"BillR" wrote in message
...
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?

I think just over 80oC is the max setting on the boiler IIRC. What does
altering this setting do inside the boiler? - does the water flow slower
through the heat exchanger or does it burn more gas to achieve the higher
temperature?

Gas supply is 22mm direct from the meter (approx 6m away). I`m pretty sure
this is ok as the previous boiler was a similar capacity.

John