Scaling up RMH for larger buildings?

I've been watching reading on this for a long time.  I'm wondering if anyone has tried to custom build a RMH for a much larger building as opposed to expensive in-floor heat units?  I'd like to have a large heated shed, but I don't want to bite off the cost to heat it conventionally, or the hefty price tag in property taxes if it's viewed as such.  

It would be neat to be able to heat a 60x100' shed on just firewood if such a thing could be designed and scaled up.  

Hi Christopher,
maybe check out this triple barrel batch box:
https://permies.com/t/193821/inch-batch-box-rocket-mass

Christopher, where are you located? How cold does it get in the winter? How well is the building insulated?

This is just an unscientific guess based on my experience. I am heating a 42' x 48' room with 15' high ceilings with a 6" batch box with a brick double skin, no barrels. I do have a traditional cast iron stove at the other end of the room that I am still running in the morning just to get a quick blast of heat. This was my primary heating source for many years. The RMH has been able to keep the room 10 - 14 degrees warmer consistently. Note that my typical overnight temps in the winter range from -10F to mid 20's F and my construction is metal skin pole barn with 2" fiberglass insulation on the walls and R30 on the ceiling.

I was constrained to building a 6" system because I already had a 6" chimney in that location from an antique cook stove that we used to run. Changing out the 6" stove pipe would have been more work than I wanted to undertake so I went with the 6" system. If I were starting from scratch I would have installed an 8" chimney. My guess is that if you're so inclined, two 8" systems at opposite ends of the area would work in an area that large. Depending on your ceiling heights a few ceiling fans would help keep the heat pushed down. Depending on your overnight temps and ability for the building to retain heat you may want to consider one of the two to have a combination barrel and masonry mass to get some immediate radiant heat. But I can tell you that my 7,000 lbs of masonry mass does a great job at keeping the area at a comfortable temperature.

Hopefully, the science guys on the forum can chime in with their BTU calculations and thermal science but they'll need to know the ceiling height and insulation details.

Here's a 12" batch box system a guy built for a big greenhouse: https://permies.com/t/174665/Huge-batch-box-rocket-stove

Glenn Littman wrote:Christopher, where are you located? How cold does it get in the winter? How well is the building insulated?

Hopefully, the science guys on the forum can chime in with their BTU calculations and thermal science but they'll need to know the ceiling height and insulation details.

I'm in the northern third of MN.  It can go into single digits and below zero for 2-3 months up there in a bad winter.  It can go to -30 or more in the worst of times.  I'd say the average performance temp I'd want to be able to best is -15 and above that.  This building doesn't exist yet, I'm just wondering if such a thing could be designed.  I'd have it well insulated if it meant I didn't have to ever pay to keep it heated.  

Benjamin Dinkel wrote:Hi Christopher,
maybe check out this triple barrel batch box:
https://permies.com/t/193821/inch-batch-box-rocket-mass

That is an awesome share!  I appreciate it!

Christopher, my shop is 2,000 sq ft with 15' high ceiling with modest insulation. You're planning 6,000 sq ft. but you haven't given a ceiling height to determine the cu ft. Have you looked at Peter's website and the Building page with detailed specs for sizes up to a 10" system?. That same page provides some calculations for a given volume and temperature differential performance to provide guidance and help you to determine if a single system will be sufficient or if perhaps 2 will be needed. https://batchrocket.eu/en/building

If you happen to know a plumber that installs hydronic heating systems they should also be able to run a BTU requirement calculation for you. I would think that one 10" system my be sufficient based on the numbers published by Peter. You can see that a 10" system has more than 4 times the thermal energy output versus a 6" system like I am running. With that said, it would be good to have someone with the knowledge to run the BTU calculations confirm this for you.

I have used:

https://kalk.pro/en/heating/heat-loss-calculator/

Large heated 60x100' shed with 15' ceiling.
Average low outside temperature of -26 C (-15 F). If this place will be inhabited I would assume at least 15 C (59 F) inside temperature. So the delta is 41 C.
I assumed walls and ceiling to be made only of 8" thick fiberglass and 30m2 used for dual pane windows and the result was total heat loss of 17 kW.
Please calculate yourself, entering the correct values and share the results here.

Glenn Littman wrote:Christopher, my shop is 2,000 sq ft with 15' high ceiling with modest insulation. You're planning 6,000 sq ft. but you haven't given a ceiling height to determine the cu ft. Have you looked at Peter's website and the Building page with detailed specs for sizes up to a 10" system?. That same page provides some calculations for a given volume and temperature differential performance to provide guidance and help you to determine if a single system will be sufficient or if perhaps 2 will be needed. https://batchrocket.eu/en/building

If you happen to know a plumber that installs hydronic heating systems they should also be able to run a BTU requirement calculation for you. I would think that one 10" system my be sufficient based on the numbers published by Peter. You can see that a 10" system has more than 4 times the thermal energy output versus a 6" system like I am running. With that said, it would be good to have someone with the knowledge to run the BTU calcTulations confirm this for you.

It'll probably have 15' ceilings.  I'd like to use the vertical space too.