Glow Worm boiler fires up but no heating

[mark2011]

Hi,

I wonder if somebody could offer some assistance please. I've recently moved into a house and I'm having a bit of bother with the boiler. It's a bit different to the combi boiler that I'm used to.

The boiler is a a Glow Worm Space Saver 60 MKII and is pretty old. Last night the heating fired up as normal but the radiators stayed cold. I've tried searching a few forums and it sounded like it could be the pump (Grundfos). I've taken the cap off the pump as suggested and the shaft seems to be rotating ok. I tried changing the pump setting from 2 to 3. The radiators were still cold and I heard a noise outside. I went out and saw that the overflow was gushing water. I now know that the overflow is located in the loft but I don't know what else is up there as the opening is a tad small to get through. I'm sure I can squeeze through if someone gives me a good reason to but it won't be pleasant. I've turned the pump setting back down so I'm back to square one. As I said, the boilers old so it doesn't have any flashing error lights or dials which I can report on but it does seem to fire up ok. There isn't a pressure dial so I'm guessing that there must be a tank in the loft? As a side note, none of the radiator thermostats seem to work. The heatings either red hot or off. Cant say I'm overly impressed with the system and I think its going to cost a fortune to run but money doesn't allow a change at the moment.

If anybody has any suggestions that I could try then I'd be very grateful. We have a separate water boiler so hot water isn't an issue.

Thanks

 

[Agile]

"Moved into a house" usually on this forum means its rented. If that is the case then its the landlord's responsibility to sort it out.

It sounds like a motor valve problem. The boiler would quickly overheat if the pump was not working.

Tony

 

[mark2011]

"Moved into a house" usually on this forum means its rented. If that is the case then its the landlord's responsibility to sort it out.

It sounds like a motor valve problem. The boiler would quickly overheat if the pump was not working.

Tony

Thanks for the reply Tony. It's my house so my responsibility. Recently bought a old property. I prefer older houses but not the problems that come with them.

Would inspecting the motor value be a job for a skilled engineer or is there anything I can try?

Thanks

 

[Hugh Jaleak]

Depending on type of valve and problem and your skill level it could be DIY able. May be possible to override the valve motor to get heating as a temporary measure. Is the hot water heating up ok using the boiler? (Not an immersion!)

 

[mark2011]

Depending on type of valve and problem and your skill level it could be DIY able. May be possible to override the valve motor to get heating as a temporary measure. Is the hot water heating up ok using the boiler? (Not an immersion!)

Hot water is a separate boiler so no problems there. The Glow Worm boiler is central heating only.

 

[Hugh Jaleak]

In that case unlikely to have any motorised valves, should be a simple setup using the pump to move the water round. Has it ever worked properly while you've been there?

 

[mark2011]

In that case unlikely to have any motorised valves, should be a simple setup using the pump to move the water round. Has it ever worked properly while you've been there?

Thanks for the reply. It's worked for the 3 months we've lived here. Only stopped yesterday.

 

[Hugh Jaleak]

No worries. Sudden stop would indicate something has failed rather than a progressive problem e.g. system bunged up with sludge.

Dont rule the pump out, it has been known for the impeller to detatch from the shaft, whilst the pump will appear to be rotating it isn't actually shifting any water. The water from the overflow is odd though, if the pump had failed i'd expect the boiler to start banging as the water in the boiler would overheat.

Initial thoughts are the system is 'overpumping', dumping the water into the feed & expansion cistern rather than round the system. Pump is putting the water into the F&E cistern, cold feed cannot put it back into the system fast enough so it dumps the excess water out the overflow. Which could lead back to a motorised valve failure, (stuck shut), giving the output from the pump no option but to go up the vent. Have a look for motorised valves, and check it/they are opening correctly.

 

[Mikefromlondon]

Firstly Mark, get in your loft, and sort out that overflowing feed and filler tank. This could be due to float valve having got stuck, or just needs replacing, so if I were you, I would first stop that leak, even if it means temporarily closing the cold water feed to the float valve, most installations will have some sort of valve fitted to turn off the feed.

secondly, I am not a boiler repair man, and therefore I don't know for sure if your model is the same as my mate's , but I know his was a Glow Worm 40 something, whose pressure switch had packed up, it failed to operate the microswitch, this part is located on the top of the boiler above the combustion chamber, so you should be Ok as long as you don't touch any gas or CC parts,

This pressure switch which cuts in when the fan is running and creates a differential pressure, if this pressure switch fails to operate properly, the boiler won't fire, so you would not get any heating, and it may throw a red fault lock out light on, and you may have to switch off from the mains to reset this fault.

 

[DP]

If the burner is firing, then find out where the heat is going. If the system is old and does not hav bells and whistles, it does not mean it is a bad syd system. Old systems are much more reliable than a steamy combi boiler.

And, also stop speculating what is wrong. Look, listen and reason why the system is not working

 

[mark2011]

If the burner is firing, then find out where the heat is going. If the system is old and does not hav bells and whistles, it does not mean it is a bad syd system. Old systems are much more reliable than a steamy combi boiler.

And, also stop speculating what is wrong. Look, listen and reason why the system is not working

The boiler looks & sounds to be working fine. I've since found that the bathroom radiator is working but none of the others are. Not sure if that suggests a possible cause to anybody? I'm planning on going up into the loft to see what's going on up there shortly.

It seems like a good system but not efficient. My 1st gas bill was horrendous. The heat is set to min but the radiators, when working, are scolding and the radiator thermostatic valves are useless.

 

[mark2011]

Nothing much to report from the loft. Small tank with float valve. I couldn't spot anything which may be causing the problem.

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• mark2011
• 20 May 2012
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• mark2011
• 20 May 2012
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• mark2011
• 20 May 2012
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[Hugh Jaleak]

Unfortunately those pictures dont tell us much. Need to logically fault find, starting at the boiler. Where does the pipework from the boiler go?

It may be possible with some minor alterations to make the setup you have more economical. If there is no roomstat then one could be fitted to switch the boiler and pump on when heat is required, if the system is relying on the boiler stat alone then this could account for the scalding rads and high gas useage.

Depending on location of bathroom rad in relation to the boiler, it is possible some circulation is taking place under gravity.

 

[mark2011]

Unfortunately those pictures dont tell us much. Need to logically fault find, starting at the boiler. Where does the pipework from the boiler go?

It may be possible with some minor alterations to make the setup you have more economical. If there is no roomstat then one could be fitted to switch the boiler and pump on when heat is required, if the system is relying on the boiler stat alone then this could account for the scalding rads and high gas useage.

Depending on location of bathroom rad in relation to the boiler, it is possible some circulation is taking place under gravity.

Didn't think the photos would be much use. Just reporting what I saw. I'm afraid I can't work out what's happening with the pipe work. There are pipes running all over the place. I can't see any obvious configuration. They disappear into a stone wall and that's as far as I can see. The boiler is located in utility room built on the side of the house. The bathroom is quite a distance away, upstairs.

Rather than waste anymore of your time I think i'll have to call a professional. I was hoping that the problem may be a common problem and obvious to someone but I may struggle to provide any detailed info as I have no idea how the system is configured.

Thanks everybody for your help. It's very much appreciated.

 

[Hugh Jaleak]

It may be something simple, just a case of ascertaining what it is! Does sound like a circulation problem, but without being on site its difficult to determine whats going on. Good luck.