Bungs

[Alex10]

Hi

First post. Go gentle please, can you advise me on bunging a central heating system to remove a radiator.

Ok lock shield vlv is Broken (won't shut) and TRV Passing also.

Can I bung the system take off small radiator 600 x 500 K1

I am thinking it's ok not to have to turn any end off anyway as this is only 2 open ends correct? Same as a pump when you remove that that's exactly the same isn't it?!


Can you advise

Regards

New plumber Alex

 

[petit_pablo]

Bleed any air out the radiators first then bung vent and feed to the CH and remove radiator.
You will get maybe a buckets worth of water if you drain the rad.
Once the rads out the way, swap the rad valves.

2 open ends should be fine, you can change 3 port valves on bungs.

 

[Alex10]

Thanks Petit! Can you explain how this works in very simple terms !

What I Can not get my head round is when I remove the radiator why air does not enter one vlv and water come out the other vise versa!

Cheers bud

 

[Alex10]

Would the same be said for replacing a heat only boiler ie cutting flow & return on bungs will that still pull a vacuum ie two open ends?

 

[petit_pablo]

Thanks Petit! Can you explain how this works in very simple terms !

What I Can not get my head round is when I remove the radiator why air does not enter one vlv and water come out the other vise versa!

Cheers bud

The Air can't push past the water at atmospheric pressure.
Stick a drinking straw in a drink, put your finger over the top and lift it out. Same principle.

 

[petit_pablo]

Would the same be said for replacing a heat only boiler ie cutting flow & return on bungs will that still pull a vacuum ie two open ends?

Yea should do, I've changed heat exchangers on bungs.

 

[Alex10]

Thanks mate.

 

[Alex10]

So are we saying here just to be clear that I don't need to turn 1 end off when in the future am replacing a TRV etc ? They can both be left open ! ?

And if for instance I wanted to cut into a 22mm pipe on the landing as long as it's bunged and I take to pressure off vis a bleed point in to a bowl etc I could cut into one of the circs having " two open sides" causing a vacuum, but cutting the second 22mm pipe I would get wet as air can enter threw that pipe pushing water out the other?!! Have I got that

 

[longdogs]

Edit

 

[diablo]

So are we saying here just to be clear that I don't need to turn 1 end off when in the future am replacing a TRV etc ? They can both be left open ! ?

No, it will decrease the flow of water,it won`t stop it completely.

And if for instance I wanted to cut into a 22mm pipe on the landing as long as it's bunged and I take to pressure off vis a bleed point in to a bowl etc I could cut into one of the circs having " two open sides" causing a vacuum, but cutting the second 22mm pipe I would get wet as air can enter threw that pipe pushing water out the other?!! Have I got that

If you think bunging your feed and vent will enable you to chop into a 22mm pipe without water p*ssing out think again. It will slow, eventually. You also have to consider position of any valve, 3 port or any air admittance valves. Golden rule: just one open pipe at a time, remember if you cut a pipe you have TWO open ends, so one end must be valved, with say the rad valve. You'll get a small amount of water coming but then it'll stop.

 

[gas112]

I have changed boilers , 3 port as well as 2 port valves on bungs and as for not being able to cut 22mm nonsense i regularly blow joints on 22mm held on bungs ...

One thing no one has mentioned hopefully your system doesnt have a primatic cylinder on it as you cannot bung that at all as it will implode

 

[jeff the gasman]

The stress free way is to drain the system. I've seen bungs fail.
Nuff said.

 

[onlyfitidealboilers]

So are we saying here just to be clear that I don't need to turn 1 end off when in the future am replacing a TRV etc ? They can both be left open ! ?

No, it will decrease the flow of water,it won`t stop it completely.

And if for instance I wanted to cut into a 22mm pipe on the landing as long as it's bunged and I take to pressure off vis a bleed point in to a bowl etc I could cut into one of the circs having " two open sides" causing a vacuum, but cutting the second 22mm pipe I would get wet as air can enter threw that pipe pushing water out the other?!! Have I got that

If you think bunging your feed and vent will enable you to chop into a 22mm pipe without water p*ssing out think again. It will slow, eventually. You also have to consider position of any valve, 3 port or any air admittance valves. Golden rule: just one open pipe at a time, remember if you cut a pipe you have TWO open ends, so one end must be valved, with say the rad valve. You'll get a small amount of water coming but then it'll stop.

Nonsense, you can have 2 open ends on bungs. So cutting in to a pipe is fine,

Yes I have had that problem before both ends fooked on a rad, if you can shut one end that is better, however even if you leave it open it should hold as there are still only 2 open ends.

 

[nickso]

In my 13 years I had the bungs fail once when one of them dropped out the cold feed.

I have had 5 open ends on bungs.....didn't know it but it still held. I changed cylinders on them, they are reliable.

 

[onlyfitidealboilers]

Nickso, do you cut into pipe as well? I've not had a problem myself.