Wondering if anyone can explain how a PRV (pressure reducing valve) works? I have a water pressure gauge connected to my hose bib right after the PRV. It measures 75psi. When I open a faucet inside my house, the pressure is dropping to 60psi. Is this normal, or not? Is the PRV supposed to maintain the 75psi when faucet is open?
Thanks!
Jen
Plumbing – Does water pressure drop when opening a faucet
plumbing
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Best Answer
A PRV is a name for a regulator. If properly sized, the regulator will maintain a set pressure. My guess is yours is set to 75 psi and when you open the hose the flow is higher than the regulator can maintain.
There can be several reasons for the pressure drop. First if the prv or regulator is not sized large enough for the flow, try flowing just a small amount of water to see if it maintains the pressure.
The second common issue I see is debris collect prior to the prv and limit the flow. Rust, scale and other debris do plug the inlets up especially if there is a screen to protect the regulator.
There are other possibilities like the pressure is set to 60 and the diaphragm is damaged or has a slight leak so with a flow the pressure drops to the regulated pressure, once the flow is stopped your pressure raises to the supply pressure.
I usually try a flow test and even increasing the pressure to verify the regulator is functioning properly, then look for blockages prior to the regulator.