I have a standpipe drain (2 in diameter) used for the clothes washer drain. The standpipe is right next the water heater.
We want to replace the old electric water heater with a hybrid electric heat pump water heater, which requires a drain for the condensation.

Is it OK to use the same standpipe drain, or are there restrictions about sharing a standpipe?

Thank you!

you are a GO for the shared standpipe

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

just stick it right into the standpipe.. no problem..
if it won't fit, use a 3 x 2 reducing coupling, upside down like a funnel..

probably code to have air gap

I don't know why. There is no connection to a potable water source.

hj I believe NP16 is referring to the standpipe having the ability to accept waste water that is being pumped from the washer and that enough air must be available or it will overflow. The height and 2" diameter accommodates the flow from the pump. You are right, it is not an air gap as needed in a potable water system.



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quote; enough air must be available or it will overflow.

Never heard of that happening.

hj you are kidding, right?

NOPE! In fact, preventing a drain from aspirating air, is often the goal so the pipe fills with water and NOT air.



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If I understand you, actually that is the purpose of the vent, to keep the drainage from being air locked.

Yes, but AS THE WATER STARTS TO FLOW and AFTER IT STOPS. Not while it is flowing. Anti-vortex drains are designed to limit the amount of air "sucked into" the pipe during flow.