Re: Liveable temp/ geothermal
From: John Faust (wjfaustgmail.com)
Date: Fri, 25 Jan 2008 16:10:19 -0800 (PST)
"... whereas I don't think there's any such thing as a climate that's too
hot for geothermal to be cost-effective."

There probably isn't one that is too hot but I'm not sure ours isn't too
dry. The Southwest deserts have water tables that are pretty deep and lots
of dry earth from the surface down. We would like to use geothermal (when we
eventually build) but the experience, I'm familiar with here in Arizona,
suggests it won't be effective. Apparently the dry soils around closed,
bore-hole type systems can't transfer the heat well enough to make it
practical. *Is there anyone else living in a similar desert environment that
has had a different experience?* My expertise is limited to what I've
gleaned from the Internet and one phone conversation with someone in
Phoenix.

John

On Jan 25, 2008 1:39 PM, <katie-henry [at] att.net> wrote:

>
> Chiming in from Eastern Village, and following up on Sharon's message. EVC
> had the same developer as TVC, and he evidently learned his lesson about low
> bidders because he went with the most expensive but most respected and
> experienced contractor in the DC area, and we have an excellent system to
> show for it.
>
> As Sharon explained, in contrast to the TVC system, where each unit's heat
> pump is connected to a specific well, our wells (40 of them, each 600 feet
> deep) are all tied together and the water is circulated throughout the
> building by a large central pump. There is an additional small pump that
> injects water into the system to maintain pressure to compensate for normal
> water loss or a leak.
>
> Our heat pumps are from Florida Heat Pump. We're pretty satisfied with
> them. I don't have experience with other equipment, so can't compare. I
> think the equipment is a bit noisy. There is no question that it is a more
> comfortable form of heat and AC.
>
> Our developer bought an extended warranty (two years instead of one) on
> all of our mechanical equipment, which turned out to be a very good move.
> Most of our equipment failures took place during the second year, including
> a circuit board in the variable-speed pump controller that blew up because
> of a power outage and would have cost about $10,000 to replace.
>
> We find our unit electric bills to be half or less compared to similar
> units in the multi-family building next door -- and they are doing
> everything humanly possible to reduce electricity usage, especially in
> summer, while we crank it up with gay abandon. We also benefit from our
> concrete bunker construction. Some of our surrounded units never have the
> heat come on at all in winter, even when the outside temp is below freezing.
>
> However, our maintenance and repair contract for the central circulating
> pump and the 16 CH heat pumps is with the very expensive specialist
> contractor who installed the equipment, and the cost gets passed on to the
> members in our HOA fees, so sometimes I wonder if we are really coming out
> ahead.
>
> As Robin pointed out, having geothermal means you don't need compressors.
> At EVC, if we had conventional split HVAC systems, we would have close to
> 100 compressors churning away on the roof. Instead, we have a nice peaceful
> green roof with a gazebo and a playground.
>
> One other point from our service guy: Geothermal systems are less
> efficient in winter than in summer. We definitely see that in our electric
> bills. We had an extreme cold spell last February or March and our CH
> electric bill spiked from about $2,400 to $3,500 because the emergency
> backup electric heat was kicking in. You don't see a lot of geothermal
> systems up north in cold climates because the cost of supplemental heating
> in winter outweighs the savings in summer, whereas I don't think there's any
> such thing as a climate that's too hot for geothermal to be cost-effective.
>
> Katie
> Eastern Village
> Silver Spring, MD
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