[Strawbale] PEX tubing in floors

[activism98201 at verizon.net]

I recall picking up Lauren Corrie's idea of using water storage aloft (in the form of liter bottles), though I haven't done anything with it; I did scratch up a design incorporating it.  I'm not sure if he actually built such a system.  There's always an issue of pumping (or pulling) hot/warm from above and circulating it down; it's always a trick to reverse stratification (or rather destratify).

In Shody's location there's an issue of continuous days of no real sun (coupled with chilly temps AND moisture).  This is really tough for any single solution system to deal with.  Heat pumps/geothermal systems might be the only real solutions, though, as pointed out, you've got to be sure to scale them appropriately (same can be said of any system, though others might be a bit easier to resize).

But if you're putting in a concrete slab it's of little cost to go ahead and put in the PEX in case you find that you do want to do hydronic some time in the future.


-Mark Nagel
Everett, WA


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From: David Neeley <dbneeley at gmail.com>

Shody,

"It seems to me if water is the best thermal storage
medium, and it could be charged with solar energy
almost daily and discharge with (from?) energy almost
nightly, wouldn't that be all the heating and cooling
that would be needed and then some? wouldn't that be
the least expensive and most efficient eco friendly
system? "

No, it would definitely *not* be the least expensive nor the most eco
friendly.

Put up a sunspace on that South/SW exposure--a low mass enclosed porch,
essentially, with operable vents into the house proper. That will direct
substantial amounts of solar warmth into the house during the colder
periods--even with the overcasts you get.

Laren Corie, a solar designer since the 1970s, lives and works in a far more
challenging climate than you do--the Upper Michigan peninsula. That is as
bad a location as anywhere in the continental U.S. for solar design--and he
is able to design houses that need no auxiliary heating at all. He uses such
a sunspace regularly, often combined with water storage in the attic (often
in 2-liter PET soda bottles, in fact) to store excess heat during the day to
release it at night into the house below. Sign up for his LittleHouses Yahoo
group and look through the files section as well as his website for more
info.

Of course, you *must* do what you can to reduce the demand to begin
with--adequate sealing and insulation will help both in cooling and heating
modes.

The size heat pump you would need is conditioned upon the energy demands of
the house. Unless you have had a good calculation run, I daresay you do not
yet know what size is appropriate. With any mechanical system, getting the
size right is absolutely critical. You lose by being either too small or too
big.

A PEX system would be somewhat redundant if you're going to put in a heat
pump, by the way. Put your money into a geothermal system if you go to all
the trouble of a heat pump, assuming the size is appropriate for what you
intend.

A catchwater system would be a good touch, and needn't be all that expensive
if you do it right. However, "cold and hot water storage" would be
excessive, I think. For one thing, your area may have a bit too much
overcast to take real advantage of a solar collector in winter. For another,
if you *do* go with a heat pump, as I have tried to explain a desuperheater
makes a real alternative for you for your water heating needs.

As for heating floors and cooling the air--the question I would have is
*why?* Working against yourself in this manner would be useless. Get the
house comfortable to begin with, and make it so you need to neither.

David

[snip]