[Strawbale] PEX tubing in floors

[David Neeley]

Shody,

Much depends upon where the house is. If most of your winter days are sunny,
for example, a solar panel for a hydronic system would indeed be very
efficient. A solar collector, after all, serves as a sort of heat pump in
moving heat energy from sunlight to the water, which further distributes it
as needed.

However, there are few areas with predominantly sunny winter days--and in
those, you simply *don't need* a heating system if you design the retrofit
intelligently.

No matter how cheap you can build it, *any* system that is not needed is by
definition *not* efficient!

Now, what would the purpose of "storing cold water" to use in cooling? With
a heat pump, the only one I can imagine would be to shift the time in which
the heat pump is running so you might take advantage of off-peak electric
rates. On the other hand, your system would be far different than the
typical packaged heat pump systems, which are designed to chill air and not
water.

What you are seeking, apparently, is referred to as a "heat pump chiller"
and they are around, only quite expensive.

A variation on the theme is an absorption chiller. These usually are a
phase-change unit that uses a fuel (typically natural gas) in its operation.
Again, these are around but *very* expensive. I do not know if you can find
one that is adequately small for your application, either.

Unless you have some reason for using a tank to cool water for later use in
cooling the house, I do not understand that it serves any purpose. In units
of the appropriate size for a single residence, I suspect you will find that
if you must go with a mechanical system that a straight heat pump will be
the most ideal.

With your three-story design, it may also be in the end most economical to
use a mini-split system. That would eliminate having to put in ductwork, and
you could have an inside unit on each floor (with up to two on one of the
floors) in a single unit if you wish.

If in your retrofit you put in a sunspace on the South side of the house,
you can also eliminate the need for a hydronic system--which would obviously
also be somewhat expensive to do in most retrofit situations.

What is most efficient often depends upon the nature of your problem. A
retrofit would not normally class as being particularly cost-efficient for a
hydronic installation--especially if you can with a little effort avoid
having to put in a heating unit at all.

David



On 5/1/07, Shody Ryon <qi4u at yahoo.com> wrote:
>
> Hi Rene,
> I am interested in very high efficiency heating and
> cooling. Perhaps, all things considered ($), a heat
> pump is the best choice. That seems to be the consesus
> so far, for a retro fit of a 3 story strucure. I am
> going to dig out the basment and replace the
> foundation, so I want to make sure I am not missing an
> oppertunity to install something under the basement
> floor that would make the heat pump more efficient, or
> obsolete.
> Is there an informative book about high mass thermal
> store and/or heat pumps and radiant floor heating? I
> have "solar water heating". I am interested on how
> things work, and how to make things as simple as
> possible in their daily operation and maintenance, but
> the theory that makes them work could be anything,
> even very complex or not.
> Perhaps I have been give all the info I need by the
> list? such as "get an energy audit". Having made it
> though the winter with minimal insulation and minimal
> heating in comfort, I think I only need a minimal
> system, so I am looking for super efficient low cost
> systems. Is there anyone who has tested a heat sink
> for cooling water and stored that cold water for
> cooling? If so, wouldn't that system require a
> fraction of the energy of a traditional heat pump? If
> not, is it because it is totally impractical (such as
> not working during a full moon)?
> Cheers,
> Shody
>
>
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