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Greenhouse glycol loop

mtfallsmikey Member Posts: 765
About your install. A friend of mine is looking into constructing a couple of medium-sized greenhouses, using a wood boiler, and I get to help! Post here, or e-mail me privatly


  • Eric Johnson
    Eric Johnson Member Posts: 174
    Greenhouse Glycol Loop

    I'm going to be running glycol through my greenhouse radiant, using a flat plate heat exchanger to isolate it from the rest of the system, which is water. Am I correct in assuming that I'll need to have a pressure relief valve, expansion tank and t/p gauge piped into it? How about an air scoop?

    My main heat source is a wood gasifier, so I'm getting variable water temps, mostly between 160 and 180.
  • Glen
    Glen Member Posts: 855
    yes to all -

    and if you are planning a warm bed for your bedding plants - then some sort of 3 way mixing valve to reduce temps in the growing bed - where max temps required are in the 60 - 70 Deg F range. The flat plate is essentially your boiler and all downstream components must be protected. BTW - which boiler are you using?? happy with it? good value for wood consumed?
  • Eric Johnson
    Eric Johnson Member Posts: 174
    Orlan EKO 60

    And I love it. Just finished installing it a few weeks ago, but I'm still working on the 1,000-gallon storage tank and hx.

    My old boiler was a Royall 6150. This thing produces an amazing amount of heat for the wood consumed, and does it all with no smoke. Orlan: 2; Royall: 0

    The warm bed is a great idea. Thanks.
  • Roland_4
    Roland_4 Member Posts: 84
    Greenhouse heating

    Hi Erich, Sweet looking furnace. Can you send more detail about the greenhouse structure? Is it a commercial or custom designed unit? I am looking to build a small (10'x24') greenhouse in my yard and energy efficiency is a priority. Can you e-mail me some information on your set-up? Thanks,Roland
  • Eric Johnson
    Eric Johnson Member Posts: 174
    Old tech

    It's an old, Lord & Burnham single-pane, aluminum-frame greenhouse probably installed circa 1979. Two sections, each 12x12'. When I bought the house, it was zoned off a (1958 vintage) Weil-McLain, 193K btu/hour gas boiler. The radiant was just a few old ci rads. It worked fine, but after the novelty of being able to garden in the middle of the winter wore off, I decided that my gas bill was high enough just keeping the house warm. The next year I installed a 150K btu wood boiler that I got on Ebay for about $300, but it didn't have the capacity to heat the house and the greenhouse simultaneously, so I heated the house with it and let the greenhouse sit, Still no greenhouse, but I didn't burn any gas, either.

    Three years later, I decided to get serious about wood heat (I have an unlimited supply of dry wood), so I bought the Orlan and now I'm in the process of getting everything set up the way I want it. At the very least, I'm sure we will be able to run the greenhouse off the wood at least through December, and probably for the whole winter, in central New York State (Utica).

    The greenhouse draws the vast majority of its load at night, of course, so it will be interesting to see how that squares with my boiler firing plans. I have a 1,000-gallon hw storage tank, with the option of expanding to around 2,500 gallons. My guess is that I'll need it all, and probably wish I had more.

    Currently, I've got it piped direct with a 3/4-inch loop off the EKO, but I think glycol is the way to go. I have a 150K flat plate hx which ought to be sufficient. It heated the whole house for the past three winters. At the moment, my controls consist of an old single-pole electric baseboard thermostat wired directly to a Taco 007. As I noted, I've got 24 feet of hw baseboard and a big ci rad in there for radiant.

    Any greenhouse you're going to buy today will be much more energy efficient, and probably not made of glass. But I'm working with what I've got and under the circumstances, I think wood gasification is the way to go.

    Attached are a few pics.
  • Bob Gagnon plumbing and heating
    Are you heating the air

    in the greenhouse Eric? I have been told that by heating the roots you can maintain a much cooler temp in the greenhouse, saving lots of energy and the plants will grow much quicker. Maybe you could heat the plant beds separately, and have a second zone just to keep the air from freezing? They also have low cost water walls for greenhouses that are inexpensive Polymax water wall bags, that will capture the heat during the day and slowly release it during the night. You can't get any simpler than that to help with the heating load. They are available at www.growerssupply.com Thanks for saving energy, Bob Gagnon

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  • Eric Johnson
    Eric Johnson Member Posts: 174
    The great thing about gardening......

    ....is the experimentation. Those are good suggestions. Not having a lot of skill or experience when it comes to heating system design, I'm trying to replicate what I know works, which is, I guess, heating the air. But there are plenty of opportunities for experimentation and improvement. I like the warm bed idea and the water heat sink idea.

    I don't know about saving energy, but I am staying off of fossil fuels and trying to get the most out of the wood--all of which is lowgrade coming from a woodlot improvement thinning project, by the way.
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