Help with my boiler issue

oldestgnome

Evening

Was hoping for some advice. I have a roughly 10 year old Worcester 24i junior boiler which has been serviced on an annual basis last done around 8 months ago.

It is a combi boiler providing hot water and heating. The heating is working fine but intermittently whilst in the shower the hot water goes cold and then takes up to a couple of minutes to run hot again, this can happen twice in an 8 minute shower. I am having to top the pressure up regularly as it goes down to 1 within a couple of days of putting it up to 1 and a half. Any ideas as I don't really want to call out the boiler person if I don't have to?

TIA

Crinkmeister

You have a small leak somewhere. You need to go round all your radiators and check all the valves and connections for signs of weeping. Any other visible joints should be checked if you find nothing there. Failing that, it may be the pressure relief valve which is not sealing properly. The test for that is to hang a plastic bag, cup or something loosely under the vent pipe to catch any water that comes out.

fezster

You have two problems, and I dont think they are related. As said above, the drop in pressure is due to a small leak somewhere, causing your central heating loop to lose water.

The shower going cold should be unaffected by this. A combi heats incoming mains water. For some reason, your shower is intermittently going cold. This could be due to incorrect pipework, or a problem with the thermostatic valve (does the shower have one)? A couple of questions:

1. Has the shower ever worked correctly?
2. I assume your combi provides hot water to your taps also? If you run a hot water tap, does it also intermittently go cold?

beaker141

I had a similar if not the same boiler with the same shower symptom, it was a worn out diaphram.

The boiler was in the bathroom so I could see if happening whilst showering, the hot water demand light would go out while I was still mid shower, and then kick back in again after 10 seconds or so.

A new diaphram fixed it up.

oldestgnome

Thank you so much for responding.

I think you are right, there are 2 issues.

I went round all the rads and found a very small leak I've tightened the nut which is leaking at top opposite to bleed valve and just put heating on to test tgat has resolved the pressure issue.

The shower worked fine up until about 3 months ago when this issue started and has got worse. The hot water demand light does go off when the shower goes cold meaning the boiler doesn't recognise it needs to continue providing hot water.

Reading about diaphragm issues it seems to be an issue with these boilers and certainly seems to fit the bill. Do you know how much you paid to fix this beaker141?

The shower does not have a thermostatic valve fitted.

When running the kitcyen sink its fine, don't think it is long enough for it to misbehave!

Le_Kirk

oldestgnome wrote: »

When running the kitchen sink its fine, don't think it is long enough for it to misbehave!

Run the shower, time how long it is on before it goes cold and the hot water demand light goes out (same thing), then turn off the shower, go to the kitchen and run the kitchen tap (or even a bathroom tap) for the same length of time it took the shower to go cold. If it goes cold, it sounds like it could be the diaphragm or water pressure switch or water pressure!