Getting a replacement boiler, current one around 30 years old. The new boiler has been sized to the cubic area of the house, and I understand that this is the correct way to do it, and appreciate the one out of three engineers who bothered to do this, and to make sensible recommendations about moving the boiler etc. Worcester CDi, 30kW heating output has been recommended. If I count up the radiators in the house 17, on average around 1000x700 double panel, then again that 30kW is probably about right.
However, I am thinking about this slightly differently. For the lifetime of the boiler there are only going to be 3 of us in the house, most of the radiators are in rooms that are empty so they are either off or low. We do have visitors using the spare rooms but they only ever come in summer. Most of our time is spent in an L shaped extension with 2 radiators in it, and there is usually one, to at most three other radiators on high, with maybe another few on for background heat. My gas bill last year was only about £600 which shows we don't use a lot of energy, and we are about to make a number of insulation/glazing improvements. Even if I am being generous I can't see a scenario where we would be using more than 20kW and so I was thinking of a 24kW heart output boiler as I don't want to lose efficiency by over sizing it for its normal use.
Is there anything wrong with my thinking here?
However, I am thinking about this slightly differently. For the lifetime of the boiler there are only going to be 3 of us in the house, most of the radiators are in rooms that are empty so they are either off or low. We do have visitors using the spare rooms but they only ever come in summer. Most of our time is spent in an L shaped extension with 2 radiators in it, and there is usually one, to at most three other radiators on high, with maybe another few on for background heat. My gas bill last year was only about £600 which shows we don't use a lot of energy, and we are about to make a number of insulation/glazing improvements. Even if I am being generous I can't see a scenario where we would be using more than 20kW and so I was thinking of a 24kW heart output boiler as I don't want to lose efficiency by over sizing it for its normal use.
Is there anything wrong with my thinking here?