Pressure Relief valve

[jnlombard]

Hi,

Found a Hot Water tank without a Pressure Relief Valve. (PRV) during an inspection.

Do some Hot water tank designs not need a PRV??

[randynavarro]

Well, I'll CMA (Cover My A_ _) and say I haven't read all the mfg's specs in the world so I guess there might be some possiblity but. . .

. . . common sense and knowing what happens to water when it overheats says absolutely. Otherwise, you can have a rocket (or bomb depending on your perspective) on your hands.

[ozofprev]

Doesn't seem possible. Heat -> expansion -> big bang. TPR is required and is a serious concern if missing.

Hi,

Found a Hot Water tank without a Pressure Relief Valve. (PRV) during an inspection.

Do some Hot water tank designs not need a PRV??

[Neal Lewis]

Some real old water heaters did not have an opening for a relief valve. The valve was installed on the hot water piping near the tank. Same goes for old boilers.

[Chad Fabry]

Indirect units can be protected by the boiler pressure relief.

[ozofprev]

So, Jan,

What type of water heater is it? We want to know.

[hausdok]

Hi,

Was it in a basement? If so, did you look for a Watts 210 valve someplace?

OT - OF!!!

M.

[Neal Lewis]

Chad,

Do you mean a tankless coil type or an indirect like a Boilermate/Amtrol type.

The indirects I've seen all have a relief valve.

[Les]

Pretty interesting question!

When I think about it, I have seen hundreds of water heaters with just a pressure relief; blow plugs, dole valves, etc. All were very old. I have had lively discussions regarding the terminology with these devices: T&P, TPR, pre-set Pressure, adjustable pressure, adjustable temp, loops, etc.

If memory serves me correctly, Arkansas was the first state to require a device to protect air compressors and water heaters re: temp and pressure.

Water heaters are the topic of lots of good inspector lore! I am not aware of any water heater, modern, that does not require a t&p device. Even those InstaHot faucets.

[Javier]

with the Watts 210 Valve i can only run a PRV at a exterior Hose Bibb that is 3/4 galvanized pipe. i cant go any other way becouse the location of the water heater does not allow me to run pipe left or right. will it pass inspection by hooking up the PRV to the Hose Bibb? [:-monkeyd

[hausdok]

Hi,

I'm not sure I understand the question; isn't the Watt's 210 designed to shut off the gas to the burners in order to prevent the temperature from going any higher? I thought a sensor was installed in the tank and wires run to a solenoid shutoff installed in the gas line; did I get this wrong?

OT - OF!!!

M.

[Jim Baird]

Do some Hot water tank designs not need a PRV??

no