I'm posting this question b'cos I want to plan ahead what to replace my 15 year 64K btu 80% natgas York furnace with. A/C is 4T, 12 seer.
My system is working now but in a few years when it need to be replace I want to be ready to know what I want.
I know a few friends who had to replace their system who is 17-18 years old. Most of them just replace what ever their local contractor ( usually joe around the corner ) recommend under emergency situation.
My house is 2 story 2100sf. Basement another 1200sf ( unfinish ).
Wall r13, attic r46.
Temp here is 15F-90F + a few colder winter days &  hotter summer days.
I have solar that provide 90+% of my electric usage. While doing an energy audit for my solar rebate application, the engineer told me to look into Geo or Dual-fuel for future replacement.
I like my thermostat set at 73F in winter & 76F in summer.
My most recent gas bill is @ $1.35 per therm delivery & all other charges included. My average gas uasage is 850-920 therm per year base on my pass 5 years history. 
Electricity is $0.172 per kWh.  Bill is $3.00  a month ( customer charge ) so far since solar.
I have seen a geothermal open loop system in my area. They don't have nat gas. Like them I have a well for irrigation.
If I do go geo, all I need is drill another well for dump( return). But is it worth the while considering I have natural gas.
So, what system is more suitable for me here in central/south NJ? GEO or Dual-fuel or a 2stage 95% natgas force-air furnace or anything. 
All input are greatly appreciated. Thanks 
 
Jadi

Posted By jonr on 27 Mar 2011 08:22 PM
At those prices, geo and nat gas (with a modern furnace) are about the same price - and that's not counting pumping costs or the initial install.

Posted By GBT_energy_freak on 28 Mar 2011 11:12 AM
I hate to do that but I seriously suggest that you take a gender in this document and then we talk.

Posted By jadi on 26 Mar 2011 02:36 PM

.
I have seen a geothermal open loop system in my area. They don't have nat gas. Like them I have a well for irrigation.
If I do go geo, all I need is drill another well for dump( return). But is it worth the while considering I have natural gas.
So, what system is more suitable for me here in central/south NJ? GEO or Dual-fuel or a 2stage 95% natgas force-air furnace or anything. 
All input are greatly appreciated. Thanks 
 
Jadi

Posted By GBT_energy_freak on 28 Mar 2011 11:12 AM
Joe,

I hate to do that but I seriously suggest that you take a gender in this document and then we talk. Do you need help in converting EER numbers to COP for cooling or you have enough expertise to do it on your own?

Posted By engineer on 26 Mar 2011 10:09 PM
Kudos to you for planning ahead as well as for your kick-a$$ PV system

Start with a load calculation if you don't already have one. Consider a blower door test to quantify infiltration and identify low hanging weatherization fruit.

After that, feel free to shop geo, but I'll bet it'll be very hard for geo to beat out natural gas given your utility unit costs.

Beware high well pump electricity consumption with open loop geo. It's an easy issue to overlook, but it has significant effect on operating costs and ROI calculation.

Posted By GBT_energy_freak on 27 Mar 2011 11:01 AM
With all due respect, I disagree with Kurt as your future Geo system will effectively obsolete your existing 4T A/C unit (sell it on eBay) and will save you substantial money on A/C cost compared to your old 12 Seer unit not to mention total elimination of NG expense during heating season. Btw, what is your source for Domestic Hot Water? Depending on your water level pumping cost may not be an issue when using new technology Grundfoss pumps. Btw, how deep your well is nad what its capacity?

Based on your post data, I deducted that your PV system is around 7KW and I wonder which panels did you end up using, how and where did you install them and if you have net metering available where you are. Also, how much did you spend on it and how long you have been using it?

Posted By joe.ami on 28 Mar 2011 09:06 AM
GBT,
love your enthusiasm, but not your numbers. Any one who has ever done an op cost calc on most of the major companies software, knows that average efficiency is 3.5 to 4 for sophisticated equipment.
Throwing around peak efficiencies is less helpful.

Jadi,
Your best bet is to get some estimates and let the sellers convince you about their product.
Since you are going to spend thousands on new equipment soon, the playing field is slanted some towards geo (with 30% tax credits on geo).
High KW price however suggests you would either want gas aux. or a larger geo system (possibly requiring duct work modification) which will impact your design/price as well.
You may also wanna look at FreeWatt.
Good Luck,
Joe

Posted By TechGromit on 28 Mar
I have a Open loop Geo system in South Jersey and do not have a return well. The ground absorbs water so well here a return well isn't really necessary.  I'm assuming your house is fairly small or extremely well insulated, based on your gas usage. $95 a month  reminds me of gas bills I had for my first house, it was only 850 sq ft.  As Joe pointed out, with the 30% federal tax rebate and the State of New jersey offers another $400 rebate, there are also 0% interest loans or additional rebates available if you meet the programs requirements. If your well can support the additional load, it's pretty much the same cost to switch to a geothermal system as replacing your old gas system.  Sometimes the math doesn't quite work out in your favor when basing your currently utilities cost with a Geothermal systems cost and savings, but you have to remember, you'll be protected from possible future price spike with gas. Not that I anticipate any price spikes in the near future, with this fraking process the gas industry has developed, there should be sufficient natural gas supplies for years to come.      

Posted By jonr on 29 Mar 2011 08:55 AM
Just a note for people considering the open loop discharge issue - depending on well geometries, one can put most of the water back into the supply well (called standing column).

Posted By GBT_energy_freak on 29 Mar 2011 12:49 PM

Posted By jonr on 29 Mar 2011 08:55 AM
Just a note for people considering the open loop discharge issue - depending on well geometries, one can put most of the water back into the supply well (called standing column).

WOW...thus further deteriorating overall system performance and efficiency.

Posted By GBT_energy_freak on 29 Mar 2011 12:49 PM

Posted By jonr on 29 Mar 2011 08:55 AM
Just a note for people considering the open loop discharge issue - depending on well geometries, one can put most of the water back into the supply well (called standing column).

WOW...thus further deteriorating overall system performance and efficiency. Is that the reason why most of your "installations" reach overall 3 COP at best???