Cat IV furnace and AC sharing same condensate line

[hausdok]

Hi All,

This is for you guys who regularly see AC systems. I've got a condensate line from a Cat IV furnace joined to to a trapped condensate line from an A-coil downstream from the trap.

I seem to recall some kind of prohibition against using the same drain for condensate from both a Cat IV furnace and an AC A-coil unless there is an air gap between the two. Did I imagine that or is there an actual prohibition? I've been digging around but I can't seem to find it. Does it ring a bell with anyone?

ONE TEAM - ONE FIGHT!!!

Mike

[Richard Moore]

No ringing bells, or code, but if the connection is made below the outlets at both the AC and furnace, so that there's no way for condensate from one to feed into the other, I don't see how it could cause any problems. It's not like they are both going to be running and creating condensate at the same time.

OK...one scenario, I suppose, would be if the termination froze up and then furnace condensate might be forced into the AC? Seems a bit unlikely, but I can see how an air-gap would prevent that.

I'm really not helping at all, am I? [:-paperba

Anyway...got a picture of the set-up? We are taking about a gravity feed from the furnace and not a pump, right?

[Terence McCann]

Refer to pick Mike.

The way mine is piped. It has to open to atmosphere so the line does not become pressurizied when the trap for the evap dries out (even though it is open to the drain). My furnace is a counterflow so the evap sits below the furnace.

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[hausdok]

Hi Terry,

Yeah, that's exactly how this one is done. I always thought there was supposed to be a separation where that furnace drain meets the evaporator drain. Guess not.

ONE TEAM - ONE FIGHT!!!

Mike

[Terence McCann]

I uploaded a Trane Upflow/ Horizontal Gas-Fired, Direct Vent

Condensing Furnaces Install Guide to the library Mike. Take a look.

One thing is odd in the piping diagram, they don't show a trap for the evap condensate line and it should have one.

[hausdok]

Hi Terry,

Thanks, I probably should have gone directly to the evap coil manufacturer's site to see what they say; but this is something that's going to apply to just about any of these and I needed to get it right in my mind so that I can retain it properly.

Sometimes, when stuff isn't my normal inspection fare, I only retain part of what I read about it here. Then, when I eventually run into it in the rare situation, such as this one, I end up cussing myself out for not being more interested in the thread where that issue had been discussed.

I appreciate the help.

ONE TEAM - ONE FIGHT!!!

Mike

[Marc]

That answer should be in the plumbing codes for your area, specifically the locations where an indirect waste receptor is required. I'm betting that if the waste connection is indirect and that the indirect connection is not in a closet or in a room serving a toilet fixture, there's no issue with the two of them being joined in that fashion.

FWIW.

Marc

[hausdok]

That answer should be in the plumbing codes for your area, specifically the locations where an indirect waste receptor is required. I'm betting that if the waste connection is indirect and that the indirect connection is not in a closet or in a room serving a toilet fixture, there's no issue with the two of them being joined in that fashion.

FWIW.

Marc

Hi,

Well, I don't know about your area, but around here the only time that AC or furnace condensate is discharged into a "waste" drain is when it's in a basement below grade level. They almost universally discharge condensate outside onto grade around here.

ONE TEAM - ONE FIGHT!!!

Mike

[Terence McCann]

Well, I don't know about your area, but around here the only time that AC or furnace condensate is discharged into a "waste" drain is when it's in a basement below grade level. They almost universally discharge condensate outside onto grade around here.

ONE TEAM - ONE FIGHT!!!

Mike

The condensate for an AC is one thing but to discharge waste from a condensing furnace onto the lawn doesn't seem kosher. ? It is, after all, acidic waste water that should be treated before going back into the food chain - n'est-ce pas?

[hausdok]

Well, I don't know about your area, but around here the only time that AC or furnace condensate is discharged into a "waste" drain is when it's in a basement below grade level. They almost universally discharge condensate outside onto grade around here.

ONE TEAM - ONE FIGHT!!!

Mike

The condensate for an AC is one thing but to discharge waste from a condensing furnace onto the lawn doesn't seem kosher. ? It is, after all, acidic waste water that should be treated before going back into the food chain - n'est-ce pas?

Hi Terry,

Yeah, I know it's acidic but I don't know how it will affect soil. Acid is, after all just water with a different PH level, isn't it? Anyway, for a lot of years, when people have expressed concern for the fact that condensate is acidic I've simply told them to take a small plastic coffee container, punch a bunch of holes in the bottom with an ice pick, fill it with marble chips and then sink it into the ground where the condensate hits the ground. It's my understanding that the marble chips neutralize the acidity somehow.

ONE TEAM - ONE FIGHT!!!

Mike

P.S.

Kind of ironic hearing about concerns with acidity in furnace condensate coming from someone who lives pretty near ground zero of the acid rain wars between the US and Canada. []

[Terence McCann]

Kind of ironic hearing about concerns with acidity in furnace condensate coming from someone who lives pretty near ground zero of the acid rain wars between the US and Canada. []

HA!

Yepper - we're ground zero for a lot of things - rivers that burn, acid rain to name a few.

I only put motor oil in my garage floor drain though []