On Mar 29, 7:57 am, "BobK207" wrote:
On Mar 29, 3:46 am, "Joseph Meehan"
wrote:





BobK207 wrote:
Adding a back flow preventer or a check valve to a domestic water
supply will create a closed system.

Usually the issue of thermal expansion in a close system is handled by
installing an expansion tank on the cold water side of the water
heater.

Could the thermal expansion in the system be handled by installing a
pressure relief valve; with a relief pressure lower than the relief
pressure of the T/PO valve of the water heater?

Of course this relief valve would dump a small amount of water every
day...... approx the amount of expansion of the cold water heated to
water heater temp.

Is the expansion tank solution "better" than the relief valve
solution? or is a relief valve a better solution?

I'm just curious........... since I can see if the relief valve is
working but the behavior of the expansion tank is internal & thus
hidden.....so I have to go on faith as to whether the expansion tank
is doing it's job.

cheers
Bob

The standard solution is the expansion tank. I would guess that the TP
relief valve is for emergency use and is likely to fail after too many uses.
Water heater manufacturers tend to use real cheap junk on them. In addition
you are loosing the warning that the system gives you anytime the TP valve
goes indication something that should not be happening but making it as
usual event.

--
Joseph Meehan

Dia 's Muire duit

I would not be using the water heater T/P valve to relieve expansion
pressure but an addtional relief valve elsewhere in the system.

The water heater T/P valve would not cycle (it's rated at 150psi) &
the additional relief valve would be 125 psi

cheers
Bob- Hide quoted text -

- Show quoted text -

125 psi is double the recommended pressure for residential use. Over
60 psi causes undue wear on fixtures.

Harry K