Hi

I noticed my my gas boiler doing the following this morning

When central heating was selected the temperature selector in the hall
was set to about 16C the boiler would fire for about 5 seconds then
stop for 15 seconds then it would fire for 5 and stop for 15, it seems
to do this often.
I've read that one point of inefficiency in gas boilers is short burn
time, durning the start up phase not all the is gas burned therefore
you don't get optimum heat from it. If my boiler is doing a start up
4 times a minute then it must be chucking a lot of unburned gas out
the flue.
The boiler is an "Ideal classic 270FF" with a "classic LX" programmer.
Is there anyway I could increase the burn time and hopefully reduce
the start ups.

Thanks Kev