PLEASE HELP - CRAZY PROBLEM! ***fixed!***

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Hi,

Hoping for some advice! -

A friend of mine was having problems with their central heating - their radiators 'died' one by one and just before the last radiator stopped getting hot, the hot water died too.

The system is conventional, not combi - about 10 years old. The boiler is a Glow worm space saver MK II. Their is a 3 way valve to select hot water, or central heating.

Initially, i thought the problem was the pump, so i changed it but it seems not to be so. The boiler only has a flow and return pipe, along with the gas and it fires up fine. The flow pipe gets HOT and the boiler shuts down presumably due to over temperature. However, upstairs in the airing cupboard the flow to the pump doesn't change in temperature...

Any ideas what this could be - i tried searching the forums but couldn't really find anything.

The pump runs, the motorised valve works and the boiler fires!

I look forward to hearing from anyone who can shed light on a solution.

Many Thanks,

Joel.
 
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Surely the boiler must shut itself down pretty sharpish? - the heat has to go somewhere.
 
Thanks for the replies so far. The system doesn't have any TRV's, its a 2 up, 2 down house so not a load of radiators/pipework. We have bled all the radiators starting downstairs and water is now coming out of them all.

The boiler runs for about 2 minutes and then the water is obviously up to max temp!

Its soo strange, the boiler is in the kitchen and the airing cupboard is upstairs in the centre of the house. Following a plan of a standard system, the entry to the pump must come straight from the flow of the boiler - it sounds like their is water circulating but it just doesn't get hot???!!!

Cheers.
 
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Hi Guys,

Thanks for the replies - i got it sorted in the end and just thought best to 'close' the topic.

Basically, the problem seemed to be as suggested down to air locks. I had never realised how much trouble they can cause till now. All the radiators appeared to be bled and the pump appeared to be circulating however this was not the case. I unscrewed the vent plug on the pump as a last resort (maybe should have been a first) and after about 2 minutes the noise in the pump changed and it was then clear that it was pumping a mixture of air and water. the radiators instantly started gurgling and required lots more bleeding. After about 20 minutes of this the pump had settled down and was running VERY quiet - making a very different sound to before. The radiators were all full and after starting up the boiler the house was toasty again in no time.

I thought this might be useful to anyone else who is having similar frustrations - at the time it just didnt make sence and i was ready to give in, however it all turned out fine in the end after alot of venting!

Thanks again,

Joel.
 
If the system is getting "air" in it, it is very likely gas caused by corrosion of the steel radiators. This also creates black sediment which will eventually cause blockages.

At the very least a corrosion inhibitor chemical should be added to the system water.

Preferably it should be given a chemical clean and flush first.

There is also a possibility that new, aerated water is getting in, which could be due to a leak, or to pumping over from the vent pipe into the F&E tank in the loft.
 

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