Condensate drain question

[jrref]

I'm afraid to start this thread but here goes.....

In my town home development, the condensate drains for the furnace and the A/C coil drains into the washer drain.

All the drains in the house are PVC, it was put together this way when all the homes were built and it was inspected by the town so all the plumbing is original and no one made any changes.

I know that there are many ways to plumb the condensate drain but the question i have is it normal to feel slight breeze where the washer hose goes into the drain when the furnace or the A/C is on?

Everything is draining properply, the HVAC and the washer. I put a CO detector that has a digital readout in the room and no CO is detected, no smell, nothing. Just feel a slight breeze when the HVAC is running. Everything else is normal.

Any feedback on this?

Thanks,
John

[jrref]

Just to be clear the HVAC is in the attic and the condensate line comes down through the ceiling and into the washing machine standpipe.

Hope this helps describe a little better how it's connected.

John

[mgenius33]

This isn't a DIY site, but with that said, I don't think you have a problem.
The P-trap (if it has one) has probably gone dry. I would recommend having an HVAC service company come out to perform a routine maintenance on the system and advise them of any issues that you think your system may have. If there is no trap, and you want a trap installed, they can do it for you at that time. Ask them for a trap with a safety cutoff; this will help reduce risk of drain pan overflow problems if the line gets clogged.

[hvacvegas]

ditto on mgenius.

[SJProwler]

Since the unit is in the attic wouldn't they want to be sure the trap itself is in conditioned space?

[captain123]

The mechanical code says: "Condensate drains shall be trapped as required by the equipment or appliance manufacturer." Most manufacturers require a trap...check on that and if you have a trap make sure it has water in it.

[Lambo]

When people say "Furnace" I automatically think gas/fuel or straight electric, in which case the A/C evaporator coil is usually separate and downstream of the blower. This would put it (and the associated condensate drain line) in a positive air pressure area of the system. With no trap, or a dry trap, you could get this whisper of air blowing out at the discharge end of the drain.
I would also assume that if you have an attic system, that you have an auxiliary drain pan under the unit---or at least the coil portion. In my area, code requires that a drain from this auxiliary pan must exit the attic through the soffit above a window. This way you can actually see that you have a problem with the main drain. We also require that a high level cutoff switch within the auxiliary pan is present.

[jrref]

Folks thanks for all of the responses.
I think the problem is that the A/C drain doesn't have a trap but the furnace condensate drain does so i'm probably getting a slight breeze from the A/C drain from the coil.

I'll check with my HVAC guy but any pro's or con's for having a trap in the A/C side instead of just letting it drain into the washer stack?

I want to know if it's worth having my HVAC guy put in the trap since he didn't do it on the install to begin with.

[crmont]

I'm afraid to start this thread but here goes.....

In my town home development, the condensate drains for the furnace and the A/C coil drains into the washer drain.

All the drains in the house are PVC, it was put together this way when all the homes were built and it was inspected by the town so all the plumbing is original and no one made any changes.

I know that there are many ways to plumb the condensate drain but the question i have is it normal to feel slight breeze where the washer hose goes into the drain when the furnace or the A/C is on?

Everything is draining properply, the HVAC and the washer. I put a CO detector that has a digital readout in the room and no CO is detected, no smell, nothing. Just feel a slight breeze when the HVAC is running. Everything else is normal.

Any feedback on this?

Thanks,
John

You never stated that the HVAC drain goes to the washer drain. Are you assuming it does?

If you open the front door wide open does the breeze go away or get dramatically less at the washer drain?

Is there a gap of some sort around or near the washer drain? Care to snap a pic?

[b26440510]

I want to know if it's worth having my HVAC guy put in the trap since he didn't do it on the install to begin with.

huh? If the mfg's install guide says the unit is supposed to have a trap then the installer needs to comply with the install instructions.

[ampulman]

You never stated that the HVAC drain goes to the washer drain. Are you assuming it does?



Per the OP: "Just to be clear the HVAC is in the attic and the condensate line comes down through the ceiling and into the washing machine standpipe."

[jrref]

Sorry forgot to mention in my original post that the HVAC is in the attic and the condensate line comes down through the ceiling and into the washing machine standpipe.

All of the town homes in my development are set up the same way and i've seen different HVAC companies do full system replacements here and they use the same condensate drain with no trap on the A/C since it's going into the washer standpipe.

This is the reason why i'm here asking for your thoughts on the subject. I understand that it's probably best to have a trap but none of the HVAC companies have been installing them, including mine so i'm guessing there has to be some reasoning as to why they are not installing them.

Could it be that the washer stand pipe has a trap and one is not needed since there is no risk of sewer gases coming into the house? Aside from code which i don't think is the issue here since they were all inspected, since the A/C condensate drain is not connected directly to the sewer with no trap, what is the advantage of having the trap in this situation?

FYI, I'll get my HVAC guy to install one but i'm looking for some reasoning before i call him.

Thanks in advance.
John

[crmont]

Sorry forgot to mention in my original post that the HVAC is in the attic and the condensate line comes down through the ceiling and into the washing machine standpipe.

All of the town homes in my development are set up the same way and i've seen different HVAC companies do full system replacements here and they use the same condensate drain with no trap on the A/C since it's going into the washer standpipe.

This is the reason why i'm here asking for your thoughts on the subject. I understand that it's probably best to have a trap but none of the HVAC companies have been installing them, including mine so i'm guessing there has to be some reasoning as to why they are not installing them.

Could it be that the washer stand pipe has a trap and one is not needed since there is no risk of sewer gases coming into the house? Aside from code which i don't think is the issue here since they were all inspected, since the A/C condensate drain is not connected directly to the sewer with no trap, what is the advantage of having the trap in this situation?

FYI, I'll get my HVAC guy to install one but i'm looking for some reasoning before i call him.

Thanks in advance.
John

In reality that is heated and filtered air just like any other supply vent so there is definitely no emergency here.

[jrref]

I agree, there's probably nothing to worry about but i was curious about the trap and why they didn't install it in this case. I'm guessing it's a grey area to do it or not for this type of install and it's up to the HVAC guys judgement.

Thanks,
JR

[Roadhouse]

No negative air pressure (no chance of water being pulled back up into the system so no chance of improper draining) in a gas furnace which is why no trap is on your furnaces own drain line, not required as it will just drain via gravity.

Manufacture recommend traps on their air handlers, not furnaces. Code as well, will pass city inspection just draining without a trap.

Here in Houston, 99 of 100 furnaces are in the attics too.

[Roadhouse]

The negative pressure is related directly to the where the blower motor and wheel is inside of a unit. If the blower is before the drain and evap coil, usually a furnace is the blower wheel and heat together and located before the evaparotor coil and the air is being pushed across those other components/openings. Then a transition (connection) to the evaporator coil where the drain line is, from the evaporator coil as that is where the condensation water that needs to be drained is produced.

In an air handler, everything is on one unit, the blower, the coil (evap) and thus the drain and the blower wheel is usually placed AFTER the coil and drain and sucks air into the blower wheel so in this case it would be trying to suck up all air and thus drain ( condensate) water too and to aleviate this problem, p-traps are used.

If you do not have a one piece air handler where the coil is located inside the same cabinet as the blower wheel and the blower wheel is not placed AFTER the coil/drain line, you have no negative pressure to deal with, no trap required.

[jrref]

Roadhouse, i think you got it.
In my case my furnace is a "down flow" so the blower is Before the A-Coil all in the same cabinet.

Not possible to get negative pressure. The other plus is that it keeps the entire drain clear of condensate so there is no chance of it freezing in the winter.

Thanks,
John