Tuesday, December 8, 2015

Rocket Mass Heater - It Burns

Sunday was the big day - the first burning of wood in the rocket mass heater while it is in the house.  I was nervous.  I kept telling myself that other folks have reported that when the heater is new, cold, and damp, it doesn't always work right away, so not to be discouraged if we fill the house with smoke and the stove doesn't draft right.  No worries though - it worked! For a while at least.  

We started by lighting a piece of newspaper and cramming it in the firebox.  I like that Brandon decided to wear his home made camouflage shirt (painted and drawn on with a sharpie for a brief flirtation he had with turkey hunting) on the rocket mass stove's first day.  What was he thinking, right?   If ever there was a day for photos, this is one!

We intentionally didn't mortar the last layer of brick around the firebox because we found out during firing the mock up, that this is the dimension that makes all the difference when it comes to getting a good draft.  Just a few inches can change the entire air flow.  It didn't take very long before we found the brick arrangement that had our flames and smoke being pulled horizontally into the stove, just like we hoped.  

Wow!  It's working.  The barrel got warm right away, and soon got too hot to touch.  The exhaust pipes took a while to heat up, and after three hours, were still only really warm about half way down their length.  Slightly warm the whole way to the wall.  What was coming out of the stack outside was white, like barely warm steam, which would quickly dissipate.  We noticed water dripping from some of the seams in the exhaust, and figured out it was the moisture from the wet clay as it dried.  

After about four and half hours of having wood burning in the firebox, the house was too warm (yay!), the dragon on the top of the barrel was beginning to make some steam, and cracks began to appear in the clay around the base of the barrel.  Uh oh.  

Along with the cracks, came smoke.  Not just from the cracks themselves, but also from the firebox.  We lost our draft.  I think it was because of the cracks and not because it finally got good and hot.  We turned on the vent fans, opened the windows, and covered the firebox to put out the flames.  The house smelled liked smoked ham for the rest of the night.  Actually, I probably smell like smoked ham right now, but I've gotten used to it.  I'm sure we shouldn't have kept it burning for so long without the rest of the cob installed, but we couldn't resist the fun.  We have a plan for patching our cracks and building the bench.  

After the fire was out, heat spewed from the firebox for hours.  We could hold our hands above the brick and feel the heat from three feet away.  I'm sure that tower of fire brick that makes the heat riser stayed hot for a long time.  Even with the fire out for the evening, night, and all the next day, I think the house was warmer.  I'm encouraged, despite the smoke.  

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