Replacing Radiator(s) Help

[NOSPAMnet]

I have replaced Ch rads etc etc on my old system but now I have a sealed system ( Combi) and I want to sometime in the future move or replace a rad or two. I know it's not the ideal time of year to be doing this but I need to do it when the urge takes me . I want to confirm what I need to do so here's what I intend doing and would appreciate if you could point out anything I have missed or don't need to do .

(1) switch off power to boiler. (2) switch off water supply feeding boiler ( is this necessary ?) (3) Drain down system ( there is a drain tap under the floor beside boiler),opening bleed valves to assist this (4) move and/or replace rads . (5) Close bleed valves ,Close drain tap,feed system with Sentinel using the installed filling point ,open water valve and open filling loop to around 2 Bar (6) Open bleed valves to expel air while watching water pressure and open filling loop if required . Continue doing this until all air is expelled . (7) switch power on and fire up boiler ,checking for any further necessary bleeding .

[Tom]

I have recently installed some TRVs and did what you mention above. But before i topped up the system i ran some water through (opened the water valve for a while) to clean through the system. As there was no installed filling point for the Inhibitor i just fed it through the top of one of the rads upstairs using some tubing. Good luck!

Tom

[Roger Mills]

Yes.

You don't need to drain the whole system. Turn off *both* valves[1] [2] on any radiators you are not touching, to keep then full during the operation. You'll then only need to drain the pipework - and won't need so much new inhibitor (assuming you have some already!)

Yes

There are various ways of adding inhibitor. I made a device to pour it into the top of an empty radiator after the blank plug had been removed.

You may need to top up via the filling loop several times.

That's about it!

[1] Make a note of how many turns it requires to close each lockshield valve so that you can restore them to the same position. [2] If TRVs are fitted, remove the heads and screw on the supplied decorating caps to make sure that the valves stay closed however cold it gets.

[NOSPAMnet]

Thx for that .I pretty much got it right . I think I've got decorators caps for the TRV's..they are all fairly new .

[The Medway Handyman]

If you isolate the rads via the lockshield & TRV, then no. Use a blanking cap on the TRV. If you are not cutting into the pipework then yes.

Close off every other rad using the lockshield & TRV, it reduces the amount needing to be drained and makes bleeding easier. That way you are only draining the pipework & rad you are dealing with.

[NOSPAMnet]

Eh...That's confused me now ,especially that last part .

Yeah .I understand that part .Someone else said to do that as well.

[The Medway Handyman]

Sorry. If you just need to take the rad off for decorating for example, then just isolate the rad, no need to turn off the supply. If you need to replace the rad with a larger/smaller one, then you would need to switch off the water supply, as you would be cutting the pipes.

[NOSPAMnet]

Ok.....but does the water supply not go via the filling loop so if it is closed then does that not mean it makes no difference ....not that it's a problem closing the water valve anyway .

[Roger Mills]

I answered 'no' to that one - taking it to refer to the cold supply for the DHW. With a combi, that surely doesn't mix with the heating circuit, but is separated by a heat exchanger?

[The Medway Handyman]

The filling loop will shut off the supply to the rads if thats what you are asking.