Pump staying on when CH and HW timed off.

[pauldoc]

I'd be grateful for any thoughts on this one....

I have a problem that when the CH/HW are timed off, the pump keeps running. The humming noise drives us insane at night and we have resorted to switching the whole heating system off at the isolating switch.

However our Honeywell 7-day programmer recently failed and I have replaced it with a Siemens 7-day programmer. I was hoping it might cure the problem but sadly not.

System:
Fully Pumped Vented Condensing Boiler Ideal Minimiser
Pump in Airing Cupboard; 2 motorised valves.
Programmer as above. Thermostat is a Honeywell programmable stat.

My thoughts:
? wiring fault -
? incompatible timer change (from ACL Drayton to Honeywell in past - possibly needs different junction box wiring)
? motorised valve prob - told these are OK when checked.
? pump problem

I'm thinking I may have to get someone to do a full wiring check of the whole system, but I'd be grateful for any ideas.

Some pics below

Pump & Junction Box

• pauldoc
• 14 May 2011
• 1

The cap of the pump is broken but the wiring is not disrupted.

Junction Box in Airing Cupboard

• pauldoc
• 14 May 2011
• 1

Airing Cupboard

• pauldoc
• 14 May 2011
• 1

Thanks for any help with this...
Paul

 

[Gasguru]

Does the boiler run too? Are the pipes to and from the pump hot? (I'm assuming there is a bypass valve. Perhaps a microswitch in one of the zone valves has failed (ie it's on) and powring up the pump and boiler even though the valves closed.

 

[pauldoc]

Thanks. No - the boiler goes off, but the pump hums on constantly.

(PS I have corrected the above post to 'fully pumped' - assuming this means that the heating circuit inside the HW cistern is pumped - the HW pressure itself is gravity).

 

[Gasguru]

The pump and boiler Live feed should be wired together and fed via the microswitches. Google S plan and check your wiring.

 

[pauldoc]

Thanks and sorry - we weren't aware of the boiler firing when this happens...but I've just turned timed both off and checked... Boiler is coming on intermittently (presume as stored HW cools slightly). Radiators not coming on (turned room stat right up). Pump remains on...

Will carry on carefully checking the wiring and call the pro's in if needed. Any further ideas very welcome.

Paul

 

[stardanny]

Might be a pump overrun fault? It happen to my solo2, was a pcb.
It's part of PCB inside boiler.

Check that the zone valves is working ok.

Dan.

 

[twgas]

If the boiler and pump are staying on then I would suggest one of the end switches, in motorised valve, is stuck.

 

[pauldoc]

Thanks for all this suggestions. Just to complete the loop, it did, in the end, turn out to be a faulty motorised valved. Sorry for the red herring in the story but I previously had these checked and they were thought to be OK because they were apparently not stuck - I assume it was an electronic fualt in them. No pump humming constantly now.

 

[45yearsagasman]

Get the pump repaired, ie that box hanging off the side presents an electrical hazard.

 

[pauldoc]

Thanks Yep - done this too. We replaced the pump at the same time.