CH Calculations

[sharpspark]

I am doing the calculations for all the radiator sizes for the house i'm fitting CH in. I understand all the basic calculations but what do I do about the doorway size opening between the lounge (21 degC) and the kitchen (18 degC) (no actual door). Is there a U factor for openings? As the rooms are at different temperatures there will be some heat flow which will up the required size of the lounge radiator.

 

[oilman]

This looks like a good situation to illustrate the limits of benefit of theoretical calculations. The lounge radiator would only struggle on a few days a year and then there would be extra heat input in the kitchen from cooking big pots of soup and mugs of hot cocoa. The temperature differences would cause a bit of air mixing which would be near the opening rather than across the whole room so practically it wouldn't matter anyway.