[Greenbuilding] in hot water

Nick Pyner npyner at tig.com.au
Thu Jul 5 22:26:41 CDT 2012


I've got strong doubts about this too. The word "gently" is quite fraught.
The only way I can see to "dump gently " is to do it slowly, and that looks
like a fatal mistake. This might not be so obvious at the storage tank, but
becomes rather glaring at the collector. There, the circulating medium looks
like a loop, irrespective of how it is treated at the tank. The efficiency
of the collector is maximised by running it as cold as possible. The only
way to achieve this is to circulate the medium as fast as practical, hence a
pumped sytem is preferabe over the simplicity and reliability of a
thermosiphon system. This does not sit well with gentle dumping at the tank.
I'm sure there are sensible limits, but I submit the ideal collector would
have the medium circulating so fast that the exit temperature is barely
above that at the inlet, no significant heat rise, yet, but all the
available energy has been totally extracted.

My own experience with grey water heat exchangers shows that flow rate is as
much a player as temperature difference. Clearly what is needed is as much
as possible of both but I am struggling to find out which is the most
important. In practical terms, I submit that, if you are short of
temperature difference, flow rate is a serious consideration. That is where
the kWh lie hidden.

Nick Pyner

Dee Why   NSW

-----Original Message-----
From: greenbuilding-bounces at lists.bioenergylists.org
[mailto:greenbuilding-bounces at lists.bioenergylists.org]On Behalf Of
Clarke Olsen

 pulling
from the bottom and dumping gently into the top, making a case for
stratification.





More information about the Greenbuilding mailing list