No hot water in shower, plenty at basins, sink etc?

Hi, can anyone offer advice ?

I have an Ariston combi boiler. If I turn on any hot tap in the house, the boiler fires and I get hot water. The shower is fitted with a thermostatic valve, but a few months back I started to notice that the shower was not as hot, at the same setting, as usual. This continued to deteriorate until the boiler no longer fired.

I figured the problem was the thermo valve getting blocked up, so this morning I removed it, soaked the cartridge in lime scale remover (+ the shower head), cleaned out the valve housing etc. I put it all back together, but still not working. The basin right next to the shower is also fitted with a thermo mixer, and works perfectly.

Does anyone have any idea what it could be ?

the shower was not as hot, at the same setting, as usual

Click to expand...

The boiler wouldn't affect that if it's a thermostatic mixer, so it sounds like the thermostatic cartridge has "gone". Some of them last one year, some twenty.
If it's a noname mixer you may not be able to get a replacement cartridge.

The basin mixer is unlikely to be thermostatic....

Thanks for the advice. I bought the thermo valve from Bathcentre, so will try and get a replacement cartridge.