Slab Leak, Water Heater Shut Off

[WFox93]

Hey everyone. Maybe I'm just being paranoid here but I'd like some confirmation. Been reading articles for hours and can't seem to find my case replicated.

I currently have a slab leak in a hot water pipe and its bad enough to seep through the floor so I've got the hot water outlet (I have two shut off valves on my heater) turned off and heater set to pilot. Cold inlet is open.

problem is, its the dead of winter and my ground water is about 40 degrees Fahrenheit. I'd like to keep the water in the tank hot so I can open the valve as needed for showers but keep it closed most of the time until the plumber shows up tomorrow.

Does leaving the heater on, cold inlet open, hot outlet closed pose a risk of explosion? My thoughts on this is that it is no different than having all the faucets in the house off.

Thank you for your time and advice.

 

[Phog]

Have you tested your T&P relief valve to make sure it's functioning correctly?

 

[Sponsor]

 

[HudsonDIY]

There are two possible scenarios.

#1 You have a backflow preventer to keep water from backing up into the municipal system in which case you should have a thermal expansion tank which would handle any expansion from the WH. It should be easy to spot, looks kind of like an upside-down mini keg with a tire fill valve on the top.

#2 You don't have a backflow preventer in which case the water should expand back up into the municipal system.

In either case, as phog mentioned, the relief valve should prevent any catastrophes. This is a good time to test it.

 

[Master Plumber Mark]

You guys are funny boys......

Just shut off the COLD water coming into the heater and leave the heat on to the heater.
only a minor amount of water will ever leave the heater as it heats up and probably will not
be noticed at all and pressure is not gonna build up cause it is slightly pissing out of the floor leak...
So Keep the heater hot, nothing is going to blow up or cause you any more damage
than you already have....

turn on the cold water when you want to take your shower
and take a fast shower and turn it off again asap....

you can limp by for weeks if you had to if the plumbers price is too high....





....

 

[WorthFlorida]

In other words leave the power on to the water heater but close both the cold & hot valves (you have a rare valve on the hot output). Open a hot water faucet for a few seconds to relieve the pressure to minimize the leak. Keeping the hot output side open and someone uses a faucet for warm water, the cold water side pressure will back flow to the water heater and you still will have a leak with pressure behind it.

 

[Master Plumber Mark]

In other words leave the power on to the water heater but close both the cold & hot valves (you have a rare valve on the hot output). Open a hot water faucet for a few seconds to relieve the pressure to minimize the leak. Keeping the hot output side open and someone uses a faucet for warm water, the cold water side pressure will back flow to the water heater and you still will have a leak with pressure behind it.

If you have pressure balanced faucets the cold side could jump across the valve cartridge and leak through the hot side.....
if that is the case just turn off the whole house and leave it off and use it only when needed until the system is
repaired...

its just like the old days when you had to go down to the well and get water......
just keep heating the water in the heater , it wont hurt anything