Remove existing chb, make good flue hole bricked outside block and plaster inside. New flue hole Worcester greenstar 12ri horizontal flue and plume kit. Condense through worktop 2x units into sink waste. Fit Magna clean. Change pump and valves 3 port, 900x450 indirect with 27" immersion, room stat, twin channel programmer and chemical flush 7 rad system. Wiring isn't too bad jus new permanents to boiler from nearby spur.