Hi, 3 story semi. Ensuite with shower in loft, main bathroom on 1st and toilet and kitchen on ground. 4 bedrooms. Double panel Myson rads and Thermostatic valves to most rooms. New extension planned and converting from oil to gas and was thinking of the above. Will re pipe the ground and 1st (2nd done 2 years ago). Any advice on best suited boiler in terms of performance, economy and dependability? Cheers!