Hi, just trying to make sure I understand how this works before getting my hands dirty!
I've read the book. Listened to the loooong podcast. Looked at tons of videos. Studied Erica and Ernie's photos. Read many threads here. Now I need to know if I've got a grasp of the basics. So:
The
RMH has the chimney (AKA riser) next to the
feed tube so the flames go up the riser and heat it. The riser MUST be insulated to hold the heat in. Then the hot gases rise to the top of the riser and go down the outside of it, but inside the barrel. The gases MUST cool fairly rapidly in order to keep the draft going and prevent back draft. The top of the barrel gets very hot and this is a good spot for a large pot of
water. The sides of the barrel near the top are very hot and it cools off as you go down the outside. This warms your space right away which is needed since most of us won't think to build a fire until we are uncomfortably cool. The remaining heat, what would be wasted in a conventional
wood stove, moves from inside the barrel into the ductwork under the bed mass. Once the bed mass is warm it stays warm for many hours and you can sit or lay on it for a comfortable warmth.
It is critical to have your cross sectional area in the ducts and the entire run of the gasses to be the same as the cross sectional area of the riser. This is what gives the rocket effect and burns all the volatiles from the
wood. You cannot have too large a cross section on your air intake without getting burn back (flames traveling back up the fuel). The J tube feed allows the fuel to continually move into the hot area and burn without needing constant adjustment. You need the bottom of the barrel removed and you need a barrel with a lid that fits tightly, but can be removed so you can occasionally clean out fly
ash. The fly ash will compromise your cross sectional area and reduce the rocket effect and you will then have smoke coming out the exhaust.
(Can't build it till I move, but learning all I can and will order plans so I don't have to do all that figuring. Don't want to have to pull it all out and start over either.)