Underground rad pipe leak....

[kjacko]

Hi all,
so after some pratting around we've identified the cause of our boiler dropping pressure every couple of hours or so. A pipe leak under the rad in the living room.....under the concrete floor
So, we've taken the decision to re-pipe all downstairs rads to above ground.
I'm planning on draining the system this weekend (as opposed to pipe freezing), so i can put full bore isolators on the 2 x 22mm pipes coming down from upstairs. I'll then put 22-15mm reducers on each pipe and then lay new 15mm above ground to each of the 2 easy to do rads. The 3rd will have to be fed from a separate rad upstairs due to its position on the ground floor.

Questions:

1. I'd like to suck all the existing water from the underground pipes prior to capping off (seeing as the leak is causing rising damp on the wall). I was looking at the sub £20 battery operated pumps, but have read mixed reviews. Obviously don't want to spend a fortune but a reasonable purchase may come in handy in the future.
2. What about putting a magna clean thingy on the system somewhere? (Baxi 105e boiler in the loft if its makes any difference). We're replacing 2 very old and gunked up rads in our bedroom with one new one so might help to keep everything clean?
3. Is there an advantage doing this whilst the system is drained?

Thanks for any advice offered?

 

[rochdalegas]

Wouldnt bother with a pump any water would not be under pressure and minimal is it bothers you pur bucket under rad valves and blow down pipe where you cut it should get rid of most water left in pipes.

A Magnaclean is a good idea and would save draining again if you did it at the same time.

Also add some inhibitor while your at it

 

[flameport]

1 - get this: http://www.wickes.co.uk/Wickes-Wet+Dry-Vacuum-with-Blower/p/215735
2 - Probably a good idea, although get an all-metal one with a drain valve, not the spill-n-crack plastic tub efforts.
3 - the advantage of doing everything at the same time is that you don't have to drain down and replace the inhibitor again.