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Dale's Rocket Mass Heater/ Grill/Pizza Oven/Hot Water Heater – One appliance does it all.  RSS feed

 
Dale Hodgins
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Posts: 6786
Location: Victoria British Columbia-Canada
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Rocket Mass Heater/ Grill/pizza oven/Hot Water Heater – One appliance.

I need a space heating, cooking (baking and frying, broiling), hot water heating and clothes and fruit drying appliance for a small living space being built as the back third of a greenhouse(see drawing). A friend is in need of somewhere to stay and since this is going on my land, I will crash there occasionally. His only duty will be to keep accurate records concerning fuel consumption and ease of use. He comes from a hot climate and is often preoccupied with worries about being too cold, so I'm sure it will see plenty of use. The little building is being built on a flattish area in full sun, overlooking a south facing hillside. See Photos at the bottom - just the site. The contraption is in my head but I will soon submit a drawing. --------------------------------------------------------------------------------------------------- --------------------------------------------------------------
ABOUT THE OVEN
This is a multifunctional oven shaped like those outdoor bread ovens, which is designed to accomplish several tasks. It uses a rocket stove feed and heat riser, but instead of a barrel,we have a brick and cob oven which can be used for cooking. A heat exchanger allows for the production of hot water. A metal plate for grilling is set a few inches above the heat riser and the bottom of this plate directs combustion gasses toward the hot water heat exchanger and to the oven. The oven door is closed whenever the rocket is used. Baking is done after a firing. Frying is done during firing. Broiling will be attempted after preheating but this may prove difficult to control. Maybe hotdogs.

The oven would function much like any other clay oven, except that the fuel is burned in the rocket stove and the hot gasses would be vented into the oven and leave through ducting. Some ash may accumulate, but less than in units that have a fire on the oven floor. The exhaust could heat a bench or a chimney could be used. Some sort of elevated exhaust may be necessary since we don't have a pump system as occurs with a barrel. The J-tube would be set into the earthen floor in order to gain some draft if horizontal venting is chosen.

The hot water would be an open system which is vented to a drain or another container. No coils to build up steam pressure, just a few large half ovals of stainless pipe which loop through the edge of the oven are open to the water tank with one opening near the top of the tank and one near the bottom. The water tank is not pressurized or connected to household showers or taps since it is possible to reach the boiling point. Consider it to be a stationary kettle accessible only to adults through a wrought iron gate with an automatic closure. A child proof tap 18 inches off the floor would be the drain and drawing point. Not idiot proof, but safer than a kettle on a wood stove stove. A thermostatically controlled valve could allow cold water to enter the system whenever a certain temperature is reached and the tank would overflow into a secondary one. Should the secondary tank overflow, this water could be directed to the hot tub.(See the link at the bottom, for a system that can never overheat.)This unit is for wash water. The stove top kettle(s) provide hot water for coffee etc.

Since the heat exchanger is open and contains no permanent fluid, it would be fine to use the oven while the water tank and tubes are empty. Stainless steel can take quite a bit of heat.

It is likely that plenty of hot water would be desired. In order to maximize heat transfer to the heat exchanger tubes, they would be set so that the hottest gasses from the riser strike the tubes before contacting other surfaces.

If baking is the priority for a given firing, a simple ceramic baffle could redirect the flow from the riser so that the brick and cob absorb more of the heat and water heating is not favoured. A similar baffle could shield the bottom of the grilling surface from the direct stream off the riser. Choices of baffle placement must be made before a firing since hands must reach inside the oven for baffle placement.

The exhaust from the oven to thermal mass would be a clean out point. Another clean out would be right at the point where the exhaust turns upward to the chimney. A little hearth floor here would accommodate a small fire which would establish good draft before the rocket is lit. ------------------------------------------------------------------------------------------------

The greenhouse will not be operated for plants in winter. A south facing glass house gets very dry when no water is added, making it the perfect spot to entertain and to store firewood. Even during the worst of winter weather, this “outdoor” portion of the building will be warmer, drier and less windy than the world beyond the glass. A wood fired hot tub may be placed here but there is no plan to heat the greenhouse during winter. French doors will connect the living area to the greenhouse. ------------------------------------------------------------------------------------------

CONFERENCE CENTRE
A big multifunctional heating unit may seem a bit much for a little 400 sq. ft. bachelor unit, and it is. This building will ultimately become a large recreation and cooking area for groups of up to 50 people who come to camp and to learn about this sort of thing. I expect that the greenhouse area will eventually be dominated by cob benches wide enough to sleep on and by cooking and hot tubing. Those benches will be laid out so that large groups can view the operation of the various systems and so that everyone has a good view of a speaker whether it be me pontificating on this or that or the leader of a group that has chartered my bus to take them to my unique conference centre in the wilderness. During inclement weather, campers may abandon their tents in favour of the warm, dry benches inside the greenhouse. The stove and hot water will be used by all.

My friend and I will be the sole occupants in the beginning, but I would eventually like to install someone with an interest in teaching specialized green building techniques such as earthen plastering etc. The little apartment would be theirs when not needed for group events. It would be that person's job to keep it clean and to move most personal stuff to one corner in preparation for group events. They will receive a generous wage when teaching and they'll have a free spot to live which includes utilities and garden space. --------------------------------------------------------------------------------------------------------

I've devised a simple way to obtain hot water that never exceeds a desired temperature. Check out - Two Tank hot water system - Quick start up and achievement of desired temperature. Easy control http://www.permies.com/t/19604/stoves/Dale-Tank-Hot-Water-System

The photos won't load from this WiFi location. I'll post them soon.
 
allen lumley
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Location: Northern New York Zone4-5 the OUTER 'RONDACs percip 36''
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Dale can't wait to see the pictures ! PYRO - ALLEN L.
 
Dale Hodgins
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Posts: 6786
Location: Victoria British Columbia-Canada
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allen lumley wrote: Dale can't wait to see the pictures !


That's what she said !!! About 30 ft from the edge is where this marvel of engeneering will be planted. The last two pictures come from areas within 100 ft.

The last photo came out really fuzzy. I found this video of a cob oven that I like. The setting is very close to my site. Just picture a valley with a river in the distance. I'm sure I've seen this guy and they mentioned an island near here, so I hope to see this one in person. [youtube]http://www.youtube.com/watch?v=x1iPEcyDt_8
[/youtube] Since mine will never be rained on, I could insert lots of smoothe rock shelves. Several tiers of tile climbing up the side could work for dehydrating.

This guy has built a few interesting things. He has used individual rockets for each device so that none of them have a long enough burn tube. I'd like a similar configuration but using a long single horizontal burn tunnel vented away from the cooking area.
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Joylynn Hardesty
Posts: 275
Location: Officially Zone 7b, according to personal obsevations I live in 7a, SW Tennessee
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Bump
Any updates?
 
Irene Romsa
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Location: Northern Colorado & Southeastern Wyoming
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I was thinking of something similar - not as multi-purpose, though. I'm interested to know how it went and if you got those classes going
 
Dale Hodgins
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Posts: 6786
Location: Victoria British Columbia-Canada
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Other work has kept me from the farm. I have built a small multifunctional unit in my cabin. It's not finished, but it works.

Other than Randy, my lone tenant, I have had zero success in attracting useful people to the farm. Plenty of people are willing to use what currently exists, but I have yet to find anyone who will put in sweat equity in exchange for a free home.

http://www.permies.com/t/43542/rocket-stoves/Dale-Rocket-Powered-Mass-Heater
 
Joylynn Hardesty
Posts: 275
Location: Officially Zone 7b, according to personal obsevations I live in 7a, SW Tennessee
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Thanks for the link, great stove!
 
I agree. Here's the link: http://stoves2.com
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