I have learned a lot about RMH on PERMIES.COM, built a couple of them myself and presently using an 16 cm system (yes, we live in a metric system here) at my 300+ years old, stone country house, which I visit 3-4 times a month.
After the four years of operating my RMH, I still get amazed how efficient it is. I also love the smokeless chimney, which does not need the services of a chimney-sweep anymore!
I have built brick and concrete bell-type heat storage mass. When starting the fire in a cold house with 5 deg C (41 deg F) inside, it takes over 2 hours before the exhaust pipe gets above the ambient room temperature, while the fire is burning at full blast! Btw, in the four years of operating my RMH, I have never experienced the exhaust pipe getting over 40 deg C (104 F).
Initially, I have experimented with various ways to preheat the chimney in order to overcome the cold plug and get the draft going. It was too much hassle for me, so I have installed an electric duct-fan in the chimney system, utilizing the airbrush principle, Now I just flip a switch and have an excellent draft from the very beginning. Very convenient, especially for someone, who needs several cold RMH starts every month.
Recently, I have discovered another easy way to have a sufficient draft in a cold RMH. I have installed an electric duct-fan to facilitate ventilation in the house by blowing fresh outside air in. This creates a positive pressure inside. (Basically the opposite way what the kitchen or bathroom fans do - sucking the stale air out of the house, while creating a negative pressure, messing up the chimney draft.)
I hope my experience will inspire fellow RMH users, especially in a cabin type of environment, where they need to start a cold RMH often.
Kare Macko
