My home has a geothermal heatpump that is about 2.5 years old. The
heat pump cannot keep up when it gets too hot out. I live in
Tennessee, and the temperature was in the high 80s and low 90s for
significant portions of this past summer. During those times, my whole
house heats up to around 6-8 degrees higher than I've got the
thermostat set, and the heat pump runs constantly. Needless to say,
this jacks up my power bills, and that kind of defeats the purpose of
having the geothermal heatpump in the first place.

I've talked with the contractor that installed the heat pump, and they
insist that it is the right size for my house. But they say that it
just won't be able to keep up when it gets that hot. honestly, this
seems like BS to me, it seems to me that either the heat pump can keep
up, or it is undersized.

Anyway, I wonder if anybody has suggestions for how to improve the
situation. Is there any kind of supplemental system that can be used
with a geothermal heat pump, something along the lines of the aux heat
coils that standard heat pumps use when it gets too cold?

With a geothermal installed properly though, that is with the coils at
least 4 feet underground (deeper in some areas and the proper length), you
should not have any problems as at that depth the ground should be a
constant 45 degrees or so, optimal for a heat pump to heat and cool.

If you have a geothermal heat pump, my guess is that the coils weren't
installed properly, in which case if you have a warrenty you should be
able to go back on the contractor and get it fixed.

you may have blockge or pinching of one of the lines. My brother
installed one for his house and he trenched 6' down and about 2250' of
line in 3 sections. and still could use more. you have to remember that
since it transfers heat, if the ground is too hot at the deapth in
question then you don't transfer much.

Empress2454 #124457


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dblho39 wrote:
My home has a geothermal heatpump that is about 2.5 years old. The
heat pump cannot keep up when it gets too hot out. I live in
Tennessee, and the temperature was in the high 80s and low 90s for
significant portions of this past summer. During those times, my whole
house heats up to around 6-8 degrees higher than I've got the
thermostat set, and the heat pump runs constantly. Needless to say,
this jacks up my power bills, and that kind of defeats the purpose of
having the geothermal heatpump in the first place.

I've talked with the contractor that installed the heat pump, and they
insist that it is the right size for my house. But they say that it
just won't be able to keep up when it gets that hot. honestly, this
seems like BS to me, it seems to me that either the heat pump can keep
up, or it is undersized.

Anyway, I wonder if anybody has suggestions for how to improve the
situation. Is there any kind of supplemental system that can be used
with a geothermal heat pump, something along the lines of the aux heat
coils that standard heat pumps use when it gets too cold?

DragonKnight wrote:
With a geothermal installed properly though, that is with the coils at
least 4 feet underground (deeper in some areas and the proper length), you
should not have any problems as at that depth the ground should be a
constant 45 degrees or so, optimal for a heat pump to heat and cool.

More like 55F at best at 6' or deeper...

If you have a geothermal heat pump, my guess is that the coils weren't
installed properly, in which case if you have a warrenty you should be
able to go back on the contractor and get it fixed.

I'm guessing it's more than likely the heat load analysis wasn't done
well (as in accurately) and the unit actually is lacking in transfer
area. It is possible they also buried them too shallowly, of course,
but more likely is simply not enough area and possibly a too-small unit
as well.

One way to guesstimate would be whether it is adequate heating from the
ground loop source during really cold weather or does it also require
the "emergency" heat a lot? In that case, I'd say it's clearly
under-powered, so to speak.

I'd first go to the manufacturer if the local installer isn't being
cooperative/helpful and ask for an evaluation. I had a Water Furnace
unit in E TN and it was quite capable in the hottest weather and we
never had the strip heating come on except for the one night Knoxville
reached -24F! It handled even the near-zero nights adequately. Water
Furnace is very good in their support of their selected
dealers/installers and (at least at that time) were pretty selective in
who represented them. I don't know whether they're still as good or
whether any other is (or was) as good.

I would also include the complaints in a written, documented form to
both the dealer and the manufacturer, not just rely on telephone/verbal
communications. This will help to establish the longevity of the
problem at least from this point on although sooner would have been
better, obviously.

dblho39 wrote:
My home has a geothermal heatpump that is about 2.5 years old. ...

In addition in to other note...was the put in for you or for a previous
owner? If not, can you find out from the previous owner whether it was
satisfactory during a previous summer indicating there's been a change
in function or was weak to start with?

The installer should be able to compare measurements of flow and loop
temperatures with those after initial installation as well in order to
confirm operation. These should match manufacturer's spec's for the
unit if properly sized/installed.

Other alternatives as well include a possibility of circulation pump or
the "ordinary" heat pump problems--low charge, dirty exchanger, dirt
filters, etc., etc. All these diagnostics and maintenance items should
also be checked and taken care of.

Anyway, I wonder if anybody has suggestions for how to improve the
situation. Is there any kind of supplemental system that can be used
with a geothermal heat pump, something along the lines of the aux heat
coils that standard heat pumps use when it gets too cold?

Of course one could add additional cooling but I'd certainly want to
eliminate the possible problems with the system first. As noted in the
other thread, had the Water Furnace unit in E TN and was absolutely
great so it _can_ work, but also as noted in the other note will need
support from the dealer/manufacturer to find out the "why" in the
present system and then decide what to do.

A simple test. Air conditioner outlet air should be about 20 degrees colder
than input air. If system is dropping the air temp this much and your house
is too warm then it is undersized. If not then it has a problem.

"dblho39" wrote in message
oups.com...
My home has a geothermal heatpump that is about 2.5 years old. The
heat pump cannot keep up when it gets too hot out. I live in
Tennessee, and the temperature was in the high 80s and low 90s for
significant portions of this past summer. During those times, my whole
house heats up to around 6-8 degrees higher than I've got the
thermostat set, and the heat pump runs constantly. Needless to say,
this jacks up my power bills, and that kind of defeats the purpose of
having the geothermal heatpump in the first place.

I've talked with the contractor that installed the heat pump, and they
insist that it is the right size for my house. But they say that it
just won't be able to keep up when it gets that hot. honestly, this
seems like BS to me, it seems to me that either the heat pump can keep
up, or it is undersized.

Anyway, I wonder if anybody has suggestions for how to improve the
situation. Is there any kind of supplemental system that can be used
with a geothermal heat pump, something along the lines of the aux heat
coils that standard heat pumps use when it gets too cold?

Geothermal heatpumps do MUCH better at keeping houses cool than heating
them up. After all, what we ask of them is to cool down from 90s to
low to mid 70s, only a 15 to 20 degree temp difference.

Consider someone inQuebec who gets enough heat from their geothermal
heat pump to keep the house comfy unless the air temp goes to -20F and
stays there for several days in a row. That's at least a 70F rise JUST
to get to 50F, and a 90F rise just to get to 70F, and the heat pump will
do this but not for stretches longer than about 72 hours.

So, you most likely have a poorly installed ground loop, or an
insufficient ground loop.

Go put a digital thermometer on the return line from the ground
loop. If the temp is running near 120F or higher, you need more
ground loop.

The rough rule of thumb is 600 sq feet of floor space for each ton of
capacity. 3 tons, 1800 sq foot home,4 tons 2400 sq ft.......

You also need to tell us how big your unit is,and how many feet of
ground loop you have, and whether the ground loop is horizontal or vertical.

ground temps at 6 feet show several degrees of temperature variation
seasonally. Deeper,say below 20 feet
and there is nearly no temp variation in the soil from month to month.

I am in a heavily cooling dominated climate.The AC will run a few days
EVERY month of the year. My HVAC contractor says 720 feet of Vertical
tubing (300ft deep wells) per ton of installed capacity, and he does
LOTS of these each year. A horizontal loop needs to be longer than a
vertical one as the ground temp does fluctuate more at the 6ft depth
typical for ground loops. Rough rule of thumb says 33% to 50% more
tubing per ton for horizontal loops.


wrote:
you may have blockge or pinching of one of the lines. My brother
installed one for his house and he trenched 6' down and about 2250' of
line in 3 sections. and still could use more. you have to remember that
since it transfers heat, if the ground is too hot at the deapth in
question then you don't transfer much.

Empress2454 #124457


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dblho39 wrote:

My home has a geothermal heatpump that is about 2.5 years old. The
heat pump cannot keep up when it gets too hot out. I live in
Tennessee, and the temperature was in the high 80s and low 90s for
significant portions of this past summer. During those times, my whole
house heats up to around 6-8 degrees higher than I've got the
thermostat set, and the heat pump runs constantly. Needless to say,
this jacks up my power bills, and that kind of defeats the purpose of
having the geothermal heatpump in the first place.

I've talked with the contractor that installed the heat pump, and they
insist that it is the right size for my house. But they say that it
just won't be able to keep up when it gets that hot. honestly, this
seems like BS to me, it seems to me that either the heat pump can keep
up, or it is undersized.

Anyway, I wonder if anybody has suggestions for how to improve the
situation. Is there any kind of supplemental system that can be used
with a geothermal heat pump, something along the lines of the aux heat
coils that standard heat pumps use when it gets too cold?

dblho39 wrote:
My home has a geothermal heatpump that is about 2.5 years old. The
heat pump cannot keep up when it gets too hot out. I live in
Tennessee, and the temperature was in the high 80s and low 90s for
significant portions of this past summer. During those times, my whole
house heats up to around 6-8 degrees higher than I've got the
thermostat set, and the heat pump runs constantly. Needless to say,
this jacks up my power bills, and that kind of defeats the purpose of
having the geothermal heatpump in the first place.

I've talked with the contractor that installed the heat pump, and they
insist that it is the right size for my house. But they say that it
just won't be able to keep up when it gets that hot. honestly, this
seems like BS to me, it seems to me that either the heat pump can keep
up, or it is undersized.

Anyway, I wonder if anybody has suggestions for how to improve the
situation. Is there any kind of supplemental system that can be used
with a geothermal heat pump, something along the lines of the aux heat
coils that standard heat pumps use when it gets too cold?


Doubtful that it is an undersized or underperforming loop as the ghp
just won't operate without sufficienct loop capacity for it's size once
it is in extreme temps.

As others have mentioned here, it sounds like the system may have been
undersized for the home. Did the contractor do a heat loss/gain
calculation before quoting the system? Did he do an energy analysis
showing what the run times and capacity of the ghp would be at both the
high and low temps? He should have.

Were there any improvements to the home that were agreed on prior to
the installation that you haven't yet made (insulation, caulking, etc.)?