Can I remove a radiator from a closed central heating system

[philwest]

I have a closed ch system (with a pressure feed/flexible hose; no overflow tank) and am looking to relocate a radiator (due to knocking out central plasterboard wall between toilet and bathroom). Would like to replace existing radiator with heated towel rail and relocate on far wall. Because I will be cutting the pipes and extending, I am assuming I will have to drain the system. I can't find any information on how to do this for a closed system. I can drain all the rads and the inverted loops (after letting the water cool and turning off the pump), but can I just refill from the pressure feed from the water tank? Does the system not use some sort of additive in the water? Any help or link to explanatory site much appreciated

 

[IanDB]

Draining off a closed system is pretty straightforward. The heating circuit is isolated so all you have to do is locate the drain valve, connect some hose to it to allow the water to drain to some convenient point. Open the drain valve and then progressively open the bleed valves on the radiators starting upstairs and working down. The water will drain out under gravity.

To refill the system, shut the drain valve (obviously) and open the filling loop a little. The system will start to fill up. I would suggest closing the bleed valves on the downstairs rads and bleeding them one at a time after they have started to fill otherwise they'll all bleed at once(!).

Then do the same upstairs. Again it would be better to close all the bleed valves, pressurise the system a bit and then bleed the rads individually topping up the system as the pressure drops.

You should add inhibitor when you refill the system. I don't know the best way to do this but I did it by getting a 3' long piece of hose with a funnel on the end and once the system was drained, flushing the inhibitor back through the drain valve. An alternative is to remove the bleed valve assembly from one of the rads and pour it in there.

Anyway, that's the way I did it and survived to tell the tale.

 

[philwest]

Thanks Ian. Can I pick up inhibitor in a DIY store or is it more specialist? Presumably the bottle will give the amount required? Also, is it OK to drain the existing water into the garden or a drain, or do I have to be more careful with disposal?

 

[IanDB]

Any plumber's merchant will supply it. The standard stuff is manufactured by FERNOX. They would also give you advice on the quantity required (as I recall it's about 3 litres for a normal system).

As regards drainage, I don't know what it will do to the garden - a drain would be better. It has to be reasonably environmentally friendly or it wouldn't be used in the first place.

This is the Fernox website if you want some more info http://www.fernox.com/?cccpage=alphi_11&sub=8

When they talk about the annual test of concentration of inhibitor in the system, you don't have to buy their test kit. You drain off some water into a container and put a nail in it. If the nail goes rusty after a few days the system needs draining and re-filling with with a fresh lot of inhibitor.

Good luck

 

[philwest]

Thanks for all this. I inspected the radiator last night and was expecting to see a valve at each end. Unfortunately there is the hand valve at one end, and the 15mm pipe seems to be plumbed straight in at the other end (there is no reference to this possibility in my DIY book!!). What I'm keen to do is remove this radiator now, separately from extending the pipes and mounting the towel rail. This is so I can take down the wall independently, and give myself less to do all on the one day with the heating out. With the pump off, would it be possible to cut the riser and get on a compression join with a valve before it floods too badly (this is an upstairs room)? Or would the pressure prevent me being able to get it done up correctly? I could connect a small piece of piping form the other end of the valve and then to a hose to outside. With the valve open theremight not be too much spillage if I was quick??? Alternatively I've heard mention of a technique where you deliberately freeze the water in the pipe to give temporary relief - do you know what you need to do this? If I could get the valves on both pipes without losing a load of water it would mean I wouldn't need to drain the system!