Architecture

Horizontal chimney flue heats café and customers' backsides

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A cafe in Buffalo has a masonry heater with a horizontal flue that heats the building and doubles as a bench (Photo: Florian Holzherr)
A cafe in Buffalo has a masonry heater with a horizontal flue that heats the building and doubles as a bench (Photo: Florian Holzherr)
The café is located on the corner of Fargo Avenue and Jersey Street in Buffalo (Photo: Florian Holzherr)
The masonry heater is warmed by burning wood (Photo: Florian Holzherr)
Heated smoke is expelled from the masonry heater into a horizontal flue chamber (Photo: Florian Holzherr)
The flue chamber is 15 ft (4.6 m) long and doubles as a bench (Photo: Florian Holzherr)
In the summer, large windows are used for ventilation (Photo: Florian Holzherr)
Lighting is attached to the roof using magnets and can be moved around (Photo: Florian Holzherr)
A diagram of how the masonry heater is construted (Photo: Florian Holzherr)
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A café in upstate New York has an innovative means of keeping its customers cozy. It features a masonry heater with a flue that runs horizontally and doubles as a bench. The building can apparently be heated for 24 hours following a single, hour-long burn.

Masonry heaters are typically built out of brick or stone, which absorb the heat from whatever fuel is being burned – in this case, wood. The structure can then radiate warmth to heat a room for long periods. The flues for such heaters generally rise straight up and out of a building. However, the masonry heater at the Buffalo café, designed by Stephanie Davidson and Georg Rafailidis of Davidson Rafailidis Architecture and the University of Buffalo Department of Architecture, has a flue chamber that exits horizontally.

The chamber is 15 ft (4.6 m) long and split lengthwise. The hot smoke is drawn out of the heater and along one side of the chamber to its far end before being pulled back down to the stove-end along the opposite passageway and being expelled from the building vertically through an exhaust pipe.

"Very long horizontal flues are unusual because smoke wants to go up, so it’s very challenging to keep it from stagnating," says Davidson. "Many of the masons we talked to said they couldn't do a horizontal flue longer than eight feet (2.4 m)."

Heated smoke is expelled from the masonry heater into a horizontal flue chamber (Photo: Florian Holzherr)

The flue chamber is built from refractory cement and decorated with intricately patterned cement tiles. No other heating or cooling systems are installed in the café. For ventilation in the summer, there are large folding windows that allow fresh air into the building, with skylights to allow warm air out.

According to the University of Buffalo, the heating system took two years of research, development and testing, and can keep the café warm all day during the winter using just six logs. The café is due to open soon once a suitable tenant has been found.

Source: University of Buffalo

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10 comments
The Skud
Clever idea! But I would worry about the possibility of the creosote in the wood smoke condensing at the cooler end of the flue with the risk of a 'chimney' fire as time goes by.
TeenLaQueefa
I've always called these incredibly efficient systems "rocket heaters." They're incredibly popular with the DIY less than affluent types of people.
Google "Rocket Heater".
Paul Robertson
Can we say hypocaust? Anybody? :-)
Reason
Rocket mass storage heaters are hardly novel and most would be at least as efficient as this product of 2 years of university research ...
Buzzclick
Good one Paul Robertson. Hypocaust is the first thing that came to mind upon reading this article. Developed by the Romans, it used the whole floor as a flue and produced a consistent and comfortable heat. Since it was all made with stone/masonry, a creosote fire just burned up within and had no risk to the occupants.
windykites
I have looked at various designs for rocket heaters, and it appears that the air intake is the same place that you insert the logs. Therefore you would be taking warm air from the room that you are heating. It would surely be better to have the air intake from the outside air. Maybe some designs do this.
It would be interesting to know the temperature of the flue gases as they leave the output pipe. I think it would be ideal if all the heat could be extracted. How about a heat exchanger between the input and the output pipes?
limbodog
@windykites1 Head over to www.permies.com where that is discussed by people who know it well.
My understanding is that you really don't want a hermetically sealed home, the air quality drops precipitously while you're in it and still breathing. So the air being consumed by a rocket mass heater *is* being taken from inside the room, but it's relatively low volume, and since the mass keeps the heat in the room, the overall loss is on par with most non-sealed homes.
Buellrider
Cool! Wait, did I just say Cool!, I meant Hot!
Ericq
Re Horizontal Chimney flue heats cafe... Did the University of Buffalo discover during their research that almost all farm houses in the Bern area of Switzerland are or were heated by this method? Usually fed from the kitchen and located in the living room, the heated "bench", raised from the floor, is made from a pained stone slab (many times sandstone). There is usually a raised, enclosed upper part, also made of stone, used to dry stuff (apple slices) or to warm food. This is usually the only heat source of the farm house!
Don Duncan
I love the rocket stove concept. Substitute all ceramic for the metal guts and it should last forever. Designs generally do not maximize thermal transfer to pot/pans for cooking. A sunken pot that covers the hole/s on a horizontal fire pit should correct this.