Leaking pressure relief valve

metro

My customer, (also a relative), had a new steam boiler installed in their home about three years ago. The installers used a very inexpensive tempering valve for the internal coil which started leaking when he tried to adjust it.

I installed a Watts 3/4" 70-A and all was good until he called to tell me that the pressure relief valve was leaking that is attached to a female fitting on the 'mix' outlet piping.

I installed a new Watts 1/2" 530C, (actually replaced what was there), all seemed good. I checked the incoming main water pressure, it was about 75 P.S.I. which appears normal.

Now the customer said this morning when he filled the steam boiler with the manual fill valve, when he shut it off, water spurted from the new relief valve, does this make any sense?

Thanks in advance to those who reply.

metro

metro

Help?

The 'mix' HW temperature from the tempering valve is normal (120F), the Watts pressure relief valve is set between 150 & 175 and the pressure relief valve is located on the 'mix' piping near the tempering valve, (about 18" away), the boiler is operating normally and when I tested the main water incoming pressure it was 70 P.S.I., there isn't a PRV installed on the main water or any check valves on the domestic water piping system, if that makes a difference.

I was thinking if an expansion tank would help but which pipe would it be installed on, the cold line I would imagine...

Thanks.

metro

Leo

Install thr exp

Install the exp tank on the cold side. Has the water meter been changed recently? They now have a check valve. Also if the pressure has increased at night, new lines out in the street or new equipment with the water department.

Leo

Chris_82

Sounds like Leo has it

I have seen that many times, not uncommon for water hammer at the boiler, as leo points out as a first step install expansion tank or water hammer arrestor, for the homeowner you can purchase the screw on units for the washing machine and see what effect they have as well.