Heating system not switching on - Worcester 20/25 + megaflo

[simond]

The relays in the Drayton LP series can get stuck and removing it off the backplate or any other jolt can (if you are lucky) free them off.

If your CH motorised valve was running intermittently it would have absolutely no effect on the Hot Water regeneration. I recall your post said no Hot Water either?

 

[broomradioman]

The original problem was no power being fed to the boiler even though the programmer had power (LEDs lit) and being in always on mode. I found that by jamming some card in the MV assembly to press the microswitch then power was supplied so I assumed it was a faulty microswitch on the MV. We'd had a power cut, two short drop outs, the previous night and so perhaps that jammed the relays in the LP522, and the MV was fine. I dont know enough about the circuitry on these things but say if the programmer was not feeding power, then would the system still be able to be energised by forcing closed the microswitch on the upper MV? If so then perhaps it was the programmer all along. Anyway, I've left it on "Twice" now and we're going out for lunch later so when we come back we'll see if its working or not. If the latter then its back to the card crowbar and call a plumber. I've seen MVs and powerheads on Ebay for ~£40 is it an easy job to fit a new powerhead? How easy is the wiring in etc?

thanks again to all

Jim

 

[simond]

Yes, with the programmer out to lunch, you can still bring on the boiler by forcing the microswitches.

It does sound to me like a typical programmer fault, especially if the make is Drayton/Invensys/Siebe.

 

[broomradioman]

That could well be it then. The programmer certainly got a few jolts as I removed it of the back plate. What foxed me was that it was powered up, and looked normal. At least now I know it may be sticky relays in the programmer and I know how to remove/replace it.

I think its called "learning thru adversity" or "necessity being the mother of invention"!!

It's a Siebe LP522 but looks identical to the Draytons so I'm guessing they are all built in the same factory and then just badged up.

thanks again to all

Jim (happy and warm cats around house now!)