Draining a system down

jeremydiy · Posted: Sun Oct 07, 2007 12:46 pm Post Subject: Draining a system down

I want to move a radiator, and have been told that instead of draining the whole system down, it is now common practice to create a vacuum in the system instead. How does this work, and how is it done? Thanks for any help.

WelshMan · Posted: Sun Oct 07, 2007 12:54 pm Post Subject:

If your moving a rad then i assume you will be adding more pipework to the system. If this is so you will have to cut into the current pipework therefore you will have to drain the system down in order to move your rad. By cutting into the pipework you are breaking the vacuum you would have made but blocking the open vent etc.

jeremydiy · Posted: Sun Oct 07, 2007 1:20 pm Post Subject:

Thanks - I created an air lock in the boiler last time I drained the system and needed to get it sorted professionally. This was when I was told (by the British Gas man) that they create a vacuum instead of draining the whole system nowadays, to avoid such air locks. Is there a vacuum that can be created to ensure air locks don't occur in the boiler?

kevplumb · Posted: Sun Oct 07, 2007 1:36 pm Post Subject:

errr some system details might help

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hi-spec plumbing heating · Posted: Sun Oct 07, 2007 1:41 pm Post Subject:

>If this is so you will have to cut into the current pipework therefore you will have to drain the system

no you don't

jeremydiy · Posted: Sun Oct 07, 2007 5:37 pm Post Subject:

I live in a bungalow, the condenser boiler is in the kitchen and it's a gravity fed system with the feeder tank in the loft. What other information do you need?

petetheleak · Posted: Sun Oct 07, 2007 6:33 pm Post Subject:

If you prepare in advance use a pipe freeze kit if you feel confident enough.

you can buy them at most DIY stores or merchants .

The single use kits aint that dear .

Air locks in gravity systems can be overcome by pushing water in by pressurising through mains.

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jeremydiy · Posted: Sun Oct 07, 2007 6:56 pm Post Subject:

Thanks mate

Slugbabydotcom · Posted: Sun Oct 07, 2007 7:14 pm Post Subject:

Quote:

it is now common practice to create a vacuum in the system instead. How does this work, and how is it done?

By plugging the feed and vent pipes there is no way for air to get into the system when you cut a pipe. Think drinking straw principle.

If you do cut a pipe and dont close off at least one of the rad valves you do risk the syphon effect taking over as you leave more than one end open to the atmosphere.

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