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Header Tank has boiling water & heating MUCH TOO HOT!

Postby Elly » Sat Nov 01, 2008 3:20 pm

We have been in a 60's semi bungalow for 19 years. Potterton f/s Kingfisher? boiler replaced like for like 4 years ago. About 2' away is Hot water tank with standby Immersion heater (Never used and I think not working) Hot water tank has NEVER filled fully with a full tank of hot water, but we managed having electric shower. We had the loft insulated at the same time. Heating had always been fine.
Cold tank in loft, and a Header tank for heating system.Last year had a problem with overflow running. Old copper Ballcock had cracked and filled with water. Replaced it with plastic one, only to happen again later?
Several months back all radiators became scaldind hot, even with heating on low and thermostats set low. Then a 'whooshing' sound followed by sounds as if the pipes were clanking and trying to break away from the walls? Very scary sounds! Turned off heating and whooshing sound reversed like water returning downhill! OH checked and Header tank water was quite warm. He also noticed that fibreglass insulation was IN the header tank. The insulating guys had stuffed some into a black sack and rested it over the tank, with no support, & it had gradually sagged and got sucked in. I worried that this may be in the system too?
1st plumber replaced pump, and admitted he couldn't understand our system? All seemed OK for 2 days then same again. He wanted to replace all of the pipework which we couldn't really afford then. He never returned.
2nd plumber said it was the boiler thermostat. That was replaced and OK for 2 days again, then same again! He then thought it was the old copper hot tank needed replacing, and would try to order one. He couldn't understand the system either, saying we had a pumped heating system but not hot water? Said it was fine to run the system with heating set at max. but boiler set on lowest setting. We managed to get enough hot water before the clanking & whooshing each time, but scary.
Still waiting for plumber's return and new tank? Can't get hold of him to get him to come. We had been away and managed to get heating working gently this week until today. OH checked loft and header tank was scalding hot and spurting spots of water out. I could see rising steam through the hatch! OH bled some air from pipes in loft.
I think we need the system draining and cleaning through? Is this something that's done? Both plumbers thought I was daft for thinking it, being a woman probably. OH is ready to have the lot out and a combi in but we can't really afford it. We are both ill and don't need this.
Any suggestions please? Thank you.
Sorry for the saga but wanted to explain fully.
Last edited by Elly on Sun Nov 02, 2008 9:27 am, edited 1 time in total.
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Postby nitro23456 » Sat Nov 01, 2008 6:43 pm

FIRST OF ALL make sure no-one is sleeping under the offending tanks in order to avoid them being scalded to death if they buckle and fail - a baby died last year from this.

Are you talking about your cold water tank being hot or your central heating feed and expansion tank being hot? We need to know this.

If you have an electric immersion turn it of and keep it off.

Does your hot water cylinder heat its water from the central heating (indirect system) with a coil going through the cylinder or from the (possibly faulty) immersion only? If it is an indirect system does your cylinder have a thermostat of its own?

Sounds like a faulty thermostat - either on your immersion/cylinder stat/boiler stat.... need more info to diagnose.

In the meantime, keep it all off and buy and electric radiator for now and use your electric shower to wash. Boiling over systems are dangerous and if nothing else will cause major damage to your roof timbers from the condensation
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Postby Steve the gas » Sun Nov 02, 2008 5:12 am

Hi Elly,

Sorry to hear of your troubles. Yes drain it all down & re-fill a couple of times then see what happens.
Also on your MV's lock them to manual if you can then report back.

Good Luck
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Postby bobplum » Sun Nov 02, 2008 11:29 am

good morning
iwould say it needs to be power flushed to just to make sure that the fibreglass is not in the system and clogging it up
you could work on the basis that once its cleaned and air free then you can start to eliminate the mechanics of the system
by the time you do this ,replacing bits etc it may be more economical to get the combi in ?
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