Boiler cutting off when heating water

rikili · 28-07-2021 8:12pm #1

Hello All,

I have an Ideal classic FF270 gas system boiler. a while ago, it started cutting off (the safety mechanism kicks in, and shuts off the boiler) whenever in use. I called a plumber who said that the expansion vessel was burst, and needs replacing. which he did.

This was done in winter, and it looked like every thing was back to normal. but now in summer, when I try to only heat the water, the boiler works for about 5 minutes, then you can hear the water in the pipes boiling, the pressure rises and the pressure gauge shows I think 2 or 2.5 bars, then the safety mechanism kicks in and shuts down the whole system. but the central heating works fine, and heats up the water without any issues.

Now to heat the water, I have to turn on the CH and open all the doors and windows (it much cheaper. than having the electric immersion on).

Would anyone know what the issue is, and if it's fixable? I tried to ring a few plumbers, but the minute I mention the age of the boiler (15+ years old), they're not interested, and they offer me to install a new boiler (The quotes I got are between 2.5 and 3k, which I find very expensive, and I cannot afford).

Any help is much appreciated.

niallb · 28-07-2021 8:25pm

Hi.

It might be old, but if the central heating is working I don't think the problem is your boiler.

It's not a combi and just heats the water that goes through it.

Did the last plumber who changed the expansion vessel look at your zone valves at all?

If the valve for the hot water zone is sticking it could cause this kind of behaviour and it would be a lot cheaper to deal with than replacing the boiler.

(I am not a plumber but have just replaced our heating system)

spuddy4711 · 28-07-2021 8:28pm

There should be a valve on the pipe feeding heated water from the boiler to the immersion cylinder, situated close to the cylinder. Try opening this valve, which will allow an increased flow to the immersion cylinder.