Boiler size for UFH and radiators

[Schuey87]

Have got a 2015 Intergas HRE 36/30 boiler at present. Looks like efficiency when searching the model online is 88.5% so still looks decent. We have a 4 bed detached house from the late 70s. 1 bathroom/shower and unlikely to change in the near future. Currently having an extension/renovation downstairs. We are looking at having an overlay panel UFH system in 54m squared of the downstairs space (open plan kitchen/living room, utility and WC). There will still be a radiator in the hall and lounge and radiators in the upstairs bedrooms. Currently no issues with hot water with current boiler, shower has a great flow rate and gets really hot. As part of the renovation we need to move our current boiler, looks like an extra ~£2k to get a new boiler vs just moving current one. Can anyone point me in the direction of any calculators/websites/advice on whether our current boiler will be sufficient for a mix of UFH/radiators, all the advice/calculators I can find via google doesn’t seem to include a mix of rads/UFH as an option!

 

[oldbutnotdead]

All you need to know is the heatloss of the house and the new extension. The boiler doesn't care if the heat it produces goes to UFH or big radiators.