dale hodgins wrote:
Here are some very useful figures for anyone who is trying to choose whether or not to include a water tank within an RMH. Cob weighs 95 pounds per cubic foot. Water weighs 62 pounds per cubic foot. The heat capacity of cob is .2 which is 1/5 that of water which has a capacity of 1.00 So supposing we want to build a RMH which occupies 100 ft.³ of space.
Dale Hodgins wrote: It is true that the cob bench could be heated to temperatures far beyond the boiling point of water. But in order to store the same amount of energy as water at 200°F, a cob bench would have to be heated to more than 650°F. This is not common practice and if it were it would result in lowered efficiency with higher exhaust temperatures and badly burned bums
Micky Ewing wrote:The idea of water for heat storage is intriguing. It complicates the heat exchange, since running ducting through a water tank will require that it all be water tight. Corrosion would be a more serious concern too.
jeff ramage wrote:Please..everyone...if you use water for thermal storage in any system, and it has the potential to get to boiling...please put a stack pipe to atmosphere.
And... connect all the high points in the system to the stack pipe.
one cup of water = 16,000 cups of steam = bada big boom, if trapped or not relieved.