Open Vented pipework with no draindown?

[rjm2k]

I'm moving a couple of downstairs rads and also possibly changing some valves for TRVs on an open vented system. There are is no drain point that I can find and the pipework is below a wooden floor.

I'm wondering if I close the gatevalve on the CW out from the F&E tank and also cap the vent, will there be enough vacuum to allow me to work on the pipes/valves? Also probably closing off all the rads to isolate the water in them? I want to avoid a full draindown if at all possible since it looks like it's going to be a pain (there's no route to the outside below the floor to drain anything and I guess it's a bad idea to drain onto the earth subfloor).

I'm planning to get the new pipework ready with a pushfit to join new to old so it would be a matter of cutting through the old pipe and attaching new pipe with that pretty quickly.

Thanks

 

[mcmoby69]

freeze it?

http://www.arctic-products.co.uk/product_list2.asp?cat1=64&cat2=59

you might get a vacuum if its 10mm pipe if you're lucky. sometimes you have to let the water go on the sub floor, it will soak away eventually.

when you do it, put a couple of drain offs in

 

[rjm2k]

freeze it?

http://www.arctic-products.co.uk/product_list2.asp?cat1=64&cat2=59

you might get a vacuum if its 10mm pipe if you're lucky. sometimes you have to let the water go on the sub floor, it will soak away eventually.

when you do it, put a couple of drain offs in

Thanks, yes I'm planning on the drain offs! I imagine there are some in there somewhere but probably under the tiled kitchen floor!

 

[45yearsagasman]

You may obtain enough of a seal but if not bung the outlet of the F/E tank.
You can also isolate and remove the rad and then use the rad valve as a drain point.
If fitting new valves, then fit valves with integral drain cocks.
Arctic kits are not the choice of professionals.

 

[rjm2k]

You may obtain enough of a seal but if not bung the outlet of the F/E tank.
You can also isolate and remove the rad and then use the rad valve as a drain point.
If fitting new valves, then fit valves with integral drain cocks.
Arctic kits are not the choice of professionals.

Thanks, only problem with rad valve drainoffs is there's a lot of pipework below that level so it would still leave some water in the pipes, better than nothing though.

Oh, and I suppose I'd better mount the JB currently resting on the floor (thank's previous owner) elsewhere if there's a danger of water getting on the sub floor!

 

[Agile]

If you close the rad valves all you are draining is the pipework, perhaps 20 litres.

The best place for a drainoff is connected under the floor and going straight out through the wall to the outside if thats possible.

Tony