Chestnut Coal in a Harmon Mark II

I'm thinking about purchasing a used Harmon Mark II. The current owner tells me that it uses "chestnut" coal. How is chestnut different from rice coal, and why can't i just burn rice coal in the Mark II ? Also, are there any problems with the Mark IIs that I should be aware of? thanks

Rice coal will just fall through the grate in a Mk II. I have Mk I and bought a bag just to try. It didn't work too well. I started out burning "nut" in my Mk I but I couldn't throttle it down enough to a comfortable temperature. I switched a few years back to "pea" and have been very happy.

If it gets really cold, I buy a couple bags of nut to mix in with the pea to raise the temp just a bit.

Jeff, how long will I be able to run the fire without tending the stove if I use Pea coal? thanks Dan

I'm just the opposite of Jeff. I burn nut in my Harman Mk I, have no trouble controlling the burn rate, and find that pea does not burn well. My guess is that Jeff has a better chimney than I do and it can suck the air through the pea better than mine.

Burn time between tendings, for me, can be as little as 9 hours if I'm really pushing it in cold weather, and as long as 24 to 26 hours when the weather is warmer in Spring and Fall. It really will depend how big an area you are heating, how well insulated (or not) your house is, and whether the stove is the right size for your needs.

As to problems inherent with the Mk II, I have not heard of any.

Dans58 wrote:Jeff, how long will I be able to run the fire without tending the stove if I use Pea coal? thanks Dan

I suspect rberq is right. I seem to have an extraordinarily good draft. I can PACK it with pea coal, throttle it down about to about 1/2 a turn on the air inlet and get a solid 20 hours out of it with only a quick shake once or twice and keep my 1200 sq/ft house at 75*(give or take).

With chestnut coal, I could never get the air balance right, it was either choked out dead, or 100*+.

Typical operation is 1 bucket every 12 hours. Keeping the ash pan empty was the most critical thing in controlling the fire and keeping it consistent.