Condensate drain blowing cold air

[David P. Valley]

Originally Posted by cbottger

My biggest concern has always been can sewer gas get into the air stream of the furnace. With a wet trap or continous flow; as some would say it would not concern me.

I concur...

[Brian A. MacNeish]

Originally Posted by kweiss

What about the ones with no trap.

I am seeing more and more of these. Around here they are all connecting to the drain at a vanity drain above the sink trap. I generally call it out and have several times had builders state that it isn't needed due to the fact that the sink drain is trapped.

Shows how much they know. Must be the same ones that don't want the duct joints without gaps and efficiency losses- morons!!

From a 1996 study, Air Of Importance, by Alternative Energy Corp:

"In the last several years, building scientists across the country have been quantifying the contribution made by air distribution systems to building efficiency loss in site -built homes. Estimates vary, but the average duct system appears to reduce overall system efficiency by 20 to 40 percent. This efficiency loss can have a multiplying effect with air-flow sensitive, compressor-based space conditioning systems such as air conditioners and heat pumps. Meanwhile, air distribution systems in new manufactured homes have received very little attention. This study is a step forward in trying to better understand air distribution in manufactured homes and their affect on overall system performance."



And the quality appears to still be going downhill in spec built mass housing!

Most people don't realize that with bad duct installations, the air handler actually increases indoor/outdoor air exchange while the fan is running. Different areas of the building become unneccessarily or more pressurized than necessary and push conditioned (heated, humified or cooled, dehumidified) air out the unsealed wall/ceilings,etc while other areas become similarly depressurized to suck in outdoor air (or crawlspace/garage air) to increase HVAC operating costs. Sealing both ducts and the building envelope will substantially decrease these costs!!

[kweiss]

Originally Posted by cbottger

My biggest concern has always been can sewer gas get into the air stream of the furnace. With a wet trap or continous flow; as some would say it would not concern me.

I agree, and if the house is not used long enough for the sink drain trap to dry out, the one in the attic would have as well. So there is not a code that requires the trap at the air handler, just that the line has a trap before the sewer?

I have run into the situation where the sink drain is very close to the unit and some people complain about hearing the rushing air through the sink drain.

[tdietrich1]

I don't know how sewer gas got into this trap conversation, or why I was red boxed.

Before more posts happen, these traps are typically 'dry' in the heating season/Non-AC season. Since they are there to prevent cold air constantly blowing through them, an efficiency problem yes, but was told to prevent condensation problem. So They are let to dry in the NON-AC season.

tom

http://ths.gardenweb.com/forums/load...574116920.html

[mthomas2]

Originally Posted by kweiss

What about the ones with no trap... I generally call it out and have several times had builders state that it isn't needed due to the fact that the sink drain is trapped.

Have them check the manufacturer's instructions; they usually require the trap to be within 12" of the condensate drain connection at the evaporator coil housing, similar to that shown in the installation instructions I posted above.

If they persist, recommend your client obtain a statement on their letterhead that the installation is complaint with the manufacturer's instructions, and that the manufacturer's warranty remains in effect.

If they provide it, fax to to the manufacturer "for verification" .

[kweiss]

It is enough to me to point it out and as Michael said, per typical manufacturer instructions. Most probably won't follow through. But at least I have made tehm aware of the possible concern.

Good dicussion guys.

[jlybolt]

If the primary condensate is connected to a lav it should be trapped at the HVAC unit. If not I always call it out as in need of repair.

[Charley L. Bottger]

As I stated before my biggest concern is no sewer gas into the air stream of the furnace I did not say that was my only concern. I see all kinds of crazy connections most of them wrong.

I look at both ends of this condensate line yes most MFG recommend a trap at the outlet of the coil which is very proper. But to me the most important item is where it drains. I see a lot of lines in attic installs that connect to a vent stack and have had HVAC contractors tell me that it is alright because they placed a P-trap on the outlet of the coil.

To me if there is a trap or not at the coil or if the vent is on the wrong side of the trap or there is no vent is still not as big a concern as where the condensate is being discharged. I want no possibility of a cross connect between the air stream and the sewer under any circumstances heat or cool season. Period

I can give another scenario of a bad install that I see quite frequently on slab foundations. Spec houses
Upflow furnace setting on top of a local return box with the return grill opening into a hall. The furnace is mounted in a hall closet with C-air provided from the attic.
The condensate drains into an indirect stub-out within the return air box that has a P-trap installed below the slab. The P-trap in the slab goes dry in the heating season and the blower for the furnaces sucks sewer gas into the air stream.
The only cure for this is to extend the P-trap inlet to above the return box within the furnace closet which is not really a cure because when the trap goes dry sewer gas is allowed into the furnace closet but with the indirect drain in the furnace closet at least water or a product such as Baby oil can be added to the trap to seal it in the heating season.

I will say this again again again and again it is not as important if there is a trap at the outlet of the A-coil as compared to where the drain is discharging.

[Charley L. Bottger]

Originally Posted by jlybolt

If the primary condensate is connected to a lav it should be trapped at the HVAC unit. If not I always call it out as in need of repair.

Ok you made this statement can you explain why

[Barry Adair]

Originally Posted by mthomas2

Have them check the manufacturer's instructions; they usually require the trap to be within 12" of the condensate drain connection at the evaporator coil housing, similar to that shown in the installation instructions I posted above.

If they persist, recommend your client obtain a statement on their letterhead that the installation is complaint with the manufacturer's instructions, and that the manufacturer's warranty remains in effect.

If they provide it, fax to to the manufacturer "for verification" .

Just in case anyone missed that part.

[Charley L. Bottger]

Originally Posted by badair

Just in case anyone missed that part.

Did not miss that part

Just stated that it was not the most important part #2 in my book.

You guys are having a hard time prioritizing
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[jlybolt]

Charlie, every manual I have looked at within the last couple of years recommends the trap near the unit. ON top of that every HVAC gurro I have worked with installs one at this location on new construction if the the drain is connected to to a lav. Thats a good enough reason for me.
I list it as further evaluation is recommended and mark the in need of repair check box as required . As long as my client has been informed and I recommend this item to be further evaluated, that is a good enough reason for me.

[Charley L. Bottger]

every manual I have looked at within the last couple of years recommends the trap near the unit.

I am not disputing that fact, it is as it should be trapped at the A-coil.

installs one at this location on new construction if the the drain is connected to to a lav.

Are you saying this is the only time a trap is installed at the A-coil if it is connected to a lavatory. I hope not.

Lets look at another situation

upflow or downflow furnace installed in a hall closet the A-coil has a P-Ptrap on the condensate line at the coil the line then travels into a crawl space and connects hard piped into lets say the bathtub drain line after the tub P-trap.

What would you report or would you report anything.

[mthomas2]

FWIW, I got curious enough about this to call Rheem's cooling division.

Their tech department gave me following reasons for requiring a trap at an evap coil under positive pressure:

1) Excessive condensation: Untrapped and under positive pressure, the cold air passing through the drain line will greatly increase condensation on discharge piping.

2) Efficiency: The drain line may be discharging to a location where conditioned air is exhausted from the structure or misdistributed within it, for example, back up the tailpiece if attached to a drain above its trap.

3) Reliability: a) You don't know what may be done post-installation to modify discharge trapping remote from the furnace or air handler. Trapping at the evap coil insures that the discharge line is trapped to start with and increases the probability that it will stay trapped in the future. b) For a trap to work properly it must be properly designed and constructed. A trap installed at the evap coil by a HVAC tech according to the manufacturer's instructions has a better chance of being right than something done later and/or at some other location by some other trade.

4) Serviceability: A trap and clean out provides access to clear blockage both up and down stream of the trap and allows easy anti-algae treatment of the entire length of the drain line. A trap ahead of the cleanout provides at least some protection against discharge of conditioned air if the cleanout is uncapped.


If I get a chance I'll call Trane as well, to see what they have to say.

[Charley L. Bottger]

Originally Posted by mthomas2

FWIW, I got curious enough about this to call Rheem's cooling division.

Their tech department gave me following reasons for requiring a trap at an evap coil under positive pressure:

1) Excessive condensation: Untrapped and under positive pressure, the cold air passing through the drain line will greatly increase condensation on discharge piping.

2) Efficiency: The drain line may be discharging to a location where conditioned air is exhausted from the structure or misdistributed within it, for example, back up the tailpiece if attached to a drain above its trap.

3) Reliability: a) You don't know what may be done post-installation to modify discharge trapping remote from the furnace or air handler. Trapping at the evap coil insures that the discharge line is trapped to start with and increases the probability that it will stay trapped in the future. b) For a trap to work properly it must be properly designed and constructed. A trap installed at the evap coil by a HVAC tech according to the manufacturer's instructions has a better chance of being right than something done later and/or at some other location by some other trade.

3) Serviceability: A trap and clean out provides access to clear blockage both up and down stream of the trap and allows easy anti-algae treatment of the entire length of the drain line. A trap ahead of the cleanout provides at least some protection against discharge of conditioned air if the cleanout is uncapped.


If I get a chance I'll call Trane as well, to see what they have to say.

This is all very true I am not again trying to dispute this you all are missing the boat here.

Does this statement you have posted say one word about where the condensate line is connected to where does it drain to. How is it connected to what. You guys have a one track mind just keep going back to the P-trap thats not the question. I already know what Rheem states what Trane states What Carrier States and all of the rest of them. What I am trying to get you to understand is what they are not telling you.

Read my post above and answer the question