Mon, Feb 15, 2010
changing over to a rumford
To whom it may concern:
We spoke on the phone the other day and here are some pictures. I ran an experiment on my own fireplace. I bought some used fire bricks and set them up in the existing fireplace. The existing is a #37 Thermocast fireplace. It appears to be a pre-fab style built into a true masonry chimney set-up. I went up on the roof and see that I have a 13" flue system all the way down. I even have the blueprints for it. (1974 house).
I have had fires in my "temporary Rumford" for the past 3 days and it draws and heats wonderfully. I am wondering if I can merely re-build inside the existing hole, mortaring in the bricks and backing up with some cinder blocks using the heat stop you spoke of. It appeared on your site that a 30" has a 13x13 smoke chamber, which mine already essentially has.
Thanks. The gal on the phone was very kind, and suggested I send some pics.
Ben Henry. Parker CO
I think what you've done is to improve (by Rumfordizing) the firebox dimensions. The shallowness and wide angle would certainly improve the radiant heat output and the straight fireback would probably improve draft and, allowing you to build vertical "tipi" fires, would make the fireplace burn cleaner and more efficiently.
I don't see that you "rounded the breast" though. By not streamlining and improving the air flow through the throat your "Rumfordized" fireplace probably takes more heated air than necessary to draw and may quench the fire sooner than necessary. You probably get away with not using a Rumford throat because the fireplace opening is relatively low. In other words, it's an improvement but you could make it even better by using a Rumford throat or at least find some way to round the breast.
So, to answer your questions, sure, you can mortar in the firebrick. I would also suggest you use a Rumford throat. See http://www.rumford.com/rumfordize.html and the examples linked to that page.
from: Deb Wormsbacher
date: Sep 16, 2010
subject: Question on the DIYS fireplace in Parker, CO
You suggested adding a Rumford throat to increase efficiency and make it work better (by reducing turbulence and redirecting airflow I think). We are in a rental house and have the same fireplace as the DIYS guy in Parker, CO. Since we are in a rental, we can't tear up and redo the fireplace but we could add firebrick to correct the shape. Any suggestions about how to compensate for the throat piece we can't put in? Thanks for any help. We use the fireplace a lot and would like it to be better at heating and more efficient.
Deb in Colorado Springs, CO
First maybe try to convince the owner of your rental house to upgrade the fireplace by "Rumfordizing" it with new mortared-in firebrick and a Rumford throat. See the reasons at http://www.rumford.com/performamce.html and examples of "Rumfordizing" existing fireplaces at http://www.rumford.com/rumfordize.html
Failing that, the example set by Ben Henry in Parker, CO are good. A cheap way to round, streamline and improve the throat would be to make the curved shape with a piece of sheet metal fastened to the lintel across the top of the fireplace opening and curving up to the damper to make a throat opening 4" or 5" front to back. Maybe that's all you need to do if you can screw the sheet metal throat to the lintel and to the damper body. You might want to fill any spaces between the sheet metal and the sides of the firebox with refractory mortar or furnace cement. A more permanent "fix" would be to leave a 1" gap at the top of the sheet metal and fill the whole area above the sheet metal form with refractory concrete like DeltaCrete or even ordinary concrete.
Send me some pictures and maybe I can be more specific.
Buckley Rumford Fireplaces
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