WB Greenstar 30Si - no CH but hot water is fine

[PAB1968]

Just thought I'd check for a quick fix for my prob before I call WB.

We have no CH. When it is turned on the boiler fires up (and I presume the pump) for about 20 secs, with the green 'flame' light on. After this 20 secs, the light goes off but the pipe to the radiators is hot and you can hear the water running through the boiler.

The CH pipe remains hot (as do the spurs to the radiators). However there is no heat to the radiators. On two (of 5) upstairs radiators the pipe leading up into the radiator gets warm, but this warmth does not flow up into the radiators. There is no warmth at all on the downstairs radiators.

Pressure is fine at 2 bars and the hot water works fine (thank God!).

My guess is that the pump is broken (as I can't hear it continually) or full of air. Gravity gets the hot water to the two nearest radiators but no further. But is the hot water sent round the house by the pump too (if so it can't be broken can it?).

I have checked all radiators for air.

Any help would be greatly appreciated!

I'm really annoyed as our local plumber serviced the boiler 3 weeks ago and has either done something wrong or failed to do his job properly.

I hope it is a broken pump cos I don't want a repair bill for someone else's cock up.

Thanks
Paul

 

[kevplumb]

try bleeding the pump View media item 17592

also check the auto air vent is open (cap loose)

 

[boilerdoktor]

the pump works on these on hw and ch so your pump is not seized / broken

 

[PAB1968]

Kev - if the CH runs off the pump too and is working OK do I need to bleed it?

 

[kevplumb]

My guess is that the pump is broken (as I can't hear it continually) or full of air.

if you bleed it it will get the air out if there is any in there
if it don't do any good it wont do any harm

and do check the auto air vent View media item 11231

 

[Ihavenojob]

The diverter valves on these can stick in h/w position if heatings been off for a while.

 

[twgas]

have you check the rads are turned on (at both ends).

 

[Agile]

Does anyone know what these do on DHW if the pump is not turning?

Its a simple DIY job to feel the shaft to see if its free to turn or if its rotating when powered. Some water may come out though.

Tony

 

[PAB1968]

have you check the rads are turned on (at both ends).

Yes Mick - all the rads are on

 

[PAB1968]

The diverter valves on these can stick in h/w position if heatings been off for a while.

The hot water is filling the CH pipes though, they just aren't in turn filling the rads.

 

[PAB1968]

Does anyone know what these do on DHW if the pump is not turning?

Its a simple DIY job to feel the shaft to see if its free to turn or if its rotating when powered. Some water may come out though.

Tony

Should I be taking the cover off the boiler to check these things?I don't want to mess around with it in case I lose the HW too or invalidate the guarantee.

 

[Agile]

If the pump is not turning then its unlikely to be covered by the warrantee.

You did ask on this site so i gave you a clue as to something you can check yourself but I would never encourage anyone to do anything they are not comfortable with.

I think its most unlikely that the problem has any connection with the service three weeks ago.

Tony

 

[PAB1968]

If the pump is not turning then its unlikely to be covered by the warrantee.

You did ask on this site so i gave you a clue as to something you can check yourself but I would never encourage anyone to do anything they are not comfortable with.

I think its most unlikely that the problem has any connection with the service three weeks ago.

Tony

Thanks Tony.I guess it's just taking out 4 screws and not touching anything so should be OK. I just don't understand that if the HW and CH are both powered by a pump in the Greenstar 30si then how can the HW be working and not the CH.Or am I missing the point?

 

[Agile]

Whilst we think that the pump is powered on DHW as its not monitored then its quitel likely that the boiler will continue to provide DHW even though the pump may be jammed.

How a boiler responds when one of its components is faulty depends on how its been designed.

It can be seen as an advantage if it will continue to give DHW if the pump has failed.

Tony

 

[kevplumb]

if the op is correct and it's a 30 si it has a plate h/ex

no pump working no hot water

more like diverter valve as already posted