Outdoor Propane Boiler

amsoil dealer Posted By amsoil dealer, Nov 7, 2018 at 12:55 PM

  1. amsoil dealer

    amsoil dealer
    Member 2.
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    Feb 21, 2015
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    Loc:
    Park Rapids, MN
    Good morning,

    Not sure if this is the correct category for this post, but I will start it here. I currently have the following setup at my house:

    Geothermal forced air in the house
    Radiant floor heat in my shop
    200 gallon Heatmor OWB feeding a coil in the ductwork of the house and a plate exchanger in the shop.

    This setup works fairly well, even though it is undersized. My Heatmor is at least 30 years old (non Stainless Steel system). I have been thinking about what to do when it comes time to replace it. I am leaning towards not getting another wood stove. Putting up the wood each year isn't so bad, but having to plan ahead for trips to make sure someone can keep it burning is inconvenient. Does anyone make an outdoor propane boiler that I could buy to replace the wood setup? The one thing I like about my current setup is I don't have as much risk for gas leaks, explosions or CO poisoning because I am not running a gas system in either building. I could install a ceiling mount propane furnace in the shop and install a backup propane furnace in the house, but now I just added those risks back in. Not to mention I don't have the space in the house for another heating system.

    I see that Central Boiler has propane backup that will heat the water if you run out of wood, so there's technology out there that can do it. Just curious if anyone knows of a turn key system that I can purchase. My plan was to put up a single stall garage in the back yard where the wood stove sits now. The garage would house the boiler and much larger water storage than I have now. could also store the riding mower and a few other things in there as well.

    Does this system exist? Does anyone have something similar that can provide feedback about efficiency?
     
  2. maple1

    maple1
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    Sep 15, 2011
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    I don't know what is available, but I would not want to burn any fossil fuel in a burner that was outdoors.
     
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  3. amsoil dealer

    amsoil dealer
    Member 2.
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    Feb 21, 2015
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    Loc:
    Park Rapids, MN
    I should maybe rename this post. I am looking more for a remote propane boiler. in other words, I would like to build a small, insulated structure that the propane fired boiler and water storage would be located in. This keeps me from having to replumb everything that I already have in place.
     
  4. leon

    leon
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    Feb 3, 2013
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    Loc:
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    What you could do that would be well conceived and managed by you is build a shed for a small propane boiler with a large open to air steel tank of 500 gallons or more to store hot water. The tank could would be insulated with standard 6-12 inch batt insulation wrapped with chicken wire to hold the batt insulation in place. The larger the tank in gallons the lower the price per gallon.

    You would need to check the water level periodically and that is easy to do with a gauge glass method of monitoring the water level adding water as needed from the water feed system at the boiler.


    You can purchase these tanks from the Wessels Tank Company or from your local B+G plumbing supply distributor.

    You would just have to settle on a tank size and purchase the gauge measuring glass system for that size tanks side or end tappings if you leave it on its side. if you leave the tank on its side you will need to have a wooden cradle made to support it BUT they also come with a welded ring base to permit you to use it vertically with an open to air venting system which saves you a lot of work as there is no need to pressurize the system as the water volume in the tank pressurizes it to prevent the circulator from cavitating and being ruined.

    Talking with a Wessels Tank Company representative would be your first step as building the tank is the easy part you just have to know where the tappings will have to be located so that you have the circulator pumping away from the boiler by having it installed on top of the boiler and pushing the water back into the top of the tank and the cooler water piped to the boiler sump where it can be reheated and stripped of air bubbles as it is pulled through the boilers steam chest and pumped back into the storage tank where the micro air bubbles would dissipate in the upper layers of hot water.

    The open to air tank would have a simple vent line that reaches the floor that would allow moisture and heated air in the tank to exit without any resistance.

    You could purchase a very small well insulated propain fired boiler(they are wrapped top, bottom, sides, and end flue breech in thick insulation) and use a very small circulator to keep the water warm at a lower temperature of low limit of 140 degrees and high limit of 160 degrees without the need for a bladder expansion tank as the system is pressurized by the tanks water volume and the atmospheric pressure of the air blanket above the water volume.

    You could use a honeywell L8124L1011 Mechanical triple aquastat on the propain boiler to maintain the boiler temperature at 140 low 160 high at all times and use a B+G-McDonnel & Miller RB122-E low water cut off to protect the boiler in the event of a water loss. The B+G McDonnel &Miller RB-122-E would be wired as the first control to protect the boiler and shut it off at the first indication of a water loss as it is a direct water contact/conductive water contact sensor Low Water Cut Off.
     
  5. amsoil dealer

    amsoil dealer
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    Feb 21, 2015
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    Thank you Leon, this is exactly what I was hoping to hear! Do you have an example of a propane boiler that I could purchase?

    My Heatmor is semi pressurized as well, so I really wouldn't be changing much. I would likely go 400-500 gallons as I am currently undersized for the square footage I am heating.
     
  6. maple1

    maple1
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    Sep 15, 2011
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    Water storage? Do you have that now?

    We don't know anything about your overall layout & plumbing scheme, or what you do in your shop, but I would lean to a simple modern efficient LP boiler in the shop. You should be able to get heat to everywhere it needs to go from there? I have no experience with LP boilers, but I don't think they take up much room? I don't think there would be need for storage, unless you are upgrading your Heatmor to a gasifying indoor wood boiler. You might gain a bit by adding some to your Heatmor setup, depending how it does now. But using storage usually means batch burning techniques - storage takes heat while boiler burns, then releases it after the fire goes out. Which means the boiler would have periods where it wasn't burning. Which may or may not introduce freezing concerns if using an OWB. And mean a lot more re-lights.

    Might just be me but having the heat source (and storage) outside of a heated space that can make use of the standby heat loss gives what could be a big loss in system efficiency. I don't think you will find a turn key system, per se - but if you could add another outbuilding to house your heat source in and also at the same time make use of that building for other things that would benefit from being in a heated space, you should also be able to come up with a solution with some planning & good LP boiler selection. That very last part I have no input on but hopefully you will get some. And even then, if you don't use that structure for anything else but do insulate it very good & size it appropriately, the amount of heat loss may end up being acceptable to you.

    (What is 'semi-pressurized'? I have always thought either it is or it isn't).
     
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  7. amsoil dealer

    amsoil dealer
    Member 2.
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    Feb 21, 2015
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    Loc:
    Park Rapids, MN
    My current OWB has 200 gallons of "water storage". When I looked into upgrading to a new OWB, I was told to step up to about 350 gallons in order to properly heat my house and shop. The current OWB sits about 30 feet from the corner of the shop. There is a loop that runs to the shop and back. This is running through a plate exchanger that is tied to the floor heat system in the shop. There is a separate loop that runs to the house which is about 100 feet away from the OWB. This runs through a coil in the ductwork of my forced air geothermal system. The shop is 1900 sq ft with 14' walls. I primarily keep the shop around 40 degrees when I don't plan on being out there and warm it up to the low to mid 50's if I am going to be spending time out there. The house is a split level that is about 2600 sq ft. I live in North Central MN where the winters get rather cold.

    I would definitely build a structure for the LP system to be housed in. Take the OWB out and build the garage where the OWB sits so the lines can come right in through the floor. I would insulate it and use it for storage (snowmobile trailer, lawn tractor/blower, yard tools, snowmobiles, etc.). This would also free up more space in my shop so I have more space to work for once!

    Regarding Semi-pressurized, I may be wrong. I was told that particular OWB was semi-pressurized because it uses a weighted ball type cap on top of the boiler. This holds about 5psi is all. Should the boiler overheat, the boiling water can push the ball up and boil out as needed. There may be a more scientific term for this, but semi-pressurized is what I was told.
     

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