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Geothermal In North Central Florida vs Mini-Split AC
Last Post 02 Jul 2013 10:20 AM by joe.ami. 35 Replies. |
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engineer
Veteran Member
Posts:2749
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| 17 Dec 2009 01:25 AM |
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I think of minisplits as excellent for retrofitting AC into ductless northern houses, but not so good for new construction in cooling dominated climates. My reasoning is that a ducted central system (whether air source or geo) offers best flexibility in that it can route small amounts of air into bathrooms, closets etc. Minisplits don't handle that well. |
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Curt Kinder <br><br>
The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is - Winston Churchill <br><br><a href="http://www.greenersolutionsair.com">www.greenersolutionsair.com</a>
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DaveS
New Member
Posts:87
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| 17 Dec 2009 10:17 AM |
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Posted By geome on 12/16/2009 6:06 PM
Dave, when considering payback, are you looking at (geothermal cost - alternative system cost)/the incremental savings geothermal would provide? I would factor in an estimate of annual electric rate increases to the denominator above. I would use figures after the tax credits as well. 30% for geothermal (no cap) and perhaps $1,500 max for the alternative system. Check with your tax adviser since I am not a tax professional.
When I started the process I was leaning very heavily toward Geothermal, I almost demanded it, but as time went on I found that it might work well, but there are no guarantees. I could not live with that. We only one shot at getting it done right and it is too expensive to take the risk of having the performance less than expected. I am working with a build team made up of a LEED person, a sustainable architect and a GREEN builder and the overall consensuses is Geothermal is not the right choice for our project.
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Bill Neukranz
Veteran Member
Posts:1103
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| 17 Dec 2009 10:48 AM |
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Posted By DaveS on 12/17/2009 10:17 AM ... I was leaning very heavily toward Geothermal, ... but as time went on I found that it might work well, but there are no guarantees. I could not live with that. We only one shot at getting it done right and it is too expensive to take the risk of having the performance less than expected. I am working with a build team made up of a LEED person, a sustainable architect and a GREEN builder and the overall consensuses is Geothermal is not the right choice for our project.
Wow.
If your advisors are supportive of geothermal HVAC but are not familiar with a well qualified geothermal HVAC professional who they have confidence can get it right, and thus fear the risk is elevated of not getting it designed/installed correctly going with someone unknown, then this concern, leading to a conclusion to not proceed w/ geothermal, I can understand.
But if instead it's because your advisors are not comfortable with or have a bias against geothermal HVAC, and it's thus more of a CYA or focus on least agressive actions to minimize (their) liability risks (in case you end up unhappy with HVAC performance), then you're clearly making a sizable mistake, in my opinion.
Take a look at this web site: http://www.enerjazz.com/house/index_house.htm .
Best regards,
Bill
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Energy reduction & monitoring</br>
American Energy Efficiencies, Inc - Dallas, TX <A
href="http://www.americaneei.com">
(www.americaneei.com)</A></br>
Example monitoring system: <A href="http://www.welserver.com/WEL0043"> www.welserver.com/WEL0043</A>
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gspike
New Member
Posts:21
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| 17 Dec 2009 04:06 PM |
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Hey, the guy did his research and decided it wasn't for him.
He lives in Florida, for all we know, he could have an average ground temp of 74, heavy clay soil and eight plus months of cooling.
Sure it can be done, but do a little math and see if it wouldn't scare you off before you judge the guy.
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DaveS
New Member
Posts:87
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| 17 Dec 2009 04:17 PM |
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Posted By gspike on 12/17/2009 4:06 PM
Hey, the guy did his research and decided it wasn't for him.
He lives in Florida, for all we know, he could have an average ground temp of 74, heavy clay soil and eight plus months of cooling.
Sure it can be done, but do a little math and see if it wouldn't scare you off before you judge the guy.
Thanks,  |
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jerkylips
Basic Member
Posts:359
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| 17 Dec 2009 05:03 PM |
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Posted By DaveS on 12/17/2009 10:17 AM
Posted By geome on 12/16/2009 6:06 PM
Dave, when considering payback, are you looking at (geothermal cost - alternative system cost)/the incremental savings geothermal would provide? I would factor in an estimate of annual electric rate increases to the denominator above. I would use figures after the tax credits as well. 30% for geothermal (no cap) and perhaps $1,500 max for the alternative system. Check with your tax adviser since I am not a tax professional.
When I started the process I was leaning very heavily toward Geothermal, I almost demanded it, but as time went on I found that it might work well, but there are no guarantees. I could not live with that. We only one shot at getting it done right and it is too expensive to take the risk of having the performance less than expected. I am working with a build team made up of a LEED person, a sustainable architect and a GREEN builder and the overall consensuses is Geothermal is not the right choice for our project.
I can relate, I'm kind of in the same boat. Initially I was going to do a stick-framed house with 2x6 16oc w/PU foam. Then I found out how much PU foam costs.. yikes. did TONS of research, decided on SIPs and an ICF basement. Geothermal was a no-brainer in this region. With the tax credits & stuff, payoff will probably be 5-6 years. Initially I wanted to do PV solar. I REALLY wanted to do that, but after reading & reading & talking to people who know more than I, I decided that I can't justify it. Even with the tax credits, incentives, etc., it would be around 10 grand out of pocket, & would save me 500-600/year. Just can't do it. Solar thermal is a better payback, but with geothermal and a DSH, it reduces the effectiveness. It's just my wife & I, not high-volume water users, so we had to rule that one out. Now the plan is to wire the house for solar so that it's easier to do later. I'm looking at drainwater heat recovery system, but it's kind of the same thing. If we have a DSH & buffer tank, how much MORE are we going to save? The other big one is 6" SIPs vs 8". Probably going to go with 6 get the best windows I can, but haven't decided completely. Anyway, you need to do what's right for you. If all of these answers were easy, everyone would do everything. Right? |
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geome
Advanced Member
Posts:987
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| 17 Dec 2009 06:55 PM |
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Posted By DaveS on 12/16/2009 5:25 PM
If you are in Florida than I believe it may be much longer than 15-20 years to get a payback. I ended up, switching to a Daikin mini-split http://www.daikinac.com/residential/home.asp. So I guess I'm saying my conclusion was it wasn't practical, in my opinion, to go with Geothermal in this area. This quote, regarding geothermal possibly taking "much longer than 15-20 years to get a payback" was the reason I asked about the payback calculation. Sometimes calculation errors can be made leading to the wrong conclusion. I'm not saying that is the case here. We simply do not know one way or the other. The OP seems convinced not to go geothermal for several reasons, and that's perfectly fine. Just wouldn't want other people in Florida not investigating geothermal without calculating the payback for themselves.
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| Homeowner with WF Envision NDV038 (packaged) & NDZ026 (split), one 3000' 4 pipe closed horizontal ground loop, Prestige thermostats, desuperheaters, 85 gal. Marathon. |
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engineer
Veteran Member
Posts:2749
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| 17 Dec 2009 11:05 PM |
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I have no issue with properly executed ROI / payback period calculations. A major unknown in those is future cost of energy.
I do take issue with the idea that geo is somehow risky... "one chance to get it right...no guarantees" as if every geo system is a crap shoot. That is incorrect. There appears to be a bevy of experts engaged in Dave's project, none of whom seem to know geo.
Parts of Florida do in fact have 74+ deg ground temps and 8+ months of cooling, and worse yet than clay, dry sandy soil...but proper system design overcomes all of that, though it may not be cost effective in every situation. |
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Curt Kinder <br><br>
The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is - Winston Churchill <br><br><a href="http://www.greenersolutionsair.com">www.greenersolutionsair.com</a>
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DaveS
New Member
Posts:87
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| 18 Dec 2009 11:28 AM |
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Posted By jerkylips on 12/17/2009 5:03 PM
Posted By DaveS on 12/17/2009 10:17 AM
Posted By geome on 12/16/2009 6:06 PM
Dave, when considering payback, are you looking at (geothermal cost - alternative system cost)/the incremental savings geothermal would provide? I would factor in an estimate of annual electric rate increases to the denominator above. I would use figures after the tax credits as well. 30% for geothermal (no cap) and perhaps $1,500 max for the alternative system. Check with your tax adviser since I am not a tax professional.
When I started the process I was leaning very heavily toward Geothermal, I almost demanded it, but as time went on I found that it might work well, but there are no guarantees. I could not live with that. We only one shot at getting it done right and it is too expensive to take the risk of having the performance less than expected. I am working with a build team made up of a LEED person, a sustainable architect and a GREEN builder and the overall consensuses is Geothermal is not the right choice for our project.
I can relate, I'm kind of in the same boat. Initially I was going to do a stick-framed house with 2x6 16oc w/PU foam. Then I found out how much PU foam costs.. yikes. did TONS of research, decided on SIPs and an ICF basement. Geothermal was a no-brainer in this region. With the tax credits & stuff, payoff will probably be 5-6 years. Initially I wanted to do PV solar. I REALLY wanted to do that, but after reading & reading & talking to people who know more than I, I decided that I can't justify it. Even with the tax credits, incentives, etc., it would be around 10 grand out of pocket, & would save me 500-600/year. Just can't do it. Solar thermal is a better payback, but with geothermal and a DSH, it reduces the effectiveness. It's just my wife & I, not high-volume water users, so we had to rule that one out. Now the plan is to wire the house for solar so that it's easier to do later. I'm looking at drainwater heat recovery system, but it's kind of the same thing. If we have a DSH & buffer tank, how much MORE are we going to save? The other big one is 6" SIPs vs 8". Probably going to go with 6 get the best windows I can, but haven't decided completely. Anyway, you need to do what's right for you. If all of these answers were easy, everyone would do everything. Right? Right. Sad, but true; if the answers were easy and we were all made of money we would do everything. So we cherry pick what we feel is best in our particular situation and hope the world doesn't end on December 21, 2012.  |
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psaprop
New Member
Posts:5
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| 31 Dec 2009 08:23 PM |
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I currently have a 4000 square foot home with two geothermal heat pumps (5 ton and 3 ton) that were installed 30 years ago. They have been great. My average electric bill here in South Louisiana has been about $200/ month for the last year. The systems are open loop and water quality has finally caught up with me. In researching replacement systems I also leaned toward geothermal but with a closed loop.
Interestingly, the equipment prices (I'm looking at either the new Rheem split units or WaterFurnace) are in line and the pricing I have from my water well guy to dig the vertical holes is reasonable. I know the cost of the pipe (I'll need about 4800 feet). With all of this known, I can't get the cost of installing the piping (heat fusing, manifolding, etc.) by someone knowledgeable in this area at a price that makes sense. Most installers around here are using a Texas well driller who charges $2,000 per hole for a 250' hole for a closed loop to the exterior unit. I realize there is some expertise involved but the cost for the basic well drilling and pipe locally is $8,000 vs. $18,000 for turnkey. The Rheem units have the pumps built in ao an elaborate flow control should not be required. That $10,000 difference is pushing the total cost out of range. The prices quoted for a total system are equally alarming -- $7,500 - $8,000/ton. That would be $60,000 to replace my units with GHP vs. $18,000 for 16 SEER+ air to air heat pumps from reputable manufacturers.
Is this what others are seeing or am I sitting here in never never land?
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engineer
Veteran Member
Posts:2749
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| 31 Dec 2009 10:21 PM |
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If you got 30 years out of open loop units, why not just do it again? The cost should be a small fraction of all that drilling and the new units will almost certainly be more efficient than the 30 year old units.
Better yet, look at what you might do to reduce load - retrofit some efficiency improvements. I wonder if 8 tons is really needed - has a load calc been run? |
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Curt Kinder <br><br>
The truth is incontrovertible. Malice may attack it, ignorance may deride it, but in the end, there it is - Winston Churchill <br><br><a href="http://www.greenersolutionsair.com">www.greenersolutionsair.com</a>
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psaprop
New Member
Posts:5
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| 01 Jan 2010 04:36 PM |
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To Engineer:
Thanks for the reply. I may go with open loop again but I wanted to do it right the second time around. The old GHP were less sensitive to impurities, and with the government pushing the manufacturers to achieve higher and higher SEER ratings, quality has reportedly suffered. I need to determine if I really will reduce my energy consumption with a less than optimum GHP installation. A new energy audit of my home is also in order to see where foam can be applied or added blown fiberglass.
Anyway, evaluating all of the options has been a real challenge as I'm sure it is for everyone.
The cost of any of the high efficiency options does not lend itself to seat of the pants decisions. |
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joe.ami
Veteran Member
Posts:4377
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| 24 Jun 2013 08:50 AM |
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Posted By braelecarmack on 24 Jun 2013 04:12 AM
I don't know if this is going to work well out for you as it did to ours, but I'd say Split ACs. For me, they are more energy efficient, helping to conserve both energy usage and the money that would otherwise be spent on it. They are easy to install and use, long lasting, and offer benefits such as the ability to create different temperature control zones within the home. 
Really? 3.5 years later? I think this ship's long since sailed. |
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Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort! |
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agagent3
Basic Member
Posts:134
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| 28 Jun 2013 01:32 PM |
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At one time I was sure that GSHP was the way to go but now have some doubts from some of the studies I have viewed. There is a lot to testimonial evidence that says it's the greatest thing since sliced bread. I for one want the hard data. There should be a straightforward, analytical process to aid in making an informed decision. I would like to see an economist, environmentalist and engineer sit down together in order to come up with such a decision aid. I envision that one would want the capability to change variables such as energy costs, inflation rate just to name a few. I would also like to see a sensitivity table incorporated based on energy costs and fixed investment. Or maybe someone has already done so? |
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jonr
Senior Member
Posts:5341
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| 28 Jun 2013 04:42 PM |
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Some of the geo manufacturers have software that does most of what you want. You can change the options and get a good idea of sensitivities. |
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joe.ami
Veteran Member
Posts:4377
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| 02 Jul 2013 10:20 AM |
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"At one time I was sure that GSHP was the way to go but now have some doubts from some of the studies I have viewed."
It's interesting to me that furnace manufaturers and air source guys do not share the burden of proof some wish to assign geo. Most studies out there are speculative and many people don't buy geo just to go green (although the greenest minded geo advocates suggest that geo is the way to go anyway because the grid is changing to renewable).
Even if a study supports geo and touts Doc-Jenser-like efficiencies in real time, people will continue to be dissappointed if they don't put contractor vetting above all else. This again is true in all technologies. People treat a comfort system as an adendum to their new house and prioritize marble counters, then wonder why they can't get even temps upstairs and downstairs from their code minimum (lowest bidder) duct system.
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Joe Hardin
www.amicontracting.com
We Dig Comfort!
www.doityourselfgeothermal.com
Dig Your Own Comfort! |
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