worcester greenstar heatslave problems

[furryneddy]

Hi everyone - just a quick question really and I think I know the answer but just to verify my theory I have a WB heatslave 18/25 oso boiler that has it's circulating pump running constantly even when there's no call for heat/water - soon as it's switched on even from cold the pump runs? I read there's a pump "over run" heat stat built in but I'm not sure (A) whether this model has it built in or (B) theres a fault on the main board it's a 87161463010 pcb board. I had a look round earlier and saw one of these "over run" boards for a different model and it looks like a smaller dedicated board for the job, custard says it's been like that for 3 years !

 

[dontknowitall]

They'll run all the time that the programmer is on (especially when the heating system is on). The idea is the boiler will only fire when the returning water is cold and will only stop firing when the returning water is hot enough that its satisfied.

If the water isn't whizzing around the system then the boiler won't know what the temperature is like at the far end of the house for example.

 

[SimonG]

Is this the oil boiler?

When you say switched on from cold do you mean at the fuse spur or clock? i.e. the power is on but the clock is off?

Does it have it's own inbuilt clock or seperate?

 

[furryneddy]

Hi simonG thanks for your reply - yes it's the oil boiler - and it has a programmer in the house seperate (2 channel) let's say the boilers been on all day hot water etc etc custard goes to bed switches off the DHW & CH switches or their programmed "off" till 6am whatever time and yet the circulator pump is still running at 2am in the morning ie. there's no call for heat no call for water and yet the pump still runs night and day until obviously until you switch the boiler off from the spur supply ?

 

[SimonG]

Is this an external model?

If so does it only happen on cold nights? If so it's frost stat.

 

[furryneddy]

Hi dontknowitall - maybe I didn't explain well enough - I understand that the pump needs to be running at the times you describe but if there's no call for heat or water why would the pump need to run ? MFI say that the pump should "shut down when the set/desired temperature is reached unless the auto reset over heat stat is triggered .. so should not be running all day and night should it ?

 

[furryneddy]

No my friend its in a garage no frost stats fitted and as I just posted to DNIA ManuF say's it should shut down just after the control stats temps are reached

 

[furryneddy]

Is this an external model?

If so does it only happen on cold nights? If so it's frost stat.

Picked out from this reply SimonG that the answer is no it shouldn't be running 24/7 should it? but my question is - is it the PCB ????????? or a faulty over run stat ?????????

 

[SimonG]

Well thats the easy one out then. But if it's in the garage it should have frost stat/pipe stat combination.

The boiler is not firing then, just the pump running continuously. Is it the condensing version or standard efficiency?

 

[furryneddy]

Well thats the easy one out then. But if it's in the garage it should have frost stat/pipe stat combination.

The boiler is not firing then, just the pump running continuously. Is it the condensing version or standard efficiency?

Its a condenser and yes it has had an attempt at frost/pipe stats being wired into it but I had to dissconect them as it was so badly done it would never have worked but thats another story (left the link in). Yes there's no prob's with the boiler firing all hunky dory but when said temp is reached or there's no "call" for anything this bloody pump keeps running night and day - PCB or faulty over run stat ???

 

[SimonG]

I'm of the opinion as DKIA that the pump will run whilst the boiler is in an 'on' period wether that be central heating demand or hot water demand.

It sounds like a sticking contact within one of the relays on the circuit board. I take it that it operates correctly on central heating and hot water, so that the rads aren't getting hot whilst its on water only?

 

[furryneddy]

I'm of the opinion as DKIA that the pump will run whilst the boiler is in an 'on' period wether that be central heating demand or hot water demand.

It sounds like a sticking contact within one of the relays on the circuit board. I take it that it operates correctly on central heating and hot water, so that the rads aren't getting hot whilst its on water only?

Well yes it does operate ok but since you mention it it does have another problem that I didn't mention because I didn't wan't to confuse thing's -it does have a diverter problem as well (Drayton valve electrics are ok tested it myself) but there's no power on the 4th pin on the pcb connector to power the synchron when the CH is called although the relay locks in when the boiler CH stat is turned up - so I'm thinking new pcb anyway but just wanted to rule out this pump running 24/7 business really

 

[dontknowitall]

I'd put my money on the overrun stat/relay/wotever (if there is one) rather than the whole circuit board.

I say this because if the board was faulty I'd suspect there'd be other issues as well.

Worcester's technical department is quite helpful and it might be worth giving them a ring. (0845 892 3366 from memory!)

 

[dontknowitall]

Just seen your "other problem" post.

Then I'd say it's the pcb!

 

[furryneddy]

Just seen your "other problem" post.

Then I'd say it's the pcb!

Well thank you both for your help :icon6: - but never really got a firm yes or no on whether the pump should run 24/7 ? but yes I will ring WB just to make sure - didn't know whether they'd dish out advice on an out of warranty boiler ?

 

[SimonG]

The pump should not run outside of it's 'on' periods through the timer. imho

 

[furryneddy]

Hi SimonG have replaced main pcb board today and the problem still exists ? pump still running and still no power on the diverter valve connection on the board (pin 3 brown) ????????? OOOHHH DEAR...........what next - have checked all the stats controls on front panel make relays click in all the right places but why o why is this pump still running

 

[furryneddy]

Ok have checked for air in the DHW store - AAV works ok no other air in the system. Someone suggested the flow switch which was fitted by someone else 2 weeks prior to me being called I turned it upside down and hey presto the pump stopped running - but so did the boiler ... completely????