I'm using my air-cooled steel RMH with integral mass of sand as well as an external mass of rock and sand for its first season of home heating. Just wondering what sort of temps are ideal for maintaining heat in a mass for daily use?
All anyone can say is "hot enough to keep the space comfortable yet not too hot for safety near combustibles or people". You will have to find out by experience how much to burn for the weather expected.
Location: S. Ontario, Canada
posted 3 years ago
I guess that's what I was already doing but wondered if there was any "rule of thumb" so to speak.
since you are a fellow "Ontarian", did you get snow last night? i got over an inch of snow here where i live last night! good thing your RMH is working.
if i had a nice mass like that, i would probably like it to be maintained around 90-95 F if possible, but im sure temps would drop eventually when not in use. i sure would not want it to drop below room temperature, but i guess that is obvious. i would guess it would be nice to have the mass between 75-95F, but if youre cold, and if the mass is in a safe fire-proof area, lets say cement floor and brick walls, im sure if could go even hotter than 100F in a safe place away from combustables.
im curious, do you often sit on the mass? does it get too hot or uncomforftable? how is the radiation from the bell? what size (diameter) is your final exhaust? is there steel in the burn chamber flame path? i cannot remember from your last thread
We've had below freezing temps the last few nights and heavy frost but no snow yet!
My external mass has been between 70F and 95F since I started it up a few weeks ago. The integral mass has run between 150F and 90F. Yesterday I let it run longer than usual and got the external mass up to 115F-75F (Hottest and coolest spots) and the integral mass up to 300-130F. The house temp at that point was 77F and went down to 68F this morning. It's an old house with plaster and lath construction and basically no insulation at all between the studs!
To answer your questions....
So far we have not sat on the external mass but plan to cover it with a sheet of plywood and a cushion. No danger of combustion there! Until yesterday it was barely warm to the touch.
The radiation from the top of the bell (not enclosed in the integral mass of sand) can be felt a couple of yards away. That portion usually runs between 550F and 300F.
My system is basically a 6" diameter except for larger portions (a 15" diameter water tank and a length of 8" ductwork) within the external mass. The stovepipe to the chimney is 6".
My entire core is steel. While I know the flame path exceeds 1225F (as it consistently melts aluminum cans) the core is prevented from glowing red as it is not insulated but rather air-cooled and embedded in sand (a heat conductor). The hottest spots on the core are around the junction of the feed tube and burn tunnel where the oxygen is feeding combustion and radiation is most intense. The 1225F + flame path is measured inside the burn tube at the base of the heat riser.