Coil Height For Condensate Drain Trap

davidchomes

Hello.

I'm installing a Goodman cased coil which is a counterflow setup.
With the coil setting directly on the floor the primary drain connection is only 2.5" from floor which isn't enough height for a trap and floor drain termination. A 2x4 or 2x6 base would probably work but seems too generic not to mention the wood and moisture combination. Could you please tell me what you guys normally do to get the needed height?

Thanks

Dave

Diesel65

So you are saying the coil is sitting on the floor ! it should not be, the correct way to do it is for the coil to sit on a sheetmetal plenum or stand.

Is it a "uplow/downflow, or horizontal coil ? either way you need to get return air in and supply air out.

Some more details would be good.

davidchomes

Hello.

The system is a downflow with the Cased coil sitting on the floor which is over a crawlspace. Supply ducts are in the crawlspace. Return air plenum is coming in from the top. I assume that most would fabricate something from sheetmetal or is there something for this situation already available? Seems that it would need to be fairly beefy with a 21" x 21" 2.5 ton coil and 90,000 btu furnace setting on top.

Diesel65

An angle iron frame the same size as the coil cabinet wrapped with sheetmetal, then line it or wrap it with insulation. (plenum box)

But then I am in South Florida and do not know the codes for your area (or one end of a furnace from the other) LOL, you may be able to build up the sub base with wood frame and line that, but I doubt it.

The other option is to leave it on the floor and install a condensate pump, fairly common with furnace / coil installs I believe.

I think the best bet would be to consult a local HVAC company, this way you are guaranteed to get a safe and code complying install.

Sorry I could not be of more help.

mdshunk

I think the trap weir dimension is much more important than the actual distance of the trap from the coil's drain outlet. I'd prefer to have had the coil installed up off the floor a bit, but since what's done is done, I'd put the trap under the floor in the crawl space. Just do yourself a favor and 90 down through the floor with a capped tee so that you can clean it out once in a while.

davidchomes

Yeah, I will ask my Hvac guy next week. Just thought I would try to get it done this weekend if I could find out how it's normally done if there was a standard way of doing so. I still invision a short "plenum box" being fabricated if a standard box isn't readily available. I was hoping someone would say just use some 2x material and build a box with that. Thats what we all use. But that was just wishfull thinking.

Thanks for the help.

davidchomes

I need an additional 2.5" to get the proper trap/weir dimensions as called for in the manual. It's not installed yet so I can still raise it up as much as I need. My wording in my initial posts did sound as though it was installed, but it isn't. Still roughing it in. I like your suggestion of running it under the floor, which I have done before, however it is not allowed by code and must terminate into a floor drain with a 1" airgap.

Thanks for the help.

mdshunk

What code would that be? Not saying there isn't one, but I'm always curious to learn about this stuff.

davidchomes

Hmmm...good question. I can't cite that paticular code out of the IRC. During my meeting with my HVAC contractor while I was showing him the system design and layout to see if he had anything that he would change, I asked him a few question and one was if the floor drain is still done the way I had it. He responded that the rim of the drain needs to be an inch above the floor and any drain lines draining into need to be 1" above that for the airgap. Thats how I've been doing it for years (except I make it flush with the floor) and never been cited for it, however its possible that there is another way of doing it that I'm not aware of. I will have my rough inspection in a couple of weeks so I will see what the inspector says about it if anything. Now that you have my curiosity up, I need to look at the code and see if I can find that.

I believe the critical part of that code is the airgap. Perhaps if an approved airgap could be provide somehow, you could drain it under the floor. Just not sure what would be allowed.

atlas06

The international mechannical code calls for condensate drain to run to an "approved" place of disposal.
This is local jurisdiction territory, some juridictions wil not allow you to connect any non-metered water into the sanitary (condensate drain and rain are two most common non-metered waters), meaning cond drain must connect to a storm drain or sump pump, or spill on grade.
The rational being that 1) the utility company cannot charge for sewage, 2) the utility company cannot predict its sewage plant capacity.

The air-gap business is typically done for kitchen sinks that I know, not for condensate drainage. Connecting cond drain lines from AC to rain leaders with a hard connection in commercial office space is done all the time.

Now, you may not need a trap at all if you are using a "blow-thru coil" (fan before the coil) instead of a "draw-thru" (fan after the coil). A draw thru fan could pull air from the trap through the condensate drain pan which has still water known to have caused legionnaire's disease. In the case of a blow-thru, no contaminated air is "sucked" into the air stream since the fan will be blowing air thru the trap in case it is empty.

MechanicalDVR

You don't need a trap on a drain with positive pressure. In my area condensate is usually piped to a sump pump or other location that won't put it in to a sanitary sewer.

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