Swapping radiator sealed system

[Kton2002]

Hi, i am planning to swap a radiator in my sons bedroom which is a single panel 600 x 450 radiator - it is a cold room in winter and am hoping putting a double radiator of similar size will help it in the colder months (600 x 500). It is a new ish build (2019) house with a sealed system. Just wanted to check my approach:

1. turn TRV to 0, and the valve the other side - close it fully (counting number of turns).
2. undo bleed valve at top to allow some water out and hopefully once the pressure left inside the rad is released, water will stop coming out of the bleed valve albeit the rad will still have water in it just not under pressure.
3. undo bottom union nut and drain water out both sides.
4. Take radiator off wall and put new one on - hopefully can re-use existing mounts or adjust them slightly as getting a slightly taller radiator (5cm taller).
5. unscrew old tails from existing radiator, clean up, and put ptfe tape round them and screw into new radiator.
6. attach valves each side to new radiator and then undo trv and valve the other side allowing water in.
7. Question - do i now top up the system at filling loop with pressure that was lost when i replaced the rad, or do i open the bleed valve? Not sure on what order to do these 2.

Also - i haven't used the heating for a few months, and the zone valves are only set to hot water circuit currently. Will i need to open the zone valve for the upstairs heating circuit before i do all of this to ensure that when i fill the system back up, it tops up the heating circuit? And would i need any new olives during this process or can i just use PTFE tape on the existing olive?

Thanks in advance

 

[terryplumb]

New olives on the tails would be wise, but there is a very good chance that the existing ones will seal ok.
When opening the valves to fill rad ,bleed air first,then top up pressure,repeat if required .
A smear of LSX on the tails and PTFE tape.
Zone valves can be latched open manually. Other rads may need bleeding.
You may find that the pipework doesn't align . When swapping single to double panel rads the latter sits further out from the wall.

 

[Kton2002]

Thanks terryplumb!

The existing is on microbore flexi hose, and I can take the current rad off the wall and there is some scope I think for having it sitting a couple of inches further forward but I guess I won’t know for sure until the new one is offered up to the pipe work. Is it easy enough to extend the micro bore pipe? Seems super hard stuff so not sure how I’d do that plus it’d involve draining down I assume , as I would have to remove the trv etc.

 

[terryplumb]

Microbore Flexi hose ?? Do you mean plastic pipe ,I assume you do ?
Yes ,system would need draining if you intend to cut into pipework , extend/ alter it.
Pics of existing set up would be useful.

 

[Kton2002]

 

[terryplumb]

Is the width 500mm ? If new rad is wider than old one ,you would need to have a fair bit of movement / free play in the pipes to make them reach.

 

[Kton2002]

Width of this one is 600, height is 450. Looking at fitting a 600w x 500. I will mount the replacement one a little higher to compensate (that’s the plan at least….!)

 

[terryplumb]

If anything,you should set it a bit lower. Fitting higher would require longer pipes !

 

[Kton2002]

Sorry what I mean is fitting it so that the bottom of the new radiator sits where the current one is, which would mean the additional height of the new one is at the top, and not lower down