It ain't rocket science - the basic idea is to have supply air "attack the load" which generally means directing supply air at windows and exterior walls while not subjecting occupants to drafts.

Posted By engineer on 04 May 2012 07:48 AM
This dialog may contribute to others' suspicions about your possible lack of field experience in these areas.

Don't forget that ICFHybrid claims to be an engineer with many houses, so he MUST know what he is talking about.

Posted By ICFHybrid on 04 May 2012 09:00 AM

Don't forget that ICFHybrid claims to be an engineer with many houses, so he MUST know what he is talking about.

Geome, your penchant for making personal attacks where you should address the discussion at hand is well documented. Maybe you should stick to commenting on the material. Unless, of course, you've run out of substance or ability to be more objective. Personal attacks are not wanted here.

I suppose that's wrong as well in your mind. Yes/no?

Regardless, the principal is still the same with the radiant tube spacing

among things not wanted by me here are amatures seeking every oppurtunity to challange a pro's opinion with pet theory de jour.

at the end of the day every delivery system has comprimises.

Another important reason registers go that by windows is that furniture is likely to go there

leading to shorter duct runs.

for low performance windows with U values north of U0.34, but adds practically zero advantages with U0.25 & lower windows.

Posted By ICFHybrid on 04 May 2012 12:19 PM

leading to shorter duct runs.

So, it sounds like some efficiency could conceivably be gained by not extending duct runs just for the purpose of siting at a window?

for low performance windows with U values north of U0.34, but adds practically zero advantages with U0.25 & lower windows.

I presume that for values in between, the advantage is appropriately indeterminate?

Posted By ICFHybrid on 04 May 2012 10:47 AM
Can I assume that you have no further data about whether it contributes to energy efficiency?

I'm not sure if ICF is unaware or being deliberately obtuse, but air from a supply register directed tangentially along a window neither impacts the glass directly nor fails to entrain surrounding air

Posted By joe.ami on 04 May 2012 06:49 PM
My bad shouldve said furniture isnt likely to block widows. That said you'd be suprised how often consumer v hvac pro determines placement and even design.
Delivering adequate cfm to a room in even a new code minimum house with a ecm blower goes a long way to evening out temps.

Posted By Dana1 on 07 May 2012 11:39 AM

... Have continuously variable ECM drives become most common sort of air handlers used  in GSHP systems, or is it mostly 1 or 2 speed?

Posted By a0128958 on 08 May 2012 02:19 PM
For my 5 ton unit with no zoning (one tstat), blower speed is one of 3 pre-selected speeds.

Posted By joe.ami on 09 May 2012 10:44 AM
knotET,
your ramblings are getting longer and more incoherent ...

Posted By joe.ami on 09 May 2012 10:44 AM
knotET,
your ramblings are getting longer and more incoherent with every contribution. why not try short and sweet.

btw if Dana has an axe to grind it's about insulation first heat plant second. characterization of anti geo simply shows ignorance to the body of work.
j

Posted By knotET on 09 May 2012 09:51 PM
with hi mass slab radiant ... what would you throw out as a % savings with mini's?

Posted By knotET on 09 May 2012 09:51 PM
SO Dana thanks again:
if I am getting a 44% savings over condensing propane, with hi mass slab radiant or same type of forced air heating with GSHP multi staging, heating MODULATING blower keeping 92 or 96F outputs, what would you throw out as a % savings with mini's?
THere are no duct losses in the equation. Right statements can be accessed about ducting, but there are none in this event.

Posted By docjenser on 09 May 2012 10:39 PM
Eh! You are absolutely right, ASHPs have made a big leap forward. And they are a great bang for the buck. But you get all excited about COP in the mid 2s to 3s, when we are at COPs in the mid 4s with GSHPs, including the 230 watts for the loopfield circulator averaged over the season. So a small load in a big room, sure, mini splits are a good alternative. But whole house heating still needs a distribution system. We have to keep the comfort in mind here too. Don't you want other rooms heated, too? Once you have to put one high wall unit in each room, the cost goes up. Sure inverter technology is a big leap forward, that is why they are getting introduced in GSHPs.

Your posts on the subject are very long, and very repetitive!

Posted By Dana1 on 10 May 2012 04:20 PM

Posted By docjenser on 09 May 2012 10:39 PM
Eh! You are absolutely right, ASHPs have made a big leap forward. And they are a great bang for the buck. But you get all excited about COP in the mid 2s to 3s, when we are at COPs in the mid 4s with GSHPs,... Sure inverter technology is a big leap forward, that is why they are getting introduced in GSHPs.

[ knowing a little of the author of this thread tries to be accurate ] Dj states: Your posts on the subject are ...  repetitive! [ do you also mean DANA1? It is not clear to this author ]

DANA1 stated to Dj:
a)
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 ----

b)
----one high wall unit in each room..." to keep the place comfortable simply isn't well founded,

c)
willing to turn up the temp ----
---
The excitement isn't COPs in the 2s & 3s per-se it's the prospect higher comfort of the higher-R envelope  at  similar upfront cost (and operating cost) of the GSHP-only----
At the warmer edge of climate zone 4 don't be so sure that GSHP installations would always beat a better class ductless on raw efficiency either.

d)
The var-refg//---[as to] Moderately high-R is pretty cheap, when designed in from the start.

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.

Posted By knotET on 10 May 2012 08:39 AM
Thank you Dj,
  'high mass'  to savings?

SAVINGS,  A)  &  B)  - Above what's missing is a two paragraph explanation. - these are for your answer- my curt format:) What I leave out is for others to be  asking about later,  -not misunderstanding your Q, I believe.

A)
the only high mass I was considering was slab in-floor radiant heating - thermal Energy flow Ex:to KWH's.
This was considered with an 88F LW to 82F EW returning from load 'reservoir'-heat-sink, and about a Refrigeration-HtP system called W:W mode GT, or even to include Raypak, Rheem, Aquacal, and POOL PAK, DEKTRON, DESERTAIRE...HW-heating to heat POOLS, too. [high mass HERE: large body of heating capacity, for comfort, -just being heated, and its heat-content allowed to warm people.]
All above was just about OBSERVED, metered  lower-KWH's allowing the GTHP Ex, thermal energy to move INTO that kind of (my thought intended) a 'high-mass' releasing Ex, kinetically from , say a concrete slab floor BUT -at a steady state- of Ex (floor not changing temperature at its surface) to be considered adequately heating a space.Also, technically, as with a mixing valve for bare slab floors in a 74-82F range of those EW settings in radiant to a basement rec or play room (or with a relatively thin floor pad).
-----
B)
 The savings is relative to  ~ 4gpm per HW ton for keeping W:W below an approx. 6F Tdiff
1- At a 104F LW from the W:W mode about 8% to 12% more KWH read 33.4 amps, as a mark here.
2- COMPARED to at only 88 to 92F LW, as the compressor discharge temperature and head pressure is lower, saving KWH's reading just 30.7 amps [edited  - for not having 2) PL55B&G kw, included,- the 28.9 is Forced-Air Heat mode, EA 2340cfm at 71F ]  at that same location and system and conditions switching from low mass flooring at joists to the slab zones.

3- not me, but only that fossil fuels nox gas emissions EPA report of 1993 comparing AirHtP SEER 14 and GTHP 26 SEER at then 34%-42%, "saving" , co-relatively, was accurate about rightly seeing TODAY  IQ Ver-Rfg savings of ~ 12% today's AHT-P (no duct losses)  over nGas and close to 22% SAVINGS by GTHP [ now add HW savings, and add a low recirculated HW for radiant designed-SAVINGS, etc., heat-recovery and within and among multi-zoned GTHP ] which supports a (here in town's forum) AiqHTP saving 22% to 27% over propane while GTiqHP is saving over40%, easily... (add the cooling savings of large loop or open well GTiqHP).

HIgh mass is desirable in a building to a certain degree

Posted By jonr on 12 May 2012 10:15 AM

HIgh mass is desirable in a building to a certain degree

I say "may be desirable". For example, if you have an office building used 8 hours/day, mass may ADD to the energy needed in the morning and extend the btu losses into the evening. On the other extreme, if you maintain a steady indoor temp 24x7, indoor mass doesn't help you either.

Exterior mass is less likely to have downsides but it too "depends on the weather".

Posted By Dana1 on 02 May 2012 04:34 PM
I've only seen a handful of geo-air systems up close & personal.... but many are multi-stage. ---- [can]  minimize wind-chill from tepid air systems in McMansions, a bit tougher in a 1000' Cape style house.

Posted By MikeSolar on 13 May 2012 12:02 PM
knotET, [(kE is fine)] [kE] -brackets
 MS:
I've been around this stuff for 30 years and thought I knew most of the acronyms but I really have a hard time reading your posts [I.E.?- what's the question, or can you just private message, if you want amplification?] 

[2) Gotta answer for the Q' ?]

[3) tangent discussions of the "ducting" etc, mass had little to do eith the real Q; I believe could me given a sign post and send us to more relavant threads to those off-topic writs.]

MS states:
Somewhere back in this thread it was alluded [Politely: just  not by the Q nor the poster] RE: to that thermal mass is not so important in energy conservation with heat pumps .
 [ and that is as a separate thought to me too,  to- ]    and I believe Dana1 said that a masonry wall has a r-3 value.
 
The current measurement scales have a hard time taking into account the thermal lag and flywheel effect that occurs in masonry homes. [((true))] [but I actually touch on how , above. I will decode in another thread on that of yours. Please START a Q'.]

MS states:
I live in a standard 3 story double brick 1800 sq ft home or 1918 vintage and my heating bills are lower than an almost any 1800 sq ft stick frame (nominal R20) home.

Point being
...I can't see how the point of thermal mass being unimportant is true......comments anyone?

Posted By MikeSolar on 13 May 2012 12:02 PM
I live in a standard 3 story double brick 1800 sq ft home or 1918 vintage and my heating bills are lower than an almost any 1800 sq ft stick frame (nominal R20) home. Point being...I can't see how the point of thermal mass being unimportant is true......comments anyone?

Posted By knotET on 13 May 2012 10:55 AM
src="https://www.greenbuildingtalk.com/DesktopModules/ActiveForums/themes/gbt/emoticons/smile.gif">

That "AIR HT P forum" is up in recent posts.

Dj:
Steady-State, mass or not, I read the amps, the data was resounding, 8% to over 10% : the Forced Air GT walked away over the 104deg HW radiant at 4gpm per ton at the gt... like 88Fdeg HW leaving at 4gpm per ton to compare (USED an existing slab for test) to F Air with 72 incoming air. Let's do that analysis at another thread so INITIAL Q's get answered. T's again ! Desiging and all that good info biting is needed.



EDITED for MikeSolar-  "MS"

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.

Posted By MikeSolar on 14 May 2012 07:04 AM
The principal is the same whether ASHP or GSHP. Close up the dT and the efficiency increases. There are two ways to do this on any given house.....reduce spacing or increase mass. The only down side to having high mass in a radiant system is response time, but if the rest of the house is high mass, the temps don't need to fluctuate quickly. We have done a number of off grid houses with radiant stoves, high mass, and the temps rarely vary more than a few deg, even without supplemental heat.

I have seldom seen a reason for low mass radiant except for a builder who is not willing to wait for gypsum cement to dry out properly.

Posted By docjenser on 15 May 2012 01:16 AM

Posted By MikeSolar on 14 May 2012 07:04 AM
The principal is the same whether ASHP or GSHP. Close up the dT and the efficiency increases. There are two ways to do this on any given house.....reduce spacing or increase mass. The only down side to having high mass in a radiant system is response time, but if the rest of the house is high mass, the temps don't need to fluctuate quickly. We have done a number of off grid houses with radiant stoves, high mass, and the temps rarely vary more than a few deg, even without supplemental heat.

I have seldom seen a reason for low mass radiant except for a builder who is not willing to wait for gypsum cement to dry out properly.

The response time is a huge issue in higher efficient buildings, which simply don't loose much heat, and usually have much solar gain.
High mass floors are taking hours to heat up and hours to cool down. They don't give you heat when you need it, and then still heat when you don't need it.
May be you can elaborate how a higher radiant mass will increase efficiency? What matters is the conduction from the pipe to the floor above. Yes, spacing is one way. Gypsum and concrete is a bad conductor, aluminum is much better.

Posted By MikeSolar on 14 May 2012 08:42 PM
Dana1, here is a link to the IEA website on the development of the ASHP and GSHP. The report is a final one detailing best practices and in it you can find some system performance data. There are some ASHPs with COPs approaching 4 and GSHPs with COPs near5.

http://www.annex32.net/field_monitoring.htm

The difference, in my mind, between North American HPs and European units is partly one of holistic design. We tend to take heat distribution by forced air system as a given which they don't do. It is considered lowest common denominator in Europe and the floor heating or radiators is included in the building design from day one. Forced air would generally not be considered because it takes up space, is more noisy and uses more energy to move the heat than heating with water.

The people I know over there use, for example, tubing with a 4-6" spacing in concrete which can result in 30C EWT and a 5-7C dT. Very different practice from here.

Posted By Dana1 on 04 May 2012 12:04 PM
Directing the air flow at windows makes comfort & window-condensation sense for low performance windows with U values north of U0.34, but adds practically zero advantages with U0.25 & lower windows.

Adding a hard-coat low-E storm window over a U0.34-U0.6 double pane adds more comfort that siting the duct under a window, and is one of many efficiency upgrades that is usually more cost effective than extra geo tonnage to cover the heat loss difference for the lower performance building envelope.

With >=R20+walls and <=U0.25 windows even point-source heating works well, and it hardly matters where registers are located, leading to shorter duct runs.

Comfort is just one reason why I prefer highest-efficiency building envelopes over highest-efficiency heating systems.

But clearly, not being in the HVAC biz I have no idea what I'm talking about (ever!) :-)

Posted By joe.ami on 16 May 2012 08:07 AM
"Correct!

The old HVAC model of putting registers directly at windows was due to the fact that windows were valued with R-3 ratings or lower. They had horrid convection. ."

It wasn't bad windows in HVAC lore......Carbon monoxide deaths in the late 19th and early 20th century had people going to sleep and never waking up. People took to sleeping with the bedroom window open to mitigate the mysterious "night death". That is why old steam boiler systems have the radiators at the windows (and are grossly oversized).

Posted By docjenser on 14 May 2012 12:22 AM
Let me clarify this.==== to lower refrigerant pressured and higher COP. Thus radiant floors can be more efficient in heatpump applications than forced air.

Posted By knotET on 18 May 2012 02:27 AM
T's Mike:

-Have to just be cutting to the chase  though.

1)
Put a compressor in between a 35 to 55% over sized air coil, and 55% oversized water coil as is the ratings mentioned, and there is the 4+ in AHP IF the energy exchanged Ex is that much greater at the over-old-standard 1:1 exchanger sizing.

Watch for the Climatemastering 40SEER, just like Hydro-Temp has IQ now... BIG Ex at having BIG HX coils....

Dana 'tis true, those putting 4 ton GT multi-multi stagers in and on 2.1/2- ton heating loads at ~ 15 to 20 above and with then 35- to 37 degre ground loops hitting 3+ gpm/the 4 tons is going to (without variable WILO pumps on the flow center, or grundfos ALPHA's on little ones, etc) get near COP 5's ONLY at the relatively leveraged mega dollar heat exchanger over-sizing. just in coldwater heating up the head pressures can be at (chilly) 85-88 degrees and suctions above 33-34 deg...  getting all that with a single 180-200 watt pump on the loop side. That is why I have metered under 8000 KWH for all HW and Heat and Cooling as well on 3500-3700 what I called 'typical' sub zero homes.
What is so interesting too is they had 80-100 dollar electric bills with propane or oil and now, with UNISULATED basements, still , have budgets under 130-134/month !!! Electric co other charges dropped with the higher kwh usage disproportionately.

2)
Mike: How many (high or low mass) steady-state Ex have you been able to see in , ugh- typical 6" wet-cellulose, wall, r-50 attic, under 35% glass northern homes are there really going to be 4+ AHP's in normal sub zero winters?  I am just asking nicely...

3)
Any 11-btuh to 11.3-btuh/sqft for comfortable 71-72 air temps? I have heard other testimony, but finding 11 btuh/sqft in more efficient HVAC forced air heating: Are there any you see way below that 11/sqft, in homes of  below zero weather, with open stairs to basement to rec area and large vaulted main floors above? About a few homes measured, but 'typical' for good air distribution and comfort is why I would like to compare to others data. (Having high return-air's)

Posted By knotET on 18 May 2012 07:58 AM
Zounds great the heating with 78 water.  Our basement rec slabs hold 71-73 with 75-78 respectively, but 5-6" first 4 runs from perimeter to 14-16" spaced in center low loads.

SOLAR boosted AHtP, as my cousine from Austrailia put it in 1981, were all for him government grant boosted and air to HW heating as well. He saw the pictures of the TETCO 1-ton w:w water heatersunder 40 gal amtrol tanks (inside DX of 4 (?30") columns of little ~2"dia.CuCoils run inside of that water vessel, a Dave Heart design of '79). Cous' is now an Engineer with directing some of the State of Victoria's Solar. Same year'81, an auto vocational teacher in Massilon near the Football Hall of fame (Canton) hybrid-looped in drain-down collectors on a ss tanker vessel -top 6- ft deep. Moist clay soil held temps down sow it was more effectual below 55 water (well water buffer, only). He believed 2) 3x6's delivered over 4500 btuh each on working on 45F waters.  

What do you think if you just raise the air temps through air solar collectors of high heat transfer, very low mass, low collector-heat-storage- capacity Air-Collector for some installed cost efficiency?  Boosting 1/3 at or in about 70% of a compressor (inside-labled) rating of 2 tons ::) then 18kB to ?20kB Ex cold-conditions might be such that we may corollate to solar air additions of near:

(ignoring constants)~  10F x 600 cfmuhmmm..! Then by a peanut Sol-Air-movement.
Seems that's under 1/6hp blowers similar to units re-capturing the heat off of gas-pool-water heaters power-vents (final stage HX pool water flowing heat-recovered) within those experimental add-on FanCoil, thin SS boxes.

200-300 watt blowers for a near 2 kw Solar Booster design of one collector in ? 10- to -10F air intake, getting over to AHP outdoor section ?

Posted By MikeSolar on 18 May 2012 01:17 PM

Not sure what this below means: ..."Boosting 1/3 at or in about ..."

Posted By engineer on 17 May 2012 10:00 PM
Windows are the source of most of our cooling loads, so I'll continue to aim cool air at them, although from well back in the room, circumstances permitting.

Posted By Dana1 on 18 May 2012 05:11 PM

Posted By engineer on 17 May 2012 10:00 PM
Windows are the source of most of our cooling loads, so I'll continue to aim cool air at them, although from well back in the room, circumstances permitting.

The vast majority of the heat gain through windows is radiated, not conducted, even with low-E windows.

Radiated heat passes through cool air just as readily as through warm air-  the net effect of aiming the cool air at the window is negligible, whereas shading that window on the exterior has a huge effect.

Posted By engineer on 18 May 2012 10:05 PM
The lowest you can get, consistent with tolerable visual light transmittance and budget. A load calc lets you model the effects of various values of SHGC. Spending more than a few extra bucks on a window with more favorable coefficients rarely pays back in a reasonable time.

Down here I push for SHGC in the 0.2x range for south and west glass unless there is excellent shade.

Posted By Looby on 18 May 2012 04:46 PM

Posted By MikeSolar on 18 May 2012 01:17 PM

Not sure what this below means: ..."Boosting 1/3 at or in about ..."

Maybe because you don't speak Klingon?

Posted By knotET on 18 May 2012 06:51 PM
isn't he just the cutest thing I wonder if he can read an answer questions at the beginning anyway .. thanks for your real effort mike and the rest what I was doing as I was estimating 1 third of the total load of absorbed heat outside ahp might need at the evaporator through the entire discussion as it was regarding solar boosting at the evaporator mode of the outdoor condensing unit a lot of people just called that condenser units section. it was merely a proposed guess to just see where they ending results would be about cfm . I wonder how many have experienced floor heating of the low mass upper level with less than 80 degrees that's great that you get something like that . Solar boosting has been discussed before I read in. 1980 Seems promising. I really wanted to pull out of the hat some things you may have come across mike so feel free to share with us as you seem to be in a 99 percentile sufficienttly enjoying this thread . I also believe blocks of ice are also part of referring to as the experienced as w.ell as a qualified technician to set things up . experience similar hardships in the humid winter weather belowlake erie. Mike--- I wonder more of what you mean by temperature differential and some other basis for your discussions about that as I read more of your responses I will understand your picture better . 'k-nough4now

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.

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.

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.

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.

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.

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.

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.

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, ...

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

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.

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

Posted By a0128958 on 24 May 2012 04:09 PM
Dana, thanks. Best regards, Bill

105F ... Each year EWT has gotten a little higher,

Posted By engineer on 24 May 2012 11:35 PM
In a cooling-dominated climate an EWT anywhere near or above ambient air temperatures begs the question of why spend $15k on a complicated system of bores, pipe and pumps when the $200 fan motor and blade on a conventional ASHP gets to reject heat into same or cooler heat sink?

I suspect that for geo to be successful in cooling dominated climate EWT must be consistently 5-10*F below design outdoor air temperature. Otherwise EER and COP fall to the point that conventional split or minisplit ASHP make more sense.

An obvious exception (that buys some of my steak and beer) is beachfront homes whose blown sand and salt air dramatically shorten life of ASHP outdoor units.

Posted By a0128958 on 25 May 2012 12:27 AM

Posted By engineer on 24 May 2012 11:35 PM
In a cooling-dominated climate an EWT anywhere near or above ambient air temperatures begs the question of why spend $15k on a complicated system of bores, pipe and pumps when the $200 fan motor and blade on a conventional ASHP gets to reject heat into same or cooler heat sink?

I suspect that for geo to be successful in cooling dominated climate EWT must be consistently 5-10*F below design outdoor air temperature. Otherwise EER and COP fall to the point that conventional split or minisplit ASHP make more sense.

An obvious exception (that buys some of my steak and beer) is beachfront homes whose blown sand and salt air dramatically shorten life of ASHP outdoor units.

My friend gave up last year, and instead of 'refurbishing' his borehole field, he cut the pipes and had ASHPs put it.  With some of the boreholes within 10' of each other, with the prospect of re-drilling these, at $1K each for 300' depth, and with the strong probabiliy of adding more boreholes, again at $1K each, along with reconnecting up the loop pipe, the cost was just too much compared to simply saying 'goodbye' to the borehole field and putting in ASHP units.

The heat here is an absolute killer.  And, the ASHP guys easily can come in, in one afternoon, and have you all fixed up.  Actually, the 'Christmas season' has already started for the ASHP guys.

I feel lucky.  My EWT doesn't yet get above 85°, no matter how hot it gets.  But I'm watching it over the next few years.

I don't know what design outdoor air temperature is for Dallas.  I do know record temperature is about 112° F. 

P.S., my visitors last year for the home energy tour asked why my grass was still green in my front yard, where I have 8 wells with a total of about 1 mile of pipe.

Best regards,

Bill

Posted By a0128958 on 25 May 2012 12:27 AM

Posted By engineer on 24 May 2012 11:35 PM
In a cooling-dominated climate an EWT anywhere near or above ambient air temperatures begs the question of why spend $15k on a complicated system of bores, pipe and pumps when the $200 fan motor and blade on a conventional ASHP gets to reject heat into same or cooler heat sink?

I suspect that for geo to be successful in cooling dominated climate EWT must be consistently 5-10*F below design outdoor air temperature. Otherwise EER and COP fall to the point that conventional split or minisplit ASHP make more sense.

An obvious exception (that buys some of my steak and beer) is beachfront homes whose blown sand and salt air dramatically shorten life of ASHP outdoor units.

My friend gave up last year, and instead of 'refurbishing' his borehole field, he cut the pipes and had ASHPs put it.  With some of the boreholes within 10' of each other, with the prospect of re-drilling these, at $1K each for 300' depth, and with the strong probabiliy of adding more boreholes, again at $1K each, along with reconnecting up the loop pipe, the cost was just too much compared to simply saying 'goodbye' to the borehole field and putting in ASHP units.

The heat here is an absolute killer.  And, the ASHP guys easily can come in, in one afternoon, and have you all fixed up.  Actually, the 'Christmas season' has already started for the ASHP guys.

I feel lucky.  My EWT doesn't yet get above 85°, no matter how hot it gets.  But I'm watching it over the next few years.

I don't know what design outdoor air temperature is for Dallas.  I do know record temperature is about 112° F. 

P.S., my visitors last year for the home energy tour asked why my grass was still green in my front yard, where I have 8 wells with a total of about 1 mile of pipe.

Best regards,

Bill

Posted By Dana1 on 25 May 2012 12:33 PM
l
 The 1% number for Dallas is 98F, so I think you have a ways to go before it underperforms conventional 1 & 2 stage ducted air source AC.

Posted By robinnc on 25 May 2012 10:14 PM
Dana......to get the price down to 6K/ton up there.....get ride of the unions     :)

Posted By Dana1 on 25 May 2012 04:28 PM
Chris- Clearly that would be a super-bargain, in my neighborhood! (Even your high-bid of $30K for 4-tons would beat the local average here by about five grand, but it's likely that SOME 4T system here would hit that number.)

You probably took the 30% tax credit, bringing the out-of-pocket to about $16K before other state & local subsidies? What was the final post-subsidy cost?

Posted By joe.ami on 29 May 2012 12:01 PM
"We leave the resistance breakers off all the time. could have gone with 3 or 3.5 ton, but Man. J said 4T...."

To be clear, manual J didn't say 4T, the system designer did. That you never employ auxiliary would suggest you are significantly oversized if you are in a northern climate and therefore could have purchased a smaller unit for thousands less.
All designs are compromises, inst vs op cost, heating vs cooling driven etc. Many designs are okay when informed choices are made. Simply wanted to remind that aux is not always the antichrist it is made out to be.
j