John wrote:
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

I would have thought 70C was too low. 80 would be more normal in a
conventional system.
However, often the temp is set to 70 as this is the point at which I believe
scalding occurs, which may be an issue if you have young children.
I wonder if the gas supply is sufficient for a boiler of this size to run at
full capacity?