I will be replacing my water heater soon and want to get two clarifications.

First, is the only issue with the current gas line that a sediment trap is missing or is there anything else that needs to be done to bring it up to code?

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My second question would be the piping for the T&P and what our the options. I have read the wording in the code, but I am unclear what should be done in a finished basement with limits options for draining. This is the setup that is currently there. The pipe exits the utility room and run behind the wall before dropping into our drain.

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  • 1
    I take it there is no floor drain or sump anywhere near the water heater that the T&P could discharge to? Jan 22, 2020 at 3:40
  • You are correct. Obviously, I would like to have a drip pan as well, but I am not sure how I could do that either.
    – junta
    Jan 23, 2020 at 2:31

1 Answer 1


All backed up

The primary problem with your setup is that what you have right now is a sanitary hazard, as there is no air gap preventing sewage from backing up into the T&P discharge line. A standard water-softener or standpipe type air gap fitting can be used for this task, though, and is inexpensively available wherever plumbing supplies are sold.

The rest of the setup, though, is OK; the cellular core ABS pipe is fine since it's downstream of the standpipe, and discharging T&P relief water to a standpipe via an air gap is an acceptable means of T&P discharge, as per IRC P2804.6.1 point 5 which permits discharge of T&P relief water to a "waste receptor", which by Code can be a hub drain, standpipe, floor/mop sink, or floor drain.

  • So installing something like this would solve the air gap issue? amazon.com/Softener-Air-Gap-Installation-Machine/dp/B01ENNXB1E/…
    – junta
    Jan 24, 2020 at 15:55
  • @junta I'd use something like this instead: amazon.com/Plumb-Pak-PP855-69-Standpipes-Grey/dp/B00FKJNVAC/… Jan 25, 2020 at 1:29
  • What would my best option be to connect the copper to the air gap without reducing the pipe? Also, the ABS runs from my boiler before connecting to the hot water heater. The boiler relief valve is setup the same way as the hot water heater. Could this system be setup the same way with the air gap you recommend?
    – junta
    Feb 6, 2020 at 4:30
  • @junta -- look for a standpipe-gap fitting that can work with the incoming pipe size you have, and yes, I would do the same thing for the boiler relief valve, presuming it's a hydronic boiler OFC. Feb 6, 2020 at 4:50

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