System drain down.....

[nick17]

Hi,

I'm going to drain my heating system a bit to replace a three port valve body that's got a stuck spindle. I was going to turn the water off first but I've noticed that the circulation pump before the three port valve seems to have a valve either side of it. Can I shut these off instead of turning the mains off and drain down using lowest radiator? The three port valve is on 1st floor so I wasn't going to drain the ground floor radiators. Will that be ok?

 

[king of pipes]

Do you have a picture ? we as plumbers would probably lock the system up and change it but it doesn't always work, so the safe way would be to drain the top floor before attempting the swap. Kop

 

[steadyon]

1. You will need to stop the flow some other way. Turning off the pump valves will not stop the flow of water into / out of the three way valve. Also, they have a bad habit off not shutting the water off completely.
2. As King of Pipes has said, unless you have a lot of experience, its better to drain down to below the level of what you are working on. From your post it would seem likely you can drain down only the upper floor(s).
3. If you turn off all the radiator valves you will retain most of the inhibitor in the system, and can probably avoid having to add new. However, for the sake of £15 or so you might want to consider a new 1 litre bottle of inhibitor anyway.
4. If you DO turn off all radiator valves, make sure you note how many 1/8th turns are needed to close each lock shield valve. That way you can open the same amount when you have finished, and retain the balance within your system.

 

[nick17]

Thanks everyone. In the middle of doing this now and I'm struggling to get the valve off the pipework. I've got the nuts off and I've even managed to saw two of the olives off but there's no space on either side of the pipework for me to Jimmy the valve out of its position. Should I loosen the nut on the pipe going into the cylinder coil and see if I can rotate that pipe a bit? I've attached a pic.

 

[ShaunCorbs]

You should be able to get the left pipe out even if it means removing a clip then remove it from that’s side, then you can lift the 3 port body up a bit to remove it from the bottom connection and then the last one to remove is the right

also looks like you need a set of new pump valves with new rubber washers

 

[nick17]

You should be able to get the left pipe out even if it means removing a clip then remove it from that’s side, then you can lift the 3 port body up a bit to remove it from the bottom connection and then the last one to remove is the right

also looks like you need a set of new pump valves with new rubber washers

I spotted the clip just before I was about to give up. It was broken anyway so just removed it. Still a pain to try and get a screwdriver in the gap. I've been halted in my tracks, anyway, because I only had one olive in the box with the new valve. I should have checked before I started.

I had a plumber out not so long ago over a slight leak on the pump, you may be able to see where it's leaked on the pic. He said he couldn't loosen the nuts on the pump so put some Fernox leak sealer in the system and it seems to have done the trick. If the nuts are stuck is it a case of replacing that bit of pipe entirely?

 

[ShaunCorbs]

I spotted the clip just before I was about to give up. It was broken anyway so just removed it. Still a pain to try and get a screwdriver in the gap. I've been halted in my tracks, anyway, because I only had one olive in the box with the new valve. I should have checked before I started.

I had a plumber out not so long ago over a slight leak on the pump, you may be able to see where it's leaked on the pic. He said he couldn't loosen the nuts on the pump so put some Fernox leak sealer in the system and it seems to have done the trick. If the nuts are stuck is it a case of replacing that bit of pipe entirely?

more likely he didn’t want to drain the system down I would replace them (the whole valve with new rubber washers) if you can manage without filling back up tonight which it sounds like might be the plan ?