valve change kit and horizontal pipe

[davidiy]

Hope this isn't too stupid a question - will a valve change kit hold the water back and let me cut a horizontal radiator feed pipe. i'm hoping to fit a new narrower towel rail in a different position to the old panel rad without draining down the system - its a cold water tank feed open vented system.

 

[footprints]

Hi david diy,

I assume you mean the rubber bung kits, you can only have one opening into the system, for example; rad valves turned off and the rad is removed you can then change one at a time, another situation might be changing a drain cock.

If you have two ends open air pressure will break the vacuum as in the case of cutting into a pipe. However if you can isolate one end by say shutting off a rad valve a bit further along it should be ok. Check for automatic air vents they can break the air lock you want to create and always have a helper to run and get bits if it all goes pear shaped!

Good luck
footprints

 

[davidiy]

thanks for that reply - i did mean the rubber bung kit. I used them when the pipe i was putting a valve on was vertical but i wondered if a horizontal pipe wouldn't stop air getting in and breaking the vacuum as i cut it. The p[ipe i'd be cutting leads only to the rad valve and thats shut off and disconnected from the rad.

 

[footprints]

Yes it that case it should work ok, still a good idea to have someone else in the house while you are doing it though I have had the odd scare using bungs in the past!

 

[kjacko]

Is there not sufficient enough pipe accessible to use a freezing kit on?
I've used them quite a few times and they've been a godsend tbh.

 

[davidiy]

thanks for your advice gents - i think i'm going to go with the devil i know slightly better and try with the bungs. i've never used a freezing kit but if the bungs prove a disaster on the first pipe then the second pipe will be frozen. i suspect it'll be a few days before i cut the pipes but i'll let you know the result.

 

[davidiy]

I've managed to pluck up courage and cut the pipes after fitting the bungs to the feed tank. About 2 pints of water came out of the pipe which i caught in a bucket and after that none. I'll never doubt the bungs again!!

 

[gas112]

Footprints there is nothin wrong with cutting a pipe and having 2 open ends its exactly the same as changing a motorised valve on bungs that is 2 open ends is it not ?

 

[CBF]

I've managed to pluck up courage and cut the pipes after fitting the bungs to the feed tank. About 2 pints of water came out of the pipe which i caught in a bucket and after that none. I'll never doubt the bungs again!!

what you should have done is open up the rad valve & wait for the water to stop before you cut the pipe just incase the bungs weren't working & you ended up with a flood

 

[footprints]

Hi gas112,
I would shut off a pump valve when changing a motorised valve myself, but there are posters on here that say they do 3 ports, it's a case of what you know a person can safely do as opposed to what you might get away with
You can take all kinds of liberties with sealed systems too as long as you close off the auto air vent on the boiler and depressurise first.

P.S. Once tried it on the DHW side of a large victorian house the cylinder imploded! My supervisors suggestion of putting it under mains pressure to push it back out again did not end well either

Best wishes,
footprints

 

[gas112]

Yep regularly do 3 ports on bungs in that instance i do close the pump valves .
Dont find any hassle blowing joints on upto 22mm pipe.
And have even changed boilers on them .


Just remember never bung a primatic system otherwise you will implode the cylinder