Central heating expansion pipe flowing water

Postby POGLEY » Wed Sep 10, 2008 4:24 pm

Hi I need some help with my central heating,

I have a Potterton Flamingo II gas boiler, Grundfos water pump and there are 2 electric valves (Honeywell) on seperate bits of the pipe work

The fault is, after moving into the house the inevitable happend DIY, Whereby I removed the radiator in the bathroom and replaced with a towel heating water radiator,

Thought i done good after filling and bleeding the system only to find the pump and towel radiator got scorching hot and both pipes from the boiler extremely hot, But the other radiators around the home did not get warm,

However i changed the pump as the original i thought was on its last legs through being noisy and was getting hotter than the pipes,

After changing the pump i learnt how to bleed it then turned the power on and this is where i need help

As soon as pump works the expansion pipe leading upto the loft and into the small header tank throws a lot of water out and into the tank,

I bled the system again and turned the boiler on water heated nice and radiators and at the same time some very hot water coming out the expansion pipe, When i turn the pump off the water stops flowing out the expansion pipe, and soon as i turn pump on the water again flows out the expansion pipe,

Im at a loss and need guidence on what to try next please, Has any one got some answers

Many thanks for your help

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Simply Build It

Postby pluton » Fri Sep 19, 2008 8:23 pm

We had this problem and as part of a Boiler replacement job got the expansion pipe moved to the inlet side of the pump. That solved the problem.
I suppose you could turn the pump round.
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Postby nitro23456 » Sat Sep 20, 2008 1:33 pm

Sounds like your original problem was an airlock and now it is the pump. Ensure the correct orientation and if it is correct what speed have you set it to?
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Postby frustrated » Sun Sep 28, 2008 2:37 pm

Hi I have a similar problem every thing was working ok but had to change a honeywell zone valve since then the cold feed gets hot and goes into the tank, can any one help?
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Postby screech » Thu Oct 02, 2008 11:34 pm

the pump should have the arrow pointing towards the valves. if that's the right way round try turning the speed down a bit, the most likely problem is a restriction in the system, normally in the pipework before the pump, causing it to pump over
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