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Discuss Worcester Greenstar 24ri - Possible airlock? in the Plumbing Jobs | The Job-board area at PlumbersForums.net

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JE-P&H

Gas Engineer
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Replaced an old Ideal Concorde WRS225a with a 24ri today, on fire up it lights for couple of seconds and overheats causing banging pipes etc.

Couldn't find a manual for the Ideal so assumed flow was on the left and return on right as left came out from top of heat ex and right from the bottom. (Check with Ideal who confirmed I was correct but still considering it's a possibility)

Have a drain off on the return so tried mains water into the system with no luck.

Boiler is in the garage with about a 8m run to the airing cupboard where the pump is, flow pipe barely gets hot past top of the boiler. Any suggestions would be great I'm struggling!
 
Checked the simple things right pumps running valves are open filter vales or anything ?
 
Ye pump runs ( Can hear it and changes through speed settings) zones valves both opening and are new, pump is still original was working fine before I assume as they had HW do newer boilers need a strong pump could be weak but unlikely?
 
how fast does it temp up?
 
About 10seconds, fires up full then goes low, then out as it overheats. Flow pipe goes red hot above boiler and return gets hot but it doesn't loop, the pipes just get hot off the boiler if that makes sense!
 
would say air lock

shove your hose on the drain off and drain it off for a good 10 mins on the return then do the same with the flow
 
Ye same I was thinking tomorrow drain it down put lever valve on flow and one on return. Then mains water through the drain off isolating one side at a time to try and push it through but if that doesn't work I'm stuck haha!
 
Ye same I was thinking tomorrow drain it down put lever valve on flow and one on return. Then mains water through the drain off isolating one side at a time to try and push it through but if that doesn't work I'm stuck haha!

dont you have a mag filter fitted?
 
I Quote them as optional customer opted out, not my choice but what can you do!

just thinking saves you draining down if you did

would put some lockshield gate valves instead of lever valves
 
Ye it's typical majority of installs have a filter but not this one! Didn't think of lockshield gate valves good alternative thanks!
 
Still no luck, drained everything including the boiler installed 2 AAV above the boiler shut off a valve each side and tried to pull an air lock through any other suggestions?
 
Are you getting just water out ? Or nothing

If your getting water could be pump
 
Just water, I have now changed the pump still the same have also swapped Flow and Return round above the boiler temporarily to see if that does anything and no luck! Baffling me system was quite old fully pumped system before but had no motorised valves etc just a Damfoss mixing valve controlling the hot water temperature anything I could have missed?
 
Photo of pipework before I took cylinder out if that helps!

I have labelled them left to right as they come out of the floor Boiler flow, Boiler Return, CH Return and CH Flow anyone disagree?

IMG_3421.JPG
 
I would say Flow? From the picture above it pumps to the cylinder and is on the flow pipe into cylinder?
 
Here's a picture just after I changed the pump with my pipework anyone see anything I'm out of ideas now haha!

IMG_3443.JPG
 
I think you should have put an air vent on the top of the heating coil, could be locking up there
 
I think you should have put an air vent on the top of the heating coil, could be locking up there
Where do you mean top of the coil? I don't think it's an air lock anymore I've put mains water through the system right up to the tank and still boiler flow doesn't even get hot heat exchanger just overheats.
 
As @ShaunCorbs mentiond earlier it might be your pump itself. @Gasmk1 said you should put an AAV on top of the coil which means where the inlet to the coil is - basically close to the coil entrance. If there is no airlock anymore try getting another pump that's what I would to see if there is any difference.
 
This is turning into quite a mystery.

Neither of the following are likely, just trying to think outside the box:

Can you be sure that the coil in the cylinder is not blocked? Perhaps a manufacturing problem. Perhaps some bungs to stop debris getting in that needed to be removed...

I can't see from the photos, does the cylinder have a secondary return? Is it possible you connected to this and capped the primary return instead of vice versa.
 
If the coil was a blocked surely CH and bypass would still work so boiler would still fire?

No secondary return on the cylinder just your standard fittings, I didn't cap any pipes tee all the returns in together and used the CH Flow. Open to suggestions if I've mixed something up? I checked the installation instructions for the old damfoss mixer and return comes out the bottom as I expected.

It also now has a new pump on no change!

Got Worcester coming tomorrow to check the boiler to rule that out, took the flow and return off and blew through to ensure no blockage etc. All clear!
 
Have you opened port valves manually ?

Do you get any heat up to where the pump is ?
 
Have you opened port valves manually ?

Do you get any heat up to where the pump is ?

Ye opened them manually, no heat and the pump heat doesn't get past the top of the boiler it basically boils itself in about 10-20secs then flow sensor cuts in! Takes a while to cool then same again!
 
There is only one thing left the boiler itself. It would be quite weird if the boiler is ok.
 
There is only one thing left the boiler itself. It would be quite weird if the boiler is ok.
I know I've ruled everything else out as far as I can see but Worcester technical just say it's a circulation issue so I have asked for an engineer visit as the Heat literally doesn't leave the boiler!
 
I know I've ruled everything else out as far as I can see but Worcester technical just say it's a circulation issue so I have asked for an engineer visit as the Heat literally doesn't leave the boiler!
I know you've changed the port valves but perhaps faulty ? It would be very weird if two are faulty but just trying to figure the solution
 
Tell us something about the controls. Is it possible that the circulation is not starting until a few seconds after the boiler fires?
 
Tell us something about the controls. Is it possible that the circulation is not starting until a few seconds after the boiler fires?

Pump is wired to the boiler on these, so the boiler controls it and sequence seems fine valve opens pump runs boiler fires then over heats! All Honeywell controls, room stat, cylinder stat, timer, valves etc.
 
Pump is wired to the boiler on these, so the boiler controls it and sequence seems fine valve opens pump runs boiler fires then over heats! All Honeywell controls, room stat, cylinder stat, timer, valves etc.

All good then.

Is the CH feed tank working correctly, i.e. not emptying when the pump starts and hence letting air in to form an airlock? Any 'inverted-U' sections of pipework that don't have bleed valves on them?

What model of pump and what is the height difference between the pump and the water level in the CH feed tank?
 
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