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Looking for ideas for a Central Rocket Heater to provide hydronic heat & domestic water.

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I am looking for ideas for hydronic heating & domestic hot water so I'll do my best to lay out my situation.

We live on the coast of Maine where the temperature occasionally drops to the negative numbers (Fahrenheit) for a week at a time. More commonly the winter temperatures are in the teens or twenties (Fahrenheit). We would use this heater during the late fall, winter and early spring. The rest of the season, we'll rely on solar for our domestic hot water.

I have access to lot's of cheap firewood that I cut myself. For this reason, the heater needs to use wood.

Our home is a duplex and is basically two houses that are only attached in one corner. We live in one half and rent out the other half. Renter's insurance prevents us from having any type of wood heat, including a RMH in the rental side. A full basement (connected) is under both sides. We have access to the basement and the tenants do not. It would be possible to have a heater that we control in the basement. There is a conventional propane furnace and hot water heater (tank type) in the basement. I'd like to get off of propane entirely, except for use as a back up and cooking. Currently, we both use the propane based domestic hot water. Our side of the house is heated exclusively with a wood stove and we burn about 2 to 3 cords of wood per year. The furnace heats the tenants side. Both sides have a footprint of 900 sq' for a total footprint of 1800 sq'. Both sides have an upstairs that relies upon rising heat. Both sides are equipped with baseboards

I'd like to only add fuel once or twice a day. This may be a necessity if I have to leave for the day for work or other obligations. I need to have a fossil fuel back up in case we need to go away for a while. I'm looking for a solution that doesn't cost a lot of money.

I'd like to build an exterior RMH that heats water that I pump into the house, but I'm worried about inefficiencies as the mass heats the outdoors. Perhaps there might be a way of super insulating the RMH so that heat loss is minimal. Ideas? I'm also unclear about the best way to extract the heat from the RMH. I've thought of coils or fins through the riser and barrel assembly, but I'm not sure on how to do this. I could conceivably run the exhaust through the foundation wall and into the basement where it could put some heat into the basement before exiting via a basement window some distance away.

Any ideas or suggestions would be greatly appreciated. Thanks, River.

Posts: 3603
Location: Kansas Zone 6a
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1. give money to the kickstarter to get the videos.
2. listen to the ernie and erica podcasts

3. You can build the RMH into an outbuilding to insulate it, but they are not really good at all-day burn. They need constant care while feeding them, then rely on the MASS to hold temp while unattended.

I would (am) build a wood boiler (conventional or RMH) that heats a thermal storage tank (to be heated by solar in the summer, eventually). My tank is a 500 gallon tank from craigslist that I will put in my basement and will insulate to R60-100 (as much as I can fit in my space). It will have a heat exchanger for domestic water and run subfloor loops for heat. If you look on http://builditsolar.com you can find examples, including DIY tank plans and many sources for good affordable tanks.
River Elkin
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Thanks for your suggestions! I like the DIY plans at http://builditsolar.com. That's good stuff. River
Posts: 4154
Location: Northern New York Zone4-5 the OUTER 'RONDACs percip 36''
hugelkultur fungi books wofati solar woodworking
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River E. : A quick review of the rocket stove, its past and future are in order !

We are at a turning point in the future of Rocket Mass Heaters, 20 years ago Rocket Stoves were built out of materials that ' let ' the Stove survive the high Temps
that allowed the Incredible efficiencies that their unique structure was capable of producing!

Since then there has been the introduction of materials that were lighter but still capable of surviving the high temperatures! Due to less heat being lost to heat energy
penetration/absorption into the Thermal Mass, the Newer built Rockets Reached their extremely high operating temperatures much more quickly, further decreasing
energy lost to earlier ' cold ' start up inefficiencies!

Tomorrows Rocket Stoves, are being made of Ceramic like materials capable of handling the Rockets extreme temperatures, with only slight heat absorption ,quickly
glowing white hot, producing their high efficiencies that much sooner !

Some Castable Ceramic Cores are now being produced for the D.I.Y. Rocket Stove Mass Heater Market. More manufacturers will enter the market, I am not personally
ready to buy and generally can not recommend the purchase of something so new to the market !

A quick review of how a rocket stove works and a quicker look at its future and we are done ! We generally say that a 6''-8'' diameter Rocket Stove needs frequent
feedings of small very dry wood to allow it to achieve its high efficiencies , usually 1-2 Xs an hour until the Heat Riser part of the Rocket has reached temperatures that
will cause the next wood chunk to spontaneously burst into (primary )flame! Thereafter it is simply a mater of feeding it wood nearly every hr, over a 6-8 hr period to
store 20-25 hours of heat storage. This is usually considered minimal attention for successful operation of a Rocket Stove!

With all the advances in Rocket Stove construction, we await the further demonstration of long term viability of Rocket Stoves that can be batch loaded, even then the
only way we will enjoy the Rocket Stoves Vaunted High efficiency is with frequent attention !

Anyone not willing to live in close proximity to their Rocket stove should look elsewhere for a heating source !

For he good of the Craft! Be safe,keep warm! PYRO Logically Big AL !

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