Partial Draindown

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Hi all, quick question. I need to cut into a downstairs radiator pipe to modify it to clear a kitchen base unit, so what I wanted to know is can I shut off the lock shields and TRVs on the rads upstairs and just drain the water from the pipes to save draining the whole system?
Cheers in advance.
 
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Sorry I should have pointed out that it is a fully pumped vented system. Just in case that is relevant.
 
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Yes, although you will need to crack a joint open to let air in since you won't be able to open the bleed valve on a radiator.
 
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Put a 22mm speed fit cap on the open vent to the F&E, twist up a carrier bag and twist it into the outlet on F & E to bung

You have now created a vacuum.

Open a drain clock with a hose run to a drain, very little will come out.

Drain the rad you want to work on,shut the valves.

Only work on one side at a time to maintain the vacuum.

When your finished, remove cap and bag, bleed rad, then check for any air in system
 
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No, your original suggestion is ok but things to bear in mind:
you need to isolate the header tank to stop it filling and drain it along with the pipework;
when you refill you may introduce airlocks depending on the pipework layout, there again you may be lucky.
I have used a similar approach and it worked for me.
 
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No, your original suggestion is ok but things to bear in mind:
you need to isolate the header tank to stop it filling and drain it along with the pipework;
when you refill you may introduce airlocks depending on the pipework layout, there again you may be lucky.
I have used a similar approach and it worked for me.

I see what you're saying, that's what I intended doing; isolating the header tank by tying off, closing all the valves and then draining down, perhaps letting one of the rads drain to allow air in to facilitate draining. This has to work right?
 
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No, your original suggestion is ok but things to bear in mind:
you need to isolate the header tank to stop it filling and drain it along with the pipework;
when you refill you may introduce airlocks depending on the pipework layout, there again you may be lucky.
I have used a similar approach and it worked for me.

I see what you're saying, that's what I intended doing; isolating the header tank by tying off, closing all the valves and then draining down, perhaps letting one of the rads drain to allow air in to facilitate draining. This has to work right?

Yep!
 
L

longdogs

Keep a 15mm push-fit end cap handy. Even with the airlock, sometimes air dislodges and you get a small surge of water.
 
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No need to drain any rads. If you use the vacuum method described above you may end up with very little water loss, but if you don't do that then air will enter via the vent pipe and the pipework will drain, so more water out.

Either way will work but you can keep all the rads closed.
 
L

longdogs

Obviously various suggestions and methods but this is the way I would suggest to be safe. Personally I would never cut into a pipe without knowing that the 'air lock has worked'.

Bung the f&e tank with a rubber bung kit

Turn off all the rad valves

Drain the nearest radiator to where you are working

You can now drain the pipe (creating an airlock) via the valve on the pipe you wish to cut - you have control of the water. You will get a small amount of water coming out.

When the water stops flowing, cut your pipe as required

Like I said, I'm not doubting other people's methods but that's the way I would do it.

Re- route your pipe

Connect back to the rad

Remove bungs

Open all valves
 
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