Our municipal water supply pressure runs 100-125psi. I installed a bathroom in my workshop and added a Wilkins pressure reducing valve to get the supply pressure down to a reasonable level. However, the valve seems to have some creep to it and I need some help in understanding what is going on.
I have the valve adjusted for around 55psi. When I turn on the water supply the system pressurizes to that setting reliably. If I turn on a fixture or flush the toilet the pressure returns to the proper setting. If I leave the system pressurized and come back in an hour or two the pressure has crept up to 70+ psi. Flow some more water and the pressure is back to the set point. Give it some time and the creep sets in.
If I make adjustments to the set point, the pressure changes as it should, but the creep issue is still there.
I purchased this valve in “new” condition off ebay. Is this typical operational behavior? Or is my valve shot? Does it have some sediment or other debris stuck in the works that needs flushed out? Is the diaphragm leaking and can that be repaired/serviced? Any suggestions on diagnosing are appreciated.
Thanks, Daen
Replies
Likely there is some seepage through the valve. Even a tiny seep will eventually pressurize the pipes, since there's no place for the water to go. I suspect this is semi-normal, but some valves are worse than others.
The other cause would be any water heater you have in the "circuit", or simply the fact that the cold water from the ground expands at room temp. This will often over-pressurize a system with a check valve.
There is a special kind of toilet fill valve that will automatically relieve the pressure, or an expansion tank can be helpful (at least in the second case).
The water heater is an electric tankless. Since this is in the desert SW, the "cold" water temp coming in is somewhere around tepid (70°F to 90°F). Municipal water supply so no "need" for a pressure tank. Being that this is in the workshop, there may be days or even weeks between water usages.
Maybe the question I need to ask is what pressure is too much for the plumbing fixtures? maybe my 70-75psi creep is not really a problem? System is combination of copper & pex with sink, toilet, shower, and clothes washer.
There's not really any hard-and-fast rules about max pressure. PEX is rated at 100 psi at 180F, copper a bit higher, but probably 85-90 is a more rational limit.
A standard T&P relief valve is set at something like 150 psi and 210F, and that is presumed to protect the water heater and plumbing from overpressure.
80psi
Code limits the pressure within the house to a max of 85psi. It's up to the homeowner to suply the PRV.
In a closed system, pressure can sometimes creep up due to the water warming up. Cold water at ground temp entering the house and warming up to the house's ambient temp, for example, can cause a pressure rise. That could contribute a few psi, but unless your Delta-T's are rather large, expansion by itself probably isn't accounting for all of the increase you are experiencing.
Bleeding the system of a bit of volume by flushing a toilet should relieve that added thermal pressure without pressure regulator admitting more water volume into the house's plumbing. If the pressure again creeps up, like you said, that's a good sign that there is some bypass in the regulator itself.
I know how to adjust the things but I can't offer any decent advice on actually troubleshooting ot repairing them.
Good luck!
One thing you can try, to figure out the cause, is to wait for the pressure to stabilize, then bleed only maybe a couple of cups of water, which should be enough to bring the pressure back down without admitting too much fresh cold water into the system. If it again rises after that then it's likely the reducer leaking.
But keep in mind that the reducer seepage probably drops as the pressure rises above its setpoint. You may want to let it go a bit to see if it gets much past 85-90 PSI. If it stabilizes there you probably don't need to worry about it.