so with shower head removed little water comes out. did water blast out through hot and cold port? its pressure balanced so if the hot or cold is restricted both will be reduced. piping plugged on way or at your valve might be the problem
Hey Jeff,
Yes, with the shower head removed, little water comes out of the arm. When we turned on the main, with the cartridge removed, we get full flow shooting across the shower to the back wall from the valve.
I've connected air line with 110 PSI through the shower arm, and I get a very strong flow of air out of the bottom hole in the valve body. So much so, I cannot hold my finger over the hole to stop the air. So why water doesn't flow up to arm is a puzzle. I agree something seems to be blocking the flow of water, upward to the shower circuit.
I've noted the cap on the bottom/tub outlet of the valve is very close to the valve. I do not see any 1/2" copper pipe hanging out of the port, with a cap on it as I expected. Seems like it's an internal cap in the port opening. Maybe only a 3 port valve but speaking with Moen, the only 3 port (shower only valves, have isolation stops on the valve. This one doesn't. Looks like a 2520.
I've thought about trying to adapt a garden hose to the end of the shower arm and try back-flushing that direction since the air didn't blow anything out.
I also liked the suggestion I read in a thread about using Sulfamic Acid to try to dissolve any debris that may stuck in the internal circuit that runs from the bottom (tub outlet) of the valve to the top (shower outlet).
I am open to any other ideas as changing the valve out will be extremely challenging due to access.