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Central heating system with no drain valve

Postby Sonic » Thu Apr 19, 2007 7:13 am

I am looking to move an upstairs radiator and so need to (partially at least to ground floor) drain the central heating system down. It's a system that heats up a combi tank (that also seems to double up as an electric immersion tank). The tank and boiler are both in the loft.

But I cannot find any drain off valve anywhere. And none of the radiators have drain valves either.

Does anyone have any tips on how to drain it down??

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Simply Build It

Postby peter the plumber » Sat Apr 21, 2007 4:43 am

First make sure the water feeds are off and no more water can get into the system.

Close all the radiator valves, but remember to open them when you have a working drain off one.

There are few ways of doing this.

You can cut the pipe just below a radiator valve if the radiator valves are close and put on a Speedfit/Pushfit drain cock on the feed end. You will get some spillage but not much.

You can just freeze a pipe on the ground floor then cut it and add a drain point.

You can use self-cutting washing machine fitting on the ground floor. (There design to be use on 15mm copper pipe.)

Then just connect a garden hose and drain down that way.

Then when the system is empty just repair the damage pipe work and fit one of the ground floor radiators with a drain off lock shield.

There about £4 and I have found work better that freeze.
peter the plumber
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Postby Sonic » Sun Apr 22, 2007 7:17 pm

Thanks for your reply Peter. Unfortunately, your answer was too late as I needn't to do it last Fri.

In the end I turned off the water, then opened the bleed valves on the downstairs radiators and allowed the water to drain into buckets. Fortunately they were fairly new rads so i was able to turn the valves so they pointed directly down into the buckets, so there was hardly any spillage. I only needed the upstairs to drain enough to plumb in a bathroom towel rail rather than drain the whole system. So this did the trick. In future i think I'll get one of those self cutting taps.

Thanks for your help though.
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