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rocket mass heaters

Can I use charcoal in my RMH?

Mark Bowers

Posts: 22

Location: Just south of the center of Vermont

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posted 3 years ago

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Has anyone ever used charcoal (briquets) in an RMH?

We have some really cold weather headed our way in a few days and in addition to sourcing some more dry wood I was thinking that adding some charcoal would boost temperatures. I realize that it would also add ash and soot that would require additional cleaning, but in the short term we would be more comfortable.

Thoughts?

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thomas rubino

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Posts: 6320

Location: latitude 47 N.W. montana zone 6A

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posted 3 years ago

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Hi Mark;
Go for it. It certainly can't hurt.
I'm not sure how much extra heat you will get but if your short on dry wood then it will certainly help.
Be sure to not block the feed tube with too many brickets.
If you block the air it will vent into the room.

If you could find some in Vermont , coal (anthracite) would do a much better job than charcoal.
What size J tube are you running? An 8" hopefully. As a child I spent quite a bit of time in Ripton / Middlebury Vermont. I know how bitter cold it can get there.

For all your Montana Masonry Heater parts (also known as) Rocket Mass heater parts.
Visit me at
dragontechrmh.com

Mark Bowers

Posts: 22

Location: Just south of the center of Vermont

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posted 3 years ago

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We have an 8" system.

As stated in previous posts the mass is incomplete and should be finished this spring/summer, so right now we're just doing what we can to coax as much heat out of it as we can.

Mark Bowers

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Location: Just south of the center of Vermont

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posted 3 years ago

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So we picked up 2 bags of coal and tried adding a little bit to a running RMH.

Wasn't expecting plastic-bagged coal to be damp and require drying out.

Now we're drying the fuel that's gonna help us dry our fuel.

One night's results show that drying the damp coal prior to adding it to the RMH is best. Once added it only takes a few minutes for it to be glowing red and adding heat.

I'll update this thread with multiple days' results.

Mark Bowers

Posts: 22

Location: Just south of the center of Vermont

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posted 3 years ago

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We are preparing for the next 3 days of hell freezing over. Highs around 0F and lows in the negatives, with blustery winds dropping the temps to -24F. The last few below zero nights we've brought our Nigerian dwarf goats into our entryway, but these next 3 days we will need to bring them into the house proper. Won't that be exciting--2 dogs, 2 cats, and 2 goats, along with our 2 young kids and us. Did I mention that our downstairs (minus the entryway) is 450 sqft? Good thing the cats stay upstairs mostly...

We've acquired some kiln-dried hardwood firewood to augment our dwindling pile of mixed firewood. They bake it at 160F for 2 days and remove 1/2 ton of water per cord (impressive).

We've also acquired a small propane backup heater to help us get through the 3 nights since our RMH doesn't have enough mass to maintain temps where they need to be (so looking forward to spring's warmer temps which allow cobbing to continue!).

We bought some nut coal, which we're adding to the RMH when it's roaring (a few handfuls each run). It adds some additional heat, but creates more ash & soot than I prefer. We're hoping that this will be the final frigid spell for this winter and we can return to only burning dry firewood.

I will update after we leave Hoth and return to more typical Vermont winter temperatures...

Mark Bowers

Posts: 22

Location: Just south of the center of Vermont

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posted 3 years ago

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As we prepare to enter a new season of RMH firing I want to reflect on last year's inaugural run.

The simple truth is that small diameter or split DRY hardwood is the absolute best for generating heat with an RMH. The dryer the better.

During times of extreme cold / lack of dry wood, you may supplement with charcoal, but I STRONGLY suggest avoiding using coal. Ever. The off-gassing the coal generated was not worth the extra heat. Noxious fumes.

This year we have built a small barn that is currently holding over 3 cords of DRY wood. Mostly hardwood. A little bit of soft. Almost all of it is split pretty small.

Looking forward to a cozy winter.

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