We have a 3bed, 2 bathroom dormer house with 3ft thick granite walls. The ch is oil with an outside boiler. We need to change the boiler as the one we have isn't powerful enough now as we added a bedroom & bathroom and will be adding a conservatory.
Should we go for a combi or stick with the type we have at the moment. The most I can find for outside combi is 90000btu and costs about 1500.