It's true that if it is really cold out in a heating dominated climate, heat pump efficiency goes down. That does not mean it crosses the line of diminishing returns. Again, the antifreeze is there as the equipment is perfectly capable of operating below freezing, and remember we are talking about 2-8 days out of a hundred here, not routine operating temps.
Not likely that loops sized for a dominate season, will be undersized on the off season.
As I pointed out in the thread I started last night, this obsession with loops is ignoring more common installation maladies.
J

I am beginning to favor the FHP contractor. An Aquarius II 5 ton unit, and separate water to water unit for radiant floor. He proposes 4 200 ft wells, with dual - whatever you call it -- twin pining down each well. Supposed to be 6+ tons of well support.

Anyone know anything good or bad about FHP?

thx Jim

Jim,

I would be skeptical of the claim that (4) 200' bores will yield 6+ tons. Depending on your local geology and climate one ton equals 150'~200' bore. I would consult others in your area for clarification of this issue.

Bergy

Agreed.

Even though Geolink says that loop is ok for solid  rock and 5 tons (but not 6), I think the 990' that you mentioned earlier  is probably better.

FHP is fine.
When you said twin loop did you mean 2 u-tubes per well (800' of pipe)?
j

Yes, that is it, 2 u-tubes.
Thanks about FHP.

That would do it in my area.
J

Yes, they say by running the pipes down again in a u (2x total) you get 50% more. Also, I hope to be mostly in rock with my wells.

Waterfurnace Geolink says about 12% better.

I'd have said ~10%, but the point is it appears they know what they're doing.
Make sure you check lots of references, if they're happy, you will be too.
J

If your coldest temperature is above 20F then a Air to watersystem is enough.
If you use it in combination with Solarpanels and a tank with electric heating for the very cold days (under 5 F) then you have a system that will be cheaper to install and good enough for your climate.
What temperature will the water approximately be that you will get up?

The nites seem to get down to 15 deg or a little lower often in the winter.

I expect the water to be about 55 deg. At least the soil/rock will be. I realize there will be a drop under load.

thx Jim.

I guess you meant a conventional air heat pump married to a radiant floor system?? or did I misunderstand?

Do yiou think the savings will justify passing up the 30% tax refund off a geo system?

A high efficiency heat pump is comparable to a GEO system without the high initial cost of installation. Most GEO systems closely match the C.O.P. of 15 S.E.E.R. air to air Heat Pumps. The only advantage to a GEO system is the loop temperature is more stable thus having an effect on the COP. OH!!! If the loops/wells aren't installed correctly there goes your savings....I service and install GEO and air 2 air heat pumps. and have seen systems that run <15 deg and > 100 degree. oppps there goes that efficiency you were looking for. Get a copy of the spec sheets for your particular equipmnet and do some research... Don't get caught up in this climate change crap. and thinking by spending a butt load of money on a GEO system that you are going have even the slightest impact on anything but your pocketbook. DJ

At what temps?

I think your confusing points COP , SEER , and EER . are all different
If you are comparing SEER of air source and EER of ground . which can be close
SEER is a seasonal average of energy effeiceincy at the location the equipment was manufacturered
EER represents a full load scenerio under uniform preset conditions .
Which most people agree is a more acurate way to compare different equipment .
There is no standard conversion that I know of but I have read that if you where to convert eer to seer the number would increase 30% .

COP is a moving target

Some sources provide an HSPF -- to convert this to a COP, divide the HSPF by 3.412.  For example an HSPF of 6.8 equates to a seasonal COP of (6.8 / 3.412) = 1.99. some 16 seer
Some manufactuerers are claiming as high as 9.5 which puts you at about 2.75  (18 seer)
these tests have the same (but ) as seer . the average is based on average climate where the equipment is manufactered . So that COP of 2.75 average might drop to 2  around us yanks , and if you want to get realy honest it could be much worse with increased defrost times and aux. which is NOT counted .

But your right if its not installed right , its no better then air source

No confusion at all. Seasonal Engery Efficiency Rating #BTU produced per watt of energy consumed, and is a better indicator of efficiency of the equipment. Enery Efficiency Rating is similar to SEER with the exception that rating is at 80deg IDB and 95deg OAT. which is great if you live in a bubble where the temperature never changes Heating Season Performance Factor is a rating the Department of Energy puts out for a Zone/Area of similar Climatolgical temp. Great for general and slightly less vague discription. But not very meaningfull for the Climatological data for your area of the country. Coefficient Of Production is a more accurate telling of how well your equipment is producing the juice you are squeezing. BTU output/ equipment watts (incl blower in this reading)X 3.412 BTU per watt = COP You will have a hard time convincing me the ground loops operate in the ideal temp range of 50-70 deg when the system is constantly cooling the ground (you might achieve this with a pump and dump system in a lake)and in cooling constantly heating the ground is the opposite effect. Once you deviate away from the ideal loop temperature conditions so does your COP rating. Ground loop temperatures are very stable but once cooled or heated they act more like a storage device. and don't give up the temperature quickly. If your loops are not installed correctly and turbidity (Reynolds number) is low you will lack the proper heat transfer for the system. If the caulking of the wells fail (like they are prone to do) the heat transfer will suffer and so will your COP. These are costly repairs for a few measly $$$ in energy savings. Granted the air to air heat pump systems are not for all parts of the country so there are pro and cons for both types of systems. In reference to the defrost and aux. heat. Most major brands of heat pumps in the last 10 years have demand defrost timers and defrost only when needed. unlike the old manual timers that defrosted no matter what the coil conditions were. A good majority of the GEO heat pump have aux heat strips installed (5- 10 KW) in the northern part of the country due to the drop of the COP and also the increased heat loss of the envelope.(Structure) so if you think you will be exclusively on the heat pump think again! I currently have an air to air heat pump with a 13.8 SEER rating. With a COP of 4.93 @ 47 deg and 3.38 @ 15 deg. This heat pump is operated a minimum temperature of 12 deg. It also operates on an average of 1230 hours over the heating season. with the highest heating cost of $60 during the coldest months operated. with subsidize natural gas heat 2500 ft2 The DOE conveiniently divided up these Great United States into 5 Zones for generalization purpose Climatological Temp Data is available thru NOAA for the heating / cooling degree days. And there is always the trusted ACCA BIN tables for your particular city. Did this clarify the difference in the ratings and the different acronyms. I have formulas galore for calculating problems with the systems. DJ

I currently have an air to air heat pump with a 13.8 SEER rating. With a COP of 4.93 @ 47 deg and 3.38 @ 15 deg. This heat pump is operated a minimum temperature of 12 deg. It also operates on an average of 1230 hours over the heating season. with the highest heating cost of $60

Malarkey , You better have a data logger to back that up , or at least post all the necessary numbers that you used to come up with that .But maybe your 14 seer unit really is operating TWICE as efficiently as any other heat pump , maybe the air around your house is that much more conductive


, and is a better indicator of efficiency of the equipment. Enery Efficiency Rating is similar to SEER with the exception that rating is at 80deg IDB and 95deg OAT. which is great if you live in a bubble where the temperature never changes

It may be better for GUESSING what it will cost to run , but far worse for comparing equipment , because the tests are not standard from one to another .


As far as a geo at 30 ewt compared to 30 degree DB on an air source , the numbers are not even close .

In reference to the defrost and aux. heat. Most major brands of heat pumps in the last 10 years have demand defrost timers and defrost only when needed. unlike the old manual timers that defrosted no matter what the coil conditions were. A good majority of the GEO heat pump have aux heat strips installed (5- 10 KW) in the northern part of the country due to the drop of the COP and also the increased heat loss of the envelope.(Structure) so if you think you will be exclusively on the heat pump think again!

In case you missed a few hundred of my previous posts I am a pro . Aux. is NOT installed on geo systems due to a drop of COP , It is done to lower the initial cost and weighed against the increased operating cost . most dont kick on except 5% or less of the time , in parts of the country where an air source unit might lean on aux 40% of the time or less .

I find it odd you seem to truly believe air source can hold a candle to geo . your comparing a Yugo to a Cadillac

If your loops are not installed correctly and turbidity (Reynolds number) is low you will lack the proper heat transfer for the system.

-Really if not installed correctly it doesn't work? How 'bout an ASHP? Let's say it's installed by a moron, won't that have an impact on performance as well?

If the caulking of the wells fail (like they are prone to do) the heat transfer will suffer and so will your COP.
"(like they are prone to do)"

-You really need to back that one up.

These are costly repairs for a few measly $$$ in energy savings.

-Your budget must be better than mine, I've never thought of thousands of dollars as measly.

.....COP You will have a hard time convincing me the ground loops operate in the ideal temp range of 50-70 deg when the system is constantly cooling the ground (you might achieve this with a pump and dump system in a lake)and in cooling constantly heating the ground is the opposite effect.

- I'm not sure where you got the notion that 50-70 is ideal, our winter design is about 34* in MI. They may test at unrealistic temps (which by the way we've pointede out around here), but so do furnace, AC and ASHP manufacturers. Peak ASHP COP's are sure not based on average winter air temps from my area.

Once you deviate away from the ideal loop temperature conditions so does your COP rating.

- Again once you deviate from ideal air temperature conditions so does your ASHP COP and fossil furnace efficiency.

-You talk out of both sides of your mouth, yes efficiency goes down as it gets colder and yes geo must be installed correctly, but you neglect to mention that the same is true of ASHPs and fossil furnaces. You also neglected to mention that a package geo system is assembled in a clean enviroment while your ASHP is assembled on site which is among the reasons that ARI says geo lasts longer. You also neglected to mention that most geo manufacturers require dealer certification which is not true of most ASHP suppliers meaning your oppurtunity for a poorly installed system is more likely with ASHP.
You'll find that most of us around here try to be evenhanded, and if you were to look you would see that many of us have stated examples of when an ASHP might make sense (over years of contributions and thousands of posts).
We have also spoken of the fact that a contractor will have more to do with satisfaction than the manufacturer will (which among other things goes towards proper install more than "most efficient").
If you are high on ASHPs that's great, some people are high on 95% efficient (by the way only about 91% average efficiency) furnaces and that's okay. But do you really believe that anyone here will believe that when it's really cold and GSHP efficiency goes down that your ASHPs performance is the same high efficiency it was at 60* ambient or that it will work at all?
We went down to -18* in MI this winter and my heat pumps still ran. Not at 4.0 COP of course, but let's see an ASHP that runs at all (no....how about at 10* warmer? or even 20?). In fact by your own account it would have to be 30* warmer for your heat pump to even run. So yep I installed aux. coils on my customer's systems to keep from grossly oversizing equipment and duct work and these coils provided supplemental heat. With an ASHP my customers would have been 100% electric (or propane or fuel oil) untill we got back to double digit weather, at which time a ASHP is going to operate around 1 COP (same as my aux. heater) and you still need help to provide supplemental heat as capacity is modest.

Real interest and data and honest opinions are all welcome here. Even disagreement or lively debate.
Please check your propaganda at the door.

Joe

Do any of you know how I would calculate the tonnage of the loop?

I suppose I take the flow rate. Convert gallons per minute to cubic cm per minute.......

What is a BTU again? How many per ton? 12,000?

thx

BTU/ton is 12,000
1 ton of loop gets more complicated as soil type and moisture contact have an impact.
Joe