[Greenbuilding] HELP: need opinions on Rumford fireplaces

[Norbert Senf]

At 04:15 PM 11/30/2006 -0600, Ian Remmler wrote:

>I asked a similar question a while back, and the concensus
>seemed to be that open fireplaces suck (figuratively and
>literally).  But the weird thing is, I have an open fireplace,
>and it might just be my imagination, but it seems to make my
>house warmer.

If you burn an open fireplace properly, you will definitely get heat
into your house. And it will largely be nice, pleasant, radiant heat.

The question is, how much?

- as you make the fireplace larger, you move more air, so your losses increase
for the same amount of wood.

- as the outside temperature goes down, your losses increase, because you have
to heat all that outside air back up to room temperature before it goes up
the flue (in fact, you have to heat it up to flue 
temperature, which is higher).

If your fireplace is very large (48" x 48", say), and the outside temperature
is very cold, say -10F, you get down around 0% efficiency or even lower.

If your fireplace is in the centre of the house, 
you have an airtight glass door on
it with a proper air supply (the "Washington state certified" version of the
Rumford), you can get the efficiency up into the 50% range, which is not bad.


-------------------------------------------
Norbert Senf---------- mheat(at)heatkit.com
Masonry Stove Builders
25 Brouse Rd.
RR 5, Shawville------- www.heatkit.com
Québec J0X 2Y0-------- fax:-----819.647.6082
---------------------- voice:---819.647.5092