Reliable and long lasting combi for 4 bedroom house

No one here can give you a specific model as a Gas Safe engineer needs to survey your property in order to carry out 'heat loss calculations' to arrive at the correct KW rated boiler. He will ask you questions such as 'do you have a high hot water demand' then on completion he will advise the best boiler/system to suit your needs and that of your property. NB: Always choose a Gas Safe registered engineer

Heatloss calculations and hot water demand are important for an engineer to work out the size of combining required, it might even be that a combination might not be suitable as the hot water demand you require might be too great, a large domestic combi will probably only give approximately 17.2 litres of hot water per minute through the combi at a temperature rise of 35 degrees C, this is providing the incoming mains water supply will allow this flow and the incoming water pressure is also acceptable, a better option might be an unvented hot water cylinder and a system boiler or similar, this gives you lots of stored hot water and the added advantage that if your boiler ever fails you have an immersion heater still, with a combi you will have nothing.