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Plumberpro
Plumberpro, Plumber
Category: Plumbing
Satisfied Customers: 634
Experience:  Heating and plumbing answers. 20 years experience
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I Have a gravity fed system powered by a stanley 80 oil boiler.

Customer Question

I Have a gravity fed system powered by a stanley 80 oil boiler. Heating system works fine no air in rads or any thing. When I switch the system to hot water only the heating system header tank fills with hot water and over flows onto the roof via the over flow. I can here water leaving my upstairs radiators when this happens and i then have to bleed the radiators. I temporarily put a stop end on the pipe that normally allows hot water to flow into this tank if the boiler over heated. That means the water is coming back up the outlet? I have had the system checked for leaks and we have none. Can you help
Submitted: 1 year ago.
Category: Plumbing
Expert:  Plumberpro replied 1 year ago.
Hi , does the hot water cylinder heat up ok, as quick as it has always done?
Customer: replied 1 year ago.
Yes it does
Expert:  Plumberpro replied 1 year ago.
Hi is it gravity hot water? Ie, the hot water not on the pumped heating circuit?
Customer: replied 1 year ago.
Yes its gravity hot water not on the pumped heating heating circuit.
Customer: replied 1 year ago.
Just to explain whats happening. System works fine when I have the heating on it also gives me some hot water. When I switch system to hot water only it drains some water from the up stairs rads and hot water overflows from the header tank.
Expert:  Plumberpro replied 1 year ago.
Hi , gravity only pipework can get scaled up so much that they may block all together. . The pipework may be blocked enough to force the pumped water up the feed or vent and into the tank. This is called pumping over
Customer: replied 1 year ago.
Is this the only cause you can see for my problem? What fix would you suggest for the scaling?
Customer: replied 1 year ago.
Would the scaling cause the rapid removal of water from the radiators I am experiencing when hot water is turned on ?
Expert:  Plumberpro replied 1 year ago.
Well it's possible that if the hot water gravity pipework is blocked it may be filled with air and as its heated pushes through and takes up water from the rads
Expert:  Plumberpro replied 1 year ago.
There's no way to remove that type of scale, unfortunately. It usually means replacing that length of pipework. .By the way has the pump been replaced as this started?
Customer: replied 1 year ago.
No the pump has not been replaced. The problem started after the summer when we did not use heating at all . Is it the outlet feed pipe from the header tank to the hot tank that we should consider replacing?
Expert:  Plumberpro replied 1 year ago.
The last system I went to that had this problem , we had to replace the pipework going into the cylinder and then back to the boiler in the return pipework and a bit of the flow. I think If you cut out a small section afou d the cylinder, you would be able to see if it is scaled and if it is how bad it is.
Customer: replied 1 year ago.
Ok we will have the plumber remove a section of pipe for inspection and let you know how I get on.
Expert:  Plumberpro replied 1 year ago.
Ok , all the best.