"MattH" wrote in message
...

I have recently moved into a larger house and am having soem problems
with the radiators not getting hot, i have tried balancing which has
helped but really my question is, is the pump i have strong enough. The
house has 23 radiators of which 18 are large doubles, the pump is a
grundfos 15/60, which i understand is a powerful domestic model, but i
cant help thinking isnt up to the job.

Can anyone advise whether i can install a more powerful version, if so
what, or how can i check that this is strong enough, i cant help
feeling it isnt.

Lots of elbows can defeat it. Otherwise put another pump in series (two
together). This will get the pressure up. I have seen a pump on the flow
and one on the return and that worked quite well. The boiler can act as a
big restrictor to flow. One pumping into the boiler and one pumping out.

It will be better if you split the system up into two zones. Say, upstairs
and downstairs, and have a pump and non-return valve on each. Grundfos do
twin pumps sets for this. Then you divide the system up. You can also have
each zone on separate temperature stats and timers. Upstairs can be off
during the day and only on during bedtime and in the mornings. This is the
best approach as it solves the problem and saves on fuel bills.