On Jun 11, 12:23*pm, Roger wrote:
The message
from NT contains these words:

Funny. You had no such inhibitions when you said "Exchanger heat
is not
lost to indoors." That is as close as you have come to giving a figure
for any heat transfer. You can't quantify it but you just know it is
large and all of it goes out the flue.
I didnt say it was large, and most of it does go outside, not all.
Keep on with the straw man game.

Oh for heaven's sake. Look what you said above. "Exchanger heat is not
lost to indoors".
indeed... we are talking here about what happens when the boiler isnt
firing

So you are back to square one - flatly denying that exchanger heat is
transfered indoors when the boiler isn't firing.

I've not changed on that, just clarify what we're talking about, since
it appears its needed.


And as for it not being large the whole thrust of your
argument is that it is the principal difference between cast iron heat
exchangers and those of other metals.
not even a bit. Most of the efficiency difference is not due to latent
heat thats lost to outdoors after firing ceases. All these posts and
you still havent grasped whats being claimed.

Talk about shifting the goalpost. You have just moved onto a new playing
field.

still not got it I see

Seems to me that you are in the same camp as Dribble in not knowing what
latent heat is. Non condensing boilers have no opportunity to recover
the latent heat in the flue gases and even condensing boilers will have
some small difficulty if they are not firing.

You've mis-grasped again. Since we're talking about when the boiler
isn't firing I thought it was pretty evident that we were not talking
about the latent heat of vapourisation. The latent heat under
discussion at this point is the heat stored in the metal heat
exchanger when firing stops. No wonder your responses have been
confused.


And I was arguing against the notion that if a boiler has a cast iron
heat exchanger it should be junked regardless of age.

For clarity, I was never discussing that question. I think we've
agreed all along that indiscriminate replacement ins't a constructive
policy.


NT