My OH has recently become ill and is virtually housebound. In previous years we have not been around the house in the mornings, but this will obviously change this Winter. My question is would it be cheaper to use the gas fire on low in the lounge (which is quite large) rather than the central heating on a low temp. and then put the CH on mid afternoon.
The fire is a 15 yr old Valor Colourway Bal.flue Radiant/convector and it states in the manual that the Gross gas cons is 3.65kW Max and the Max output is 2.7kW, but unless zero temps we would not have it on max.
If you intend to heat the house then you cannot do that with a "fire" in a single room - in any case, fires are hideously inefficient as pure heat sources and their only merit lies in their intended visual effect (if that is your taste). If a house is to be heated by central heating then it is known that keeping the heating on continuously and governed by a thermostat is the most efficient way rather than intermittent heating whether automatically timed or manually switched on and off (unless days are to pass between heating periods). To avoid draughts doors to individual heated rooms should generally be left open and all rooms heated to similar degrees (rooms left/abandoned to the cold probably best left closed although all rooms should be heated to avoid condensation).
As to how well the heating works depends on how well the radiators are placed (should be under windows, near external doors and not crowded around internal doors as is sickeningly common), the system's balance, boiler and system controls, and the quality of windows and insulation.
Tilly...put simply, air inside houses contains moisture from daily living/breathing/ cooking/washing etc and the warmer the air, the more moisture it can hold. So, colder places (like unheated bedrooms) with their colder surfaces are the places that the moisture will come out of the air and deposit on walls, windows...in fact everything in the colder room...hence, mould on walls, clothes etc.
Agree with Karl 100%. keep background heating on throughout the house, having areas of different temperature causes draughts and leads to cold spots where condensation occurs.
We turn the radiators off and close the doors of the 3 bedrooms that aren't in regular use and there's no condensation problems (double-glazed windows).