Condensate line question

[Marc M]

I have two FAU's in the attic. Anyone know if the two primary condensate drain lines can be connected together? They are trapped at the FAU and drain into the bathroom sink drain-before the trap.

[Jim Luttrall]

A 3/4 inch drain line is good for up to 20 tons. I don't understand how you would connect two units "in-line" but if you mean two lines joined and then run to the drain, I see nothing wrong with that.

[Marc M]

Roger that...thanks

[A.D. Miller]

WTF is an FAU?

[John Arnold]

WTF is an FAU?
Forced air unit? As in, air handler?

[A.D. Miller]

Forced air unit? As in, air handler?

JA: OIC.:D

[Ron Bibler]

JA: OIC.:D

Bagdad Bob....I.D.U.E....:D

Best

Ron

[A.D. Miller]

Bagdad Bob....I.D.U.E....:D

Best

Ron

RB: IDKTMWIM . . .

[John Goad]

I wouldn't want 2 units on one condensate drain line, particularly if they are equipped with secondary type shut-offs. One blockage shuts off both units. You could also argue that the manufacturer asks for a 3/4 drain on every unit & although there is nothing that expressly prohibits it, I would not consider it a best or even good practice.

[Marc M]

I wouldn't want 2 units on one condensate drain line, particularly if they are equipped with secondary type shut-offs. One blockage shuts off both units. You could also argue that the manufacturer asks for a 3/4 drain on every unit & although there is nothing that expressly prohibits it, I would not consider it a best or even good practice.
John, I feel the same way, just looking for other opinions. Thanks for the input.

[A.D. Miller]

M1411.3.2 Drain pipe materials and sizes. Components of
the condensate disposal system shall be cast iron, galvanized
steel, copper, polybutylene, polyethylene, ABS, CPVC or
PVC pipe or tubing. All components shall be selected for the
pressure and temperature rating of the installation. Condensate
waste and drain line size shall be not less than 3/4-inch (19 mm)
internal diameter and shall not decrease in size from the drain
pan connection to the place of condensate disposal. Where the
drain pipes from more than one unit are manifolded together
for condensate drainage, the pipe or tubing shall be sized in
accordance with an approved method. All horizontal sections
of drain piping shall be installed in uniform alignment at a uniform
slope.

[Bruce Ramsey]

Seems like we discussed this recently but cannot find it so here goes again...

The high efficiency forced air gas furnance has a condensate line. The attached A/C has a condensate line. They are both 3/4" PVC properly sloped away from the unit. About 3 feet from the unit, the two pipes join into a single 3/4" pipe.

The pipes join but do not increase in size. The furance and AC would never be running at the same time so as long as the pipe is adequately sized for a each appliance, then joining them should not make a difference, right???

Instead of two holes in the foundation wall with two pvc pipes dripping on to the backyard, they used one pipe and saved $3 on the ten foot piece of pvc. It just seems wrong.

Whadda ya think?

[David Bell]

The 2 together are fine, when it is in heating mode they are both trapped to maintain system pressure per manufacturers instructions,, in cooling mode only the coil is drained and seperatly trapped so,,no problem.

[kirk mcloren]

I favor a separate line for each unit. I saw an AC in Palm Desert Ca with a plugged 3/4 condensate drain from a jello like bacterial substance. Carpet around air handler was soaked because the water had no place to go.
Just when you think you have seen it all.

[Clifford Mark]

Hey guys,

In Texas we always call an exterior primary condensate drain line installation 'deficient' if not extended at least 36 inches straight out from the foundation. At a recent seminar, a fellow inspector was told this 36" requjirement is not in 'the code.' It seems to be rather common practice to keep moisture out from under the clay-dominated soils we have in many Texas locales. Is it part of the mechanical code, an advisory matter, a common practice thing, a practical recommendation that has become a standard (like common law) or is it just a HI myth?

Cliff

[Jerry Peck]

Hey guys,

In Texas we always call an exterior primary condensate drain line installation 'deficient' if not extended at least 36 inches straight out from the foundation. At a recent seminar, a fellow inspector was told this 36" requirement is not in 'the code.' It seems to be rather common practice to keep moisture out from under the clay-dominated soils we have in many Texas locales. Is it part of the mechanical code, an advisory matter, a common practice thing, a practical recommendation that has become a standard (like common law) or is it just a HI myth?

Cliff

Cliff,

Not in the IRC, it could possibly be like the Florida Building Code, Residential in that the condensate drain line is required to discharge a minimum of 1 foot from the foundation, not because of expansive soils, but because of protection from termites.

Not sure if Texas has something like that or not, but from past information on codes in Texas, Texas uses the IRC, so the answer would likely be 'No, there is no code requirement for that, but ... there may well be a local requirement or soil engineering requirement for that because of the expansive soil.'

[Rick Hill]

If your FAU's are 90% furnaces your condesate is acidic in winter. You do not want it coming in contact with your cement foundation as it will eat away at it.

[Mike Schulz]

I don't think the water is acidic for it would eat away at the coil. It has metallic properties and will kill the grass. Has anyone ever tested the water ?
The common practice is to get it away from the foundation because it can produce several gallons a day and saturating the soils at that location causing uneven soil bearing from the dry soil areas. For instance clay would be expanded at that location.

[Binford Tools]

I don't think the water is acidic for it would eat away at the coil. It has metallic properties and will kill the grass. Has anyone ever tested the water ?
The common practice is to get it away from the foundation because it can produce several gallons a day and saturating the soils at that location causing uneven soil bearing from the dry soil areas. For instance clay would be expanded at that location.

The water coming out the furnace is it is slightly acidic. The water comming off the A/C coils in the summer is not. The code here has changed and they don't want the furnace water in the sewer drain. They like it to go into the flower beds.

[David Bell]

Condensing furnaces typically have a PH of 3.5 to 3.8 which is only slightly more acidic than beer, tho I try not to pour that down the sink either, it is not because I am afraid of rotting anything but my liver. (tongue planted firmly in cheek)