Trying to decide between regular wood stove, Rocket Mass Heater or vortex mass heater

Hi!

I've heard about RMH a few years ago, always wanted to get started, but never actually had the necessity for one. I have an uninsulated metal frame garage I'd like to heat during cold harsh winter (~ -25C) to be able to work. It is about 12x20'. There is no chimney, so I would need to install one. It is on bare ground and I still hesitate to make some kind of floor since I might move the shop into the barn later. I don't have a lot of time, already got tons of stuff to do and I already have a small wood stove which would be quick to install and good enough. I still think it could be worthy to make a small rocket mass heater, since some of these don't seem hard to build. I was wondering if I could get some guidance on which stove to choose for this kind of garage that would be simple to make. I've found out about vortex mass heater, which seems quite compact and simple, but there doesn't seems to be much information about these. Maybe they have another name?  Maybe there's something even more simple that would be good enough.  Since I don't plan insulating the garage, I wonder if there is an actual advantage to go for RMH, since it takes more time to heat than a wood stove. Maybe it would be worth it to combine the wood stove I got to an RMH?

Hi Jordan;
Pretty chilly place you live in! Do those temps last a long time?
Here in Northern Montana we can and do get similar temps but they only last  a short while and then we go back to a norm of  -10C at night and around 0C during the day.
A  non-insulated 12x20 metal building that you only want to be warmish while your working out there.
No matter what, you defiantly need a class A chimney jack thru the roof.

Now about Rocket mass heaters.
The simplest ones to build are the original "J tube" design.   Fast simple and relatively cheap to build.
The draw back to a J is it needs cook stove size wood every 45  minutes or so (8" J ) and has an open feed tube.
Next are Batchbox stoves. I suspect that these are what you are calling a vortex stove.
There is also a variation of   a batch called a  double shoebox stove.
Batch stoves burn hotter and longer , use larger wood , wood is loaded horizontal, there is a door.
They require some metal work that is not difficult to make or is available for purchase from me at https://dragontechrmh.com/
Here is the website for batchboxes  http://batchrocket.eu/en/

In your situation  I think I would start by getting your chimney  thru the roof (not wall)
And then for now, I would use your existing wood stove (I know shocking the RMH guru is suggesting this!)
I highly suspect that you will be moving your shop into the barn or slabbing and insulting  the metal building.
You need fast radiant heat to attempt working in that building.
Having a warm mass as a bell or a  bench to sit on would be nice, but it will take most of the short winter day to warm it up and by the next morning it would be cold again.

Stack clay brick near your box stove to catch and hold some heat.
Add some firebrick inside your box stove if there is room.
Realize that maybe its just too damm cold to work with a dirt floor and  no insulation .

This summer collect a pile of 30-40 clay (not concrete) bricks.
Sticking to given  size parameter's .  Build a J tube rocket in the yard.
Dry stack at first to get the idea and then use a clay sand mortar so there are no air leaks.
Roast hot dogs on sticks , marshmallows , just experiment with an open J tube.
Once you have that basic core design figured out, then adding a barrel and either a piped solid mass or a brick bell is so much easier.

thomas rubino wrote:Hi Jordan;
Pretty chilly place you live in! Do those temps last a long time?
Here in Northern Montana we can and do get similar temps but they only last  a short while and then we go back to a norm of  -10C at night and around 0C during the day.
A  non-insulated 12x20 metal building that you only want to be warmish while your working out there.
No matter what, you defiantly need a class A chimney jack thru the roof.

Now about Rocket mass heaters.
The simplest ones to build are the original "J tube" design.   Fast simple and relatively cheap to build.
The draw back to a J is it needs cook stove size wood every 45  minutes or so (8" J ) and has an open feed tube.
Next are Batchbox stoves. I suspect that these are what you are calling a vortex stove.
There is also a variation of   a batch called a  double shoebox stove.
Batch stoves burn hotter and longer , use larger wood , wood is loaded horizontal, there is a door.
They require some metal work that is not difficult to make or is available for purchase from me at https://dragontechrmh.com/
Here is the website for batchboxes  http://batchrocket.eu/en/

In your situation  I think I would start by getting your chimney  thru the roof (not wall)
And then for now, I would use your existing wood stove (I know shocking the RMH guru is suggesting this!)
I highly suspect that you will be moving your shop into the barn or slabbing and insulting  the metal building.
You need fast radiant heat to attempt working in that building.
Having a warm mass as a bell or a  bench to sit on would be nice, but it will take most of the short winter day to warm it up and by the next morning it would be cold again.

Stack clay brick near your box stove to catch and hold some heat.
Add some firebrick inside your box stove if there is room.
Realize that maybe its just too damm cold to work with a dirt floor and  no insulation .

This summer collect a pile of 30-40 clay (not concrete) bricks.
Sticking to given  size parameter's .  Build a J tube rocket in the yard.
Dry stack at first to get the idea and then use a clay sand mortar so there are no air leaks.
Roast hot dogs on sticks , marshmallows , just experiment with an open J tube.
Once you have that basic core design figured out, then adding a barrel and either a piped solid mass or a brick bell is so much easier.

Thanks a lot! That is what I planned to for the small wood stove (adding bricks around), so that confirms my intuition for it. I'll defenitely look out for J-Tube and class A chimney. As for the temperature, I don't remember how long it stays that low, but it gets pretty cold. But I've been working in the barn during some cold months without heat and started using a small electric heater until it got so cold, I wasn't able to use my hand for long enough without freezing. There is so much snow here, I could probably insulate the garage with snow now that I'm thinking about it.