Relief valve problems

JohnNY1

The last couple of indirect water heaters I've installed have been having problems w/ the relief valves discharging from time to time. I believe it is a pressure issue and not related directly to temperature. In neither case did I use a check valve in the installation but in both cases I've used mixing valves.
Any input is greatly appreciated.

[Deleted User]

Watts Industries

manufacturers a small presure gauge that can be applied to the drain valve of the water heater. It has a follower guide that will show the highest pressure seen.

In many cases, the water meter has a check valve built into it and this causes an increase in pressure from the expanding water.

If the discharges are pressure related, you'll want to start including the cost of installing a potable water rated expansion tank in your estimates.

ME

John Abbott

Discharge?

the "relief" valve on a HWH indirect or otherwise is actually a temperature and pressure relief valve.It will discharge typically at 150 psi or 210 degrees.Temp discharge is rare but possible.The most likely cause is a check valve on the water meter as Mark described. On well systems the check valve is before the tank so the tank absorbs the expansion.If you need a potable water expansion tank it must be sized based on the incoming water pressure and the capacity and temperature of the storage.

John