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Using a Trombe Wall, Earth Heating, and a Rocket Mass Heater to heat our house  RSS feed

 
Coralee Palmer
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We just started to build a solar driven heating system. It is will not be finished until later in 2013. We call it the RET Heating System. It uses a:

( R ) ocket Mass Heater
( E ) arth Heating
( T ) rombe Wall

Our objective is to be completely off the Grid and propane free at the lowest cost. It is easy to get off the grid if one has a lot of money, but we do not; thus, we are Do It Yourselfers.

( T ) rombe Wall - The first part of system is the Trombe Wall.

Advantages of Trombe Wall

Passive - No moving parts, no maintenance and no operating costs.

Comfortable Heat - Radiates in the infrared, which is more penetrating and pleasant than traditional convective forced air heating systems.

Effective - Our Trombe wall will be 18 - 24 inches thick built inside of a south-facing lean to greenhouse. This wall is made of dark rock which absorbs rays from the southerly winter sun.




Lean To Greenhouse Required

Heat loss to the outdoors is minimized because of the lean to greenhouse, which creates an air space around the Trombe Wall.

The heat gradually conducts through the rock. Since this diffusion of heat is slow, the Trombe Wall does not begin radiating heat until the late afternoon or early evening. Specifically, heat travels through a rock wall at an average rate of 1/2 inch per hour, which means that the heat absorbed at noon will enter the living space by around 8 p.m. This time lag, combined with a reduction of temperature variations, allow the use of variable daytime solar energy as a more consistent nighttime source of heat. The Trombe wall has a window in the house wall at the top of the wall to let hot into the house and a windows in the house wall at the bottom to let cooler air back.




( E ) arth Heating System

The soil at 10 feet deep is always 58 degrees – everywhere in the world. During the day when greenhouse temperatures’ can be in excess of 90 degrees, solar powered fans pump this hot air into the much cooler soil below it through underground tubing (shown in the picture below), warming the soil to as much as 10 -15 degrees.

This simultaneously cools the greenhouse and warms the soil. At night, when temperatures dip to 40 degrees, the fans bring that warmed underground air back up into the greenhouse. Solar powered computer programming enables this system to keep the greenhouse at optimal growing temperatures.


( R ) ocket Mass Heater

When all else fails build a fire.

A rocket mass heater is an innovative heating system that you could build yourself.

Get Pauls new wood burning stoves 2.0 DVD for more information.

It is a hyper-efficient wood-burning stove. Wood is gravity fed into a 'J shaped' combustion chamber, from where the hot gases enter a heavily insulated vertical reburn combustion chamber.

This is where our rocket mass heater will be different, the mass the exhaust passes up through the vertical TROMBE WALL. The stone wall mass is large enough to retain heat for many hours.

Since we live on the coast in Oregon, we do not have a big need for a lot of heat, but to have no heating bills would be a blessing.




 
Bob Ramlow
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Location: Amherst, Wisconsin
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Do your research on the earth heating system. These systems have been indoor air quality disasters. The tubes constantly get condensation in them and all kinds of nasty stuff grows in there - mold, etc. I have heard that there is a company that makes a tube that contains an anti-microbial ingredient that will lessen this. I do not know the company. I would be hesitant to do this.

Bob
 
Coralee Palmer
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The tubes constantly get condensation in them


You are right; there will be get condensation in the perforated drain tubes. That is why the system works. The "miracle" is that by inducing temperature change over the phase change barrier we have the potential to harness 5 times the energy normally the case if we simply tried to solar heat objects in the greenhouse.

Our system is explained in great detail on John Cruickshank’s website, http://www.sunnyjohn.com/indexpages/shcs.htm . The system works by taking warm humid air in the greenhouse, and pumping it through a set of perforated drain tubes, which are buried in the earth, eventually exiting back into the greenhouse minus some heat and moisture.

It is based on the phase change of water, from water to vapor, back to water and the cycle starts again. When the heat of the greenhouse reaches a certain set temperature, a thermostat will turn on the fan. The air and water vapor are pumped into the cooler soil where the water vapor condenses. The condensed water holds much of the energy that it took to lift it into the air as vapor.

This technology allows us to use the thermal mass of the ground as a storage tank for surplus energy. At the same time the SHCS is storing heat in the soil it is also cooling the greenhouse, the daytime cooling aspect. There is another thermostat that will turn on the fan at a low temperature. This will take the stored heat in the soil and transfer it to the greenhouse, the nighttime heating aspect.

The perforated drain tubes have been purchased, the barrels bought, and the backhoe is ordered. Of all the reports we have found, we cannot find any reports of indoor air quality disasters. If you know of any, please lets us know before we dig.
 
Bob Ramlow
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Location: Amherst, Wisconsin
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I don't have any specific examples of mold polluting the air. Perhaps one reason is that all of the systems like this that I have encountered have been capped off and abandoned. All the systems like this that I am experienced were in homes. They were used for cooling during the summer and for make-up air in the winter. There is no question that mound will grow in these buried plastic pipes. I know it is well documented, but I do not have any references on hand. Perhaps the mold issue would not be as big a concern in a greenhouse as it was in a home where people are living all the time. Also, if it wasn't an issue, then why would a manufacturer go through all the trouble of making anti-microbial drain pipe.
 
R Scott
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Location: Kansas Zone 6a
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There are a couple key things from the greenhouse systems that make them different than "typical" earth tubes for houses:

Closed loop with FAST air exchange--5 times an hour is crazy fast compared to typical house tubes. Do the math on that on your house--it is a lot of air and you will hear it while it is running.

Perferated pipe backfilled with rock and controlled vapor barrier floor. That lets the moisture escape the tubes and then reabsorbed into the air or drained from the sump. You HAVE to get this right.

It can be done, but make sure you get all the details right or you will have a mold problem.

 
Coralee Palmer
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Closed loop with FAST air exchange--5 times an hour is crazy fast compared to typical house tubes
Perferated pipe backfilled with rock and controlled vapor barrier floor


Thank you for you comments. We agree that the air in the greenhouse needs to be exchanged 5 times an hour.

What we did leave out of our initial description and, is misleading in our diagram, is that the air from the house is complete sealed for the air of the greenhouse. There is a sealed plenum chamber behind the Trombe Wall and from this plenum chamber is where the house is drawing its heat, not the greenhouse.

There is still an argument if we will put 3/4 rocks with the tubing or not. We find mixed reviews on this subject. There will be a vapor barrier coving the greenhouse floor.







 
Sean Kettle
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Hi Coralee, what became of this project? I'm thinking of building a home along similar lines, would love to know how you got on.
 
allen lumley
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Coralee Palmer : Yes, Please ! Any information you can share on this topic is important to the general growth of passive houses and ALL forms of energy conservation

While it has been several years since I investigated this topic at the time I was seeing suggestions of air exchange rates as high as 7 Xs an hour, which reduced my

desire to explore this topic further ! For the Good of the Crafts ! Big AL

 
Coralee Palmer
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The lean to green house has evolved into a Go & Grow House© with a milk jug wall and a pebble rocket mass heater build into the floor. It is planned to be a total standalone passive Greenhouse with a Manual Composting Toilet We still believe that the air exchange rate should be 5 times to insure the plants healthy, but we have not tested it yet.


This feature of the Go & Grow House© uses five key elements necessary for a productive greenhouse: solar input; heat storage; and conservation.




An example of a 12 X 12 Go & Grow House will look when completed

Collecting, converting, and storing is accomplished through the use of:
1. Orientation
2. Glazing
3. Thermal mass
4. Insulation
5. Venting

The Go & Grow House is designed to uses these features to be a off-the-grid self-contained passive solar greenhouse that would only need, soil, sun and water to grow plants,





Orientation - The Grow House takes advantage of the changing angles of the sun throughout the seasons.

The coldest months (winter) the sun heating is increased.

The hottest months (summer) the sun heating is reduced.

The design acts like a thermostat. It produces heat in the winter during clear days. When the seasonal temperatures warm, the structure reduces the solar heating input.
The Winter Sun … The winter sun travels in the southern portion of the sky, rising in the east and setting in the west. Therefore, it is important to face the Go & Grow House’s big windows as close to true south as possible. The path of the winter sun will always be lower in the sky with a shorter path than the summer sun.

Glazing … By using double wall Solexx glazing, with an R 2.1 rating, it is intended by using the Solexx it will eliminate the need for heaters, fuel tanks, and fuel.



Thermal Mass … Rain Water is harvested and is stored in black barrels. Milk jugs are used with permanent water stored in them. They need them for heat storage. Water in milk jugs absorb 90% of the solar radiation. They will hold three times more heat than brick or rock wall Trobe Wall.

This increased heat storage holds night temperature higher longer into the night and will extend the growing season on our Oregon Coast Go and Grow House.
Disposable milk jugs are spray painted flat black and filled with water. When placed in the Go and Grow House on a series of bookshelves.
Milk Jugs want have been known to raise the nighttime temperatures to 39°F with no supplemental heat when outside temperatures dropped to -17°F.

Insulation - Walls and roof that do not collect heat are fitted with insulation to prevent the heat lost. They are fitted with 3 ½” of rigid insulation with an R rating of 21.

Venting – The top windows are designed to vent the hot air on hot sunny days with automatic window openers. Humidity levels are kept low to prevent plant disease.

Moisture – Moisture and mold is a problem in Oregon. Therefore all the walls are built to have air space on both sides of the wall. The outside of walls must have a cavity between the outside surfaces to keep the rain away from the insulation.

Manual Composting Toilet

The second feature of the Go & Grow House© is a toilet option called the Earth Auger©.

The Earth Auger was designed based on work by a retired professor at the University of Washington and is being funded by a Gates Foundation Grant.
This is a pedal-operated dry toilet. Urine is diverted and stored. The faeces is also stored.
The main innovation with the toilet is the mechanized, foot-pedal-actuated dry-flush system and sawdust delivery system that uses no water.
When the pedal is operated, the faeces, paper and sawdust are mechanically processed through a big pipe with an auger inside, which mixes, aerates and moves them through a chamber for storage.


For more details

Human Waste
Pathogens, which are the disease causing organisms, gradually die off during the period of time the faeces stays in the Earth Auger’s storage pipe.
Health organizations suggest about 4 months in warm climates, and possibly 6 months in temperate climates. Storage of faeces is detained in storage for 1-6 months. The time is dependent upon number of uses. The storage container will store 120 uses. Direct handling of excreta by the user is not required as the whole process is pedal-operated until harvest.

At that time of harvest, the material is totally dry. This material can be used on nonfood producing soils.

Urine is high in Nitrogen and is sterile when it exits the body. The separated urine can be used on food producing soil when mixed with 1:10 with water.

A study conducted by the Stockholm Water Company diverted urine from four housing projects to a grain farmer outside the city. The scientists concluded not only that urine could replace quick-acting mineral fertilizers, but also calculated that one adult’s urine provided enough plant nutrients to grow 50 to 100 percent of a person’s food requirements.

Present Status of Project
The floor of the house has been laid and the walls are starting to being built. The fixed floor is 12 feet by 8 feet. The South wall is built to fold up, so it can be transported on a trailer down the highways. It is 4 feet by 12 feet long. When the South wall is folded out the Go and Grow House© will be 12 feet X 12 feet. The metal tubing for the Solexx is installed after the South wall is folded out

The Earth Auger© has been fitted and ready to be installed.

Volunteers are welcome
 
Roberto pokachinni
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Cool project! I just wanted to clarify:

So the system has evolved away from the plenum Trombe Wall RMH interface, replacing it with the water Trombe wall. You are keeping the RMH, but you are going with a pebble version,

You will have additional rain black barrels for heat storage within this greenhouse somewhere?

Is the RMH inside the greenhouse, or is it on the other side of your water wall? Is the RMH going to be right against the water wall?

Venting – The top windows are designed to vent the hot air on hot sunny days with automatic window openers. Humidity levels are kept low to prevent plant disease.


We still believe that the air exchange rate should be 5 times to insure the plants healthy, but we have not tested it yet.

Does this mean that you are not going to use the heat exchanging earth tubes (with the potential moisture issues that you discussed, above), or are you solely using the ventilation of the thermostat operable windows...

What sort of system are you using to store your urine, and for how long?
 
Coralee Palmer
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What sort of system are you using to store your urine, and for how long?


the answer of each point raised is based on the research we have done, therefore we will list our research sources we use and how we used it. We post the research on our Pinterest account.

Our Pinterest Account


The urine is save in sealed 1 gal milk jugs for 30 days before it is used. At the present time we only use urine from the seven people of End of the Road Off the Grid Ranch Community that do you use any medications.

Our big interest is converting wood chips into compost without have to turning the pile. We do this, by blowing air through tubing in the pile and spraying the pile with urine
 
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