Hello all -
I'm looking at homes in Central Pennsylvania.
A new one I will be checking out has the following:
R-49 insulation, geo-thermal heating, solar panels.
How does geothermal heating work, vis-a-vis a "standard" hot
air or hot water heat system? Do they actually save any
money in heating costs?
These may look attractive when new, but what are the
long-term maintenance costs?
Your using the ground as a sink.
I thought about what if, after I had gas/air installed. If its installed,
the big cost of digging or drilling is already done. All you got now is a
Heatpump. These are likely to last as long as other air conditioners. Is it
brand new ? I'm sure you will save money, but talk of increasing rates near
If initial cost is not a concern it is very worthwhile for the long
term. It'll do both heating/cooling. In the 78's I looked at it when
I was building my third house, bakj them I was looking at 25K for a
typical residential house. I now think cost increased but also
Like any other HVAC system, that will mostly depend on the type of
system and even more importantly on the quality of the installation.
Well disposal system can expect more than a closed ground loop simply
owing to there being another component (a well).
I had a Water Furnace (manufacturer brand) closed loop installed in E TN
about 20 yr ago. AFAIK (sold house about 10-12 yr ago now) it is still
operating as well as was when left w/ no issues since last talked to new
owner about 3-4 yr ago.
It cut our electric bill compared to the air-air unit it replaced by at
In theory, geothermal heating (or cooling) pre-heats (or cools) the air to
the temperature of the earth underground - usually about 56F. So, if the
ambient temperature is, say, freezing, the air gets raised to 56F before
regular heating kicks in.
That is not how it works. Geothermal uses a HEAT PUMP.
It's like a regular heat pump system, except that instead of
using outside air, it uses water from wells or a ground loop
providing around 50F constant temperature source year
round. That makes it low on operating costs, but given
the digging and installation involved, expensive on the initial
install. I've yet to see one that could be cost justified, absent
any unusual subsidies.
On the other hand, since it's already in a house he's considering
buying, it could be a good thing if he gets the
house at the right price and the system was correctly installed. I
saw one a while back on Holmes where they
had to install one all over again that was 3 years old because the
install was done all wrong, but hopefully that
is the exception.
On 9/26/2012 7:55 AM, email@example.com wrote:
That's the way I would feel. Also I may not consider it a plus over
other systems , that is would not pay extra for it. I have not
investigated but some options for example an in-ground pool does not add
to the value of a home. Just don't know about geothermal.
That all depends like all real estate on "location, location,
location"....in some local areas it would be killer to not have the pool
in most cases.
You think it's not an advantage to have a heating system that's from 30
to as much as perhaps 65% less expensive to operate than conventional
air-air heat pump in a northerly climate? Makes sense to me.... :(
Again, it'll depend on the various factors which weren't given/aren't
available but as I noted above the ground-loop system in E TN (which
isn't even very cold and has relatively low TVA electric rates) was a
clear winner cutting our operational costs by about 2/3rds.
I just don't know. Back in my short stint as a realtor quite a while
back I had seen lists of home improvements and what a homeowner might
expect to get back when he sold the house. I just picked the pool out
of thin air as remembering it was a zero option around here. I'm saying
I would not consider paying more for the house with this option.
Methinks that's short-sighted attitude; things are different w/ energy
costs these days and are likely to only get more so.
It's probably not a huge difference either way; the incremental cost of
installation (assuming ground loop) is generally much less if it was
part of new construction vis a vis a retrofit as our was since the dirt
work can in all likelihood be accomplished in conjunction w/
foundation/basement/etc. rather than necessitating a separate
exacavation period. Other than that, there's very little difference
between the systems and the ground loop is in many ways simpler as the
reject heat side is simply one small circ pump...
It's a feature in my book and suspect it's getting to be more so
generically all the time and will only become even more of a feature w/
I generally agree that a geothermal system is probably an
advantage to a house. But it also would depend on where
the house is located climate wise and the cost of electricity
there versus alternate fuels. Here in NJ with electric at 18c
it may not look as good compared to nat gas as someplace
where it's 10c.
And the age of the system and the replacement cost. I know
a lot of the big cost is the outside part, but I wonder how much
replacement of just the inside heat pump part costs as compared
to replacing a gas furnace/AC unit?
On 9/26/2012 3:39 PM, firstname.lastname@example.org wrote:
Well, of course, but the choice here isn't against competing systems for
a new install; it's already in. Unless it was a case of a demo house or
the like one would presume at least some of those considerations went
into the choice.
Well, that's true for any system, whatever the type. Have you priced a
hi-eff gas system recently? :) You also get "free" A/C w/ the heat
pump--don't forget to add in the cost there in the replacement as well.
And, if the A/C is used, many have the option of using the waste heat
there for water heating that is another input energy cost reducer. In
TN for the entire summer months and much of spring and well into fall
the water heating was essentially free. Obviously that's not as big a
deal as one gets more and more into more temperate climates so I'd not
expect a unit in PA to have it.
I'm not saying it's always going to be the best possible choice or that
even in this case it's a real plus but I'd surely think odds are it's a
positive as opposed to run-of-the-mill furnace you'd find in the average
house on the block for sale.
All in all, though, after my experience, I'm sold on the concept...
A few things to keep in mind:
- Heat pumps in general are pretty efficient these days, and of course
provide both heating and cooling.
- In heating mode, an air source heat pump becomes inefficient as the
air temperature nears the freezing point. Ground source heat pumps don't
have this limitation since soil temperatures at the loop depth don't get
- In cooling mode, an air source heat pump becomes inefficient when the
air temperature gets above a certain point and the heat pump has
difficulty dumping the heat it's moving into the air. Ground source heat
pumps don't have this limitation since soil temperatures at the loop
depth don't get that warm.
- Early ground source heat pumps relied on deep drilled wells or
vertical loops or sometimes very long horizontal loops. More recent
research has shown that these installation methods are not needed since
the ground has a tremendous thermal mass. The new installation method is
trenched vertical coil, where a large Ditch-Witch type trencher cuts a
trench and the plastic tubing installed in a vertically oriented
overlapping coil configuration. This takes far less installation space
and less expensive installation equipment. Installers that are heavily
invested in other technologies like drill rigs may try to persuade you
to spend more for their method, but the scientific data show there is no
benefit to the older methods.
- A loop is a loop is a loop, so in the event the heat pump needs to be
replaced due to failure or to a higher efficiency model, it can be
connected to the existing ground loop and thus have minimal installation
costs. In the event the house is added on to and more capacity is
needed, the existing ground loop may be large enough to accommodate a
larger heat pump, or additional ground loop may be added to the system
without the need to "throw away" the existing loop.
So, in PA, absolutely a ground source heat pump is a positive,
especially if nat gas service is not available in the area and thus
another relatively inexpensive heating option is not available.
That depends on your definition of inefficient. In a thermodynamic
sense today's heat pumps deliver more heat output even in the
single digits than an equivalent electric resistance heater, which is
100% efficient. At 32F they are probably delivering at least 2.5 X
of a resistance heater. The total output decreases as well, which
is a potentially bigger problem.
Whatever temp that occurs at, it's apparenty not a problem in a
practical sense because AC works OK at 110F in Arizona.
It's been over 30 years, but I remember people talking how it cost them per
month for refrigerated air. Hundreds of dollars. What does it cost now in
the desert ?
It costs me roughly $25 a month in Pittsburgh. I know the units are a lot
Possibly, but others have mentioned "a heat pump is a heat pump"...
The current thinking at least in my area is to use wells with loops of
tubing dropped in them because the heat you can get from burying the
tubing in soil isn't enough for a typical installation (normal size
I am in PA know a few savvy people who could not get natural gas and ran
the numbers and put in a ground source heat pump.
Trenched vertical coil installation is effective on even small sub acre
properties. If you compare wells to old style single tube long run
horizontal installations certainly those obsolete horizontal
installations required a lot of space. The TVC with it's overlapping
coils puts that same loop length in a much smaller physical area which
has more than enough thermal capacity unless it's a very dry soil with
very poor thermal conductivity.
They are a good investment in northern climates, particularly with the
less expensive TVC installation method which reduced the cost
differential from other options.
Here in N. TX the climate is moderate enough that an air source heat
pump works well. There are few winter days when the HP has to switch to
backup heating, and in the summer there aren't many days when it's hot
enough to have issues.
The discussion was about how attractive a geothermal
system would be to a potential buyer. The relative costs
of generating heat from geothermal via electric as opposed
to a system using natural gas are directly relevant. If
the geothermal house can be heated for $1000 a year,
while using nat gas in a similar house would cost $2000,
then it's an advantage. If it's the other way around, then
it's a disadvantage.
The specific issue I raised is what the replacement cost
of a geothermal system is. I'm very familiar with what the
replacement cost of a nat gas/AC system is. I have no
idea what the cost of replacing the geothermal eqpt is.
I'm suggesting that it might be a good idea to find that out.
If it costs 2X, then that should be factored in together with it's age
when considering if it's an advantage or not.
As for natural gas and AC, I think they are remarkably
cheap for what you get. I bought a 120K BTU gas
furnace and 5 ton AC for $4500 two years ago.
You also get "free" A/C w/ the heat
On 9/27/2012 8:31 AM, email@example.com wrote:
I believe that's what I just outlined above--you (or others, I forget
where in the thread all the sidebars on repair costs and all was
actually introduced altho it may have been earlier) brought in the other
factors and I simply added some points in those areas to consider...
On operating cost alone I don't think there's any way you'll find a
cheaper source long-term...natural gas or no even given the present
abnormally low n-gas pricing (that isn't going to last).
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