Bob Eager expressed precisely :
On Thu, 20 Dec 2007 17:06:55 UTC, "Roger Mills"
wrote:

In an earlier contribution to this discussion,
Bob Eager wrote:


My understanding is that it's the flow temperature that's regulated by
the stat. This doesn't need to be as high all the time....and keeping
it lower increases the condensing effect.

But I'm not an expert either!


It's certainly true that the flow temperature of a non-condensing
non-modulating boiler is controlled by the stat - but I'm not sure whether
that applies to modulating condensing boilers.

What's your understanding of how modulation works?

That it modulates between 'nothing', and the stat setting...but I still
await others!

My understanding is that the flame size is modulated or adjusted
depending upon the difference between the stat set temperature and the
actual temperature of the water exiting the boiler. The closer the two
temperatures, the less heat input is needed.

--

Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk