How Long to Drain?

gpbenton · Posted: Sat Dec 16, 2006 12:11 pm Post Subject: How Long to Drain?

I had a pinhole leak appear in a radiator at about 5 O'clock last night. I isolated the radiator, and opened the bleed valve to encourage the water to drain out.

This morning, the water is still dripping, about once per second. It filled less than half a washing up bowl overnight.

The water is cold, even when the heating is on, so I don't think the valve is leaking, but is this normal for just emptying a radiator? Its only a small 480x750mm size.

plumbnuts · Posted: Sat Dec 16, 2006 12:27 pm Post Subject:

How long it takes to drain is dependant on the size of the pin hole. The valves may be letting by very slightly, are the pipes into the radiator stone cold?

breezer · Posted: Sat Dec 16, 2006 12:36 pm Post Subject:

since you need to drain the one rad, and you have turned the valves off why not put the bowl under one valve and undo it slightly.

also water will only come out if air can get in, so you may want to undo the bleed screw too

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JohnD · Posted: Sat Dec 16, 2006 12:42 pm Post Subject:

I presume you are going to buy/have bought a new radiator of the same size to replace it? You may as well leave it to drip until you are ready to remove the old one and fit the new.

Paint the new one before fitting (if you're not too cold), it will be much easier than after fitting.

BTW you probably have corrosion in all the othe rads as well, so invest in a chemical cleaner and an inhibitor for when you refill.

gpbenton · Posted: Sat Dec 16, 2006 2:49 pm Post Subject: Still Dripping

Thanks for the help guys. It's still dripping, so I've turned the Central Heating on to see if the pipes get hot at all.

I turned the bleed screw last night, and water rushed out quickly and then slowed down, but I was expecting the dripping to have stopped by now. Currently, it seems to drip at the same rate whether the bleed valve is open or not.

I've just been to B&Q to check out radiators. They have 400mm and 500mm widths, and the current one is 480mm. The pipes have been bent in slightly to meet the 480mm width. I have no experience of this, so would the pipes be flexible enough to be pushed out to 500mm, or should I buy the 400mm

Thanks again

Graham

JohnD · Posted: Sat Dec 16, 2006 3:15 pm Post Subject:

Wooden floor or concrete?

gpbenton · Posted: Sat Dec 16, 2006 3:18 pm Post Subject: Quick Update

With the CH on, the pipes leading to the radiator are stone cold.

Does this mean that if there is a leak in the valve, it is too small to worry about

I'm quite happy leaving it dripping, it's in the bathroom, so I can empty the water from the bowl easily, and the odd drip on the floor isn't a problem. I just wonder if I will need to drain the system before removing the radiator.

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KWhat? · Posted: Sat Dec 16, 2006 3:18 pm Post Subject:

20mm 'play' is possible if there is some movement in the pipeork. Better if its an older type property and you have floorboards below, not concrete...

Just as long as the valves (inlet & lockshield) line up and are compatible with the connections on the replacement radiators.You should be okay.

Otherwise drain down and alter pipework to suit.

gpbenton · Posted: Sat Dec 16, 2006 3:20 pm Post Subject:

Its a wooden floor, upstairs

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plumbnuts · Posted: Sat Dec 16, 2006 3:24 pm Post Subject:

Buy the 400mm rad and buy 2 chrome radiator adaptors. These screw in the end of the radiator and make the width adjustable. If you decide on this, there are 2 sizes available. Let me know and I will explain more. It is unlikely that you will get these in B & Q, you will need to visit a plumbers merchants.

JohnD · Posted: Sat Dec 16, 2006 3:30 pm Post Subject:

Sorry, I don't agree. If the new rad is only 20mm longer than the old, and the pipe stubs come up through a wooden floor, I would expect to find they will move to accommodate it, especially if the existing pipes have been squeezed in a bit to fit the old one.

You would be very unlucky to find both ends are jammed up against a joist. If necessary you can lift a board and perhaps free off a pipe clip.

A 20% smaller rad will give noticeably less heat.

keego · Posted: Sat Dec 16, 2006 6:09 pm Post Subject:

I agree with you John, apart from the difference in the heat output using rad extentions for a 80mm difference would look dam ugly.

ChrisR · Posted: Sat Dec 16, 2006 6:14 pm Post Subject:

It's possible the old valves "let by" a drip or two - ignore it, while you put the new rad in! 500 here, too.