Central heating trips out but HW fine

[joninlufbra]

Hi Guys,

I have a problem with my central heating which I cannot seem to get to the bottom of.

Basically the hot water works just fine, but when I turn on the CH (from cold) roughly 15 mins later the system trips the RCD on the main consumer unit. When I reset it, the CH then trips within a minute or so.

I have tried changing the programmer (Potterton EP2002, I had a spare front panel), and still no luck. The programmer has its own 3A fuse which doesnt blow.

Boiler is a Myson Apollo (looks pretty old but seems to be working fine).

The pump works fine for HW so can't see why that would be a problem? Could it be that the rads are sludged and causing the pump to work hard but only for CH?

No visible leaks around pumps/motor valves.

Please help!!!

 

[simond]

Places where you need to look are the 2 port CH valve, or the 3 port valve if you have one of these instead.

The minute delay is the valve opening up and closing an internal microswitch.

If the system works fine on HW this pretty much discounts the boiler, wiring and pump.

Assuming your Mvalve has an earth connection (eg: it is not double insulated) then it sounds like there is a problem with the insulation on the syncron motor or the switch. Easiest solution is to change the valve actuator head.

 

[joninlufbra]

Fantastic, I suspected it could have been this. There are 2 x 2 port valves, one for CH and one for HW. I will try swapping them over and see if I get the same problem in reverse i.e. HW instead of CH.

Thanks for your help.

Jon