I'm in the process of selecting a company to install a geothermal unit,

but we've received contradictory information. I'm hoping this group can

shed some light on the situation.


We've had 2 companies come out and give estimates with 2 more lined up.

Interestingly enough one company based the size of the unit on cooling
demands, while the other based the unit on heating demands. If we go
with cooling it will be equvilent to 3.5 tons, whereas heating is 5
tons. I"m not sure who to believe. Does anyone have any advice or
experience?


Jessica

Sorry, I left out some details. I live in Maryland, and would probably
go with backup electric heat.

wrote:

I'm in the process of selecting a company to install a geothermal unit,

but we've received contradictory information. I'm hoping this group can

shed some light on the situation.

We've had 2 companies come out and give estimates with 2 more lined up.

Interestingly enough one company based the size of the unit on cooling
demands, while the other based the unit on heating demands. If we go
with cooling it will be equvilent to 3.5 tons, whereas heating is 5
tons. I"m not sure who to believe. Does anyone have any advice or
experience?


Where are you located? Could judge better if had some idea of the
climate.

If there's a marked over/under-sizing on either side performance will
likely be less than satisfactory. I'd be particularly worried about
undersizing heating capacity in a cold climate, however, as if you don't
have sufficient capacity there you'll be forced to run on auxiliary
("emergency" in some nomenclature) heat for perhaps extended periods.
This will easily negate any hope of ever recovering the initial higher
installation cost by lower operational costs.

Had WaterFurnace installation in TN Valley--was very successful at
operational cost-effectiveness relative to air/air heat pump
conventional A/C unit. That area is, of course reasonably moderate both
summer and winter, w/ summer cooling demands normally just a little
higher than winter.

I'd get some more input...did the estimators run actual heat load
projections or were they simply "back of the envelope" estimations?
Authorized WaterFurnace installers have detailed estimating/sizing
programs. Other sources of information may be your local power
company--many have programs for cost share for energy-efficient
alternatives.

"Duane Bozarth" wrote in message
...
wrote:

I'm in the process of selecting a company to install a geothermal unit,

but we've received contradictory information. I'm hoping this group can

shed some light on the situation.

We've had 2 companies come out and give estimates with 2 more lined up.

Interestingly enough one company based the size of the unit on cooling
demands, while the other based the unit on heating demands. If we go
with cooling it will be equvilent to 3.5 tons, whereas heating is 5
tons. I"m not sure who to believe. Does anyone have any advice or
experience?


Where are you located? Could judge better if had some idea of the
climate.

If there's a marked over/under-sizing on either side performance will
likely be less than satisfactory. I'd be particularly worried about
undersizing heating capacity in a cold climate, however, as if you don't
have sufficient capacity there you'll be forced to run on auxiliary
("emergency" in some nomenclature) heat for perhaps extended periods.
This will easily negate any hope of ever recovering the initial higher
installation cost by lower operational costs.

Had WaterFurnace installation in TN Valley--was very successful at
operational cost-effectiveness relative to air/air heat pump
conventional A/C unit. That area is, of course reasonably moderate both
summer and winter, w/ summer cooling demands normally just a little
higher than winter.

I'd get some more input...did the estimators run actual heat load
projections or were they simply "back of the envelope" estimations?
Authorized WaterFurnace installers have detailed estimating/sizing
programs. Other sources of information may be your local power
company--many have programs for cost share for energy-efficient
alternatives.

Suggest ( in Maryland ) size for the heating load and go with a two stage
unit that has a variable speed blower.

And don't ever skimp on your ground loop sizing when putting in any geo
system.

--

SVL

Duane Bozarth wrote:
wrote:

I'm in the process of selecting a company to install a geothermal unit,

but we've received contradictory information. I'm hoping this group can

shed some light on the situation.

We've had 2 companies come out and give estimates with 2 more lined up.

Interestingly enough one company based the size of the unit on cooling
demands, while the other based the unit on heating demands. If we go
with cooling it will be equvilent to 3.5 tons, whereas heating is 5
tons. I"m not sure who to believe. Does anyone have any advice or
experience?


Where are you located? Could judge better if had some idea of the
climate.

If there's a marked over/under-sizing on either side performance will
likely be less than satisfactory. I'd be particularly worried about
undersizing heating capacity in a cold climate, however, as if you don't
have sufficient capacity there you'll be forced to run on auxiliary
("emergency" in some nomenclature) heat for perhaps extended periods.
This will easily negate any hope of ever recovering the initial higher
installation cost by lower operational costs.

Had WaterFurnace installation in TN Valley--was very successful at
operational cost-effectiveness relative to air/air heat pump
conventional A/C unit. That area is, of course reasonably moderate both
summer and winter, w/ summer cooling demands normally just a little
higher than winter.

I'd get some more input...did the estimators run actual heat load
projections or were they simply "back of the envelope" estimations?
Authorized WaterFurnace installers have detailed estimating/sizing
programs. Other sources of information may be your local power
company--many have programs for cost share for energy-efficient
alternatives.


I live in Southern Maryland, Waldorf (20601) to be exact. It's about
35 miles south of DC. Both companies are WaterFurnace Installers. THe
company that suggested we base the size on cooling load walked through
the whole house measuring windows, rooms, doors, and inspected the duct
system. He back and said we have 45,000 BTU for cooling and 95,000 BTU
for heating. If we put in a cooling load system, the threshold for
heating would be 27 degrees. Anything below that we would have to use
back up heat.

The second company walked through the house and looked at our current
system. He didn't measure anything. He is to call me this week to go
over his estimate... but told us we would install based on heat load.

wrote


I live in Southern Maryland, Waldorf (20601) to be exact. It's about
35 miles south of DC. Both companies are WaterFurnace Installers. THe
company that suggested we base the size on cooling load walked through
the whole house measuring windows, rooms, doors, and inspected the duct
system. He back and said we have 45,000 BTU for cooling and 95,000 BTU
for heating. If we put in a cooling load system, the threshold for
heating would be 27 degrees. Anything below that we would have to use
back up heat.

I work for a large HVAC company but they refuse to get into geothermal (I
still think they are missing the boat). I know of several companies that do.
Could I ask who the two companies are (that did your estimates)?

I'm in Gawd's Country (St. Mary's County)

;-]

I'd go with the first guy who sizes on cooling load, especially if you
have high summer humidity levels. Normally the backup heat will be
auxiliary heat. It will run IN ADDITION to the Water Furnace, NOT
instead of it. The operational cost of some strip heat usage should
not hurt too bad. With geothermal, the heating capacity won't degrade
with the weather. The first guy did the survey properly, I think you
will be happier with him AND his installation.

Stretch

Stretch wrote:

I'd go with the first guy who sizes on cooling load, especially if you
have high summer humidity levels. Normally the backup heat will be
auxiliary heat. It will run IN ADDITION to the Water Furnace, NOT
instead of it. The operational cost of some strip heat usage should
not hurt too bad. With geothermal, the heating capacity won't degrade
with the weather. The first guy did the survey properly, I think you
will be happier with him AND his installation.

If it's set up that way...the fella' that did the installation of ours
put an external thermocouple in addition to prevent them from cutting on
before about 25F...but even then, I don't think we ever had them come on
for any extensive period except once when it got to -20F (in Knoxville,
TN area, no less!). But it was sized for heat load, essentially. It
actually was a little large for the cooling load, but not so excessive
to be a real problem.

I recommend the WaterFurnace highly, btw, as long as the installer is
really experienced...cut operating cost to nearly a third of what the
air-to-air heat pump had been--of course, it was an old, cheap unit.

According to :

I live in Southern Maryland, Waldorf (20601) to be exact. It's about
35 miles south of DC. Both companies are WaterFurnace Installers. THe
company that suggested we base the size on cooling load walked through
the whole house measuring windows, rooms, doors, and inspected the duct
system. He back and said we have 45,000 BTU for cooling and 95,000 BTU
for heating. If we put in a cooling load system, the threshold for
heating would be 27 degrees. Anything below that we would have to use
back up heat.

We're in southernish Ontario (Ottawa). The one Geothermal dealer we spoke to
(there may only be one in our area ;-( sizes for heating load.

[Roughly 1 ton/800 sf, one hole per ton.]

What you should do is ask the guy doing "cooling load" estimate how
much backup electricity you'll use.

There's another factor to consider - the geothermal will shut down
even if it's above the threshold if it figures the ground loop has made
itself too low. So an undersized unit may "freeze out" it's heat
exchange branches during sustained low temperatures, and effectively
not work at all.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

"Chris Lewis" wrote in message
...

There's another factor to consider - the geothermal will shut down
even if it's above the threshold if it figures the ground loop has made
itself too low. So an undersized unit may "freeze out" it's heat
exchange branches during sustained low temperatures, and effectively
not work at all.


And with many properly installed / sized geo units operating with a COP of 4
or better these days, then if / when the system defaults fully to the backup
heat strips then it's well to remember its gonna cost you 4 times as much to
run at capacity.

--

SVL

Chris Lewis wrote:

According to :

I live in Southern Maryland, Waldorf (20601) to be exact. It's about
35 miles south of DC. Both companies are WaterFurnace Installers. THe
company that suggested we base the size on cooling load walked through
the whole house measuring windows, rooms, doors, and inspected the duct
system. He back and said we have 45,000 BTU for cooling and 95,000 BTU
for heating. If we put in a cooling load system, the threshold for
heating would be 27 degrees. Anything below that we would have to use
back up heat.

We're in southernish Ontario (Ottawa). The one Geothermal dealer we spoke to
(there may only be one in our area ;-( sizes for heating load.

[Roughly 1 ton/800 sf, one hole per ton.]

What you should do is ask the guy doing "cooling load" estimate how
much backup electricity you'll use.

There's another factor to consider - the geothermal will shut down
even if it's above the threshold if it figures the ground loop has made
itself too low. So an undersized unit may "freeze out" it's heat
exchange branches during sustained low temperatures, and effectively
not work at all.
....

If that happened at all frequently, that would indicate the loop is
either too small or not deep enough. In Canada, of course, the ground
cooling is much more significant than it was in TN where I was or in MD
where OP of the thread is. Being "that type of guy" , and one of the
first non-lake-loop installations the local fellow did, we put
thermocouples on the loop piping at the intermediate- and
bottom-of-trench levels at the inlet and the outlet ends and monitored
them for a couple of years. IIRC, the bottom of the trench was ~6 ft
and didn't change but about 7F from mean during the year. The mid-level
was more like 12-15F. These are a long time ago, but I think that was
pretty close...

According to PrecisionMachinisT :

"Chris Lewis" wrote in message
...

There's another factor to consider - the geothermal will shut down
even if it's above the threshold if it figures the ground loop has made
itself too low. So an undersized unit may "freeze out" it's heat
exchange branches during sustained low temperatures, and effectively
not work at all.

And with many properly installed / sized geo units operating with a COP of 4
or better these days, then if / when the system defaults fully to the backup
heat strips then it's well to remember its gonna cost you 4 times as much to
run at capacity.

If it's at all capable of doing so. We had a geothermal company out,
and they were spec'ing it with a mere 5Kw of backup heat. Which if the geo
primary goes out, you're going to freeze.

[We could only get away with that because we have _baseboard_ heat, and
we weren't planning on tearing it out.]
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

According to Duane Bozarth :
If that happened at all frequently, that would indicate the loop is
either too small or not deep enough. In Canada, of course, the ground
cooling is much more significant than it was in TN where I was or in MD
where OP of the thread is.

Ottawa will be slightly worse than MD, but probably not by that much.

Being "that type of guy" , and one of the
first non-lake-loop installations the local fellow did, we put
thermocouples on the loop piping at the intermediate- and
bottom-of-trench levels at the inlet and the outlet ends and monitored
them for a couple of years. IIRC, the bottom of the trench was ~6 ft
and didn't change but about 7F from mean during the year. The mid-level
was more like 12-15F. These are a long time ago, but I think that was
pretty close...

As a FYI: I don't think they do horizontal loops here. For each ton
of heating, they drill a 100' deep 3" diameter vertical hole. IIRC,
they were 10' apart minimum. As it was explained, at peak loading,
you might "lose" a small amount of available operating time due to
freezing the ground.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

Chris Lewis wrote:

According to Duane Bozarth :
If that happened at all frequently, that would indicate the loop is
either too small or not deep enough. In Canada, of course, the ground
cooling is much more significant than it was in TN where I was or in MD
where OP of the thread is.

Ottawa will be slightly worse than MD, but probably not by that much.

Being "that type of guy" , and one of the
first non-lake-loop installations the local fellow did, we put
thermocouples on the loop piping at the intermediate- and
bottom-of-trench levels at the inlet and the outlet ends and monitored
them for a couple of years. IIRC, the bottom of the trench was ~6 ft
and didn't change but about 7F from mean during the year. The mid-level
was more like 12-15F. These are a long time ago, but I think that was
pretty close...

As a FYI: I don't think they do horizontal loops here. For each ton
of heating, they drill a 100' deep 3" diameter vertical hole. IIRC,
they were 10' apart minimum. As it was explained, at peak loading,
you might "lose" a small amount of available operating time due to
freezing the ground.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

I gather that it's not too hard to dig there...in TN that would be
bedrock and pretty expensive drilling...but I'd agree the deeper the
better...as noted, at the time I put in the system in TN, the only local
installer was almsot exclusively working in a development on Tellico
Lake and using the "loop in lake" ploy...

According to Duane Bozarth :

As a FYI: I don't think they do horizontal loops here. For each ton
of heating, they drill a 100' deep 3" diameter vertical hole. IIRC,
they were 10' apart minimum. As it was explained, at peak loading,
you might "lose" a small amount of available operating time due to
freezing the ground.

I gather that it's not too hard to dig there...in TN that would be
bedrock and pretty expensive drilling...

It'd be bedrock here too. We're on the Canadian Shield ... Granite,
quartzite, with relatively shallow sedimentary overburden in places.
Probably very similar to TN - old hard rocks.

but I'd agree the deeper the
better...as noted, at the time I put in the system in TN, the only local
installer was almsot exclusively working in a development on Tellico
Lake and using the "loop in lake" ploy...

That's not geothermal. That's a water-source heat pump. There's also
ground source heat pump that operates by circulating an anti-freeze or
alcohol solution through pipes buried in the ground - either in trenches,
or in deep holes. Or, ones that pump water out of the ground (and either
back into the ground, or simply dumping it on the ground) for their heat
source.

Geothermal is slightly different. Geothermal is where you put the
exchange coils of the compressor _itself_ underground. Rather like
unravelling the plumbing on the back of your fridge and burying it.
These things use "real refrigerant" (often a freon of some sort)
in their buried loops. Not a heat exchange liquid.

These are more efficient than water-source heat pumps, because there's
only one loop rather than two. One heat exchange interface, not two.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

Geothermal is slightly different. Geothermal is where you put the
exchange coils of the compressor _itself_ underground. Rather like
unravelling the plumbing on the back of your fridge and burying it.
These things use "real refrigerant" (often a freon of some sort)
in their buried loops. Not a heat exchange liquid.

These are more efficient than water-source heat pumps, because there's
only one loop rather than two. One heat exchange interface, not two.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.

Would you care to share a source for this information? I can just see the
government letting you bury freon lines in the ground... LOL

Chris Lewis wrote:

According to Duane Bozarth :

As a FYI: I don't think they do horizontal loops here. For each ton
of heating, they drill a 100' deep 3" diameter vertical hole. IIRC,
they were 10' apart minimum. As it was explained, at peak loading,
you might "lose" a small amount of available operating time due to
freezing the ground.

I gather that it's not too hard to dig there...in TN that would be
bedrock and pretty expensive drilling...

It'd be bedrock here too. We're on the Canadian Shield ... Granite,
quartzite, with relatively shallow sedimentary overburden in places.
Probably very similar to TN - old hard rocks.

but I'd agree the deeper the
better...as noted, at the time I put in the system in TN, the only local
installer was almsot exclusively working in a development on Tellico
Lake and using the "loop in lake" ploy...

That's not geothermal. That's a water-source heat pump. ...

Exact same technology, only different hear sink...all I did was mention
the system we did was this particular installer's ground instead of
water loop....

According to LBaker :

Geothermal is slightly different. Geothermal is where you put the
exchange coils of the compressor _itself_ underground. Rather like
unravelling the plumbing on the back of your fridge and burying it.
These things use "real refrigerant" (often a freon of some sort)
in their buried loops. Not a heat exchange liquid.

These are more efficient than water-source heat pumps, because there's
only one loop rather than two. One heat exchange interface, not two.

Would you care to share a source for this information? I can just see the
government letting you bury freon lines in the ground... LOL

There's many different kinds of freon, some of them are bad for the atmosphere,
some of them aren't. The treaties are on _specific_ freon compounds - R12 is
one of the baddies.

PremierE WaterFurnace uses R410-A for example.

Here's a link - it shows the more traditional heat pumps as well as the
full geothermal types.

http://www.earthenergy.ca/tech.html

http://www.energy.gov.on.ca/index.cf...s_geotherm al

Some other closed systems use ethanol or methanol. (They've decided
to not permit methanol in Ontario).
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.