partly draining a vented Central heating system and refillin

[N1ckD]

Hi,

I want to put a new radiator and move an existing one on the top floor of the house ( 3 stories). Rather than draining the whole central heating system I thought I could partly drain it to just beow this level - using the vents on the two other radiators at this level to draw in air- but still draining with hose attached to a drain valve on the ground floor . Will there be any problems refilling it? i.e will re-opening the vents on the top floor ensure it is refilled - or will I cause an air lock by only partly draining it?

Also is it still OK to use the push fit plastic isolating valves in central heating systems - I have noticed that all the recent ones stocked in shops seem to say not for use in central heating systems - yet ones I have used before did not!

thanks

Nick

 

[45yearsagasman]

You don't say if your system is open vented or sealed. In any case, part draining is fine and refilling should present no problems. Don't forget to put in new inhibitor. You mention isolating valves? Waste of time unless you use full bore valves as flow could be restricted. Adding rads is fine but a system balance will probably be required and is your pump OK?

 

[N1ckD]

Thanks for the reply

yes open vented - said vented in title but meant open vented. The pump is fine - pretty new - about 18 month old.

RE the isolating valve - it is because at this point I do not have one of the radiators (needs to be non standard size and have not sourced yet) and therefore wanted to terminate the pipes for this with isolating valves to save having to drain again.

yes will put in inhibitor - any recommendations - the last was put in by the engineers when a new boiler was installed just under a year ago and the sytem was power flushed.

Nick

 

[45yearsagasman]

Use full bore iso valves.More expensive but worth the extra. Boilers instructions should recommend inhibitors. Fernox F1 or maybe Sentinel X100.