radiators

[strain]

my radiators take a long time to heat up - there are 11 in the house  - 3 were added this year - is my boilder and pump sufficient  - they were not replaced but it takes the house a long time to heat

[woofgang]

Here's a website that tells you how to calculate boiler capacity http://www.idhe.org.uk/calculator.html

You might just have a sludgy system. If you draw water from a radiator, is it clear? brownish or blackish but clear or does it have sediment in it? Changing radiators can get old sediment on the move in an old system. You could try draining it down and refilling, adding fernox or similar, then run it hot for a few weeks and repeat. Hope this helps 

[BillyNoMates]

As a quick 'try-it' fix you could look at the pump and see if it has a variable speed switch on the side. Most modern pumps have 3 speed settings so you could turn it up to the maximum setting to see if it has any effect.

Good suggestion above re. sludge in the system. 

I haven't looked at the website suggested but look at the BTW output from the boiler and do some sums !