from a fan could develop enough vacuum and stop water draining into a pipe, that drops down to the floor defies physics. If you drain is shallow, that may pose an issue, however, the traps should be clear so the home owner can check it.
Can you please make some Videos about Wireless thermostats And Smart Venting Dampers when we do a multi zones thermostats...thank you
I was always taught the need for a trap only applies in negative pressure systems. And have seen first hand this exact problem happen when one wasn't put in. But I've never had a problem running a positive pressure system w/o trap.
Same in my experience and HVAC-degree education classes. Also the issue of checking for and avoiding multiple traps would have been good.
You are amazing, I lear a lot from you !! Keep it up the good teaching!! Best!
Thank you! Will do!
normally gravity is dragging the condensate water to drain, vacuum effect in the drain hole is a caused by a dirty evaporator and air filter..even of you dont loop the drain line the water can still flow, the good thing is looped drain line can make a barrier from outside air..
If you were to added a condensate pump where would you run the discharge hose? To the p trap? After the p trap?
you only need a trap in 2 cases, when the evaporator is on the negative side of the furnace , and when the condensate is tapped into a house vent, alot of times we drain it into a soil stack. in pittsburgh we have basements. sometimes that's the only way.
This is a positive set up and pulled a negative pressure what are you talking about?
I've got a condensate drain going from my downstairs AC unit, behind my hot water heater, and draining directly into the tub of my laundry sink four feet away. No trap. Ive never had any issues and it's been running for three years in a high humidity area.
My question was, is the trap even needed really? I mean, once the unit is of it drains.
You are very GOOD, thank you! Very well explain, great teacher; you're truly know this stuff, wow.
Additional information
Another tips and ideas
Thanks for sharing dude.🤔
Thanks other 91 solution!
I didn’t know you had a workbook! I’m buying that!
Absolutely! We put 8 months of work into fine tuning those questions and they are the very ones I would like every tech to know pertaining to the book, thanks!
My coil is is under positive pressure from the furnace air flow . The airflow that comes out the drain at the coil i would say is significant to warrant a trap but by the time the air flow gets to the outside drain point ( about 30 feet away ) it is less air flow than a human breath. So i did not use a trap . That been 21 years with no stopped up drain pipe.
My system has positive pressure on the drain pipe. It blows the condensate out. No P trap, no problems.
While that is a true point, however, a trap still serves a purpose in a positively pressurized cabinet (or unit), as it prevents the conditioned air from escaping. In terms of wasteful energy, can be compared to why they seal all the seams in the ducting.
Does all A/C require a trap? My A/C never had one. My vertical A/C unit flow sequence is 1) Filter on bottom, 2) Blower, 3) Furnace, 4) Drain tube/pan/evap coils.
Great explanation, very informative. Great video. Thanks for making.
Glad you enjoyed it!
so if youre not sure if you have a positive or negative pressure system, installing a p-trap would work on either one, correct? Positive would just blow the water out while running, while a negative needs the p-trap to allow water to drain while running. Do you recommend a vent AFTER the p-trap in both situations? And a T connection b4 the p-trap to allow for cleaning in the future?
Best video on ac
Wow, thanks
I love how clear your explanations are. Great channel!
Thanks a lot The Air Conditioning Guy!
isnt the trap only required when the evap coil is on the negative side?
Yes but a trap would stop low temp air from leaving the system and the building to go negative pressure while the system is running by blowing the low temp air outside. Also a trap will stop any gases in the area from making its way into the system especially if the drain is hooked to the septic line, thanks!
NEVER EVER attach hard condensate pipes to a septic vent(can create disease or sickness) use a condensate pump with the 3/8 poly tube in the septic vent... always install a trap in the positive or negative side of the ac... (basic ac 101)
The trap is not "required" on a positive pressure system. Any system where the blower is pushing air across the evaporator is a positive pressure system. If the evaporator is being pulled on by the blower, thats where your negative pressure situation comes in to play. The drawbacks of having a trap on a positive pressure system outweigh its benefits as the amount of cold air loss through a 3\4" pipe are insignificant and the traps will eventually plug up and cause an overflow/shutdown scenario. Should you be concerned about a positive pressure system allowing odors from your drain, there is a fundamental flaw there... The unit is pushing air out of the drain pipe. If you ever do have a smell being picked up and drawn into the ductwork when the blower is off you should consult a plumber about why that drain is so gross to begin with.
@@whitewigglesworth this is what happens on my system with the trap. The drain plugs every year. I now blow it out before the season. I was wondering if I should eliminate it. My evaporator is on the positive side. I thought the trap was there because they ran the drain to the septic pump cover in the basement to stop the gases. I rerouted the drain and installed an ejector pump but left the trap. I hate that it plugs every year.
@@whiteowlone Take it out and straight pipe it. PVC is cheap and youll be happier.
I’m just an ignorant home owner do I have an ignorant question. Would a typical cooling cycle actually condense enough water to overflow the pan in Arizona even n the monsoon time? If not, would the pan holding the condensate simply fill, drain, fill, etc? It seems to me that the trap also provides a service escape every year. Please don’t misunderstand my questions. I’m trying to learn pros & cons in Arizona.
I would say that the accumulated water would drain out when the ac turns off. It would also be the reason the trap is self priming. As he said with high volume units or units that run continuously, the pan would run over or trip the safety switch.
The Venturi effect. Something that I thought was cool when I was learning the trade , mite sound stupid. When most people see temperature they think hot and cold. °F and C° is a measurement of heat , you're still measuring heat at -22 or the lack there of .