Repressurising sealed CH system.

[amfisted]

Morning all

Just a question about refilling a sealed CH system (Ideal Logic combi) after draining to work on radiators.

I've done this a few times over the years and always proceeded as follows: drain the system, work on the pipework or rads, refill/ repressurise using the loop, drain air from the highest point then check all other rads for trapped air. Then, and only then, run the CH then turn it off and check again for leaks/ air. Thing is, I'm sure I've read somewhere that you can run the pump without heating the rads, but I've never worked out how. Reason I ask about this is that after repressurising the system and turning the heating on, the rushing and bubbling sounds from the boiler tell me firstly that there's air in the system that I still need to get rid of, and secondly those noises are so dramatic that they indicate that I'm doing something wrong.

Is there something I should be doing differently?

TIA

 

[kidgreen61]

I can't think of how that can be done unless you have a fairly recent Logic, in which case there's a "vent system" function in the menu.

 

[amfisted]

I can't think of how that can be done unless you have a fairly recent Logic, in which case there's a "vent system" function in the menu.

Thanks for that. I should have clarified and said that on previous occasions it was a Worcester Greenstar system that I was draining/ filling, but we're now using a Logic combi fitted in 2022 and I've just drained and refilled to install a heated towel rail. So maybe it'll have the function you mention. Also (edit), that “rushing and bubbling” sound vanished once I removed all the air from the towel rail, so all is well now.