use of bungs

[apcdave]

Hi all,

I have a small job on tomorrow - ( just replace a radiator valve ) - I don't want to spend time draining down an entire heating system so am thinking I 'll try bunging it. Am I correct in thinking I'll close both valves , drain radiator and remove from wall ( want to run a hose thro it outside ) - then bung the vent pipe and feed pipe. Take old valve off and replace - and then refit the rad. Remove bungs and hey presto ! hopefully......

Have I missed anything?

cheers

dave

 

[Winston]

I have used them and all has been ok but you really must insure that they are correctly fitted otherwise you will have a mess 😱 I for one have felt far safer if someone is up there to hold them in if need be.

 

[welly2510]

if your replacing a faulty valve that dont shut off i would bung the tank first, shut the good valve off and drain some water of by cracking the nut open, you all ways get a small amount of water out before it holds, then replace valve and remove rad, iv use bung kits daily and never had any probs with them not holding.

also check to see if the system has any automatic air vents in, if so screw the cap down or the water wont hold.

 

[nijjy]

great information, just what I needed. I have an open vented system. How do I know where to check for automatic air vents?? [I want to change a rad valve on a downstairs rad.]

 

[cr0ft]

You guys are braver than me. Not a chance in hell that I would take the risk of using a bung myself. I know most of the time you will be ok but it just needs 1 to pop and you have a right mess!

 

[SimonJohns]

If your only doing the one. I wouldnt even bother with the bung. Couple of towels. And switch valve off first

 

[nijjy]

simon and croft, thanks for the info.

Hi Croft, regarding bungs, I have been advised to use a bung that expands, which comes with a wing nut? someone else I spoke to uses a parsnip!! if I go down the bung road, should I bung both header tank and cold water feed tank? [both are in the loft]

Hi Simon -switch off which valve? I do have a valve. [think its called a gate valve]installed in the feed pipe from my header tank.

 

[Plumbstar Tom]

carrot and a potatoe iv heard

just bung the feed and expansion tank for the CH

 

[dontknowitall]

Carrot's for stuffing in the customer's mouth to prevent them screaming and potato's for chopping in half to squash in their ears to stop them hearing your French ...

 

[mikimac]

Ahhh, carrots for stuffing in the Mouth....that's why I don't get many call backs 😀

 

[dontknowitall]

I don't know - with some customers if you push a carrot in one ear it will go all the way through to the other ...

 

[nijjy]

do apologise in advance, as I am not a plumber, but try to do small jobs myself if I can. mainly because the rcession has pushed me out of work, and I have to watch my money a little. so thats I'm gonn have a go! changing two rad valves is nothing to a professional, but quite a lot to a complete novice!! can i get clarification on the tanks in my loft.. on eis called a cold water feed tank [the big one] and one ios called a header tank [the small one] am I right? so what is the feed and expansion tank? potatoe plugs what exactly?? by the way, before doing this jpb, i will be armed with an emergency cap end, and millions of towels!!

 

[dontknowitall]

Small cistern in loft is called the feed and expansion tank. It feeds water to the radiators and if/when the water becomes too hot it can expand into this tank. If the cistern cannot cope then the excess water will go through the overflow pipe to outside.

1. Stop water entering F&E cistern. Isolate ball valve or tie up with string/hold up with something.
2. Drain system. Find a drain point downstairs (sometimes on a radiator, usually one on or near boiler.
3a. If radiators to be altered upstairs, start undoing valves when you feel it's safe.
3b. If radiators downstairs you'll need to empty the radiator by removing valves - can get messy if you've not got the correct tools/equipment - for example a wet vacuum makes this a piece of cake.
4. Change valves
5. Fill and check for leaks during fill.
6. Before totally full pour in inhibitor.

 

[nijjy]

thanks very much, dontknowitall. I will let you know how I get on!! all the best.

 

[diamondgas]

thanks very much, dontknowitall. I will let you know how I get on!! all the best.

Don't under any circumstances bung the domestic hot water storage tank or you'll find out what damage atmospheric pressure can do to a copper cylinder !!! Good luck 🙂 Once you've used the bungs a cupl of times you get use to them. You need to close off all auto air vents, if you have any, by the way!

 

[nijjy]

hi Diamondgas. the hot water storage tank is in my airing cupboard, not in the loft; and it all looks sealed to me, so this won't get bunged!!. Should I bung the cold water tank in the loft, as well as the the F&E tank?

where would the auto aur vent sbe located, if I have any. and, what do they look like? sorry, but I am a complete novice, but a fairly sensible one!!

 

[leelister6]

Don't under any circumstances bung the domestic hot water storage tank or you'll find out what damage atmospheric pressure can do to a copper cylinder !!!

Why would this damage the cylinder?! If you bung the tank and open the taps, the cylinder doesn't empty!

 

[diamondgas]

Why would this damage the cylinder?! If you bung the tank and open the taps, the cylinder doesn't empty!

If it's a steel cylinder you may get away with it but a copper one shrinks ... I believe it'll depends on which tap you open. if it's below the cylinder you'll get atmospheric pressure squeezing the cylinder, likewise if you conect a hose to the botom and drain away the cylinder will colapse in on itself if you've blocked off the feed and vent pipes... The open vent/cold feed allows atmospheric pressure remain neutral ... I believe that's how the theory goes 🙂

 

[nijjy]

so, I 've got two tanks in my loft. I know tha ti should bung the feed and expansion tank [ the smaller of the two].

do i bung the cold water tank? [the larger of the two]. my thinking is that, If the cold water tank, does not feed the CH system, then why would I need to bung it?

also my hot water storage cyclinder is also not part of the CH system.. am I right?

 

[PlumbBobBob]

no you don't need to bung the larger loft tank just the smaller one. the hot water cylinder is indirectly part of the heating system in that the same water from the boiler that goes through the coil in the cylinder to heat the water that comes out through your hot taps, also goes round the ch system

 

[dontknowitall]

Steve's correct but if you're emptying the F&E cistern there's no need to bung it as you've isolated the water!

 

[nijjy]

Steve, thanks very much. I am gonna give this very small job a go. Having read through some of the posts on this site, I reckon that there is a whole load of knowledge needed to go round and fix water and gas systems. I dont think people should complain if a plumber charges say £60 [or more], for an hours call out work. to come to a house, diagnose the problem, and plan and do repair work- needs a broad knowledge..

 

[rocketman]

If it's a steel cylinder you may get away with it but a copper one shrinks ... I believe it'll depends on which tap you open. if it's below the cylinder you'll get atmospheric pressure squeezing the cylinder, likewise if you conect a hose to the botom and drain away the cylinder will colapse in on itself if you've blocked off the feed and vent pipes... The open vent/cold feed allows atmospheric pressure remain neutral ... I believe that's how the theory goes 🙂

Sorry to reserrect an old thread. I've used bungs on F&E vented systems for valves and or rad chages before. I was about to use them the other day but stopped after I got the kit out of the van. I've got a Regin REGR05 kit and although very battered and torn, the instructions had a warning to use on heating system only. Misuse could lead to the collapse of the hot water storage cylinder. I was changing two sets of taps and the hot water gate valve is kancked. Customer was not prepared to wait for me to drain system down and replace gate valve. To be honest neither they nor me had the time free to do it there and then so I was thinking about using the bungs. Then I read the insructions.

Now I'm not stupid and have a reasonable grasp of phsics and understand pressue and vacuums quite well. I'm a qualified refigeration engineer and also an advanced diver, both of which require a good undertanding of the subject. However, I cannot understand how turning a gate valve off on a vented cylinder is different to using a bung to stop the supply of cold feed. They both do the same thing, stop the supply of cold water into the cylinder.. yes or no ??

Could someone help to put me out of my misery as I'm starting to doubt myself now :confused5:

 

[Popell]

I have bunged the header tank for the hot water .its no different to closing the gate valve and does allow swapping out of a knackered gate valve

 

[Stigster]

The problem can occur when you bung the vent as well as the cold feed. You can create a powerful vacuum if you block the vent/feed and open a tap below the cylinder level. I've never done it but there are of pictures of caved in cylinders online.

It can also more easily be done by blocking the feed and vent and then draining down the cylinder with a hosepipe out the window or whatever.