Replacing Gas WH Questions

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hj

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quote; The current T/P line is 3/4". City code says that the drain pan line must be 1".

YES they should be separate, and since your T&P line is 3/4", you could not use it for the pan drain anyway according to your code.
 

Nukeman

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If you could use the 3/4" line for the pan, I might use that for the pan and perhaps route the T&P with a connection to the washer drain (w/ trap and using air gap) assuming that the area is unfinished (this assumes not being able to run both lines outside).

I totally agree with hj. Although the T&P may not release much if opened, it could release a lot depending on why it lifted and if anything caused it to stick. Even with a 1" connection, you won't likely be able to keep the pan from overfilling if the T&P stays open for more than a brief burst. The T&P is often large enough to carry the full flow capacity from your incoming water supply. If you imagined cutting the main water line coming into the house, you will realize just the amount of water that could be coming from the T&P. The best situation is to play it safe and run a second line to outside.

The pan is really only designed to collect small leaks from the WH and won't help much if things go really bad.
 
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Sjm133

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Alright. Here's the official word from the city.

The two lines, drain pan and T&P valve, can only be connected together if they are run with 1 1/2" lines. Otherwise, either 1) run them separately, 3/4" for T&P and 1" for drain pan or 2) this one really gets me, simply plug the drain line for the pan so you'll be able to see any water gathering in the pan and connect the T&P to the existing line. So the city says I have to have a pan but it doesn't have to go anywhere. Hmmmm.

So I guess my plan will be to connect my new T&P line to the existing 3/4" outside drain and run a new 1" line behind the washer against the wall and put a new hole in the outside wall and run it out.
 

Nukeman

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If you are allowed to have just the pan (without it connected to anything), you could install a water detection type alarm in the pan that would alert you if anything went wrong. Also, sometimes for A/C units, they will install a float switch in the safety pan and causes the unit to kick off when it fills with water (the idea is that you will then check the unit to see what is going on and see the full pan). You might be able to do something similar? Not sure if that would be worth it, though.

With the drain line to outside, the only thing that I don't like is it makes a nice path for hot/humid air to come in during the summer and cold air in the winter. Also makes for a nice path for insects to come in. You could add a trap to take care of these issues, but the trap would dry out if you didn't add water from time-to-time (or install a trap primer).

Since it is in the laundry area, at least the pan could be inpected fairly often (whenever you run a load). Hopefully, a small leak would be noticed before it became a bigger leak. Even with the pan + 1" drain, you won't be saved if the leak is really big (like a rupture of the tank). Because of the location of the WH, I would be inclined to just cap the pan and install an alarm. That should cover you most of the time. If you were gone on vacation and were worried about it, you could turn off the water/gas while away. If the tank was somewhere where you didn't see it often (attic, crawlspace, closet, etc.), I would try to run the line outside or an indirect waste receptor.

Here, we have to run the pan with 3/4" minimum piping.

This isn't for AL, but should be fairly close (see Chapter 5):

https://www2.iccsafe.org/states/Virginia/Plumbing/Plumbing_Frameset.html
 

Jadnashua

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The WAGS valve is exactly what Nukeman brought up after my earlier post. It triggers upon detecting water in the pan, shuts off the incoming water and disables the gas valve so the WH stops heating. Well, it doesn't have an alarm on it, but you could use the switch in it to trigger an alarm rather than shut the gas valve control off.
 
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