Discuss Worcester Bosch Greenstar Regular Boiler - Always ON in the Central Heating Forum area at Plumbers Forums

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Morning all,

I've noticed very recently that our Worcester Bosch Boiler is constantly ON and making a fair bit of noise.

The flame is not on, but certainly sounds like the pump is running, AND the water temperature does seem high considering we've not had any demand for it for a good 48hrs or so. Boiler is a 40cdi Greenstar Regular, Setup CH only and an unvented cylinder.

I recorded a video to help describe what i'm seeing/hearing, that can be found HERE

My questions are
:-is this easy to fix?
:-if not, is it expensive to leave it like this till i get an engineer out? (ironically i think this started happening after it's last service a couple weeks back!.. so hoping it's just a setting they've wrongly activated)


thanks for your help all,

Ged
 
That pump shouldn’t run unless demand so could be a stuck port valve and in regards to the heat temp probably siphoning heat out the cylinder so best to check the hot water port valve electrically
 
That pump shouldn’t run unless demand so could be a stuck port valve and in regards to the heat temp probably siphoning heat out the cylinder so best to check the hot water port valve electrically
thanks Shaun, are both those things straight forward to check? Valve-wise this whole boiler runs off of HIVE, so I could just make a demand for hot water to test the valve?

also, the boiler is still under warranty so Im wondering am I best to just turn it off at the wall till an engineer takes a look? If its not igniting but running the pump is it expensive / damaging to leave it on as it stands?
 
Last edited:
thanks Shaun, are both those things straight forward to check? Valve-wise this whole boiler runs off of HIVE, so I could just make a demand for hot water to test the valve?

also, the boiler is still under warranty so Im wondering am I best to just turn it off at the wall till an engineer takes a look? If its not igniting but running the pump is it expensive / damaging to leave it on as it stands?

Wouldn’t say it’s a boiler problem as the pump is external and the issue might be external

As for testing you would need a multi meter and some experience testing as your working with live components etc
 
Wouldn’t say it’s a boiler problem as the pump is external and the issue might be external

As for testing you would need a multi meter and some experience testing as your working with live components etc
Thanks Shaun, Bit of an update

I did just see the flame come on despite there being no demand for CH/Hot Water. It only came on for a minute or two. Assuming it got the temp back to target and went back off.

I activated demand for hot water to test, didn't notice any difference on the boiler (other than the hive control panel thingy lit up accordingly showing demand for hot water)....assuming no difference on boiler because essentially it's already at temp to satisfy the demand. Also all the radiators are cold, but I suspect if I run a shower now i would get hot water....

Given all that do you think it sounds like the valve for the unvented cylinder is constantly open and that is triggering the pump into action?

**EDIT: I just noticed the valve is set to 'manual' Is that normal for this type of setup or should it be on Auto?

449045417_2239847126186006_3710074414898638505_n.jpg

ED
 
Last edited:
Thanks Shaun, Bit of an update

I did just see the flame come on despite there being no demand for CH/Hot Water. It only came on for a minute or two. Assuming it got the temp back to target and went back off.

I activated demand for hot water to test, didn't notice any difference on the boiler (other than the hive control panel thingy lit up accordingly showing demand for hot water)....assuming no difference on boiler because essentially it's already at temp to satisfy the demand. Also all the radiators are cold, but I suspect if I run a shower now i would get hot water....

Given all that do you think it sounds like the valve for the unvented cylinder is constantly open and that is triggering the pump into action?

**EDIT: I just noticed the valve is set to 'manual' Is that normal for this type of setup or should it be on Auto?

View attachment 94633
ED
There’s your problem

That should be on auto push the lever slightly to the right and let go should go all the way to the left
 
There’s your problem

That should be on auto push the lever slightly to the right and let go should go all the way to the left
yes thanks, I assumed so... maybe they put it like this during its last service.

It's gone all the way to the left now, if that was the cause should I expect the pump to quieten down imminently?
 
yes thanks, I assumed so... maybe they put it like this during its last service.

It's gone all the way to the left now, if that was the cause should I expect the pump to quieten down imminently?

Yes will be on pump overrun so check back in 15 mins should be quiet
 
Yep, spot on. Thanks for the help trouble-shooting Shaun, really appreciate it.

BG must've put it manual during its last service for some reason...not looking forward to my gas bill this month!
 
Yep, spot on. Thanks for the help trouble-shooting Shaun, really appreciate it.

BG must've put it manual during its last service for some reason...not looking forward to my gas bill this month!

Or elec bills as it would be running constantly since the service
 
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