Thursday, January 6, 2022

Heating plan if things go into the septic tank

 

What one gentleman in northern Minnesota did to increase the amount of heat his woodstove put into his living space

I have two weaknesses in my ability to roll up the sidewalk and tell folks to get off my lawn.

One of my shortcomings involves water. The water table is 45 feet below the surface so I need some kind of submersible pump should the grid go down. Suction can pull pure water up about 30 feet and water with dissolved gasses about twenty feet.

The other shortcoming involves heat. The average nightly low for January is 20F and the average high is 30F but there have been weeks when a Polar Vortex kept the windchill below -20F for the entire week.

The fireplace insert

I have a fireplace insert. When I have electricity it can put between 15,000 and 20,000 BTU per hour into the house. Not enough to run around nekkid when it is -20F but enough to keep the pipes from freezing.

The problem is that the blower pulls 140 Watts of 120V alternating current. No electricity means almost no heat out of the unit AND not running the fan will overheat the firebox and damage can result.

Being the smart fellow that I am, I bought a small, very efficient "inverter" generator. At low load, defined by the manufacturer as 400W draw, it can run 11 hours on a gallon of gas.

Sounds great, right?

One gallon of gas has about 115,000 BTU of heat-energy. Running the fireplace insert for 11 hours at 15k BTUs will net me 165,000 BTUs. Not quite the slam-dunk I was hoping for.

Battery assist

At 400 Watts, there is enough power (on paper) to run the fan and charge a glass-mat, deep-cycle battery. A battery that holds 1200 Watt-hours costs about $250 and has a five-to-ten year life.

In our perfect, theoretical world at 400 Watts the generator could run the fan and fully charge the battery in about five hours. That would be fifteen hours of heat (15 times 15k BTU/hr equals 225k BTU) at a cost of 57k BTU. In round numbers, that is 4 BTU of heat for every BTU of gasoline burned.

Solar + batteries + genny back-up

Stand-alone solar without batteries is non-starter in the north. Days are short. Nights are long and cold.

1200 Watts of solar capacity might provide enough energy to run the fan on the fireplace insert for 16 hours most days. Sixteen hours being the amount of time there is a responsible adult awake to feed the fire.

The smart money would have at least two deep-cycle batteries. They really do not like to be fully drained. Two batteries cycling in the top-half of their capacity will last far longer than one battery being 100 percent drained daily.

And there will be weeks when the clouds shut down the solar. That is when the generator comes into play.

The fine print

Lots of detail about inverters and such were left out. Batteries are Direct Current storage devices.

Universal motors can miraculously run on either AC or DC current as long as the voltage is appropriate. Unfortunately, that means a boatload of 12V batteries (for DC mode) or an inverter.

Why not a stand-alone woodstove?

Great question.

The ever-wise and ravishingly beautiful Mrs ERJ and I engaged in years of negotiation.

Her concerns were the risk of a child or grandchild (or one of us once we are old) falling into a stand-alone, middle-of-the-room woodstove. If you watch the video at the top of this post you will see the inventor recording temperatures on the outside of his woodstove of 400F.

My proposal to surround the woodstove with a fence was objectionable from an aesthetics standpoint.

Our resolution was the fireplace insert and blower .AND. I have a woodstove in the garage that can be moved into the living space if/when things get REALLY bad.

Note to self: I need to get additional stovepipe, thimbles to pass through ceiling and other hardware. Just in case.

16 comments:

  1. Buy it now! I just bought a used wood stove dirt cheap. Took 3 days and a couple hundred miles to get all the pipe and accessories to install it.
    But with propane doubling in price this year I've got to have a backup plan.

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  2. That "Extra heat" setup?
    He just made a creosote condenser unit.
    He's either gonna have liquid creosote coming on the floor or flake creosote building up in that abomination of pipes constantly.

    Now of you kept the generator inside and made a similar heat trap for the gasoline engine's exhaust you might have something.

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  3. Rural King is the store that has the best price on stovepipe locally. I do not see the price of anything decreasing in the future, so your money is worth more now than in the future....

    Stovepipe does not go bad like bananas do, so stocking up now is not a bad idea.

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  4. Are you looking over my shoulder? Same virtually exact thoughts running through my house.

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  5. I have no long-term heat source but a few short-term ones. The plan is: (1) small generator to run NG furnace (with gas for 2 days); (2) inverter on Chevy Volt to run NG furnace (another 1-2 days); (3) small Chinese diesel heater that requires 12V to run fan (maybe 1-2 days before 12V batteries die); (4) 23,000 btu kerosene heater (maybe another 2 days); (5) move to Florida.

    There's no place in my house where a wood stove would work except the basement and that wouldn't put the heat where it needs to be. I looked into a fireplace insert but they want a lot of money to install one. Did you install your insert yourself? The tough part appears to be the liner.

    The Phantom

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    Replies
    1. I have had a fireplace insert for 13 years now. We did not install a lined pipe up the chimney, we are using the chimney for exhaust. So far it has worked for us.

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    2. The basement can be a fine place for a wood stove -- heat rises, and just running a wood stove in the basement may supply sufficient heat to the house to keep pipes from freezing.

      Even if you can't easily install a passive grate above the stove to allow heat to reach the first floor, you can always bring the people and the cooking down to the stove...

      Delete
  6. Thanks to our Chinese friends sending us the Emerald Ash Borer I have a steady supply of firewood standing dead to dry and we heat both homes with wood . My old Shenandoah R-75 is in the basement where it warms the floor quite well and convects the heat up to the top without any need for electric . The wood detail provides me with needed excercise at 72 years of age and I have always enjoyed dressing for winter and getting out in the woods . 11 degrees with 15 mile an hour wind today and I'm getting ready to go cut a couple 75 footers today . Stay warm and get tough ! The fusa ain't your Daddys country anymore !

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  7. This is something I've thought about a lot lately. There are fireplace grates that use natural convection to circulate heat. (see https://hastyheat.com/products/14gr-f-fanless-fireplace-heat-exchanger)

    There are also what are masonry heaters / Russian fireplaces / rocket masonry stoves which store the heat of a hot, fast fire burned once or twice a day and slowly release it so that you don't need to constantly tend the fire. (see https://www.youtube.com/watch?v=GfygkTCLDtw and https://batchrocket.eu/en/)

    -Brutus

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  8. For temporary indoor heating I have thought about getting one of the Mr Buddy heaters. They are supposed to be very good for indoors as they supposedly don't have fumes. Has anyone ever used one of those?

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    Replies
    1. I have used many of them in the boat and in my travel trailer. They are clean and odorless, but they can consume all of the 02.

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    2. They also release a lot of water vapor which can saturate insulation and create a black mold problem in the long-run.

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    3. I have and they work good, but the one pound tanks don't last very long. When we lived in our RV full time for a couple of years, we got a long supply hose and snaked it through the "kitchen" window hooked to a 20# or 30# propane tank.

      That was several years ago and we still have it for emergencies.

      Delete
  9. Concur with Ron, they 'supposedly' have a low O2 cutoff, but we never used them in a completely sealed space. Always left a vent open to move oxygen into the tent/boat/camper.

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  10. A couple of thoughts that might be useful.

    Rather than a 120v AC blower, what about a 12v DC blower from an car heater? I doubt it will move the CFM that the AC blower will, but it should still keep you warm-ish and avoids the AC-to-DC conversion inefficiency.

    You might also consider the small diesel heaters (yep, Chinesium) that I see a lot of the tiny home and vanlife bunch using.

    ReplyDelete
  11. In the "Off Grid Water Department":

    I use a 12V submersible "Bilge Pump" to keep a cistern full. Google: "IL280P pump" to see the one I use.

    My well is "low yield" (~1.5 GPM!) so this works well for me with 12V solar.

    A second "pressure pump" is used between the cistern and house to provide higher pressure and flow. 12V diaphragm pump for off-grid, 120V pump and pressure tank for on-grid.

    ReplyDelete

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