I recently had an old boiler replaced with a wall mount conventional
(Ferroli Tempora - 100K BTU) on an S plan - pressurised CH, gravity HW. I
did all the wiring myself and added a new cylinder stat and room stat. The
boiler supplies approx 14 rads [mixture of old cast iron and new 'modern'
rads] at the moment with 2 more planned.
So far I`m impressed with the operation of the new boiler. The system heats
up very quickly and I`ve checked operation of all the valves/stats
successfully.
What I`m concerned about is the following:

Particulary with the cold weather, I`ve noticed the boiler is on (firing)
all the time during its programmed operation period (7.30am-9am, 5-9pm). The
corgi who commisioned the boiler mentioned that the boiler wasn't operating
near its full capacity (100k btu). I don`t know if the boiler modulates or
not or if I have to change a setting on the board. There is a temperature
setting on the front panel which is set to 70oC - is this too low?
At the moment the house does get warm enough (assuming the boiler is firing
all the time) but with the weather being colder - its not quite enough to
trip the room stat off.
If I change the output (BTU), will the boiler use more gas but operate for
less time? - I`m not sure what I should be changing to get the optimum
efficiency..

John