>     Firstly was the design of a water filled heater box. I am going to
>     buy one bare J-tube (cost about 7 quid) this weekend. Basically it's
>     a heater box exhaust tube - without the heater box shroud and fins.
>     I am going to weld a water tight tube around this J-tube as below:
>
>     J tube \ ___
>             /               water tight tube
>       out__|_____________ /
>             \_|__________|___
>               |__________|_
>                             in
>

This sounds like a pretty good idea to me! My concerns would be: 1) the system
must have an expansion tank since it's a closed loop, and 2) there must be
some sort of relief valve (like on any heating vessel) in case your water pump
fails or your expansion tank isn't big enough. I think that you did mention
some sort of tank to let off steam. If that includes a relief valve, you'll be
in good shape.

Later. . . . .Brad
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Brad Snyder | Lehigh U.: bls3@Lehigh.EDU | BBS, the First Floor: (610) 760-0527
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