I have a Moen single handle shower. With only the hot water on, the flow is extremely weak. If I turn on the nearby faucet, the water pressure to the shower increases dramatically.

Any thoughts? Thanks!

Hi Mrdunph:

Sounds like the hot water side of the cartridge or shower valve is getting clogged. Here, you need to shut the water and remove the handle and trim from the valve. Then remove the copper CLIP by pulling up on it, remove the cartridge (YANK HARD and mark the UP side of the cartridge so you can replace same way), and then turn the water on to purge the lines clear of any sediment that may be present.

Inspect the cartridge for any obvious issues. Then re-install the cartridge (push hard), install copper clip, trim and handle. See how that works.

Worst case, the cartridge doesn't come out and you may need to purchase a cartridge puller from home depot, Lowe's or menard's stores.

That increase in pressure you see when the other faucet is on is only the increased water pressure/volume at the faucet backing up the cold line and showing up at the shower valve... I think.

Check out www.moen.com for more info.

Try this and let me know how it works out.

MARK