DIY Doctor UK DIY Forums

Hi, I have a combi-boiler set up. The combi is a Worcester Bosch Greenstar 37cdi with about 1.2bar of pressure in the system.

Recently I've noticed the shower in my loft is not working as it should. Initially when you turn on the tap (via wall mounted valve that's over a bath) you get hot and cold water ok through the shower head.

Then, after about 2 mins of running the shower, the pressure fades. This happens on both hot and cold supply. However, it doesn't happen when running either the basin tap or bath tap.

So, the question is, do you think this points to a problem with the shower valve (which is about 10 years old).

I unscrewed the shower head from its hose (and it does feel like you don't get a pure jet of water, coming out. This led me to think we might have air in the system, but I'm told that's not possible with a combi system. I also removed the taps on the wall to see if there's anything obvious about the valves behind them and I can't tell.

Any advice?

Hi orangekiwi
If you have a thermostatic shower valve this may be failing and replacement is probably the best solution.
Regards S

Before junking the thermostatic valve it would be worth removing it and checking for / cleaning out debris in the filter baskets on the water inlets to it.

Also - do you have hard water? Could be scale build up somewhere along the way.