Re: Re: Energy/heating/design issues
From: Jeffrey O. Hobson (
Date: Tue, 8 Nov 94 10:48 CST
I think this will be my last post to the list on this subject, unless
there's more than just Roger and I still interested (Roger, we can
communicate directly if no other cohousers are into it).

Roger Diggle wrote, in response to Ray Gasser:
>The second idea has to do with the possible necessity of using 8 boilers (one
>per unit) rather a single or a few larger boilers.
 . . . . 
>some of the most efficient boilers available these days are small ones.

For example, Mor-Flo makes the Polaris 34 and Polaris 50, two condensing
water heaters (34 and 50 gallons each), which are intended for combined
space/water heating use.  They have a 94% recovery efficiency, a 0.86 energy
factor, and a 100,000 Btu/hour recovery rate.

I don't know about, but would be interested in hearing about, efficient
small boilers.

Roger also wrote:
>The other possibility, depending on local codes, depends on the source of
>domestic hot water you will use.  It is possible, in many locales, to use
>domestic hot water directly for heating if the piping, the heat exchanger and
>pump all use materials acceptable in domestic hot water piping.  
In California, copper is perfectly acceptable for domestic and floor piping.
Polybutylene, long used in Europe, is preferable for floor piping (it is
often cheaper, always has a more stable price, and is easier to work with
than copper).  It is sometimes code-acceptable, without an intervening

Here in Davis, where codes are supposedly stricter than most of California,
our company recently was able to use polybutylene floor piping without a
heat exchanger - on a trial basis as part of a utility energy-efficiency
project.  I attribute that mostly to our ongoing relationship with the
building department, and an interest in supporting innovative work.  I would
guess you Ithaca folks would have a shot at convincing a building official
to go along with you.

Roger also wrote:
>a reasonable approach to initial installations might be to build "solar
 . . . . 
>In this regard, high on my list for hot water heating system preparation
>would be provision for adequate (large) indoor heat exchange design.  

Being a solar-fiend myself, I support these ideas, but I've never been sure
how to do it in practice, since the solar-ready installation seems to depend
on a prior knowledge of the particular solar design.  How do you pre-place
collector mounts if you don't know how many collectors, or what size, or
whether they'll be integral-collector storage, thermosiphon, or active
systems?  etc.  If you Ithaca folks do go ahead, or if Roger, you've heard
of folks who have done this, I'd love to hear about it.


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