questions about a rocket mass heater.

 some day i will build a smaller home  1200 sq feet with  a loft . im looking for a base idea for a mass heater im thinking about a front load with a small door so i could get bigger pieces burning, would a 6 inch system work good? how many feet of duct to get the most heat?

i kinda worry about using a barrel with the high heat? is there a more heavy duty idea out there?

one idea i had was to put a watertank in the cob with a pressure valve to supply my hot water tank whats your thoughts on that?

what is the plan when your duct needs to be replaced tear up the cob and rebuild?

The barrel does get mighty hot with intense heat at the peak of the burn. In a properly built rocket that poses no barrel longevity issues. Some folks have replaced their barrels at the 20 year mark as part of general maintenance, only to find the old barrel in perfect condition.

If you're in a rather cold climate where you can have a fire every day, and if your new place is to be highly insulated (i.e. R38 ceiling, R22 or greater in the walls; US R-values) then a full masonry bell style stove may be an attractive option to consider. For some ideas check out the 6" batch-box all masonry designs on Peter van den Berg's site:

Batch Rocket Masonry Bell Heater

byron not sure what a bell style is? what about welding a steel plate on the top of the barrel? what size barrel for a 6 inch system? and whats peters sight?

im thinking about a batch box style for sure if people will help guide me to a long lasting safe rocket mass heater:)

mike kline wrote:whats peters sight?

Click on the link (blue text) provided in my post above, and it will take you to Peter's site.

Batchrocket.eu (where the link above leads) is Peter van den Berg's site.

The bell design is described there; basically, it is a big brick box which the hot combustion gases flow into. The hottest rise to the top, give their heat to the masonry, cool, and fall to the bottom where the exhaust to the chimney is.

The site has all the dimension and construction details you need, which you can adapt to the layout of your particular space.

thank you Byron:)

thank you Glenn:)