Small house Boiler setup

[RonJon1190]

Hi Everyone, I am brand new here, and have been heating my 600sf ranch with wood for 3 years now. I first had a horseflame 517 pony, then after accidentally breaking the stove glass while cleaning the stove, I upgraded to a lopi answer. The lopi has been a great stove, and easily (too easily) heats the house. My main gripe is that it is difficult to balance long burn times, without overheating the house.

I have no experience running a wood boiler, but I have been kicking around the idea of installing a wood boiler in an unused bay of my woodshed, (about 20 feet away from my house), piping it in parallel to my oil boiler in the house, and using that to heat the house. I think I could achieve greater control of the temp in the house, and use a fan coil in the vented crawlspace under my house to dissipate excess heat created in the boiler. Which I think would keep my floors pretty warm and I wouldn't need to worry so much about frozen pipes.

I have access to a used Tarm MBO 40 for next to nothing, and about 20 feet of Selkirk 6" stainless insulated pipe, but would need everything else for the installation. Does this sound like something I should pursue?

Any and all input is appreciated!

 

[sardo_67]

that boiler sounds waaaaaaaaay over kill for your small house. to use it best you would need a few hundred gallons of hot water storage.
I think if you have $1,500 to invest into a system and are handy yourself it would be a very good investment.

basically you fire up the boiler and get the storage tank to around 190* and your house will then use the hot water in the tank to circulate thru the house and not the boiler. more efficiently than directly from the boiler itself.

 

[warno]

I agree with the above post. If a boiler is terribly over sized it will idle itself into creosote city. If the boiler is good enough to buy then look into a storage setup and heat the home from the storage water.

 

[maple1]

I might pursue it but likely only if I could also add storage. As said above, the boiler will likely otherwise spend most of its time smoldering & making creosote, that is a very small house and likely even a smaller heat load being in CT.

Wonder about the possibility of using a fan to get some of the extra stove heat you have now, down into your crawlspace? That would likely mean putting crawlspace air into your house - which I am not sure if is a good idea or not. (No crawlspace experience here...)

 

[JohnDolz]

Hi Everyone, I am brand new here, and have been heating my 600sf ranch with wood for 3 years now. I first had a horseflame 517 pony, then after accidentally breaking the stove glass while cleaning the stove, I upgraded to a lopi answer. The lopi has been a great stove, and easily (too easily) heats the house. My main gripe is that it is difficult to balance long burn times, without overheating the house.

I have no experience running a wood boiler, but I have been kicking around the idea of installing a wood boiler in an unused bay of my woodshed, (about 20 feet away from my house), piping it in parallel to my oil boiler in the house, and using that to heat the house. I think I could achieve greater control of the temp in the house, and use a fan coil in the vented crawlspace under my house to dissipate excess heat created in the boiler. Which I think would keep my floors pretty warm and I wouldn't need to worry so much about frozen pipes.

I have access to a used Tarm MBO 40 for next to nothing, and about 20 feet of Selkirk 6" stainless insulated pipe, but would need everything else for the installation. Does this sound like something I should pursue?

Any and all input is appreciated!

Wondering if there is a typo on the house size?

 

[Bad LP]

Wondering if there is a typo on the house size?

Good point.

 

[RonJon1190]

nope, not a typo. it is really 640 sq feet. I like the idea of storage tanks. what does everyone use for those? blowing off excess wood stove heat wouldn't be feasible, as the crawlspace needs to remain separate from my living space for air quality issues.

 

[JohnDolz]

nope, not a typo. it is really 640 sq feet. I like the idea of storage tanks. what does everyone use for those? blowing off excess wood stove heat wouldn't be feasible, as the crawlspace needs to remain separate from my living space for air quality issues.

Reminds me of San Diego size. You can buy prefabricated tanks from Tarm USA (woodboilers.com) or many folks use propane tanks. I am in Burlington, CT and happy to you you a storage set up if you ever want to take a drive over.

 

[Chris Hoskin]

for that set up I'd want to see you use at least 1000 gallons of thermal storage. Many folks have had success converting old propane tanks. Given the size of your heating load, I think you might be best served with a small mod/con propane boiler - even then I'd recommend a small buffer tank for that. Or maybe a heat pump. (no, I did not really say that out loud... )

 

[Chris Hoskin]

a back of envelope calc using 25 btu/square foot as a way to figure peak heating demand x 640 square feet yields a design load of only 16,000 btu/hour ON THE COLDEST DAY OF THE YEAR. I think the smallest mod/cons are about 60,000 btu/hour and can modulate down to about 20% output? Anyway, that's why I recommend a buffer tank even with the mod/con.

 

[Chris Hoskin]

https://www.pmmag.com/articles/96765-alternate-methods-to-pipe-a-buffer-tank

 

[sardo_67]

1,000 gallon storage? sarcasm lol?

also HS Tarm heat tanks are $$$$$$$$$$$$$ 400gal tank is $3,200

 

[BoiledOver]

If the poster has the ability to get that size boiler and a 1,000 gallon propane tank on the cheap, I think it is a grand idea. One load every two or three days to charge storage, woohoo! Granted, it would be a poor direction at new purchase prices.

 

[JohnDolz]

1,000 gallon storage? sarcasm lol?

also HS Tarm heat tanks are $$$$$$$$$$$$$ 400gal tank is $3,200

RonJon said he was considering a Tarm MBO 40 because he can get it cheap. I imagine when Chris recommended a 1000 gallon storage he was factoring in the boiler output & load demand from 640 sqft house.

 

[sardo_67]

there is a guy on here selling a 500 gal tank for $300 in Coventry not too far from the OP, he already welded in some bungs as well

 

[Tar12]

Wondering if there is a typo on the house size?

Wondering that myself....

 

[Bad LP]

there is a guy on here selling a 500 gal tank for $300 in Coventry not too far from the OP, he already welded in some bungs as well

And by doing so, the tank lost it's ASME rating. I've worked with some pretty good fabricators and one is a good friend who is more than capable of welding on any pressure vessel. Let's not forget a vertical tank sold by Tarm is a lot lighter than the same size LP tank by a lot. I had easy assess into my basement and two guys took the tanks from a horizontal position into vertical and in place with not a lot of effort. Now sure a reworked tank could last a lifetime with no problems however if there was a problem and the insurance company denied the claim are you willing to write the check?

I'm not saying the Tarm tanks are the cure all but I will say spending 1% of my homes value on certified tanks was a no brainer knowing that the insurance company would be looking for a way out IF there was a claim due to my boiler installation. FWIW questions were asked by my insurance company on it. They were not allowing a non licensed boiler tech to do the job. I have the paid invoice saved in a safe space.

Now with all that out of the way the money spent for tanks and piping buys a new boiler and a hellofa lot of LP to heat 640sqft.

 

[sardo_67]

are you saying all the people here who have made their own storage tanks for cheap from repurposed tanks did something stupid?

also what is the failure that would need an insurance claim?

 

[warno]

also what is the failure that would need an insurance claim?

Insurance companies are always trying to get out of covering claims or giving policies to any wood burners. Their list of rules and stipulations is insane. Then they send a person, who has no idea what they're looking at, to "inspect" your install.

 

[sardo_67]

yes I realize that but unless you pressurize your water system to like 200psi and it blows up in a finished basemen or a major failure from some half assed workmanship you won't have any issues.

compared to fire risk its a lot lower.

 

[JohnDolz]

yes I realize that but unless you pressurize your water system to like 200psi and it blows up in a finished basemen or a major failure from some half assed workmanship you won't have any issues.

compared to fire risk its a lot lower.

Everyone has different risk tolerances. For example I do not insure my vehicles (other than Liability) but carry a big Umbrella policy - not everyone agrees with this approach but it works for me. As a point of reference I have 2 500 gallon propane tanks stacked horizontally but if I ever do another system I will probably go with vertical "Accumulator tanks". Reasoning having nothing to do with insurance.

 

[Bad LP]

are you saying all the people here who have made their own storage tanks for cheap from repurposed tanks did something stupid?

also what is the failure that would need an insurance claim?

Absolutely not am I saying they did something stupid. I'm saying it was a risk I was not willing to take. Many things could go wrong in any wood burning boiler located inside the dwelling.

I'm not willing to give the insurance company an easy way out. The risk to me is too high.

 

[BoiledOver]

The OP stated "I have been kicking around the idea of installing a wood boiler in an unused bay of my woodshed, (about 20 feet away from my house)".

Risk taking of any degree is a personal matter. Some people are scared of most everything while others fear nothing, and every category in between. Fortunately hydronic heating systems use pressures below 30 psi and there are safety valves, dump zones and such to protect from "catastrophic events". Personally I have repurposed propane tanks for thermal storage and have had zero problems with them.

 

[Fred61]

Insurance companies aside. If you're concerned about a repurposed propane tank exploding, you've got to be scared to death of the tin foil boiler vessels out there.

 

[maple1]

I can see both sides of that issue.

If there was a failure, it would likely be a weld failure - that's why I had my welding done by a pro with ASME certification. He didn't certify my tank when he was done, but should know how to weld.

My pressures are always under 20, and I have my tanks (and welds) boxed in. So if I have a failure, the worst that would happen (I think) is I would have 3/4" of water on my (unfinished) basement floor. If it all got out before I saw any signs of a leak. I can isolate the wood boiler & storage part of my system, from backup boiler & distribution. Yes, it's all a personal risk assessment - so as the saying goes, proceed at your own risk.