Outdoor Propane Boiler

[amsoil dealer]

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?

 

[maple1]

I don't know what is available, but I would not want to burn any fossil fuel in a burner that was outdoors.

 

[amsoil dealer]

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.

 

[leon]

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.

 

[amsoil dealer]

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.

 

[maple1]

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.

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).

 

[amsoil dealer]

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.

 

[Karl_northwind]

2 things to consider in this application: heat loss from underground pipe. it can be substantial, and if it's anything but foamed thermopex or logstor or something don't burn propane to heat the ground.
second: condensate disposal. you won't have a lot if you are running at 160-180 F, but you do need a way to dispose of it. in full condensing, a gallon of LP burned yields you almost a gallon of condensate. if you are running hard, you could have 2 gallons an hour to dispose of. then it freezes outside.

 

[amsoil dealer]

the piping in the ground is thermopex or something similar (insulated pipe). should be no worries there.

regarding the condensate, I don't know much about propane systems. Where will the condensation be accumulating?

 

[maple1]

All insulated pipe is not the same. So could still be a heat loss issue there. Maybe a big one. Especially if it is as old as the 30 year old Heatmor.

The condensation would be in the flue gasses.

 

[amsoil dealer]

The previous owner got the boiler as partial payment for a job that he did. Not sure what year it was installed, but I know it's less than 22 years old as that's when the house was built.

 

[Karl_northwind]

a thorough figuring out of what your underground heat loss is needed. if it's acceptable, a non-condensing boiler (which will get you up to about 85 % efficiency) could be installed at your outdoor boiler location.

I am considering doing exactly this for my house and barn, currently served with a G-200 and 300 feet of logstor pex underground. the heat loss will be a concern, but I plan on this running only when we are away. the simplicity of the low cost propane boiler, no chimney required is appealing.

 

[amsoil dealer]

Been away for a while and decided to try and resurrect this post.

To reiterate, I would like to remove my outdoor wood boiler. In it's place, I would like to build a garage (the more I think about it, the larger it gets....). I would have the lines that currently run to the shop and to the house come right inside the garage and hook to a propane boiler. The garage would be spray foam insulated and the boiler would likely be in it's own partitioned room to maximize efficiency.

https://www.ecomfort.com/Noritz-CB1...8CAnP2VSQfQuG2yQLiJG0yS04FOiFr5oaAiKrEALw_wcB

Would something like this, sized accordingly of course, do what I need it to do? Would you want to have water storage in the garage with it or run it directly to the house and shop? My thought is with let's say 500 gallons of water storage, it wouldn't have to run as much. The storage tank would be spray foamed as well to minimize heat loss. I have to think that this would be much more efficient than my current 200 gallon OWB that isn't insulated all that well.

 

[salecker]

Been away for a while and decided to try and resurrect this post.

To reiterate, I would like to remove my outdoor wood boiler. In it's place, I would like to build a garage (the more I think about it, the larger it gets....). I would have the lines that currently run to the shop and to the house come right inside the garage and hook to a propane boiler. The garage would be spray foam insulated and the boiler would likely be in it's own partitioned room to maximize efficiency.

https://www.ecomfort.com/Noritz-CB1...8CAnP2VSQfQuG2yQLiJG0yS04FOiFr5oaAiKrEALw_wcB

Would something like this, sized accordingly of course, do what I need it to do? Would you want to have water storage in the garage with it or run it directly to the house and shop? My thought is with let's say 500 gallons of water storage, it wouldn't have to run as much. The storage tank would be spray foamed as well to minimize heat loss. I have to think that this would be much more efficient than my current 200 gallon OWB that isn't insulated all that well.

Hi Amsoil
It was mentioned before...
Could you show us what your lines that go under ground look like?
And unless you are batch burning a wood fired boiler/water heater there is no need for storage.Storage will actually cost you more money to heat then without it.The only time storage would be of any help would be if your propane,oil,pellet boiler/water heater was too small for your heating needs. Then you could have the small unit running 24/7 to charge the tank,and you could draw from the extra heat stored.That would be a very temporary fix to help heat your house if you heating units were to small.The danger being if it got cold enough your stored BTU's may not keep up.

 

[maple1]

If your garage is going to be well insulated, and it can use some heat in the winter, there's likely no advantage to putting an LP boiler in its own other insulated room.

And if you mean not burn wood at all anymore, rather just LP, there likely wouldn't be any advantage to using any storage.

Which should all make for a fairly easy install.


EDIT: Slow on the draw this time...

 

[amsoil dealer]

ok, so I was TOLD that the pipe in the ground was insulated. Never really looked into it. Attached are pictures of where it comes into the garage to go to the house, then where it comes into the shop. I always assumed that the insulated portion was in the ground and then these lines were spliced into that, but upon further inspection I am not so sure that is the case. So I am really not sure how much heat loss I have.

My entire idea was based on the premise that the lines in the ground were insulated and in good condition, so why dig them up.

New idea: Sell the old Heatmor. Remove all lines from the ground. Install a new propane boiler in my shop and run new insulated lines to the house. No water storage needed. Figure out a different way to convince my wife that I could use more storage space...

Thoughts?

 

[maple1]

I couldn't say for sure from those pics. Would one where it goes into the ground at the boiler show more?

You could measure heat loss with a decent thermometer(s) that has a probe - put the probe against the pipe, or a fitting close to the pipe end, wrap pipe insulation around it, and observe the temps over a period of more or less constant flow. Do that at each end - where it leaves the boiler and where it comes out of the ground. You might get decently reliable temps with a good IR gun - mine doesn't seem to do very good on piping. Digital BBQ or smoker thermometers can be good.

I think I see galvanized fittings? Those generally aren't good to have on heating system piping.

 

[amsoil dealer]

I looked where they come into the wood stove and you can't tell anything there either. I am guessing he cheaped out when he did the install. It would align with a few other things around the property.

That being said, I am leaning towards something like this: https://www.ecomfort.com/Noritz-CB180DV-LP/p82302.html?utm_term=8230282302&var1=ecomfortusa&var2=adwordsfroogle&var3=64883&keyword=GOOGLEPLA-64883&gclid=Cj0KCQiA14TjBRD_ARIsAOCmO9ZGQIZaDmYZ2583abXMonW8CAnP2VSQfQuG2yQLiJG0yS04FOiFr5oaAiKrEALw_wcB

Need to figure out the proper sizing to heat the shop and house with one unit. I plan to have a heating guy come out and give me a quote on what it would cost to install. I think this is the best option for what I am trying to do. I would much rather keep all of the risks of propane in the shop and out of the house.

I have someone interested in my old Heatmor. The thing works great, but I am just tired of dealing with the inconvenience of not being able to be gone for very long/lining up someone to fill it. Any idea what a 30 year old non Stainless boiler would be worth?

 

[amsoil dealer]

I had a guy come out and we discussed the situation. He mentioned installing 2 separate units rather than running piping through the ground and the heat loss involved with that.

So, larger propane boiler in the shop to cover the floor heat. I could couple that with either a propane forced air ceiling mount unit or a coil unit that's ran by the boiler with a fan behind it to take the chill off in the shop.

Another unit in the garage due to my space constraint downstairs. This could provide some heat to the garage, but it's main purpose would be to heat the coil in the ductwork in the house. Regarding sizing of this unit is where I am confused. I don't know that you would need to size it for the square footage of the house. If I was heating radiators, yes. but there is literally a 2'x2' coil inside the ductwork that the hot water is running through. The guy that I talked to mentioned that the unit for the house could be much smaller and still be effective.

I am still waiting on pricing, but I think this is likely the route we are going to take.

 

[maple1]

The furnace should ideally be sized to the heat loss of the structure, and not the size of the coil that is there. Hopefully the coil that is there was also +/- sized to the heat loss of the house also.

 

[salecker]

I had a guy come out and we discussed the situation. He mentioned installing 2 separate units rather than running piping through the ground and the heat loss involved with that.
[/QUOTE
If you use good quality lines and insulation there will be almost zero loss of temperature underground.
Your guy doesn't really know much i would find another guy!!

 

[salecker]

If you use good quality lines and insulation there will be very little temperature loss underground
Your GUY dosn't know much and i would find another Guy !!

 

[amsoil dealer]

If you use good quality lines and insulation there will be very little temperature loss underground
Your GUY dosn't know much and i would find another Guy !!

If I was still going to do the original idea of a separate building to house everything, I would agree. The size of the unit needed to heat both structures is pretty big and costly. Not to mention $10/ft for insulated lines to run the 100' from the shop to the garage.

I also like the idea of 2 separate units as I can get the house done this year and do the shop next year so it isn't such a blow to the pocket book.