High efficiency furnace condensate disposal [2003 IRC]

[TimNY]

Hi All,

Curious as to what is being done for condensate disposal-- in particular, I have combo AC/heat units installed in attics in freezing weather. Presumably they are creating condensate year-round, so I would accept connection to the DWV system.

I see G2427.9, which can get you to G2427.8(4).

Is there a section that requires indirect connection? I see the commentary on receptors references condensate, but I don't see where condensate is required to drain through an indirect connection. Would compliance with the 2" provision in the trap section facilitate a direct connection?

What about neutralizing condensate-- has anybody had scenarios where this is required? I have seen it run through marble chips, but I don't find anything to require this.

Furnace manufacturers instructions for condensate disposal are two sentences.

Thanks for your help,

Tim

 

[klarenbeek]

check in the plumbing code. There is nothing in the mechanical code about indirect drains, but at least in our jurisdiction (odd situation, uniform plumbing code but international mechanical code) the plumbing code requires indirect drains for condensate. Any way of getting the drain down to a sink on the floor below, dumping it into a tailpeice on it? Definitely heat tape on the drain line in the attic, though.

 

[TimNY]

Thanks for the reply. No way to do anything with a sink that looks acceptable (residence). I will look into the P sections of the Residential Code and see if I can find anything in there. I don't have a preference one way or the other, I just noted that the commentary for the residential code mentions condensate in relation to the indirect drains. Just wanted to make sure I haven't missed anything.

Direct connection is looking okay otherwise. But I will check.

 

[klarenbeek]

Is ther a place a drain could be run down to a drain in the basement? I've seen a few jobs where the contractor found a closet he could tuck a 3/4" drain in a corner from the attic down through the closet into the basement. I even had one where the contractor fished 3/4" pvc and refrigerant linesets from the attic down a wall 2 floors to the basement (old home with no fireblocking in the walls)

 

[TimNY]

I would definitely prefer to see it ran like that, but at this point I don't see anything to prohibit the installation. There is a prohibition on running waste in unconditioned space, but heat tape would handle that. Realistically I think the condensate would not freeze to begin with, but gotta do what the code says.

 

[mtlogcabin]

I think the condensate would not freeze to begin with, but gotta do what the code says.

Isn't the condensate trapped? Is the trap located where it might freeze.

We have a lot of condensate drains discharge thru a condensate pump into the washing machine stand pipe.

 

[TimNY]

Yes, condensate is trapped, and it is in an unconditioned attic, and therefore is subject to freezing. My personal opinion is that it won't freeze, but it's just that-- my opinion.

 

[Francis Vineyard]

Tim,

The condensing gas furnace has an integral trap. There are specific installation requirements listed in the manufacturers installation guide. For example it may instruct when discharging into the evaporator condensation drain it must be down stream of the condensation trap. There may be additional instructions for adding winterizing anti-freeze into the condensing trap. It usually instructs where and how this condensation may be disposed.

See M1411.3 for evaporator condensation disposal.

Neutralizing may be an issue where a large amount of fluid is being discharged into a septic system or the sewage plant is not able to efficiently treat the volume, this is a local provision.

P2601.1 allows you to go to IPC 314.1 which states that this condensation may be discharged to an approved plumbing fixture; this is not a direct connection to the DWV. The plumbing code addresses the direct connection of plumbing fixtures, appliances and appurtenance, which this gas furnace is not by the plumbing definitions. Other waste may be indirectly discharge into the sewer systems as approved by the code or AHJ.

Per P2603.6, 2706.1 & P3301.2; Check your area to protect against freezing if there are 4,000 or more ‘heating degree days’ reference in the IPC. Suffice to say the reason this condensation occurs because there is not enough heat in the exhaust to carry the moisture outside, so it can freeze. Don’t know if this is reference in the UPC.

It takes some time to thoroughly read all of the manufacturer’s installation materials but after a couple of times you may learn exactly where to find this information with different manufacturers.

 

[peach]

probably needs to be indirect.. with a flow switch that alerts the occupants that "we have a problem Houston"..

 

[TimNY]

Francis,

Thanks for all the info. I have looked through about 10 different manuals for Amana and they are lacking to say the least. Some models say don't trap as there is an internal trap (as you said).

"Appliance, Fuel-Fired" includes furnaces. P3001.1 would then kick in.

@peach- the installer did install a separate secondary line which dumps through the soffit. I think the switch would be a better solution in freezing space, but as long as the line is heat-taped I don't see an issue.

 

[Francis Vineyard]

This is typical of installation manuals;

"The condensate which is generated must be piped to an appropriate

drain location"

http://www.djsonline.com/amv9ownersmanual.pdf

 

[TimNY]

This is typical of installation manuals;"The condensate which is generated must be piped to an appropriate

drain location"

http://www.djsonline.com/amv9ownersmanual.pdf

Francis,

Yes, that's pretty much what I found. Some of the Amana manuals instruct not to install another trap as the unit is internally trapped. Also was a note regarding interconnection of A/C condensate drain requiring an open tee to account for pressure.

It seems to me that the actual disposal of the condensate is not mandated by he manufacturer (other than "appropriate" or pursuant to the local jurisdiction). Which would lead me back to the IRC. A furnace being an appliance it could be connected to the DWV.

While googling I read something about fear of methane gas traveling back through the condensate line into the furnace-- not sure if that is a bona fide concern.

I would like to see an indirect disposal method, but I can't see making them replace what they have-- if there is nothing prohibiting it.

 

[BSSTG]

Greetings,

I had a new system put in a year ago and it was put in improperly. It did about 5K in damage to my house. There was a malfunction with the condensate gizmo within the unit and there was no overflow pan installed underneath per man specs. As a building inspector you would think I would have caught it myself but didn't. I didn't even know that it is not unusual for these systems to generate a gallon or 2 per day of condensate. That said the man specs doesn't require specifice guidlines for condensate removal, only the requirement of a pan. Go figure. End result is that the pan was installed, condensate will be run to the DWV system prior to being run again. Contractor ( being not too good apparently), and after having to make a sizeable insurance claim, would only do exactly what the specs called for which is really messed up. They did put in a pan with a hi level limit, but they drained the condensate into the pan which to me is really stupid. I will be redoing in myself similarly to the condenser setup. By the way, there is some type of internal trap device on this system and that is what was leaking to begin with. It's a Lennox too I might add.

I inspected one yesterday and the contractor and when I questioned the lack real condensate drain and only a pan with a limit he too showed me specs as that was what is required. I think I am going to amend our local ordinance to alleviate that as it is a pile of crap as far as I'm concerned.

Byron

 

[TimNY]

BSSTG sorry to hear about the damage.

I did a final on a really nice house (complete with billiard room, home theater etc). Attic access was via a hatch. I asked the contractor for a ladder and he responded, "why?" I say "i need to check insulation, wiring, and make sure the air handler has the required pan under it"

"It does now," he responds, "it leaked about two weeks ago and we had to replace the ceiling and moldings. I wish you were here a month ago!"

Anyway, M1411.3 has condensate disposal covered. The condensate must be drained to an "approved location". AHJ will determine the approved location. You must have two separate drains OR a float switch in the pan and one drain.

 

[peach]

Personally, I don't like attic installations.. no one (read home owner) ever gives them a second thought. A float switch to shut the system down is the best way to get their attention. "dang, honey, it's awfully hot in here"...

 

[TimNY]

I spoke with the homeowner a few days ago. His wife went into the spare bedroom to find the ceiling ruined.

I'm not really sure what happened since it was piped into the DWV and the pan had a secondary drain into the soffit.

I did come out looking like a rockstar even though I have no idea why it happened. I am told the drain to the DVW was repiped. I have to got see what they did.