Xtra Rads

[peely]

Hi
How many rads could I run off my optia ff50 boiler, plus the hot water? I have six at the moment and the system seems to cope fine. I was also wondering if it is ok to use micro bore pipe to fit the new rads as it appears to be a bit more flexible to run in.
Thanks
peely

 

[meldrew's_mate]

Depends how big your new rads are, and how far the run is. BS states no more than 2.5 m/s flow velocity which translates to about 30,000 btu/hr for 15mm copper, so you would be at the limit on 8mm microbore at about 7,000 btu/hr assuming your system is clean and the pump runs properly.

OK, so if you understood that you wouldn't have asked the original question about "how many rads can I.....?" so heres one empirical way. How long does the burner run for when starting up the heating only from cold? If all the rads are hot within 10 minutes you have spare capacity. If it's still burning after 30 mins it probably doesn't. In between is marginal and open to interpretation.