[Strawbale] [SB-r-us] Radiant energy and Law of Inverse Squares (was Re: Forced air)

[David Neeley]

Rob,

You're giving an unnecessarily bad rap to the ground source heat pumps.

It is true that most early ones were open--they took in groundwater, added
or removed heat to/from it, then discharged it. These were fraught with
problems, especially where the groundwater was high in mineral content.

Today, a much more popular option is a closed loop system using flexible
piping with water or a coolant circulating in it, which is either in a
series of trenches or into and out of a couple of wells drilled into the
ground...depending upon the location and its characteristics.

The result is the most efficient and long-lasting mechanical HVAC system you
can buy today, assuming you're in a location with suitable soil conditions.

That said, the colder the average soil temperature is in your latitude, the
less heat there is to pull from it to provide winter heating. You'll have to
find out from the suppliers whether your locale is a suitable location for
one of these systems.

Here in the Dallas area, the soil is nearly ideal for the purpose and the
average ground temperature is within the comfort zone (low 60s Fahrenheit).

Several companies are making these units, and at least one (from
Waterfurnace) has an EER of 30, at least 50% higher than that of the most
efficient air-to-air heat pump. In addition, these units are likely to last
more than 20 years before having to be replaced--much longer than the other
kinds of units.

David

On Jan 8, 2008 5:16 PM, Robert Tom <archilogic at yahoo.ca> wrote:

>
>
> And about cooling and that ground-sourced heat pump ... maybe it'd be
> simpler and more reliable to just dig a deep hole in the ground, put a
> thick, well-insulated lid on it, hop in and call it "home" ?
>
> (Most of the ground-sourced heat pumps that I've encountered in my
> neighbourhood (or more correctly, the owners of those GSHP systems)
> reported failures of the heat exchangers, usually within 3 years, at $2000
> - $10,000 a pop to replace the HX, leading one of the afore-mentioned
> owners to rip out the GSHP in disgust after the 3rd failure, offering it
> for free to anyone who wanted it.)