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Problem with hot water / central heating

Hello,

I have a gravity hot water / pumped central heating system. I drained the system to replace a radiator, and on refilling have the following results:

Hot water is not heating. Boiler turns on, but cycles off after about

30 second. Radiators are not filling up with water, despite tying to bleed them.

I have checked the header tank, and it is full. The layout of the heating is that the boiler and hot water cyllender are on the first floor, with all the central heating pipes in the ceiling of the ground floor (with pipes going down to each radiator on the ground floor).

Any ideas?

Thanks for any info,

Tony Lennard

Reply to
tonylennard2000
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Probably airlocked - connect hose pipe to drain c*ck and gently introduce water untill it comes out of the header tank overflow, then try bleeding rads as normal, finally don't forget to add inhibitor to the system

Regards Jeff

Reply to
Jeff

I agree with that. Another thought - is there a tap or gate valve in the feed from the fill and expansion tank to the system? If so, is it open?

Yet another thought - you *are* looking at the right header tank, aren't you? The important one here is the small fill & expansion tank which feeds the primary circuit - *not* the larger header tank which feeds the hot DHW cylinder. Make sure that there is water in the small tank - and that it's ball valve isn't stuck shut.

Reply to
Set Square

These are the kind of problems that made me convert to a fully-pumped, sealed system last year. It was quite easy after a bit of planning. The hot water heating is much improved and I never have air in the system (since I fitted an air separator). The FAQ covers most of what you need to know.

Rgds Alec

Reply to
Alec

I would strongly suspect a limescale plug at or near where the feed pipe enter the main circuit.

Reply to
Ed Sirett

Thanks for the promt reply - it worked a treat!

Thanks

Tony Lennard

Reply to
tonylennard2000

It would be helpful if you you quoted part of the message to which you are replying - so that we can see *which* solution worked.

Reply to
Set Square

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