Southeast Michigan. We keep the home between 65-70. The greenhouse doesnt need to stay very warm. 50-55 would be fine. I have natural gas but I own a tree service do wood is free. I split about 20 bushcord a year and the business is only 2 years old. So how much all in, including plenums, plumbing etc and how many bush cord/year am I looking at? My guess is 10k for the set-up and 25 cord/yr.
Good underground piping isn't cheap, and you want to use the good stuff. And make sure it's big enough. No idea what kind of distances you're looking at, or your local piping pricing situation, but I would budget $15/foot. I would also likely up the overall budget to at least $15k. But the inside stuff can eat up funds, depending what you want to do, & what your existing system is.
My existing inside set up is natural gas forced air with a tankless on demand natural gas water heater. It would be great to leave these online somehow to switch back to in the summer. As far as the greenhouse, I would only use it 9 months a year. Dec-February would be too cold I think.
This +100 Throw in drain tile also if the grade will allow it. I just did a dig up , add insulation and drain tile on a prior owner poor install this summer . Wasn’t fun.
That Garn system is interesting. I wonder if an old cistern could be used to tonstore heated water from the Garn? Would have to be insulated from the ground that surrounds of course.
How about more estimates on number of cords it would take to feed such a beast as the GARN 2000. 20 cords? More?
When talking about an efficient gasser like the Garn, it isn't the size of the boiler than chews the wood, it is the heat load it's hooked to. Have you got any heat loss numbers for what you're planning? Otherwise it's just a big guessing game. If you know what you have historically spent on gas, you should be able to ballpark a wood estimate from that. If loads will be the same. I don't know much about greenhouses, or the size of yours, but keeping one warm all winter in Michigan sounds like a fairly big load.
I know of a place in northern Michigan that is heating 3 greenhouses.... each has 200,000 btu heater and they burned 900 gallons of propane in just 10 days !!!!
If you have enough land and equipment to dig trenches, you could consider doing something like this for the greenhouse..
My boiler is rated for 7500 sq ft. I'm heating 2640 of insulated space. 1600 is auto shop that the doors open & close on a lot. 10X12 X3 doors. Non gasifier , open loop system. I burn 12-15 cord per year. Way less overnight when the shop's closed. You're gonna want a big boiler & plan at least 25 cord for a winter. I'd bet on 15-18K up front if done well with good piping. May be a good roi if you're gonna be there a while.
