Solinoid failing

jwall

I have a 70yr old 1pipe steam system with a new Weil McClain 45 Boiler. The Solinoid on the water feeder valve has failed for the 2nd time. First time it stopped feeding water. Second time it overfilled the boiler. The water pressure going in is usually bt 65-70 but it sometimes spikes to 80-90. The city water is 105psi. There is another bigger pressure reduction valve after the water meter. We added a 30psi pressure reduction valve before the solinoid water feeder valve after the first fail. After a blow down the pressure before the water feeder valve is about 20. It slowly moves to the end of the gauge 60+ after a few days. I am not using it now because I don't trust it so I have the water shut off and I am checking it 2x/ wk. Any thoughts on why this feeder is failing?

EBEBRATT-Ed

sounds like you pressure regulators are not working. When the pressure reg shuts down and it is not feeding the regulator should close down. They always overshoot a little maybe 10 psi or so but if the pressure creeps up between the solenoid and the pressure regulator the reg is not working.

There is an issue sometimes because the pressure reg acts as a check valve (allows no back flow) and the solenoid is closed and there is cold water in the pipe as the water warms to room temp the pressure will rise. Sometimes an air chamber between the reg and the valve is needed or a domestic water expansion tank. The lower the pressure the solenoid sees the better. I would remove and clean the reg near the solenoid and try it again and get the pressure down to 20-30 psi.

I would also check with Asco (looks like an Asco solenoid) to find out how much pressure the valve can close against.

mattmia2

Is there a gauge on the domestic water piping? Is there an expansion tank for the DHW? Perhaps the combination of the check valve of the main prv and a missing dhw expansion tank is causing the pressure in the system to get to a point that it forces past the prv.

JUGHNE

Could the sol valve be installed backwards?
There is an arrow to show flow direction.

Sylvain

Pressure reducing valve should better not reduce pressure of more than a 2 factor.
It might be necessary to reduce pressure in two stages.
Is the PRV after the meter functioning correctly and at what setting?
And, for example, It is better to use a 1/2" pressure reducing valve on a 3/4" pipe (one size below the pipe size whatever it is) to avoid excessive wear.

jwall

Can you explain 2 factor?

jwall

What is 2 factor?

jwall

jwall

I just attached this gauge yesterday and turned on the  cold water line. Looks like I have extremely inconsistent pressure, I think. I will check again tomorrow. There is an expansion tank on the hot water tanks. I'm not sure if it's working as it should either. The small PRV is set to 30psi. The larger PRV bt 25 and 75. The solinoid is facing the correct direction. Thank you for all your time. I have learned alot from this forum.

mattmia2

take the pressure off the dhw expansion tank and check the precharge on the air side

Sylvain

jwall said:

Can you explain 2 factor?

reducing with a PRV from 90 psi to no less than 45;
if necessary using a second PRV for reduction to a lower pressure.

Jamie Hall

The reason for the times 2 rule of thumb (and it is) is that any greater pressure reduction will damage the throttling valve inside. At greater reductions, the valve must be very nearly closed for all but the largest rated flow, and this leads to erosion (commonly called wire drawing -- though that's not always the actual mechanism) on the seat and valve, which gets worse with time, which leads to failure.

Pumpguy

Have you considered putting the solenoid valve downstream from the PRV?

This would provide a lower and more stable set of conditions for the PRV to see.

dko

You cannot reduce pressure with a single PRV by more than 60% at a time without causing cavitation. Cavitation is what causes the damage Jamie is talking about such as erosion damage.
Simple video explanation:
https://www.youtube.com/watch?v=gRsvO4Gpnf0
https://www.youtube.com/watch?v=d1flDpIUdJk

Gordo

I'd like to recommend a different solenoid, a model S-45 made (currently) by Robertshaw.
It's been around for over 50 years and rebuild parts are available.
Or you could install a VXT feeder (that has the either the S-45 or its clone, the DEMA Engineering 443P)