Water heater plumbing

[billrd01]

Is it advisable to install a shutoff valve in both lines at the water heater ?

Thanks,

Bill

[majakdragon]

Bill,
This is a personal opinion. Even though you can stop the hot water by turning off the cold water supply, there are times you want to turn off both lines. If your hot lines go to upstairs fixtures and you don't want to drain them all the way down to do maintenance on the heater, then a valve in the hot water line is useful. I put them in all the water heaters I install for my own use. Cost is the reason they are not put in during construction. I always use brass ball valves. It is really a decision that you have to make after thinking about if it will benefit you later. Good luck.

[Ed Imeduc]

Id say stay with just one on the cold water is all. if the units is in the basement might look into the flow check valves to go on the top of the tank. This way the hot water cant come out and up in the cold water lines are hot water lines till you turn the water on some where in the home. They also have copper loop traps that will do the same thing for you . Go right on top of the tank in the water lines.

ED ;)

[lefty]

Ed Imeduc and majakdragon are both right, even if they DO disagree!!

You have to look at the installation.

Like majakdragon said, if the WH is at a lower floor than the valves (sink, shower, tub, whatever), then a shut off on the hot side MAY be useful. It's not something you'll need more than once in a blue moon, but it MAY be handy if it's there. and cost during initial construction is why you won't find them.

The check valves that Ed is suggesting work just as well -- but 1 ball valve is quicker and cheaper to install than 3 or 4 check valves!! Either way, it will keep the water from draining back into the WH on that rare occasion where you don't want it to.

[DUNBAR PLUMBER]

Plumbing inspectors in my area will not pass a shutoff on hot side.


Imagine this scenario:

Homeowner doesn't have a clue what is wrong with his electric water heater.
He/She notices extremely hot water.......goes and start shutting off valves to the heater.


Goes to the panel and shuts off the wrong breaker.......heater continues to generate temperature and pressure.....and years of corrosion has the T&P closed shut.


You now have a pressure cooker with no release whatsoever.


The inspector's point of view is this: the possibility of someone opening a valve at any fixture is greater than someone realizing that both valves are shut off at the tank with no pressure relief until there is an explosion.


I know that sounds dramatic........but I know all of us plumbers in here has pulled out a closed up T&P valve.......with no chance of pressure or temperature enough to open it.


I can post pictures of water heater explosions if I look hard enough..........but not just because of dual valves...............numerous situations can cause this situation.

Water heaters scare me the most in installations.........the fear of something going wrong with the heater and turning into a bomb in the basement.

[billrd01]

I am putting in a valve in the cold inlet. Something about shutting off the hot water with the heater active somehow bothers me even though I have a T&P valve installed The elec water heater is inside a small one story house.

Thanks again.

[rav12]

I think that the view on not having a shut off on the hot side is subjective. I cannot see how it makes the install more dangerous. If the water heater keeps heating due to the failure of the thermostat or for some other reason and the T&P valve is stuck shut the heater is going to explode if the energy cannot be released in any other way. One is assuming the homeowner happens to be in at this time and is going to open something to relieve the pressure but not see the dangers of leaving the hot side valve closed.

Unless this does happen for real and has been documented through studies I don't think is a good argument for not having such a shutoff. Maybe there is proof that this is the case though - maybe I'm not correct in assuming this.

Better protection on the water heater should be the solution to prevent overheating. I have a 240FX tankless that uses a thermal fuse which melts in the event of the thermostat and hi-limit fail. If for some reason even the thermal fuse fails the T&P valve is still there. Of course tankless heater are not anywhere as dangerous as tanks in terms explosions since the water is only the water in the pipes around the heat exchanger and only a few cupfuls in quantity.

Another possibilty is the use of a second PRV in addition to the main T&P valve for redundancy.

[majakdragon]

This thread turned out very well. Different opinions, different reasons and all valid in their own right. This is why I like DIY so much.