Geothermal and Air Heat pump Temps for AIR COMFORT
Last Post 30 May 2012 12:25 PM by joe.ami. 124 Replies.
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docjenserUser is Offline
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20 May 2012 05:03 AM
Posted By MikeSolar on 18 May 2012 06:41 AM
Posted By knotET on 18 May 2012 02:27 AM
Watch for the Climatemastering 40SEER, just like Hydro-Temp has IQ now... BIG Ex at having BIG HX coils..../>


GSHPs usually don't have a SEER rating, I am sure you meant ERR in the 40s. It doesn't really come from the coil, it comes from the inverter driven compressor.
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20 May 2012 05:44 AM
Posted By Dana1 on 14 May 2012 11:29 AM
Posted By docjenser on 12 May 2012 01:15 AM
Posted By Dana1 on 10 May 2012 04:20 PM
I've not seen credible 3rd party data to support the notion that the average full system GSHP seasonal COP is in excess of 4 yet, despite the onesie-twosies at the 2 sigma margins.  But if you can show me where to find third party survey data on instrumented & monitored systems such as the dozens of mini-splits in the NW Ductless project I'd be very interested to look at it. The smaller-scale studies I've seen to date all point to mid-3s as the system average.


http://www.builditsolar.com/Projects/SpaceHeating/InField%20PerformanceTestingofGSHP_updated%2011_11_2010.pdf

You are right, good published studies are lacking, the one above is quite bad with very inefficient systems and lots of variances, which make me question the data. We see average total system COP in the mid 4s with 3 ton dual stage W-A, with an average heating season EWT of 38F. We have 15 Welserver online, and should summarize and publish the data.

I'd already seen that one, and it's consistent with several others. Question the data all you like, but until there's published evidence that the industry average has has moved forward from that point, I don't see any reason to believe that a typical GSHP installation are even close to averaging in the 4s yet.  In fact I haven't seen ANY third party tested system that beat 4 as a seasonal average, but I wouldn't necessarily be shocked to find an existence proof some day. Yet I tend to believe people who actually measure stuff when they have no financial interest in the outcome rather than blindly accepting vendors' spec sheets, or the marketing literature/protestations of installers.  Allegations aren't evidence.

Just as with mini-splits- the average in-situ performance of tested systems can hint at what's possible, but from the prospective buyer's point of view it's unwise to assume that you'll beat the industry average.  Best-case scenarios are rare, but of course better-studied better-designed implementations can industry averages.  Just as I wouldn't assume an average COP of 3 for a ductless in US climate zone 5 (even though I believe it's possible with an optimized oversizing factor), I can't assume an average COP of 4 for GSHP based on an installer's say-so or industry-insider lore.  \

Say whatever you like, but show me, and don't be too sensitive when others call THAT data into question.

As a crude measure of where to place expectations, in US climate zone 5, for now I put the backstop at 2.5 & 3.5 for ductless & geo respectively.  While it might be at the lower-efficiency side of dead-center on the bell curve, it's probably within a single standard deviation.  In US climate zone 4  that moves up to 3.0 and 3.5 based on the available evidence.   But the fact that average for one of the zone-4 sub-region in the BPA study was 3.4, the possibility that at least some installation in that mix was averaging about 4, seems likely while others were only 3. 

Of the two non-instrumented systems in climate zone 4 that I have first-person reported billing data on, an average north of 3 would be consistent with the power use.  A 4 average would be a bit surprising, but not entirely out of the question for one of them, but it hasn't been up for an entire heating season yet.

Note that the testers in the BPA study were unable to achieve the HSPFs published by Mitsubishi, either in the lab or in-situ, but were able to demonstrate that their lab measurements were consistent with the field-monitored performance.  But they COULD reproduce the Fujitsu-published HSPF both in the lab and in-situ.  But since Mitsubishi holds the lion's share of the installations in that study it's conceivable it skewed the averages downward slightly.  As the state of the art moves forward it should all be moving up incrementally.




The IEA data was a nice compilation of filed test out there in Europe. A few things came to my mind.
1) Many of the data was from installs 5-15 years ago, and monitored over a nice period of time. HP efficiency has significantly improved since then. 2) Pretty much everything on GSHPs was W-W. The systems performing with a lower COP were radiator heat, which requires higher supply temp. Understand the impact of the lift, and you can design more efficient systems. 3) A main reason for lower system COP is the parasitic loss of the loopfield circulation pumps, which were 10-35% in the commercial applications, and between 6-25% in the residential applications. In the typical W-A application here in the US, what is the difference between the AHRI COP rating and the actual field? The loopfield circulation power and the high torque for the fan. The loopfield can be designed differently with lower pressure drop, and you can get the pumping done with a high efficiency circulator consuming 100 watts. Plus add an amp for the higher blower torque. But that's is about it. So add an average EWT in the upper 30sF, (remember the COP is rated at 32F EWT for second stage), and you will see COP performance number in the mid 4s.
We only have real time COP displayed on some of our systems, I have to reprogram the WELs to display the average COP over the season, but will do so soon. The manufactures tables are actually very accurate and very reproducible. You are feeding a heatpump with a certain amount of flow and temperature, and it will perform in a very predictable way.
So why do you always have to imply financial bias as soon as someone disagrees with you. Just because someone works in the industry and therefore has a certain amount of expertise does not mean he is not doing everything he can to stay objective.
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20 May 2012 07:42 AM
docjenser, what is the percentage of w/w vs w/a systems you put in? I put in the IEA report partly because Dana1 had not seen much evidence of higher COP systems but also to show the complexity of design out there. My point is that the W/A or A/A must run at a higher output temp for comfort reasons where W/W or A/W can modulate down to good radiant temps and the higher COP systems are typically W/W for that reason, which is why we don't see them as much here.
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21 May 2012 12:32 PM
"So why do you always have to imply financial bias as soon as someone disagrees with you. Just because someone works in the industry and therefore has a certain amount of expertise does not mean he is not doing everything he can to stay objective."

It's not all about suspicions of financial incentive (though I acknowledge those factors exist).  HVAC installers and system designers do not generally use the same level of measurement standards of scientists & engineers, nor should they.  (But I'm sure your WELs all use NIST calibrated instrumentation that you keep updated with periodic testing, right?  )

And it has nothing to do with someone agrees with me or not, it's about backing assertions with evidence.  A forum poster's word isn't enough when the published evidence is all over the place, and doesn't support the case. The published evidence demonstrates to me that there's a design risk, and that optimistic assessments of actual efficiency are often not borne out in the real world implementation.  The real world pumping and air handler power would seem to be harder to nail down in practice than the performance of the HP itself.

It's not like I'm treating ASHP data any differently.  In the NEEA/BPA ductless test data the installations in the coldest locations (Eastern Idaho, the warm edge of zone 6/cold edge of zone 5) averaged a seasonal 2.84 for COP, but I'm wouldn't base expectations on the measured results of exactly 9 systems.  (Most of those were installed 5+ years ago too, shall we pooh-pooh it as lower-than reality, since the technology has since improved?)   It IS safe to say that any decent ductless should be able to average 2.5 or better in that climate though, even though I'm sure some installations in that climate will be operating well into the 3s.
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22 May 2012 12:25 AM
Posted By Dana1 on 21 May 2012 12:32 PM
"So why do you always have to imply financial bias as soon as someone disagrees with you. Just because someone works in the industry and therefore has a certain amount of expertise does not mean he is not doing everything he can to stay objective."

It's not all about suspicions of financial incentive (though I acknowledge those factors exist).  HVAC installers and system designers do not generally use the same level of measurement standards of scientists & engineers, nor should they.  (But I'm sure your WELs all use NIST calibrated instrumentation that you keep updated with periodic testing, right?  )

And it has nothing to do with someone agrees with me or not, it's about backing assertions with evidence.  A forum poster's word isn't enough when the published evidence is all over the place, and doesn't support the case. The published evidence demonstrates to me that there's a design risk, and that optimistic assessments of actual efficiency are often not borne out in the real world implementation.  The real world pumping and air handler power would seem to be harder to nail down in practice than the performance of the HP itself.

It's not like I'm treating ASHP data any differently.  In the NEEA/BPA ductless test data the installations in the coldest locations (Eastern Idaho, the warm edge of zone 6/cold edge of zone 5) averaged a seasonal 2.84 for COP, but I'm wouldn't base expectations on the measured results of exactly 9 systems.  (Most of those were installed 5+ years ago too, shall we pooh-pooh it as lower-than reality, since the technology has since improved?)   It IS safe to say that any decent ductless should be able to average 2.5 or better in that climate though, even though I'm sure some installations in that climate will be operating well into the 3s.


I indeed make the effort to check the precision of the probes for the WELs prior to installing by hanging them all in a bucket of water, and they are surprisingly accurate, usually within 5/100 degree F. The biggest issue is then how the probes are mounted then, and I always calibrate them with a NIST calibrated needle thermometer, which gets it down to a 1/10 of a degree F. They are mounted with a heat transfer compound usually used for laptop processors (to conduct heat away). Given that we usually shoot for a 5 degree delta T, the margin of error is around 0.1F, or 5%. If I see a diversion from last years data by more than 5% I usually go out there and make sure the sensors are calibrated again.

http://www.builditsolar.com/Projects/SpaceHeating/InField%20PerformanceTestingofGSHP_updated%2011_11_2010.pdf

However, all the objective 3rd party studies do not standardize and control the installation standards. The above study is the best example. One system using 2 circulation pumps consuming 800 watts, even if only one heatpumps is running in first stage, adding up to 40% parasitic losses. In the other system they could not get the air out of the loop.
So far, I am missing any description in any studies about the efficiency of the system design. How good is than the best measurement standard if the systems measured are inefficiently designed?
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22 May 2012 12:04 PM
"So far, I am missing any description in any studies about the efficiency of the system design. How good is than the best measurement standard if the systems measured are inefficiently designed?"

I share your frustration, but this is exactly the design-risk problem I refer to (often), and why I don't have faith that the industry average efficiency of GSHP has hit the 4s yet, and even though it's possible (or maybe even likely) that YOUR averages may beat that average by good measure.  Designing a maximally efficient system is not a trivial task.

With ductless ASHP the design risk is low since it's a "system in a can", even though sizing relative to the actual load has an effect efficiency.  But in cold climates it's going to be significantly less efficient than GSHP, most of the time.

In the 2010 paper you linked to, the full system wintertime average peformances of the three systems monitored were in the mid-3s, and at least in the CT & VA systems a better-class ductless would match or even beat them on seasonal performance at about 1/3 the upfront cost.  (I'd be pretty disappointed to have paid $40K for a system that performs no better than a $12K multi-split, as the VA client did.)  In the VA system, even though it's a large house, I question whether they really needed 6 tons to heat & cool the place too.  I suspect they could have stripped a lot in cooling load with better-optimized glazing & window placement, and the wall-R only meets the current code-minimum.  It feels like a case of designing the house off a prescriptive list rather than energy-use modeling, and without optimizing for value on non-so-cheap mechanicals against a higher-performance building envelope. But just as the system details are lacking, the envelope descriptions are also pretty sketchy.

Clearly system designers need to do a better job of maximizing the efficiency potential of GSHP.  Sure, it's just three systems, but it's consistent with the other drips & drabs of 3rd party tested systems out there (albeit dated evidence, in some cases.)  Should we be setting expectations based on three systems?  Maybe not, but in the absence of better evidence it becomes the "...you should be able to achieve at least..." benchmark.  Presuming those to be statistical outliers would be wrong in the absence of evidence to support that thesis.  Safer to assume you'd be able hit ~3.5, before plunking down the $30-40K (as those customers did), than building your financial analysis on an assumption of hitting 4.0,  just as it's safer to assume with ductless that you'd hit a COP of at least 2.5 in a US zone 5 climate based on the entirety of the available evidence, even though it's been demonstrated that 2.8+ is possible even on the cold edge of zone 5.
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22 May 2012 11:32 PM
Posted By MikeSolar on 20 May 2012 07:42 AM
docjenser, what is the percentage of w/w vs w/a systems you put in? I put in the IEA report partly because Dana1 had not seen much evidence of higher COP systems but also to show the complexity of design out there. My point is that the W/A or A/A must run at a higher output temp for comfort reasons where W/W or A/W can modulate down to good radiant temps and the higher COP systems are typically W/W for that reason, which is why we don't see them as much here.


I agree. About 70% are w-a, the rest w-w. I try to design new w-w system for 85 degree supply temp for that reason. Not possible with water to air.
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23 May 2012 12:27 AM
Posted By Dana1 on 22 May 2012 12:04 PM
...this is exactly the design-risk problem I refer to (often), and why I don't have faith that the industry average efficiency of GSHP has hit the 4s yet, and even though it's possible (or maybe even likely) that YOUR averages may beat that average by good measure.  Designing a maximally efficient system is not a trivial task.

With ductless ASHP the design risk is low since it's a "system in a can", even though sizing relative to the actual load has an effect efficiency.  But in cold climates it's going to be significantly less efficient than GSHP, most of the time.



You certainly make a good point that the risk is lower with a mini split, since their system design is very much standardized. And that the risk is higher with a geosystem. But the point is, what everyone here is stressing, that there are good guys out here, who build and design efficient systems and that a good installer should be a first criterion, so you don't put your mid 20K (I don't know where the $30-40K average comes from) at risk.

I still don't see how you can weight a whole house system with a ductless. Both have their places, but they are different, as discussed to the exhaust here.

You can pretty consistently hit mid 4s with W-A, but that is it unless you are dealing with higher EWTs. W-W you can easily get above a COP of 5. I'll post it here soon and hope you find the methods legit. The reason I cited that paper is because it was a perfect example for inefficient system design.
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23 May 2012 10:04 AM
Posted By docjenser on 23 May 2012 12:27 AM
 
so you don't put your mid 20K (I don't know where the $30-40K average comes from) at risk.


Yes Dana,
You are fairly even handed, but doc and I have quoted mid 20's to less than 20k (respectively) for heat pumps installed turn-key, yet you keep insisting that systems are much more expensive.

Perhaps they are in some location, but as we speak from our own experiences, I cost compare to about 18K for a 3 ton. ASHPs get a lot less attractive with that in mind.

If it were 40K for a 3 ton around here, I probably would push air source.
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23 May 2012 11:59 AM
Posted By docjenser on 23 May 2012 12:27 AM
...You can pretty consistently hit mid 4s with W-A, but that is it unless you are dealing with higher EWTs.

I agree. In my case, I consistently hit near 5.0 COP whenever I measure it. Indeed, I never see EWTs lower than 60 degrees F. Thank you for providing the article. I read it with interest. I believe that COP needs to be measured statistically, and not per the article's methodology. In the histogram below, it shows every COP measurement for every 1 minute, for an entire month, with no need to make judgement on which data points are good and which ones are not. This is actual data for my WF Envision GSHP. Best regards, Bill
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23 May 2012 12:31 PM
The $30-40K wasn't an average, it was the reported system costs to "...those customers..." as documented in the paper docjenser referred to.

http://www.builditsolar.com/Projects/SpaceHeating/InField%20PerformanceTestingofGSHP_updated%2011_11_2010.pdf

If you're gonna post it, why not actually read it, eh? :-)

The $40K system was 6 tons, not 3, which at $6.7K/ton would be a bargain at local rates for GSHP.. In MA installed costs for recent systems on geo averages just shy of $9K/ton, according to reliable MA state sources, which would put a typical 3-tons in the $25K-30K range. That is consistent with my (less-thorough and non-compiled) sample set. I've never seen or heard of a local quote for 3 tons of geo that came in under $20K, but again, it's a small sample- that may happen. Until there's data indicating otherwise I'll use the MA-state $9K/ton figure for generic estimation purposes rather than Joe's $6k/ton, unless that $18K for a 3-ton system the cost after the 30% tax credit subsidy(?).

I'm thrilled to know that there are good guys out there who can deliver designs that consistently hit the mid-4s, but it would be more comforting if third party investigators going out to measure performance on (presumably) randomly selected systems were coming up with averages better than mid-3s. It would be stupid to presume that they just randomly hit the bottom-of-the-barrel system designs, and that those designs not representative of where the industry average is.

This is comparable to the differences between "best-possible" and industry-average on the in-situ performance of retrofit condensing gas boilers- sure, a good designer can get 95%+ out of them, but in the average system they're struggling to beat 86%, despite equipment that scores in the mid-90s on an AFUE test. And of course better designers (or even alert amateurs) can point to why those underperforming systems don't hit the mark, but that doesn't affect the reality of where the industry average lies. The average customer may still be happy with the 86%, given that the typically oversized high-mass beast that was replaced was likely running in the 70% range. I suspect the typical GSHP buyer isn't an energy nerd sniffing hard at the true performance, but is rather just thrilled at how much less it costs to run than propane or oil.

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23 May 2012 12:47 PM
Posted By Dana1 on 23 May 2012 12:31 PM
... In my installed costs for recent systems on geo averages just shy of $9K/ton, according to reliable MA state sources, ...


C'mon, how does any geo professional get any residential customers at $9K/ton? For conventional W-A, closed loop, with a bore hole field? Nothing but granite to trench/drill through, requiring Interstate Highway construction size equipment to trench/bore the loop field, with an army of 100 workers? At what point does the cost of heating oil or electricity have to get to where the residential customer can see even a 10 year break even point? Best regards, Bill
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23 May 2012 03:18 PM
Posted By a0128958 on 23 May 2012 12:47 PM
Posted By Dana1 on 23 May 2012 12:31 PM
... In my installed costs for recent systems on geo averages just shy of $9K/ton, according to reliable MA state sources, ...


C'mon, how does any geo professional get any residential customers at $9K/ton? For conventional W-A, closed loop, with a bore hole field? Nothing but granite to trench/drill through, requiring Interstate Highway construction size equipment to trench/bore the loop field, with an army of 100 workers? At what point does the cost of heating oil or electricity have to get to where the residential customer can see even a 10 year break even point? Best regards, Bill

How, you ask?

Massive subsidy (both state and federal), and sky-high regional propane and oil pricing, pure and simple.  It's likely that the average $/ton will drop if the subsidies go away, or if the competition in the local industry picks up.  But I'm not just making this up, if that's what you're thinking- the roughly $9K/ton number comes from multiple sources.

I'll try to dig up the MA state cost data and post the link- it's available on-line, but buried in a larger energy policy document, not a 3 pager. IIRC the approximate average for GSHP systems was cited at $8.8K/ton for closed-loop, ductless air source $2.7K/ton, both of which are consistent with recent experience.  Other documentation I've seen (which may or may not be online) indicates that in neighboring CT systems that qualified for rebate under a state sponsor GSHP subsidy averages about $9K/ton for residential systems. 

A forward-looking analysis developed for the MA D.O.E. projects that future costs for GSHP systems will be $7.5K/ton (see section 7.4.1, p.95, p. 104, pdf pagination ) after further market development, and base their financial projections on a $7.5K/ton number.  But that number is speculative based on a number of factors, not existing-reality documented average, whereas the recent CT rebate program figures are based on hard data. (That paper also cites the $9K/ton number from the CT state program, albeit without referencing a hard documentation source.)

If you can beat that price with ease, maybe you could get rich by moving here. (PLEASE move here, I'd LOVE to see the cost drop to $6K/ton, if you really think that is realistic!)  But the available data points to $9K/ton is what it costs here, now, today.  Like the range of real-world average COPs the range in system costs is large, but to date I've yet to see or hear of any geo system (any size) installed in my neighborhood for under $20K.  Maybe they exist (just like systems with actual seasonal COP of 5+),  but they must be as rare as Catamounts- while everybody has heard the rumors, almost nobody claims first-hand experience. YMMV.

Electricity prices average ~15cents/kwh in this state, but there is a wide variance among the municipal utilities and between them and the larger regional operators.  Subsidized geo is an easy argument for most, but is still viable without subsidy on a longer time frame when the competition is $3 propane or $4 oil.  I've seen multiple instances this year of houses with heat loads under 3 tons that paid over $4K for heating fuel this season, and this was one of the mildest winters on record.  But for those people the payoff is 5 years or less (if not as deep as GSHP in a 20 year analysis) by retrofitting ductless ASHP to handle a large fraction of the heating load, even assuming a COP of 2.5.  It gets even shorter if one pushes the envelope and uses an average of 3.0, a performance I believe to be possible for ductless in this climate, but would not assume it to be typical.
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23 May 2012 05:30 PM
seems to me any GT oversized exchangers for low 1st staging load comparison can come up with 5cop. And now 1.4 t at compresor IQgshp ver rfg. Low stg. in a size 4.1/2 "ton" typically is found today with near 6 ton air and water coils getting easy high's then. BUT D1's annual cyclic eff near 4 is so very design/er specific for 55 to 50 earth loops as he pointed out
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23 May 2012 06:28 PM
Dana, thanks!

Wow! What a different market than what exists here in the Dallas area. For us, heating is an after thought, and NG is common to have for heating. Size the HVAC equipment (whatever it is) for cooling, and you don't have to worry if you've got enough heating capacity.

Versus (from the report you cited - thank you by the way):

"... only 29% of households in MA currently employ central air conditioning."

"... and for those that have it, most residences report using air conditioning on a limited basis - usually at night."

"... and further for those that have it, over 50% say they use air conditioning 2 of fewer days during the week in the cooling season."

The report goes on to say, for using GSHP in MA, at the estimated $8.8K/ton cost:

"5.3 years simple pay back if replacing electricity space heating."

"9.2 years simple pay back if replacing fuel oil space heating."

"41 years simple pay back if replacing NG space heating."

So it looks like the market average price per ton for GSHP in MA is in line with the pay back. Here in TX, where all of the dynamics are different, still, it's the same on simple pay back, at 5 - 10 years.

So if I read the report correctly, GSHP installation professionals, for residential, should be in MA, not TX, to maximize their gross revenue at $9K/ton, because it is definitely *not* nearly that high in TX!

But, at least here in TX it's not so difficult: casually walk through the home and tell the customer it's easy simply using the same amount of tonnage as currently exists (no need for a Manual J), contract with a drilling company for a standard one 300 ft borehole per ton drilling into sandy loam clay soil, slap in a GSHP unit up in the hot, unconditioned attic where everyone else's A/C air handler and furnace is, connect up the water pipes and purge, reconnect the supply and return main ducts, and you're done! Don't even have to have a refrigeration license because the most harmful medium you'll mess with is water (don't even need antifreeze)! (Never mind the professional, technical and geological expertise needed to make it all work well.)

Thanks,

Bill
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American Energy Efficiencies, Inc - Dallas, TX (www.americaneei.com)
Example monitoring system: www.welserver.com/WEL0043
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23 May 2012 07:28 PM
PA OH WV KY TM IA MI
Hello MA:

About states where there are several who could ---

Deliver GT systems with 4 zones control and 6 dampers dual compressors 3 staging plus supplemental, and
priority hot water heat recovery 100% while cooling, and On-Demand
and at least 1 ton oversized coils , 4 stats; and ON SITE startup in MA, gladly, near any 4.1/2 "size" GTHP
...@
Well under....14k. BEFORE CREDITS.... WITH DHW 1/6hp bronze and
Flowcenter and kit to unit.... infra red palm 8 sensor logging, etc.
Plus loop or well connected and setting in place and distribution duct, etc
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24 May 2012 09:17 AM
KnotET

"Deliver GT systems with 4 zones control and 6 dampers dual compressors 3 staging plus supplemental, and
priority hot water heat recovery 100% while cooling, and On-Demand
and at least 1 ton oversized coils , 4 stats; and ON SITE startup in MA, gladly, near any 4.1/2 "size" GTHP
...@
Well under....14k. BEFORE CREDITS.... WITH DHW 1/6hp bronze and
Flowcenter and kit to unit.... infra red palm 8 sensor logging, etc.
Plus loop or well connected and setting in place and distribution duct, etc"

Well under...14k,?? then my Hydro-temp dealer made a killing on me!!! And a piss poor warranty to boot!!

If I had learned more about GSHP systems before I purchased, I don't think I would have gone with Hydro-Temp. They got me hook, line and sinker, system does everything I want, radiant in basement, air on main floor and 100% DHW. It is very cheap to operate, but I am scared to death of repair bills in 4-5 years!

ChrisJ
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24 May 2012 09:34 AM
Posted By Dana1 on 23 May 2012 12:31 PM
The $30-40K wasn't an average, it was the reported system costs to "...those customers..." as documented in the paper docjenser referred to.

http://www.builditsolar.com/Projects/SpaceHeating/InField%20PerformanceTestingofGSHP_updated%2011_11_2010.pdf

If you're gonna post it, why not actually read it, eh? :-)

The $40K system was 6 tons, not 3, which at $6.7K/ton would be a bargain at local rates for GSHP.. In MA installed costs for recent systems on geo averages just shy of $9K/ton, according to reliable MA state sources, which would put a typical 3-tons in the $25K-30K range. That is consistent with my (less-thorough and non-compiled) sample set. I've never seen or heard of a local quote for 3 tons of geo that came in under $20K, but again, it's a small sample- that may happen. Until there's data indicating otherwise I'll use the MA-state $9K/ton figure for generic estimation purposes rather than Joe's $6k/ton, unless that $18K for a 3-ton system the cost after the 30% tax credit subsidy(?).

I'm thrilled to know that there are good guys out there who can deliver designs that consistently hit the mid-4s, but it would be more comforting if third party investigators going out to measure performance on (presumably) randomly selected systems were coming up with averages better than mid-3s. It would be stupid to presume that they just randomly hit the bottom-of-the-barrel system designs, and that those designs not representative of where the industry average is.





The cited study is the "bottom of the barrel" design. Grossly oversized loops (nice EWT though), multiple inefficient circulation pumps, inability to purge air out of a loop. I would be embarrassed! No word on how the instruments were calibrated and the numbers were measured. But the fact that 3rd party investigators did it makes this study now creditable and valid as a norm?

www.buffalogeothermalheating.com
Bill NeukranzUser is Offline
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24 May 2012 09:35 AM
Further thinking about GSHP installations in MA:

It looks to me that, in the case of a home having a NG supply, and already having a forced air duct system, noting that there's little need for cooling, it would be a no brainer in favor of putting in classic, NG forced air furnaces, versus GSHP.

Best regards,

Bill
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24 May 2012 03:36 PM
Posted By a0128958 on 24 May 2012 09:35 AM
Further thinking about GSHP installations in MA:

It looks to me that, in the case of a home having a NG supply, and already having a forced air duct system, noting that there's little need for cooling, it would be a no brainer in favor of putting in classic, NG forced air furnaces, versus GSHP.

Best regards,

Bill

Most gas fired heating in MA is hydronic, either steam radiators or pumped hot water baseboards (sometimes radiators, or radiant floors), but 2-stage condensing gas is starting to become common in code-min tract homes where they want ducted air-conditioning as well.  Most MA homes where AC has been retrofitted are still heated with hydronic systems.

All mid-sized cities in MA are on the gas grid, but not all streets in those cities are on gas mains. There are still a lot of homes off the gas grid in the less dense areas, where traditionally heating oil has been the predominant fuel of choice, but with a sizable number of propane-burners too, as well as (believe it or not, even at 15-22cent/kwh) electric baseboard & electric radiant heated homes.

Retrofitting THESE homes are what is going to drive the heat pump market here, but in the 'merican tradition of never looking past 3 years for payback on any home improvement (18months is long for most), GSHP is still a hard sell even with subsidy.  But now that (relatively) cheap ductless has improved to the point that it can deliver significant heat southern New England design temps and is pretty much guaranteed to deliver seasonal COPs well north of 2, and can even bump on 3, the payback on them is pretty quick, and should be an easier sell to those with short horizons.  In CT there's a $1000 rebate for mini-splits, and a $1200 ton rebate for GSHP.

The only people I know personally in MA who have installed GSHP are A: Living in their dream-homes for the long term B: VERY well-off financially (the 2%, if not all 1%-ers ) and C: Very environmentally conscious, willing to spend more for the higher efficiency, up to a point.  The hard-corps middle-class greenies in MA spend it on the building and heat with mini-splits, living in more modestly sized, modestly appointed but quite immodestly-insulated houses, and if there's a trend, it seems to be more toward the PassiveHouse/Net-Zero end than toward bigger-better-nicer houses with highest-possible efficiency mechanical systems.  But if GSHP were running $6K/ton and regularly hit the 4+ COP potential, there would be more interest from the local green crowd.

In CT there's a $1000 rebate for mini-splits, and a $1200/ton rebate for GSHP, but note the average  system size is 4.77 tons, and average system cost is over $40K, given the average cost/ton of $8,782.00 (see the table in the middle of that page.)   Ratepayer & taxpayer money going into the pockets of the very well off, mayhaps?  Rebates for high-efficiency ductless ASHP is a more modest $1000-max and then only for homes/zones hard-wired with electric resistance heating.  From a policy point of view there's more lifecycle carbon being offset per rate/tax-payer subsidy dollar with the ductless rebate program, a technology that is not being incentivized by Uncle Sugar the way GSHP systems are.  OTOH the reduction in wintertime peak grid loading isn't as good with the ASHP either, since at CT-style design temps the COP is only in the low 2s, so it depends on what the total mix of policy goals are.

Note that the lifecycle cost analysis and other financial comparisons in that MA analysis paper use $7.5K/ton for GSHP costing, despite having mentioned the current actual $8.8K average cost.  At current real-world costs the simple payback periods are longer, the IRR smaller, NPV lower, since the upfront cost is 17% higher than in the analyses.
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