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Summary
part 2 of a 2 part podcast
Paul, Steven and Alexandra continue discussing the Fisher-Price house
RMH.
Paul comments that he puts the larger sticks near the barrel and Alexandra agrees that this helps keep the burn even. The ideal burn is even and the fire stays low at the bottom of the
feed. If the fire starts to go up the feed, it warms up the feed and you get a competing chimney which leads to, in Paul's words, a sucky burn. They discuss strategies to overcome this and resolve it if it happens. Alexandra says one issue is wedging too many sticks in so they jam in the feed and this can cause the fire to climb up.
To burn efficiently the fire must get to at least 1300°C to burn the smoke and creosote. Optimally it needs to burn hotter than that, and this is achieved by having the fire in an insulated space.
They discuss how much
wood is used. Some years ago they did a test and used 0.6 cords of cord-wood, and Paul thinks 0.2 cords
should be achievable, maybe by harvesting fallen sticks and off-cut wood from the
workshop, they could use zero cord-wood.
If you want fast heat, smaller sticks burn faster. Alexandra says that's because the ratio of surface area to mass is higher. Steven comments about sawdust though, a pile of sawdust won't burn, you have to sprinkle it on an existing fire.
Paul asks how much time Alexandra spends messing with the RMH, she guesses at 10-15 mins per hour burnt. Paul thinks with his level of
experience he spends about that much time per day. Paul translates the time into hours per month and equates that to pay, it costs less than paying other people to supply gas or electricity.
Alexandra comments that beginners seem to think you have to shove the sticks into the burn tunnel and that hurts the efficiency, the burn tunnel needs to be clear so turbulence can happen and mix the exhaust gases to aid a complete burn. Paul says the burn tunnel is also not built to take that, and could be damaged.
Relevant Threads
Rocket Mass Heater forum
All about SKIP, PEP, Badges, BBs and More!
Operate a RMH for One Month - PEP BB rocket.wood.month
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