hot water turns on heater (vokera excell 80sp)

[gmmonkey]

Hi,

I'm wondering if anyone has any idea what is going on with my boiler. A number of strange things have been happening.

A few nights ago I came out of the shower (water heats from boiler) and noticed the central heating had turned on. I checked the thermostat and was switched right down, so it should never have switched on. I noticed the pressure was creeping up to 3 to 4 bar. I de-pressurised the system back down to 1.5 bar, and it was still creeping up even when the boiler was turned off. I worked out that the filling loop ball valve, which is used to let water into the system to pressurise it, was leaking. So, I replaced that and it solved the pressure creeping up. However, the boiler is not working properly. When I turn on the hot water tap the boiler fires up and intermittently makes a clicking noise. I switch off the hot water but the boiler stays on and still heats up the radiators. If the pressure hadn't went so high I would have thought it was the diverter valve. However, it would suggest that the high pressure in the system has done something to the boiler. What do you think the problem is? Any tips on what to check?

I'm worried that the high pressure has done some serious damage to the system. Can that water pressure (4 bar), for a sustained amount of time (I'm thinking it's been like that for several days), cause leaks to happen?

Cheers.

 

[45yearsagasman]

You have a fault with the internals of your diverting valve, among other things.
There are kits to repair these valves but the work is challenging to say the least for a diyer.
Sustained over pressure can and will cause damage to seals in the boiler and also the system components.
The pressure relief valve should have opened before getting to 4bar.
I would get this checked by a competent repair specialist.

 

[Agile]

Exactly!

If the pressure relief valve does not open to prevent excessive pressure in the system then that risks damaging seals in the boiler.

But there is also a serious risk of bursting a radiator with the associated flooding and water damage.

Tony

 

[gmmonkey]

Thanks for the replies guys. The boiler hasn't lost any pressure that I can see. I closed off all the radiators and the boiler stops firing up, so it seems to be working in that respect. The actuator that pushes the lever on the diverting valve seems to move when I turn on the hot water, so does that still suggest it's the diverting valve?

 

[gmmonkey]

Just thought I'd update this. It turned out to be the microswitch and the diaphragm that was bust/perished. Switched them out. It was a straightforward job and everything has been running great since.