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Hi all,
A recently found out about the Rumford design am very enthusiastic to use it for a smaller, outside fireplace using perhaps different materials than your normal masonry fireplace.
I have searched high and low and it is very difficult to get clear, complete and unambiguous scientific specs about the size, area and interrelations of the Rumford fireplace concept when disregarding masonry and building code restrictions or conventions for a moment.
My main questions are these:
1. What is the relation (ratio) between the INNER measurements of the
throat opening, the front of the fireplace and the surface area of the
smoke chamber and the surface area of the chimney?
2. Is the smoke chamber important at all for the efficiency of the fire?
or is it merely an artefact from having to connect the wide fire place
to a smaller chimney, while still accommodating the narrow throat
opening?
3. Could one, in theory, completely do without a separate smoke chamber
and have the throat go over into a chimney straight away? Is a larger
area right about the throat required for the Venturi effect?
If so, what is the minimum ratio of throat-to-smoke chamber area to get
an effective fire?
I have been experimenting with smaller Rumford fireplaces for outside and have
created a Rumford Calculator in Excel (click here to download) to help with different
sizes. I now realise the Calculator is probably off the mark
considerably.
I have included pictures of the first two quick trails and I am in the
process of building me first real prototype, roughly 21.5" (55cm) wide
You see, for the measurements I have gone of the plans that can be found
on Rumford Fireplaces, combined with other information, comments and ratios found
elsewhere.
The problem I now realise, is that most Rumford builders on the web approach the design from a builders
perspective, with the measurements of bricks, standard flue liners and building codes first in mind.
This is understandable of course, but for the most, the mention the OUTSIDE measurements of flue tiles and throat, which is not helpful when trying to figure out what the INSIDE measurements should be.
I would love to have more definitive INNER area measurements and the relationship between them. Also, because my fireplace will be on the small side, the margin of error is smaller and of importance i think.
As a part-time engineer and weekend-inventor, I am keen to get the measurements right.
I am very keen and willing to experiment with different materials to
make the fireplace as small and light as possible and have clear
boundaries for the thermodynamic principles at work would be essential I
feel.
If anyone would like to share the ratios and margins of error when it comes to throat, smoke chamber and chimney my fireplace will be a roaring (sorry) success and I am for ever in your debt and will sing the
praise of Count Rumford all this summer!
Cheers,
thijs
A recently found out about the Rumford design am very enthusiastic to use it for a smaller, outside fireplace using perhaps different materials than your normal masonry fireplace.
I have searched high and low and it is very difficult to get clear, complete and unambiguous scientific specs about the size, area and interrelations of the Rumford fireplace concept when disregarding masonry and building code restrictions or conventions for a moment.
My main questions are these:
1. What is the relation (ratio) between the INNER measurements of the
throat opening, the front of the fireplace and the surface area of the
smoke chamber and the surface area of the chimney?
2. Is the smoke chamber important at all for the efficiency of the fire?
or is it merely an artefact from having to connect the wide fire place
to a smaller chimney, while still accommodating the narrow throat
opening?
3. Could one, in theory, completely do without a separate smoke chamber
and have the throat go over into a chimney straight away? Is a larger
area right about the throat required for the Venturi effect?
If so, what is the minimum ratio of throat-to-smoke chamber area to get
an effective fire?
I have been experimenting with smaller Rumford fireplaces for outside and have
created a Rumford Calculator in Excel (click here to download) to help with different
sizes. I now realise the Calculator is probably off the mark
considerably.
I have included pictures of the first two quick trails and I am in the
process of building me first real prototype, roughly 21.5" (55cm) wide
You see, for the measurements I have gone of the plans that can be found
on Rumford Fireplaces, combined with other information, comments and ratios found
elsewhere.
The problem I now realise, is that most Rumford builders on the web approach the design from a builders
perspective, with the measurements of bricks, standard flue liners and building codes first in mind.
This is understandable of course, but for the most, the mention the OUTSIDE measurements of flue tiles and throat, which is not helpful when trying to figure out what the INSIDE measurements should be.
I would love to have more definitive INNER area measurements and the relationship between them. Also, because my fireplace will be on the small side, the margin of error is smaller and of importance i think.
As a part-time engineer and weekend-inventor, I am keen to get the measurements right.
I am very keen and willing to experiment with different materials to
make the fireplace as small and light as possible and have clear
boundaries for the thermodynamic principles at work would be essential I
feel.
If anyone would like to share the ratios and margins of error when it comes to throat, smoke chamber and chimney my fireplace will be a roaring (sorry) success and I am for ever in your debt and will sing the
praise of Count Rumford all this summer!
Cheers,
thijs
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