AHJ's opinion differs from code...how would you write it up?

This is a continuing story from this thread.

I sent an e-mail to the head of the city plumbing dept. regarding this install being improper. I got a response today saying that the city does indeed allow this and it is widely accepted in installations below grade (this is in a basement). Although I disagree, they are the AHJ, at least in the city limits.

How would you guys write up something like this? Would you say the installation is improper, but the AHJ says it is OK? Or would you just say the installation meets their approval? I’ve just never had to deal with a city official saying something is right when the code says it isn’t.

I have saved a copy of the e-mail in my files in case it is needed in the future.

I just want some other opinions on this, and any stories out there regarding other’s battles with AHJ’s.

Try this. I’ve used similar verbage for other situations like this. . .

The drainline for the water heater TPR valve drains uphill. Although this application may have been approved by this jurisdiction, you should be aware that this set-up is not recognized by California Building Officials as an approved method for discharging of the water heater TPR valve. This set-up could also prevent the TPR valve from proper operation, which would be a significant safety hazard, and we recommend that it be modified to conform to Nationally recognized standards.

Tweak this how you wish, but the information should be clear;

  1. It’s installation is contrary to California Building Standards
  2. We unequivocally recommend that it be changed
  3. It could become a significant safety hazard

Thanks Jeff. That’s a good way of wording it without using the “C” word.

I told the city inspector that he was wrong, and showed him the code reference, but it just went in one ear and out the other.

The manufacturer’s installation instructions would be handy also. :wink:


Like your verbage, but I have a question:mrgreen:

What exactly is wrong with the TPRV flowing up hill? I know the code says it shouldn’t be plumbed that way, but I’ve never understood why it shouldn’t be plumbed that way.

The way I understand it this valve is here for the rare occurrence when the water heater overheats and creates excess pressure inside the tank, right?

If that is the only purpose of the valve, then one would think that the excess pressure would send the water/steam up hill just thru the pipes, no?

Not trying to start a fight, just never understood that particular requirement.

– bz

The way I understand it, if the valve leaks, even a little bit, and the moisture can’t drain out, then the inside of the pipe could corrode, which would block the pipe.

To expand on Joe’s response. . .

It’s certainly possible that the pipe could become obstructed to the point where the relief valve couldn’t discharge. But more to the point, the valve itself can easily become corroded to the point that it may fail to operate.

You also lose any advanced warning of a potential problem. With an uphill drain, you will not notice if the valve is leaking. A leaking valve could indicate that the heater is over-heating.

The piping should not be installed in a manner where discharge could go unnoticed.

Exactly what I wanted to know. Thanks!

If the discharge pipe for a TPRV is pitched uphill… It becomes problematic if the TPRV develops a leak… Water accumulates in the ‘downhill’ side of the pipe (essentially a water trap)… If the TPRV were to open due to excessive pressure in the water heater, the escaping pressurized water would slam into the ‘trapped’ water with exploding consequences… It’s the equivalent of driving into a concrete wall… Glenn

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In addition to the above information, a TPRV drain line that slopes up hill will fill with water, which will act to restrict the flow of steam through it. Those valves and drain lines need to move a lot of heat through them in a short period of time in order to do their job. The trapped water reduces the rate at which they can relieve the pressure.