Shower rough is a Matco Norca, approx 10 yrs old. It had been slow dripping for a while,then turned into a slow stream so I replaced the cartridge. To do this I turned off the stops on the valve. When I opened the valves, the hot water was no more than a trickle. I figured the stop valve may have deteriorated and clogged the control valve. To remedy this I had to have the building water shut off. I replaced the stop valves, but not with Matco Norca, as they weren't available at the time. But the replacement valves (Danze) fit and the plunger depth seemed to match the existing. I also replaced the balance spool. Once replaced, I had the water turned back on and all worked well, let it run for 15 minutes. Later that evening I turned on the shower, it ran fine for 30 seconds or so, then the hot water reduced to a trickle. Cold remains fine. Now, still, the hot water will run at good pressure for no more than 30 seconds before it turns to a trickle. Should the whole shower body control be replaced? Is it possible the hot water stop is defective? But why would it work for a short time, then not? Totally perplexed.Thank you.

Remove the balance spool and determine whether or not the spool is freely moving inside. While you have it out, rinse/flush it out at another faucet.

The balance spool moves freely, and it's brand new so perfectly clean, but rinsed it out anyway and saw now debris or sediment. Another odd symptom: when I move the shower handle to cold,cold water flows freely, indefinitely. When I move it towards hot, pressure slows to a trickle and stays like that even when I move the handle back towards cold. If I come back to it in a few minutes, cold comes out strong again. ??? Thanks.

do the same with the cartridge. remove it, run water with it out, inspect it and re-install..

I have done that.

I have removed the cartridge and balance spool, then opened the stops, with the same result: water flows at first then slows to a dribble.

If the rough were clogged somewhere in the ports between stop and cartridge/spool then wouldn't it just not flow at all?

I'm not only mystified by this but also trying to troubleshoot ahead of breaking the wall to replace the whole thing.

Thanks for your time.



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