Grohe Europlus Tub/shower valve 34-066

[jadnashua]

After some work on my water heater, my Grohe thermostatic shower valve only has low flow. I will end up taking it apart to check the filter screens, but at first, I had good cold volume, but now both hot and cold are quite slow, so I think it's more likely to be pressure balance function. The WH was changed and it had shutoff/isolation valves, so cold wasn't really affected. I think it's more likely that the pressure balance spool is stuck (I'm assuming it has one in addition to the temperature control). This part is the volume/diverter control 47-364 and 47-302 is the thermostatic control. Does anyone know whether it's more likely in one verses the other? I don't want to take things apart without a little more info.

[jadnashua]

I'd e-mailed their tech support yesterday, and the response today is that it's likely one of two things: clogged filter screens, or maybe more likely, debris caught in the check valve(s). So, since you need new fiber washers (which are a metric size and I couldn't find so need to order as well) in most cases when you take it apart, I'm going to wait for new check valves in case I can't clean the ones there. Frustrating, as the flow (unless I want a cold shower!) is meager, but had to order them.

Next time, when the water has been off, I'll open other faucets first so the check valves don't receive the brunt of the action when the air is purged...it probably wouldn't have been an issue if they were newer, but the o-rings, etc. get stiffer as they age, and are more likely to stick.