What size pump do i need or what pump would you recommend to efficiently run 25 radiators ?
25 rads is actually not so many if you have one or more in each room and hallway etc. However the pump is not so related to the number of rads but the boiler. The boiler will be rated for a certain heat output at a certain water flow so all you have to do is to match that design water throughput. Obviously you need a central heating type pump working inline and not just any pump such as a power shower but I would hope thats obvious. A 4 bed house could easily have one rad in each bedroom, one each in 2 or 3 toilets/bathrooms, 4 or 5 in hallways, 3 or 4 in a main lounge, 2 or 3 in a dining room and 2 in a kitchen.
