creating a vacuum - bunging feed and expanison tank

[liverpoolboy]

Can you create a vacuum in the system (by bunging the cold feed and vent of the feed and expanison tank) to remove a rad or is it only allowed for one open end only-eg to change a rad valve?

also when creating the vacuum (bunging the 2 open ends in the tank) do you need to release some pressure, eg open a rad bleed valve, drain some water from a drain cock 1st or can you just open the valve, drain it (if changing the TRV) ...

thnaks for any tips...

 

[superdupergasman]

You can have 2 open ends and no need to release the pressure if you are careful.

you should not even need to bund it if you are taking a rad off.

 

[Kristoflampie]

Yes you can bung the tank at the vent and feed and it will effectively air lock the system but its not perfect usually. In my experience it slows draining water to a trickle which makes it easy to change a trv or such providing you can catch the trickle with a basin or towel from the open ends. Take the gravity pressure off via the drain first until water slows to almost nothing which retains most of the water in the system then you should be able to swop rad valves or zone valves etc without a complete drain down. Done it loads of times and havent flooded anywhere yet!!!..... but as I said its not always perfect so check and check again before blindly whipping fittings apart.
Dont forget to take the bungs oot!!

 

[D_Hailsham]

The blurb for the Drayton DrainEasy Kit says:

It can only be used where the header (feed and expansion) tank is no more than 30ft (9 metres) above the lowest point in the system and only one break in the system is being made at a time.

More info at Drayton. It's under Ancillaries and Spares.

 

[nickso]

bung it, crack open whatever you want to change (2,3,4,5 open ends if you want) wait until the water stops coming out, make sure there are no gurgling noises when you remove the item(s) and robert is a reasonably close relative.

 

[steved101]

I have created a vacuum before using 2 expanidng plugs and it worked fine, this was to change a TRV. But after seeing the Drayton Drain Easy kit in B & Q - which looked good and the bungs much better and thicker than mine, I was puzzled a little as it said you can use it to change a pump, etc . I didn't know if 2 open ends - eg to change a pump, etc would be acceptable, as I only though 1 open end at a time was allowed and it had to be vertical, eg a TRV/Rad valve....

so if a pump/motorised valve, etc can be changed too then that would be brilliant.

ABout the radiator, if you no longer have TRV caps for the same make TRV then maybe it can also work for this even if there are 2 open ends quite far apart???

 

[seco services]

you can have two open ends on pipework with system bunged.
used this many times when pipework needs altering for new rad etc.
trv, if you no longer have the caps i use the 5p method on trv

 

[ollski]

This may help with bunging:
http://www.plumbingwoes.co.uk/midpos.html

 

[steved101]

i really didn't know you could have 2 open ends! i read you had to have only 1 open end and it must be vertical!! so changing a mid position valve with 3 open ends horizontal is OK too?!!!

I am putting a new rad up in my mums house at the weekend, a fancyish type so will alter the pipework under the floorboards, obviously this will mean draining the system!! what corossion inhivitor would you recommend-i was thinking of getting Sentinel X100? Is that the best???

 

[Paul Barker]

I bung systems as a matter of routine saves loads of labour never had a failure.

important to shut aav on a combi and if you can't shut flow and return or will never work.

Have failed on freezing manytimes never failed on bunging. After initial 1/2 bucket of water to create vacuum water just sits there looking at you.

 

[ChrisR]

(2,3,4,5 open ends if you want)

You reckon?
I've worked with two open ends and found suddenly there's a few gallons dumping out of one of them.
I also find that conical bungs won't reliably work in tank connectors which have splines inside them - which seems to be the majority. I made a tool which does work for those, though I usually can't find it.

So I really don't use them much - too risky.

 

[nickso]

(2,3,4,5 open ends if you want)

You reckon?
I've worked with two open ends and found suddenly there's a few gallons dumping out of one of them.
I also find that conical bungs won't reliably work in tank connectors which have splines inside them - which seems to be the majority. I made a tool which does work for those, though I usually can't find it.

So I really don't use them much - too risky.

i use them twice a day on average. ive had a cylinder and diverter valves out at the same time totalling 5 ends iirc. you have to listen for the gurgling if you have that many open though.

3 ends is completely safe IMO and ive never damaged a customers property through using bungs.

 

[Gasguru]

Bleed all the radiators etc otherwise you'll spend ages pulling the vacumn. Feed tanks with splined tank connectors just cut the feed pipe and cap.

 

[wilhelm]

I think ive watched too many episodes of this

or ive contracted rabies, anyway nickso, I will give your method a go.



If it works, then gawd bless ya.

 

[nickso]

I think ive watched too many episodes of this

ive never had loads of sweaty germans (thankfully) in the same room or had any explosions using bungs either.