I am considering replacing our conventional (very old) gas boiler with a gas condensing combi. I therefore used the following IDHEE site to get an idea of the boiler size required.
http://www.idhee.org.uk/calculator.html
I live in quite a small detached house that is well insulated with upvc double glazing. Using the above calculator - it was suggested that 13.2kW was sufficient to run the central heating and hot water. This value includes a 'standard' 2000kw for hot water. However if I was to remove the existing hw cylinder and connect the basins/ bath/ sink direct, the notes on the calculator imply that this 200kw allowance can be set to zero since drawing hot water temporarily disables the central heating. That would make the boiler about 11kW rating!?
This seems very small compared to the recommendations from other DIYnot members who have suggested using as much as 30kW for terraced dwellings. The IDHEE calculator above stresses how inefficient over-sizing can be yet I have read that 24-28kW should be the smallest size of condensing combi considered and that 20kW is probably the smallest available. What am I missing? Any help would be appreciated.
http://www.idhee.org.uk/calculator.html
I live in quite a small detached house that is well insulated with upvc double glazing. Using the above calculator - it was suggested that 13.2kW was sufficient to run the central heating and hot water. This value includes a 'standard' 2000kw for hot water. However if I was to remove the existing hw cylinder and connect the basins/ bath/ sink direct, the notes on the calculator imply that this 200kw allowance can be set to zero since drawing hot water temporarily disables the central heating. That would make the boiler about 11kW rating!?
This seems very small compared to the recommendations from other DIYnot members who have suggested using as much as 30kW for terraced dwellings. The IDHEE calculator above stresses how inefficient over-sizing can be yet I have read that 24-28kW should be the smallest size of condensing combi considered and that 20kW is probably the smallest available. What am I missing? Any help would be appreciated.