Our shower goes cold for aprx 30secs before going hot again, it happens every few minutes. It only happens in the shower, all other taps run fine and no error codes on boiler. We only moved in in November but suspect shower unit quite old. There is also an occasional banging, not a tapping, an actual bang which we assume is the pipes... Anyone have any ideas?

Hi Piscesbird:

How many single handle faucets/valves do you have? It's possible that one of the mixing valves in one of your other faucets/valves has gone bad. This could allow cold water to enter the hot water at the defective faucet/valve which could end up causing cold bursts into your shower as you present... kinda like a cross connection occurring.

Start by shutting off the hot water valves to all single handle faucets (under sinks) and then take a shower again and see if that fixed the issue. If it did then you'll need to turn the hot back on to one faucet at a time until you find that the shower is an issue again. Once you identify the faucet/valve in question you can replace the mixing valve or the cartridge and you should be all set.

Once you disturb a shutoff valve you may get leaking from the nut around the shutoff handle. If so, hold the valve with one hand and tighten the PACKING NUT (nut behind the handle) a 1/4 turn clockwise... should stop any dripping.

If you have other shower valves that can't be isolated then you may simply need to replace the cartridge to these to fix all this, but do the shutoff tests first.

Back to you...

Mark

Thanks for coming back so quick! Funnily enough, our hot tap in the bathroom sink hardly lets any water out and we figured this was down to washer/old tap, which just needed replacing. You think the two could be connected then?

I wish it was that easy...

Start by shutting off the hot water shutoffs to each single handle faucet/valve and see if the shower is improved. After that, you can turn back on the bathroom sink first to see if the issue returns... but first we need to know if isolating all single handle faucets/valves fixes the issue.

Keep me posted...

Mark

Will do - thanks!