Old Glow-Worm 45-60B

[robertbullen]

Hi,

I have an old Old Glow-Worm 45-60B. The boiler keeps cutting out, that is the main burner shuts off after a minute or 2 of running and is back burning within 5 minutes.

The pump keeps running and the thermostat in the hall is nowhere near the desired temperature.

Any help would be appreciated.

I am a novice but want a heads up before calling in someone for repair. I could do with it seeing me through one more winter.

Thanks in advance.

 

[Hugh Jaleak]

Is the pump pulling the heat away from the boiler? If rads are slow to heat it could be a circulation issue rather than the boiler.

 

[45yearsagasman]

+1

 

[robertbullen]

Not very scientific, but listening to the rads, you can hear water seemingly rushing through. Is there a simple way to test the flow?

 

[ChrisR]

Feel the pipes by the rad valves. One for every rad, starting with the rads nearest the pump, should start to get warm.

 

[robertbullen]

The rads do get very warm eventually, it just takes up to an hour with the boiler cut outs.

 

[Hugh Jaleak]

Still sounds like it's a circulation issue rather than the boiler. Has the system got sufficient water in it and what colour is this water? Black would indicate sludge, which is a common issue causing poor circulation!

Check smaller of probable 2 cisterns (tanks) in the loft, does this contain water? (Should be about 1/3rd full). Bleed a radiator, if water dribbles out a filthy black colour then sludge likely an issue.

 

[Agile]

The boiler is probably over rated for the heat load compounded by a poor flow rate due to a weak or blocked pump. See FAQ on finger test.

The boiler flow temp is probably reaching the set 70 C or whatever and turning off as it should.

You should measure the temps on boiler flow and return pipes. Should be up to 11 C difference. I suspect due to poor flow its more than this!

Tony

 

[robertbullen]

I've drained down and refilled the system, using mains pressure to push out what we can, not much sludge came out, the water looks reasonably clean.

Is it worth trying replacing the thermostat and phial if I can get one?

 

[ChrisR]

Does the flow pupe get too hot to touch, if you turn the boiler stat up?
If not, stat, if so, pump. Assuming you really have cleaned it out.

 

[robertbullen]

The pipe does get very hoy around the pump with the stat up, too hot to touch.

The pump is spinning fast.

 

[Hugh Jaleak]

Pump spinning does not necessarily mean it's circulating any water! If heat is getting to the pump but not much further past it, I would be looking at the pump as a possible culprit.

Boiler stat is doing as it should, water is boiler is reaching temp so shutting burner down. Until the heated water gets away from the boiler, it will not fire again. Poor circulation may well be faulty pump if system is clean.

 

[robertbullen]

Thank you all for your advice.

I was convinced it was the thermostat on the boiler and was looking here for confirmation. I've not got it so I must be wrong, then again I really do know nothing.

Right, here's where I'm at.

I've put a small screwdriver into the "spindle" under the bleed cap on the pump with the pump off. I then start the pump and I can easily prevent it from spinning. Once it's going, it spins very fast but I can stop it easily. Shouldn't there be more power from the pump?

I've just "flushed" a cold rad, a lot of black stuff came out but it wasn't thick, now what I would call sludge, just black. Re filled the rad and it's hot.

I'll be honest, money is tight so I could do without spending too much. How about this. Add acid, leave it for a few weeks, drain the system, flush every rad individually (I have and try again?

One more thing, the boiler also cuts out frequently when just the hot water system is on without the heating.

Would I be able to get a second hand working pump? I'm loathed the spend £170 on a new one just in the now slim chance the problem lies elsewhere,

 

[robertbullen]

Duplicate

 

[Hugh Jaleak]

Pump for £45: http://www.screwfix.com/p/wilo-smart-pump-domestic-circulating-pump/33590 if needed. I'd expect the pump to take more than you describe to stop if it was healthy, and also, just because the shaft is rotating, doesnt mean the pump is actually moving any water!

Sludge may not be helping matters, if HW is gravity circulation then there may be a partial blockage in the primaries slowing things down. Are you getting plenty of hot water? To clean, have a look at Sentinel, either X400 which can be left in a for a few weeks without issue, or the X800 which you'd need to be more careful with.... http://www.sentinel-solutions.net/product/listing/central-heating/liquids/