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CH problems - HW OK, Radiators upstairs Cold

Postby MAC2007 » Mon Nov 12, 2007 7:18 pm

Hi, I have what I believe is a gravity fed CH system with gas boiler downstairs in kitchen and hot water tank in bathroom with expansion tak overhead.
the hot water in taps is fine; the downstairs radiators (2 double and 1 single all hot, but upstairs - 2 double and 1 single are all cold. I have tried bleeding all upstairs radiators with the circulating pump off, the radiators get warm, then I switch system on, and after about 10 minutes they go cold again.

Now the radiator valves are leaking ! I have turned the cold water supply off to the expansion tak and drained the hot water cylinder. I am replacing radiator valves - how do I then recharge and balance system. All help greatly appreciated.
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Simply Build It

Postby marrtin » Mon Nov 12, 2007 9:26 pm

Open all the new valves fully, and close all bleed nipples.

Turn water on, and allow header tank to fill. Starting downstairs, bleed each radiator in turn until full. Try and ensure header tank does not run dry whilst doing this. Now continue and bleed upstairs rads. When all done, and header is full fire up boiler. Bleed rads again as necessary after system is full.

When all rads are hot balance them. Read the article in the DIY projects section of this website.

I wonder if you have solved the original problem though?????
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Postby dibnah » Tue Nov 13, 2007 8:31 pm

have you sorted your heating out?
If you've emptied the system, depending on the age of the set up, there may be a check valve next to the pump, (a longish looking thingy that is hexagonal in shape) at the end of the return line, this has a small screw in the top, crack that open and you should get a burst of air and usually, if that is your problem it should start to flow as normal! (that is assuming you've bled the rest of the rads, I usually start with the ones downstairs, and work my way up to the last one nearest the pump.) You may have to do this acouple of times, to clear the check valve, I left mine open for an hour just dribbling in to a small dish between the floor joists. It only needs to be very slightly open to do this though.
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