here with some newbie questions.

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warno

Minister of Fire
Jan 3, 2015
1,237
illinois
Reading up on building a wood burner for my garage for the past few weeks. I'm tried of it being freezing cold out there when I go out to work on the weekends. Right now I'm heating with a ready heater which does ok for short periods of time. But it's starting to produce fumes and the cost of kerosene is starting to add up.


I guess I should start by saying I don't have the money to buy a prebuilt wood burner and my insurance company says I can't put it inside the garage so I started reading about building one to put outside. I have been a certified welder for the past 8 years, so the building part doesn't scare me. I have wood supply for free.

My garage is about 21 X 21 with insulated walls. I planned on using propane tanks for my fire box and air chamber. I was going to simply push cold air in through the air chamber that's around the fire box then back into the garage. But I started reading up on building a boiler and I was wondering if that way would be more cost effective. let me explain my reasoning on thinking this. Where I work we build evaporater coils and heat exchangers, so I could build my heat exchanger out of our scraps left over from production for the cost of scrap. I have a friend that is giving me a blower fan for free. The amount of pex tubing I would need wouldn't cost me too much. A hot water pump is pretty cheap for what I would need.

I was thinking I could build basically the same unit, I would just fill my air chamber with the water, let the fire box heat it, pump the hot water into my garage through my heat exchanger then back to the tank. With a fan on the heat exchanger of course. I could incorporate a vent system in case of boil over. Is there more involved in this than what I'm thinking?


I guess it's time for my questions.

Is a boiler system better than a forced air?

How much water is minimum in these systems?

How to prevent water tank from rusting out?

Do you run antifreeze in the unit to prevent freezing if pump isn't running and fire goes out?

Do you filter the water going to the pump?
 
On a budget I don't think you're going to find wild success building something outside to heat your garage. Further, if your insurance guy doesn't want a wood burner in the garage he will also dislike a burner "relatively" close to the house on the outside. Ask your insurance guy how close you can have a boiler to the house and he'll probably throw quite a distance at you.

And yes, building a boiler is vastly more complex than most would expect. And they are very dangerous if built incorrectly.

I'd suggest you find a way (maybe a different insurance guy?) to make something like a barrel stove work. Dirt cheap, been around for a long time.
 
The insurance company told me that I need to build the unit a safe distance from the garage. And they will be fine with it.

I have been reading like crazy on outdoor forced air units. I have decided to go that route at least unit I can get more knowledge on a boiler setup. I have 2 ex-HVAC installers I work with. I have been picking there brains like crazy on getting my duct work done properly. They both seem to think with proper insulation around my air chamber and duct work it should work just fine.

By my calculations I'll be in this for the cost of duct work, insulation and my time.
 
I guess it's time for my questions.

Is a boiler system better than a forced air?

How much water is minimum in these systems?

How to prevent water tank from rusting out?

Do you run antifreeze in the unit to prevent freezing if pump isn't running and fire goes out?

Do you filter the water going to the pump?

Ok, so a few answers, that are all subject to debate.

A boiler system is not necessarily better or worse than forced air. But its easier to move BTUs with water compared to air.

Minimum amount of water depends on a lot of factors, usually you want more instead of less, especially when heating with wood.

If you have a closed system, the tank wont rust out once the dissolved oxygen in the water reacts with the steel of the tank. Then there is no additional oxygen present to cause rust. If you have an open system, you need to use chemicals.

Antifreeze is a good option if you are worried about freezing, or wont be home to tend it all the time.

You can put a strainer on the pump for startup, but once you run it for a while, you shouldnt need it anymore (again, unless its an open system).

As far as building a system, I barely know how to operate mine somedays. Good luck to you! Wish I had the skills to weld stuff!
 
Anyone else have any input for me?


You will sink enough money / time into a home built that you MAY end up wishing that you had spent the money on a designed boiler / furnace in the end. Everything else that crossed my mind has been covered. Saftey comes to mind. Solid fuel heat doesn't just shut down.
 
The insurance company told me that I need to build the unit a safe distance from the garage. And they will be fine with it.

I think I would try to get them to commit to a certain distance. 'Safe' is a very relative term, and if something happens, they will likely deem that whatever the distance was, it's wasn't 'safe'.
 
You will sink enough money / time into a home built that you MAY end up wishing that you had spent the money on a designed boiler / furnace in the end. Everything else that crossed my mind has been covered. Saftey comes to mind. Solid fuel heat doesn't just shut down.

This! Have your insurance company provide specifics on how far from your house, garage trees that you need to be.

Otherwise, tell them to get their backsides there with a measuring tape, 4 posts, a camera, building inspector and notary to have them tell you exactly
where it is that you need to lay a pad down. They can stake 4 places (based off the size of the building you are going to need) and they can work it out with the building
inspector. Then the insurance company , you and the notary can sit down and work out a contract saying that where the insurance agent wants to put the shed will be covered under insurance :)

I'm obviously kidding about most of that... but the agent needs to be specific so that you can work with building inspectors if necessary.
 
I realize now that I'm not actually building what is considered a "boiler" but rather a water heater. I will be putting in an open vent system. so even if the water did boil it would just run out the vent on to the ground. Maybe this is why most of the responses sounded concerned.

I do have a few other questions on the design part though.

Does anyone run a chimney damper? My dad has heated his house with a wood furnace in the basement since I can remember. And he recommended I use a chimney damper to help with burn times.

When the furnace is in "idle" mode is the air intake shut down completely or just most of the way?

I noticed that alot of manufacturers drop the chimney down into the fire box as apposed to using a secondary burn chamber for burning off the gases. Which way is better?

Thanks in advance for any help.
 
Reading up on building a wood burner for my garage for the past few weeks. I'm tried of it being freezing cold out there when I go out to work on the weekends. Right now I'm heating with a ready heater which does ok for short periods of time. But it's starting to produce fumes and the cost of kerosene is starting to add up.


I guess I should start by saying I don't have the money to buy a prebuilt wood burner and my insurance company says I can't put it inside the garage so I started reading about building one to put outside. I have been a certified welder for the past 8 years, so the building part doesn't scare me. I have wood supply for free.

My garage is about 21 X 21 with insulated walls. I planned on using propane tanks for my fire box and air chamber. I was going to simply push cold air in through the air chamber that's around the fire box then back into the garage. But I started reading up on building a boiler and I was wondering if that way would be more cost effective. let me explain my reasoning on thinking this. Where I work we build evaporater coils and heat exchangers, so I could build my heat exchanger out of our scraps left over from production for the cost of scrap. I have a friend that is giving me a blower fan for free. The amount of pex tubing I would need wouldn't cost me too much. A hot water pump is pretty cheap for what I would need.

I was thinking I could build basically the same unit, I would just fill my air chamber with the water, let the fire box heat it, pump the hot water into my garage through my heat exchanger then back to the tank. With a fan on the heat exchanger of course. I could incorporate a vent system in case of boil over. Is there more involved in this than what I'm thinking?


I guess it's time for my questions.

Is a boiler system better than a forced air?

How much water is minimum in these systems?

How to prevent water tank from rusting out?

Do you run antifreeze in the unit to prevent freezing if pump isn't running and fire goes out?

Do you filter the water going to the pump?

=====================================================================================================


Don't make mountain out of your mole hill.

A home made boiler is not worth your time or money and if it is pressurized your going
to have to have it certified to have an H stamp on it.


Save your money and invest in either a wood pellet stove or a small coal stove
like a Koker. The coal stoker will make you want to keep the doors open all the time anyway.

If you have and store flammables and a set of smoke wrenches you should invest in a
lockable flame safety cabinet and leave it outdoors with the gas bottles and the cart
chained up and make sure the gauges are off the bottles and the caps are on the bottles
as well as having flashback arrester's installed on the gauges.

A small pellet stove from TSC will be more heat than you will want anyway.
The other issue is heating the garage before plan on spending any time in there and
that will require time to warm up the work space.

It will be even simpler if you use a box fan to exchange the air in the garage with the
torpedo heater operating to get more fresh air.

Does your torpedo heater have a thermostat?? If not you can buy thermostats that plug in
between the outlet and the heater to control the temperature.
 
=====================================================================================================


Don't make mountain out of your mole hill.

A home made boiler is not worth your time or money and if it is pressurized your going
to have to have it certified to have an H stamp on it.


Save your money and invest in either a wood pellet stove or a small coal stove
like a Koker. The coal stoker will make you want to keep the doors open all the time anyway.

If you have and store flammables and a set of smoke wrenches you should invest in a
lockable flame safety cabinet and leave it outdoors with the gas bottles and the cart
chained up and make sure the gauges are off the bottles and the caps are on the bottles
as well as having flashback arrester's installed on the gauges.

A small pellet stove from TSC will be more heat than you will want anyway.
The other issue is heating the garage before plan on spending any time in there and
that will require time to warm up the work space.

It will be even simpler if you use a box fan to exchange the air in the garage with the
torpedo heater operating to get more fresh air.

Does your torpedo heater have a thermostat?? If not you can buy thermostats that plug in
between the outlet and the heater to control the temperature.


I replied to this thread stating that I realized I'm not actually building a boiler. It will simply be a hot water heater to run hot water through a heat exchanger to heat the garage. I will incorporate a vent that will vent any boiled water onto the ground.
 
Last edited:
Started out heating the garage. Now it is a water heater.

Focus.
 
Started out heating the garage. Now it is a water heater.

Focus.

By that I meant to run hot water through a heat exchanger in the garage for heat. By "hot water heater" I meant the system will be open meaning non-pressurized. so I assume it's not technically a boiler. I edited that post reflecting this to avoid other confusion.
 
If it heats water for heating, it's commonly referred to as a boiler. Even though it doesn't boil the water. And even if open to the atmosphere. Usually the term 'water heater' is use to refer to something that heats domestic hot water.
 
If it heats water for heating, it's commonly referred to as a boiler. Even though it doesn't boil the water. And even if open to the atmosphere. Usually the term 'water heater' is use to refer to something that heats domestic hot water.

Thanks for clearing that up. It just seemed everyone was concerned about it when I said I wanted to build a boiler.

Could anyone help me with my design questions?

Does anyone run a chimney damper?

When the furnace is in "idle" mode is the air intake shut down completely or just most of the way?

I noticed that alot of manufacturers drop the chimney down into the fire box as apposed to using a secondary burn chamber for burning off the gases. Which way is better?
 
Thanks for clearing that up. It just seemed everyone was concerned about it when I said I wanted to build a boiler.

Could anyone help me with my design questions?

Does anyone run a chimney damper?

When the furnace is in "idle" mode is the air intake shut down completely or just most of the way?

I noticed that alot of manufacturers drop the chimney down into the fire box as apposed to using a secondary burn chamber for burning off the gases. Which way is better?

I don't think there are straightforward answers to the questions.

There are two types of chimney dampers. Barometric, and key. Boilers typically use barometric - but needing one depends on the draft conditions of your chimney, and how much draft your boiler needs to burn right.

Usually when a boiler 'idles', the damper is shut tight. But some don't or can't idle (mine being one) - and idling is something you should try to limit. But not likely possible with a simple boiler design.

I have not personally seen a boiler that drops the chimney into the firebox. But doing that is in no way a substitute or replacement for a secondary burn - it is likely a bubble gum approach to trying to get the hot stuff to stay in the firebox longer so more of the heat will transfer to the water jacket, and would do nothing for burning off gases.
 
I am quoting the posts of other people in part at least here.
Far more knowledgeable tha I on boilers.

"On a budget I don't think you're going to find wild success building something outside to heat your garage. Further, if your insurance guy doesn't want a wood burner in the garage he will also dislike a burner "relatively" close to the house on the outside. Ask your insurance guy how close you can have a boiler to the house and he'll probably throw quite a distance at you.

And yes, building a boiler is vastly more complex than most would expect. And they are very dangerous if built incorrectly.

I'd suggest you find a way (maybe a different insurance guy?) to make something like a barrel stove work. Dirt cheap, been around for a long time.
Jan 7, 2015ReportBookmark
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"Don't make mountain out of your mole hill.

A home made boiler is not worth your time or money and if it is pressurized your going
to have to have it certified to have an H stamp on it.


Save your money and invest in either a wood pellet stove or a small coal stove
like a Koker. The coal stoker will make you want to keep the doors open all the time anyway.

If you have and store flammables and a set of smoke wrenches you should invest in a
lockable flame safety cabinet and leave it outdoors with the gas bottles and the cart
chained up and make sure the gauges are off the bottles and the caps are on the bottles
as well as having flashback arrester's installed on the gauges.

A small pellet stove from TSC will be more heat than you will want anyway.
The other issue is heating the garage before plan on spending any time in there and
that will require time to warm up the work space.

It will be even simpler if you use a box fan to exchange the air in the garage with the
torpedo heater operating to get more fresh air.

Does your torpedo heater have a thermostat?? If not you can buy thermostats that plug in
between the outlet and the heater to control the temperature."


Don't think me a smarta** BUTT you are ignoring great advise because you aren't seeing what you want to hear.
 
For the record, I am not saying it can't be done. It has, by others.

But it won't be easy, and you have to know what you are doing, and you have to have the resources/metal experience, and you have to be prepared for disappointment. ESPECIALLY if you have no experience even using one.

I have run a boiler in this house for 20 years, and have no desire at all to build one. I would find a decent used one first. To each their own though.
 
Don't do this! You'll waste enough money to buy a whole lot of fuel.

I'd say go electric, if it's only weekend heat. Or direct vent propane heater.

Anything but this idea that you can build a boiler. You have some loop system with a water jacket or coils.. and all you're going to do is make creosote and transfer a small amount of heat.

You've gotten great advice above.. take it! please!

JP
 
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Why is everyone giving this guy a hard time?

He's a certified welder.

Building a boiler with a tank within a tank is relatively easy, especially if you know how to weld.

When the draft control is closed down, you still need some airflow to keep the fire going.

I do not use a damper on the exhaust but I think this would likely improve the efficiency.

Boiler pumps are cheap on craigslist. I let mine run 24/7 during the winter to keep from freezing. If you don't plan to use yours every day, then it makes more sense to use antifreeze.
 
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