Tankless water heater condensation drain connected to AC condensation drain.

[Gene South]

The condensation drain from this attic mounted tankless water heater connects to the main condensation drain of a nearby attic mounted HVAC unit. The HVAC had two drains, the main drain, and the secondary drain connected to the HVAC drip pan. The water heater drain was connected to the HVAC main drain line.

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[Jim Robinson]

I'd probably check the manual to see if it mentions having to use its own drain, but I wouldn't think it would be a problem. If nothing in their book about it, I don't think I would mention it. The drain is supposed to have water in it, so no problems there that I can see.

[Gene South]

Thanks Jim,

Gene

[Lon Henderson]

#7 is the requirement that doesn't seem satisfied by that installation.

504.6 Requirements for discharge piping.
The discharge piping serving a pressure relief valve, temperature relief valve or combination thereof shall:

1. Not be directly connected to the drainage system.2. Discharge through an air gap located in the same room as the water heater.3. Not be smaller than the diameter of the outlet of the valve served and shall discharge full size to the air gap.4. Serve a single relief device and shall not connect to piping serving any other relief device or equipment.5. Discharge to the floor, to the pan serving the water heater or storage tank, to a waste receptor or to the outdoors.6. Discharge in a manner that does not cause personal injury or structural damage.7. Discharge to a termination point that is readily observable by the building occupants.
8. Not be trapped.9. Be installed so as to flow by gravity.10. Not terminate more than 6 inches (152 mm) above the floor or waste receptor.
11. Not have a threaded connection at the end of such piping.12. Not have valves or tee fittings.13. Be constructed of those materials listed in Section 605.4 or materials tested, rated and approved for such use in accordance with ASME A112.4.1.

[Gene South]

#7 is the requirement that doesn't seem satisfied by that installation.

504.6 Requirements for discharge piping.
The discharge piping serving a pressure relief valve, temperature relief valve or combination thereof shall:

1. Not be directly connected to the drainage system.2. Discharge through an air gap located in the same room as the water heater.3. Not be smaller than the diameter of the outlet of the valve served and shall discharge full size to the air gap.4. Serve a single relief device and shall not connect to piping serving any other relief device or equipment.5. Discharge to the floor, to the pan serving the water heater or storage tank, to a waste receptor or to the outdoors.6. Discharge in a manner that does not cause personal injury or structural damage.7. Discharge to a termination point that is readily observable by the building occupants.
8. Not be trapped.9. Be installed so as to flow by gravity.10. Not terminate more than 6 inches (152 mm) above the floor or waste receptor.
11. Not have a threaded connection at the end of such piping.12. Not have valves or tee fittings.13. Be constructed of those materials listed in Section 605.4 or materials tested, rated and approved for such use in accordance with ASME A112.4.1.

Hi Lon, I am referring to a tankless water heater condensation drain, with a dribble of water coming from it, not a TPR drain. The water heater condensation drain is connected to the cooling system condensation drain.

[David Miller]

Hi Lon, I am referring to a tankless water heater condensation drain, with a dribble of water coming from it, not a TPR drain. The water heater condensation drain is connected to the cooling system condensation drain.

I do not see an issue with the tankless water heater sharing a condensation drain with another appliance. However, the TPR valve extension as it appears to be plumbed is a code violation. As stated in #7 it must terminate in a location that is viewable to the occupant. Also, here in Illinois, plastic is not an approved material for the TPR valve extension.

[Gunnar Alquist]

I think I see what is going on with the responses. David and Lon both saw the PVC drain line on the TPRV and were mentioning it as an aside, not an answer to Gene's question. I assume Gene saw and reported it.

I know of no problem sharing a primary condensation line, as long as there aren't a whole bunch of appliances draining into it. Obviously, the secondary condensation line and the TPRV discharge line have to be separate.

But, you knew that. :cool:

[Gene South]

I think I see what is going on with the responses. David and Lon both saw the PVC drain line on the TPRV and were mentioning it as an aside, not an answer to Gene's question. I assume Gene saw and reported it.

I know of no problem sharing a primary condensation line, as long as there aren't a whole bunch of appliances draining into it. Obviously, the secondary condensation line and the TPRV discharge line have to be separate.

But, you knew that. :cool:


Thanks guys, BTW... that water heater TPR drain is CPCV (not PVC). It terminates to an outside location that is viewable to the home occupants, provided they are outside of course. CPCV is a common TPR drain material here in Texas and attic water heaters commonly terminate to outside of the house.

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I think I see what is going on with the responses. David and Lon both saw the PVC drain line on the TPRV and were mentioning it as an aside, not an answer to Gene's question. I assume Gene saw and reported it.

I know of no problem sharing a primary condensation line, as long as there aren't a whole bunch of appliances draining into it. Obviously, the secondary condensation line and the TPRV discharge line have to be separate.

But, you knew that. :cool:


Thanks guys, BTW... that water heater TPR drain is CPVC (not PVC). It terminates to an outside location that is viewable to the home occupants, provided they are outside of course. CPVC is a common TPR drain material here in Texas and attic water heaters commonly terminate to outside of the house.

[Glynn Penn]

Gene, Not a good idea, when do you know if the T&P valve is leaking, also as you know the
T&P line exits 6 inches above ground pointing down, his puts moisture in soil at one spot, not a
good idea in North Texas.

[Jim Luttrall]

Gene, Not a good idea, when do you know if the T&P valve is leaking, also as you know the
T&P line exits 6 inches above ground pointing down, his puts moisture in soil at one spot, not a
good idea in North Texas.

GLYNN, I think you misunderstood, the CONDENSATION drain, not TPR is tied to the existing condensation a/c drain. This question has nothing to do with the TPR as Gene said, it is correct for our area's AHJ's.