while listening (enjoying) the 2nd 'innovators event' podcast, i heard all agree to Paul's statement that a vertical chimney is about 2.5 times more effective than the heat riser, in terms of pump-power.
reading through this post (
https://permies.com/t/27052/rocket-stoves/external-chimney-RMH), i can also refer you to Peter's quote of: "Make the chimney taller. Double hight of the heat riser (and barrel) gives approx. double pumping power."
also from the same post, also from the same Peter: "As long as the temperature inside the heat riser is much higher than in the space between the insulation and the inner surface of the barrel, the pump
should work. So the exhaust gases can be cooled down to any temperature without affecting the function of the RMH."
i will be piping my 8"
RMH into an existing, 35ft chimney. if the above is true, and an 8" system gives me 50' run of horizontal ducting (incl. 5ft per elbow) through the mass... do i then have at least (a theoretical) 100' of additional run to play with? or is this outrageously simplified?
provided my exhaust is above the condensation-point of 122 degrees f, and the chimney flue is warmer than the outdoor ambient temp, can i add another 'run'? though, what i have in mind is not more horizontal ducting.
what i do have in mind is if i can seal-off the fireplace and make 2nd bell in there? or, preferably, a plunger-tube within the sealed fireplace?
i would like to keep that hot air (above 130f) in-house as long as possible, in contact with mass for as long as possible.
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