Drained Central heating still has water in pipes

[BigJim]

Hi, I'm hoping someone can help me. I've drained my central heating system after ensuring that the cold water supply to the boiler is off. I have an unvented cylinder system. I opened the bleed valves to the radiators and it took a while but it seemed like all the water had drained out. I needed to put an isolater valve on a 15mm pipe going to the kitchen radiator for some work in the future but when I cut the pipe about half a bucket of water still drained. Then I went to the first floor and opened a compression jpint straight coupler in order to replace some piping to make it longer to fit a radiator I had to move. Lots of water began flowing out again and didn't calm down. I tightened up the compression joint and have stopped for the minute. Tomorrow I was due to cut into a 22mm pipe, insert a T and reducef to 15mm for a new towel rail but I'm worried that half a tonne of water will flow when I do that. The space is very tight so I won't have space for a bowl to collect the water.

Does anyone know what I've done wrong here? One thing I just realised is that all radiator bleed valves were still open. I've just closed them, will that put the system back into vacuum and help me out tomorrow?

Thanks for any help you can offer!

 

[ALCPlumbing]

Are some radiators on separate drops? If so they will need to be drained individually as obviously water isn't going to travel back up the pipes and find it's way to drain point on a different drop of pipework. Also you're brave putting isolating valves on to a heating system. Personally I never put them onto heating pipes are notorious for leaking especially with temperature and pressure changes that a heating system goes through. Obviously if it leaks it means draining down and changing. You'd be better off just draining again when you eventually install the radiators.

 

[BigJim]

Thanks for the advice. So I will drain again and remove the isolators when we know where the new kitchen rad will be.

The other issue is still bothering me though. All rads are on the same 'circuit' as it were. I've only cut into the 15mm Spurs coming off the 22mm ring so far so not sure if there is just some residual water in here but I now have a fear of bucket loads of water gushing out as soon as I cut into the 22mm pipe. Hmm. I can't have drained the system fully but not sure what else I can do as all radiators were bled. Any other thoughts on this? Thanks again!

 

[BigJim]

This is what I am cutting into by the way. Not enough space for a pipe cutter so going to have to use a hacksaw and file. So much fun in this job! Ugh.

Untitled

• BigJim
• 2 Nov 2014
• 1

 

[mfarrow]

I have a collection of old towels for this kind of work, or rather they became old when I started using them for this kind of work

As for the valves absolutely agree had some gate valves underfloor which I removed and pressure didn't drop like it had been doing once they were gone. Compression stop ends are your best friend here or use a coupler and put a blanking nut on the other end.

 

[Jackrae]

Judging by the width of those notches I'd have thought there was plenty of room to get one of this type of cutter to work
http://www.ebay.co.uk/itm/MONUMENT-...DIY_Materials_Plumbing_MJ&hash=item2a46b6cad7

Yes I know it's a 28mm one but they also come in 15 and 22mm versions

 

[twgas]

If you're going to remove them when you do rads why not use draincocks, you can then reuse them at the new rad!

 

[Jackrae]

Roasting dish or tupperware box and a wet&dry vacuum cleaner when cutting pipes can save a lot of panic.