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No geothermal manufacturer will market an area with natural gas. Natural gas is the cheapest way to heat a home.
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The OP's drawings actually show 2,200 square foot per floor.Originally Posted by tedkidd
One might expect ~1,300 therms as a seasonal heating requirement for a 4,400 square foot residence with 550 square feet of glass.
That's about 15,000 maximum kw-Hrs for a conventional moderate-efficiency 60,000 BTU/hr heat pump in a 6,000 Cooling Degree Day region.
at $.08 / kW-Hr ... $1,200 / heating season. GEO might save 40% or $450 per year.
Designer Dan __ It's Not Rocket Science, But It is SCIENCE with Some Art. _ _ KEEP IT SIMPLE & SINCERE ___ __ www.mysimplifiedhvac.com ___ __ Define the Building Envelope & Perform a Detailed Load Calc: It's ALL About Windows & Make-up Air Requirements. Know Your Equipment Capabilities
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IF - Good - Building / Sealing Practices are followed -
With Winter infiltration limited to 0.30 ACH & 35,000 cubic foot volume =10,500 ft^3/ hr=~170 CFM, heating capacity required would be ~ 52,000 BTU/hr...
Total energy for 5,000 Heating Degree Day season is reduced to 950 therms = ~ $ 950 @ $0.08 / kw ... GEO savings for a more Moderate Winter = $380 annual
Columbus OH
http://www.wunderground.com/history/...q_statename=NA
Last edited by dan sw fl; 09-09-2012 at 10:00 AM.
Designer Dan __ It's Not Rocket Science, But It is SCIENCE with Some Art. _ _ KEEP IT SIMPLE & SINCERE ___ __ www.mysimplifiedhvac.com ___ __ Define the Building Envelope & Perform a Detailed Load Calc: It's ALL About Windows & Make-up Air Requirements. Know Your Equipment Capabilities
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Energy Star, I would be glad to send you copies of the quotes on both the air-to-air (Carrier) and geothermal (Waterfurnace) systems. I stand by my earlier post that the two systems are comparable in cost when the 30% tax crdit is factored in.
In case you haven't read the earlier posts, the geothermal is pump-and-dump. The water well is not included in the cost because I have to drill a well for domestic water needs anyway.
As for cleaning the heat exchanger, I plan to do that myself. I rarely hire someone to do home repairs and maintenance, preferring instead to handle myself. I guess I'll have to assign a value to my time....
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If you are you licensed by Water Furnace (Example) if you clean that heat exchanger yourself.......you may just void the warranty!
My email is my profile.
I would price out a variable frequency drive water pump.
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Why wouldn't someone use a small plate HX as "insurance" and really extend the life of the heat pump with CLEAN, Closed loop ?
http://www.pexsupply.com/Hydronic-He...eries-5-822000
Designer Dan __ It's Not Rocket Science, But It is SCIENCE with Some Art. _ _ KEEP IT SIMPLE & SINCERE ___ __ www.mysimplifiedhvac.com ___ __ Define the Building Envelope & Perform a Detailed Load Calc: It's ALL About Windows & Make-up Air Requirements. Know Your Equipment Capabilities
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Ted accused me of being emotionally committed to geothermal. I am a Mech. Engr. (by training although I am not employed in the field). I also have been in sales for 30+ years. Anyone who has dealt with engineering types in a sales situation knows that they do not make decisions based on emotion....it's all about the numbers.
Now with the back and forth between you and Dan, I think the correct answer is somewhere between you two.
My last house was about 3,400 sq ft. It was a relatively energy efficient design...2 story with partial basement, rectangular shape with, 2x6 walls and above average tightness (documented with a free blower door test thanks to the local electric co-op). I kept records of all electric and LP gas usage over the 25 years I lived there (yep, I plead guilty...I'm anal as hell!). We kept the thermostat at 66-67 degrees in winter and 75-77 degrees in summer.
Of course, every winter is different but my best estimate is that it was costing me about $1,200 in recent years to heat and cool and about $350 to heat water. This was based on a moderately efficient Carrier HP with LP backup. One of my complaints about this setup is that the control logic called for the LP to finish the heating cycle after the defrost was complete...so, the LP furnace ran a lot when the HP could have handled the load...Grrrr! I called Carrier and they offered no alternative.
Had we kept the thermostat at 70-72 in winter and 72 or 74 in summer, I would guess that our total heating/cooling costs would have been close to $1,500 to $1,600 per year.
As for your calculations, Dan, you are forgetting the higher cost of backup heat when temps are too low for the HP and also during defrost cycles. Also, you used $ .08 per KwH....I wish I could buy electricity for that. In my last house I was using about 350 gallons of LP just for backup heat. If I had electric backup, the cost would have not been much different at $2 per gallon for LP and $ .10 per KwH for electric.
So, I think I probably am looking at savings of $500 easily with geothermal in my new house (heating/cooling and water heating. Since the original cost is about the same, it's an easy decision for me to opt for the geothermal.
One of the geothermal companies I got a quote from installs a seperate meter on EVERY ONE of their installations. The reason is obvious...it provides hard evidence of what their customers are spending for heating and cooling. If they exagerate savings it would catch up with them real quickly.
One last comment on Energy Star's post where he said that no geothermal mfr. will market an area with natural gas....here in the Midwest, most of the people living in the cities and villages have NG available. However, no one living in the rural areas have access to NG. So, there are many geothermal installations in the rrural area and virtually none in the cities. Obviously, any marketing of geothermal is intended for those people who can't get NG.
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I'll check on the warranty issue....
I've already made the decision to use a variable frequency pump.
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Tedkidd and energy star, how many geothermal systems have you installed/sold in the past two years?
If that number is zero then you obviously don't know the differences between air source and geo. I started geo aout 4 years ago, really got into it about 3 years ago and realized the HUGE differences that are sometimes intangible benefits. Can you promise your fancy carrier Invertor air source will last 25 years out in the elements? Geo HAS stood up to the test of time and has efficiencies up to 5.3COP and 41EER.
And to energy star, we routinely market geo to area with natural gas because it is not the most efficient. If natural gas was the most efficient then why do we all talk aout heat pumps in dual fuel operation. I just installed my first WaterFurnace variable capacity in a gas area about two weeks ago. They wanted it because of things that had no relation to payback. Now in Batmans case there is an instant not even a 5 year payback that I often shoot for when designing a system.
Batman71 if you would like I can also look at those proposals for you since I am a WaterFurnace dealer. My email is Travis at my username dot com
If you would like to see a three ton system operate it can be viewed here. 3 Ton active energy monitor
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Sky it seems to me you have been to too many sales classes at Water Furnace. I have put in many systems, all kinds and it is a financial loser in my opinion. If you consider all costs. AND you don't actually install them yourself do you, you have installer's correct? You ar coming at this from the paper end not an applied end 15 years down the road.
ps: I used to pick the Water Furnace regional rep up at the air port to bring him to our shop, he is the one that told us about how water furnace will not market in an area with nat gas.
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God Speed, Jim. We'll miss you - 2-26-23
About 130 bucks less with electric aux heat over LP.As for your calculations, Dan, you are forgetting the higher cost of backup heat when temps are too low for the HP and also during defrost cycles. Also, you used $ .08 per KwH....I wish I could buy electricity for that. In my last house I was using about 350 gallons of LP just for backup heat. If I had electric backup, the cost would have not been much different at $2 per gallon for LP and $ .10 per KwH for electric.
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I HAVE seen 40 year old ashp's still operating in Fairport and honeye falls. Last year I replace an 8 year old pump n dump in Victor Ny. And this was a Hydron Module! So 25 year arguments wear dentures.
The one advantage of pump n dump that I see, ground loop have huge variability wrt return temp, which can drop efficiency to well BELOW that of air source well before spring. Is risk of higher maintenance and reduced longevity recovered by lower cost and higher efficiencies? Too many "it depends" to honestly say.
Batman, there was no accusation, why is there shame in having emotion play a part in decision making? You delude yourself if you think engineers make decisions without emotion, and that is the only dangerous assumption. There is a lot of risk in this decision that you simply will not be able to put a scale to, so built intuition, emotion, is going to have a big vote at this table.
I've seen sprayfoamed geo houses with HUGE bills. While the argument that water source multi exchange (vs dx) is guaranteed, or even consistently delivers electricity savings in real world I find highly doubtful. And bringing coal plants into the discussion, these are both emotional to me.
Dans numbers are getting much closer to what I'd expect from a good model. From all his posts my intuition tells me he is very good at what he does. Keep in mind, when you take GOOD models and compare to actual they tend to be high. Real world? The cost is what I'd expect from an average 1990's build with basic "high efficiency" equipment.
Sky, you probably sell a lot of geo, so you have skin in this argument. But seeing something go in and tracking results seem to be very different things in this marketplace. Of all the installs you've 'seen', how many have you analyzed the use of? A homeowner telling you "wow our bill is really low", or "January was half of last year" is not data, it's anicdote.
With all the parts of this decision that emotion will have to participate, why do it there?
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Ted, I agree that intuition oftentimes has to come into play in the decision, but intuition and emotion are two different things.
You wrote..."Keep in mind, when you take GOOD models and compare to actual they tend to be high." Your statement was contradictory. If the model is good, it WOULD accurately predict actual results. If it doesn't it's not a GOOD model
Lastly, not sure how the coal fired plant issue has anything to do with emotion. If there is a strong likelihood of stronger EPA emission controls, then we can LOGICALLY (not emotionally) conclude that the cost of electricity from coal fired plants will go up. There was no mention of whether I am for or against stronger EPA controls, an issue which could perhaps be regarded as an emotionally driven.
Lastly, I agree with you regarding anecdotal evidence....drives me crazy. However, your statement that you've "seen 40 year old ashp's still operating in Fairport and honeye falls" is just that...anecdotal evidence. We've all probably seen 50 year old rifrigerators still operating. If it happened to be a Frigidaire, that doesn't mean every Frigidaire is expected to last 50 years. Similarly, I replaced a 17 year old Carrier ASHP on my last house. I was not pleased at all with 17 years of service life but perhaps that is the norm.
Let's not open the DX vs water loop debate or we'll be at this ad finitum!
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With regard to natural gas vs. HP (ASHP or Geothermal) I offer the following....
Assuming a 90% efficiency, a gas furnace will deliver a heat at a cost of about $ .97 per therm assuming a cost of $9.00 per thousand cubic feet which was about what Ohio consumers paid last winter. If electric is $ .10 per KwH and the HP has a COP of 3.0 the cost per therm will be about the same as for the NG example. Obviously, a COP of 4.0 or better will make the HP considerably more cost effective. This ignores maintenance costs and original equipment costs.
In the winter of '06/'07 Ohioans were paying about $15.00 for NG! At that cost and electreic still at $ .10 per KwH, the breakeven COP is only 2.0. In other words, at a heat pump COP of 2.0 or better, the HP has lower cost to deliver the same energy.
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I see we're I failed. My simantics are poor, misleading. Sorry.
From my perspective inside the industry there are bad models, good models, and true models. Typically true models occur when you do a very accurate model and "true" it to historical consumption. Truing nearly always means DOWN to actual consumption, an average of 25-35%.
With an unbuilt house you can't have a true model, and good is pretty rare but really the best you can expect.
Also, your math on delivery is way too simplistic. Cop depends on a lot of factors that are continuously shifting, as does furnace efficiency. As just a simple example, what delivery efficiency will the hp deliver at 40f? At 10f? How much of the seasonal btu will be delivered at those two temps? How will duct design impact delivery at different flow? All of these things can have big swing in impact. Hindsight seems the only way to see it. I think a year after moving in this may become apparent.
Same on the gas furnace (which can typically deliver MORE eff as temps drop, as the hp goes the other way which makes hybrids a really nice option).
Finally, the plant delivering electricity to your ashp's will be the same as the plant delivering to your gshp.
This has been an interesting thread.
With the New modulating GS units that's probably how I'd lean. Many deciding factors would be emotional. I like cool technology. If carriers has load matching features (ala infinity systems) the decision would be certain. I wouldn't want to mow around an outdoor unit, and with the tax credit it might actually be cheaper than GREENSPEED. built in dehumidification would be an expensive option these systems have that i'd love. No weight would be because I'd be expecting much incremental energy savings, because I wouldn't be. If I can take Liz to dinner on the savings a few times, that's gravy.
I would definitely be testing water hardness, and hope for 17 years of operation.
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What is Good?
A GOOD Load model should be < 15% overdesign.
A GOOD Energy estimate is < 25% over the actual costs.
Accurate is a Relative term. "Exact" absolutely Never applies.
Science gets one a VERY LONG way to a problem resolution - -
but, with many variables ( equipment selection, location/house orientation, weather & owner lifestyle /preferences, one's effort to refine a model)
being somewhat indeterminant,
Judgment (art, experience, NOT emotion ) will Always come into play in Any design.
No exact answers exist in HVAC - there are Always at least 6 ways to solve an issue.
What is GOOD ?
... it is a final set-up where a customer is satisfied > 85% of the time.
Designer Dan __ It's Not Rocket Science, But It is SCIENCE with Some Art. _ _ KEEP IT SIMPLE & SINCERE ___ __ www.mysimplifiedhvac.com ___ __ Define the Building Envelope & Perform a Detailed Load Calc: It's ALL About Windows & Make-up Air Requirements. Know Your Equipment Capabilities
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I actually have only been to training on products, never a geo sales class. I just firmly believe in the technology since every customer we have put it in so far is incredibly happy they didn't go with AS heat pump or gas etc. and the changeouts we have done have all been so happy with the geo they put in 20 years ago that they did it again.
Maybe 15 years ago WF did not market to gas but they do now and gas is at 5 year lows. WaterFurnace now has specific dual fuel pricing guides to compete against air source and either propane or NG as a backup. Yes is mostly for LP but it's a cost effective add on solution for somebody that has a newer gas furnace but wants the best.
I just so often see the argument to only do geothermal if the numbers logically work out which they do in this case, yet when I bought my high end SUV I bought it for its features, not because it was more fuel efficient so why do so many treat geo in a cost savings only manner and even still the only touch on the parts of the system that have not cost savings were its nice not to have to mow around it. That's what needs to be brought up more. Plus what were energy costs 20 years ago, look forward 10+ years and you know energy will not cost the same. Here in Oregon we rate houses with an Energy Performance Score and an Invertor air source rates the same as a 9.0 HSPF air source while a geo rates much higher. So resale value will also be recouped for many reasons. Like I said, no sales classes just customers that are happier than my XL20i customers and Invertor heat pump customers.
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Sky, let me get this straight. Keeping the utility bill out of the equation (cause it's not about that!).
If you walked in the front door of a house, are you saying that you could tell the difference between a geo thermal system and a top of the line 20i from comfort alone? (or even a 16i) As you said, you GT customers are happier, is that just from a mower stand point or the 10 year warranty when the 20i is twelve?
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All I can say is I guess my customers are different than yours. I had a customer with a $40 a month electric bill switch from an 8 year old heat pump to geo, I had anger customer delay a car purchase to be able to afford his geo system first even though the numbers showed a 9HSPF would have been a better investment than geo. I did not lie to or falsely promise, these customers came to me looking for what geo offers. They wanted zero electric bill because that's what was important to them, the wanted the luxury of never hearing or looking at an outdoor unit because they had minimal land but enough to drill. I have customers that buy because even though it is not cost effective they are more self sufficient with this type of system and often no need for backup heat(depending on design)
Now I understand that the above is not the norm, but in my area that's how about 30% or more of my customers feel. So if there is a customer looking at payback I'm saying you need to assign cost savings to things that you want as a consumer even though they don't save you on utility bills. No outdoor unit is huge to many, even with 2 acres so many homeowners in my area with 4,000 half million dollar homes hate ANY outdoor unit location. And from my car examples below I am saying things like heated seats never save you any gas(they add to the cost of fuel) but how many people flock to by them. Geo has these same benefits and I am saying that there are benefits associated with that, therefore it deserves better numbers.
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So I was correct, you can't tell. To be self sufficient, do you offer or up-sell generators? Enough of this thread for me. We have lots that cost 150k to 2 Million around my home. I just don't believe in the whole Geo game. I will say it has been brought to my attention that the new Geo systems that use no water have me interested in this new latest technology. That said, I would still be reluctant to purchase for my home. I will say I admire your enthusiasm in the HVAC biz!, and enjoy talking on this forum with you.
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