Greetings,
Would like some advice from the Pros and Joes on the forum.

I'd like to do away with my oil heat/domestic hot water system at my 2200sqf house. I also have what I believe is a 4 ton air conditioner with ducting in my basement and an outside component for that as well. My oil based domestic hot water system is 20+ years old and services a 4-zone baseboard system as well as heats our drinking/bathing water. At $4.50 a gallon of oil last year I spent about $6,000 on oil, $2000 on electricity. I expect my oil costs to increase an additional $1,500 this year if the current oil lockin price for next year remains at $5.50. I'd like to get fossil fuel expenditures down as close to zero as possible. In the winter I heat the house to 68-72 during hours people are here and drop it 5 degrees or so when they are not. Cooling is set to 72 with AC on.

The majority of that cost was heat. My house is a 1937 built cape that was retrofitted for the AC and expanded in the mid-90s by the previous owner. Windows were updated at that time too. From my investigations of the home insulation it looks pretty standard rolled insulation in what passes for the attic(i'm not an insulation pro.) I put a new GAF roof on last year. My basement is not insulated (i'm evaluating doing it, yes.)

I'm looking at a geothermal system to service my heat/cool energy needs. I'd like it to replace my domestic hot water solution as well rather than leave it in place. I've got an acre of mostly square cleared property. Don't know what the soil type is for Wolcott, CT. Drainage where I am is pretty good if that helps. I am basically on the plateau edge of a hill. House also has a well water hookup. Well is 50-75 feet. I recently retired my propane inground pool heater. Wouldn't mind heating the pool if its practical to do as well, although its optional from my perspective. I have a contractor quote for a solar heat system for that already that is under $3,000. Less if I DIY. Looks like a geothermal pump would cost more than that.

In any case the questions I primarily have are
1. Is any particular set of manufacturer equipment better than another from a system efficiency perspective or do they all tend to be fairly close in this respect?
2. Horizontal closed loop vs vertical. I think I get the difference in that a vertical has a more stable temperature range and costs more. What's the general cost structure for horizontal vs vertical? How much more is a vertical system than horizontal? (ball park percentage perhaps)
3. Is it practical to tie a PV solar system to power the heat exchanger?
4. Is it practical to run domestic hot water 100% off of geothermal? If not, how close can I get to that?
5. Do any of the geothermal systems include the domestic hot water system directly, or is it limited to a high temperature storage tank feeding an existing system?

Thanks for you help.
Patrick Cannon
p.s. If any of you are geothermal contractors who operate in CT your welcome to contact me about bidding on the job that will come out of this.

Patrick,

Welcome to the forums.

#1- With EarthLinked DX geothermal, you'd have about 15%-25% higher efficiency than any closed loop water geothermal system.

#2-The biggest difference between horizontal and vertical is the footprint, or space needed to place the loop. Typically, you'd see virtually the same efficiencies with either loop. However, usually vertical will be more expensive, mainly because of the drilling cost.

#3-Not sure what you mean by powering the heat exchanger. If you mean powering the heat pump, heat pump compressors have a large demand of power upon startup. This would require a large (usually not worth the extra cost) PV system.

#4-Geothermal will heat domestic water to about 120 deg. F. max. Anything above that has a law of diminishing returns. The capacity and efficiency of the water heating greatly diminishes as you increase water temperature. Some manufacturers claim 145 deg. F. water. However, they don't like to disclose that it's hard on the compressors, and that it is achieved only at the very end of a long run cycle. What you'd most likely see is that the geo unit will pre-heat the water to 100-120 deg. F. water. Then the domestic water heater (a separate oil/gas/electric water heater) draws off of that water and finishes heating it to your desired temp.

#5-The EarthLinked DX geothermal system heats water as a priority. The other option is a desuperheater. Desuperheaters will heat the domestic water as a byproduct of the cooling. Before it sends the heat out to the ground loop, it dumps its superheat into the domestic water. Desuperheaters are NOT priority. With EarthLinked's SW model unit, you have the option--from one geothermal heat pump unit--to do forced air heating and cooling, along with domestic water heating. We've done this many times, and people love it.

I'd like to refer you to the EarthLinked manufacturer's sales rep in your area. He'll know what dealers are near you, and he can assist you in any other questions you may have about the specifics of getting it installed on your house. His name is Mel Hensch.

Mel's contact info is:

Mel Hensch
[email protected]
508-328-4735 phone

Also, visit www.earthlinked.com for more info on this brand.

Feel free to post any other questions, and keep us informed in the process. Geothermal definitely will save you thousands of dollars each year. It's a great choice.

In your experience with the products you are selling what type of savings do homeowners typically see with geothermal DHW?

For instance if I am using 500 gallons of oil during the winter months to heat is it reasonable to expect that I can get this down to 100 or so?

pjc

We don't have heating oil users in our area. I'm not sure what percentage you'd be using for water heating. It does depend a lot on your family's particular hot water usage.

I would guess, based on my own bills, that out of your 500 gallons in the winter, maybe you're using about 75-125 gallons of it for heating domestic water. Of course, that's a sheer guess.

What efficiency is your boiler? When I get a chance, I have a program that will show me more accurately what you'd save. I'd need to know how many people use the house, and what hot water appliances (and how many) there are.

This program allows me to compare the geothermal DHW to fuel oil DHW. Just guessing, if you went with the geothermal DHW, your oil usage would probably drop from the 75-125 gal/month down to probably 15-40 gal./month of fuel oil.

One of the major inefficiencies of oil-fired indirect hot water so common in the northeast is the need to heat the whole system all summer (furnace, flue, jacket, associated piping) just to drive the domestic water "zone". Nameplate efficiency for typical oil heaters is 85%, but this drops radically in practice during the summer because most of the heat goes to keeping the unit hot (160-190 Deg F) just to maintain a tank of hot water.

I agree with points 2-5 in Clark's first reply. I'd really like to see some third party confirmation or similar side-by-side comparison of efficiency of DX geo vs conventional indirect closed loop to back up the 15-25% efficiency difference.

The ability to priority heat domestic water is a major point in favor of his brand. His brand does not allow for two-speed compressors, which allows for quieter, more efficient part load operation on all but the hottest / coldest days. Major brands of conventional geo (Waterfurnace, Climate Master) have 2 speed models. Another advantage of 2 speed systems is longer runtimes at part load, providing better dehumidification and more even temperature control.

To more completely analyze we also need your summer and winter electricity costs. Be sure to find out if your utility has a lower rate for all electric heat and that it applies to geo systems.

I did notice in the Earthlink brand that they use copper in the ground loop which also squares with my conversation with a reseller here in CT.  I shudder at the cost of all that copper. I have copper pipes in my plumbing. Completely pain in the wallet when I have to replace some of it.

Clark is copper the only option for the ground loop? Can' I go with polypropelene if I beat up my reseller enough? I appreciate that next to gold and platnum its the best conductor (and probably accounts for a fair amount of the Earthlink DX efficiency gains over the competitors), but I would expect polypropelene to be so much cheaper that even having to get more of it to get enough surface area to conduct heat through that its probably worth it, right?

I think I will end up getting equipment with a DHW in it. It sounds like since geothermal is a forced air system I am also going to have to rip out my AC ducting which is a bummer. I was hoping to defray my costs by not doing that but the AC vents are all going to be near the ceiling rather the floor so I'm s.o.l. I think. It also sounds like I will have to rip out my baseboards and if that is the case my 4 zone equipment in there currently is all useless as well. Ironically thats all a ton of copper too. Maybe I can get who does the job to credit me for the copper!

I have a contractor coming into do a Waterfurnace analysis. Trying to find a local Climate Master reseller as well to do the same. The ballpark amount the Waterfurnace contract was sky high and they only do vertical closed loop. I don't get why they would limit themselves that way.

Copper is required for DX systems - poly is permeable to refrigerant and does not have a high enough pressure rating. However, even with the price of copper these days, the tubing is small diameter (correct me if I'm wrong Clark) and is a relatively small fraction of the whole system cost.

As for efficiency, copper is indeed a much better conductor than poly, but it has an almost negligible effect on system efficiency. The soil conductivity and other factors end up being much more important. the claimed efficiency benefits of a DX system are primarily due to the higher condensing/evaproating temperatures since the system eliminates a water-refrigerant heat exchanger. There is also a small benefit from the elimination of the ground loop pump (this can be a bigger advantage when compared to poorly designed overpumped closed loop systems or open loop systems with a high head).

Not to pick on Clark, but I agree with Geodean. I acknowledge the _potential_ efficiency advantage of DX systems, which actually turned out to be greater than i had thought when I ran the numbers. However, as far as I can tell most DX installations use this advantage to utilize shorter loop lengths rather than to maximize efficiency. As I said in another thread I think this is fine - I would imagine in most cases this is the right way to go in terms of economics.  The lack of technical information and case studies on DX systems is frustrating. The ARI certifies the system at a given loop temperature, but I have never seen any data that shows DX loop temperatures over the course of a season. Without data like this it is impossible to do an apples-apples comparison of DX vs water based systems. I suspect in most cases the incoming refrigerant temperature is lower than the incoming water temp is on a closed loop system. Depending on how much lower it is the system could be more efficient or less efficient than a water system.

Here's a thought - you could consider a water-water system (or DX-water) feeding your existing baseboard and a fan coil(s). The baseboard alone probably won't have enough capacity on very cold days, but you could supplement it with the air coil below a certain temperature. It might be more comfortable and would give you the option of picking up a larger % of your DHW load.

By the way, what do you pay for electricity?

Feeding the existing baseboard and hydronic air handler(s) is a really good idea. You could heat the hydronic water for the baseboard down to a certain outdoor temp, and then switch over to a forced air refrigerant coil blower. The only drawback I see, is that when heating water above 100 deg. F., usually COPs drop with any system.

The capacity, and efficiency of any refrigeration system is based on the number of pounds of refrigerant the evaporator evaporates, and the condenser condenses per hour, along with the required power. With that in mind, the biggest reason EarthLinked DX--not just any DX--has a documented higher efficiency is because of its refrigerant controls. These controls ensure NO superheating, and NO sub-cooling of the refrigerant. When this is the case, the compressor can do more "work" with the same amount of power as any other compressor. OR, to get the equivalent amount of "work" out of the compressor, it doesn't require as much power as other systems. By installing EarthLinked's refrigerant controls alone, it raises the efficiency of a refrigeration system--(whether it's a water source geo, air source geo, conventional condensing unit, refrigeration box, chiller, etc)--by 15-25%. It's not really the copper loop. It's not just the absence of pumps. It's the controls. At the heart of it, that's the biggest reason it's more efficient.

Now, on economics, it's also usually a lower installed price, but only when comparing to closed loop systems. Open loops are most always cheaper, as there is usually not much excavation/drilling required. With an EarthLinked heat pump, I could use a properly designed water loop with pumps, or use an open loop. It just needs a water heat exchanger, just like any water source system uses.

However, one point here, again, is that the loop is already completely designed and engineered. All you have to choose is whether to do vertical, diagonal, or horizontal. Next, you need to know ground temp. We don't care AT ALL about the thermal conductivity of the ground loop. WHY? Because we do a latent heat exchange (unique to DX geothermal), NOT a sensible heat exchange. The short explanation of that is that we change state of refrigerant directly with the ground. We're not trying to pick up temperature, rather, we're trying to pick up BTUs. Part of the sizing of the system is to ensure that the heat pump will have a max. run time of 90%. That means we must have backup heat supplement the heat pump to the point that it has no more than a 90% duty cycle. If this is not exceeded, the ground will ALWAYS have enough heat in it to be able to make the latent heat exchange down to the ARI rated, full load COPs. At 50 deg. earth, and with a vertical 1 loop per ton loop, that COP on a 4 ton system drops from 5.0 down to 4.2. What's the water based geo's full load COP? On closed loop, they are lower than EarthLinked DX's.

This point of the loop being designed and engineered based on orientation and ground temp. should be very inviting to geo designers. Unfortunately, they see it as a big eraser. By that, I mean it almost erases the need for IGSHPA. Why? Because IGSHPA is most all about loop design, including ground conductivity, test bore holes, pumping, head loss, pump sizing, loop design, loop design, loop design. When it's already engineered, there is absolutely NO guesswork. Neither is there ANY test bore holes required. No loop pumping. No loop maintenance (periodically purging/re-charging/pressuring of the ground loop). No loop pump maintenance. Guaranteed loop performance. It sure gives me more peace of mind. It allows any HVAC company that can follow simple directions (while using accurate load calculations--hopefully they do this with any type of system) to properly size, design, and install a completely functional, economic geothermal system.

So, if the installed price is lower, and the efficiency higher, how is it not a no-brainer. I do agree, that in part load conditions, a 2 stage compressor could offer a bit more comfort, and a bit better dehumidification. Dehumidification, though, is always ignored in my area.

One point on the dehumidification...hopefully I can explain this well enough... With the refrigerant going to the evaporator coil at ground temperature (condenser temp.) dehumidification usually starts within the first 30 sec. of running.

I fully agree that they need more data available on the internet. We've begged them to provide more, but it's taking a long time to get things added to their website.

Oh, and I completely don't feel picked on. I by no means know all there is to know about geo. Please feel free to educate me more. Hopefully I'm educating others on what I know for EarthLinked DX. I generally find this forum very informative, and I've learned a lot from you guys.

'Here's a thought - you could consider a water-water system (or DX-water) feeding your existing baseboard and a fan coil(s). The baseboard alone probably won't have enough capacity on very cold days, but you could supplement it with the air coil below a certain temperature. It might be more comfortable and would give you the option of picking up a larger % of your DHW load.'

Is it typical to pull out the baseboards? Am I correct that it would likely be replaced just with forced air vents?

On another note is there a short hand method to determine how many tons I would need?

Am I correct that if I short it a half ton or a ton that would mean the system would take longer to heat/cool the home and perhaps if we were at a serious outside temperature extreme might not get the ambient internal temperature to where we prefer?

What happens if the system is overdone and I have to much tonnage?

In respect to my electricity costs I don't have my bill in front of me, but the utility's website says its basically 13cents. I converted to the new low wattage bulbs last winter which saved me a ton of money. I spend about $150-200/month. Summer that is $250 because of my in ground pool.

Engineer (and others) mentioned several systems and expressed opinions on them. What's your take on Boreal's solution?

Geo is generally incompatible with baseboards

There is no short hand method for load calc - doing it right distinguishes good contractors from hacks. On the other hand, a good contractor can bid your system, even estimate the tonnage without doing a load calc - the load calc comes after getting the job and correcting the estimated load by a half ton or ton makes little difference in total job cost since equipment costs don't vary much in that range.

Being short a bit is generally better (cheaper up front, quieter, more efficient, better dehumidification, more even temperatures) than oversizing. It won't kill you to be a couple degrees away from setpoint on the coldest / hottest days of the year. The system should be sized to get you your desired indoor temps on what is called a "design day" A design day is NOT the hottest / coldest day of the year, and that is deliberate.

With respect to costs per Btu we are in a really peculiar period right now - Electricity at 13-15 cents per kWh actually compares favorably with $4-$5 gallon propane and fuel oil, even if that electricity is used resistively to run strips or heat water. In my decades of experience with relative costs of energy I never thought I'd see that happen...how long that'll last I can't begin to guess...will we return to $2-3 fuel or shortly see 25 cent electricity?

Is this one of those things where you typically drop the bottom and top 5% outside temperatures and spec for that? I do a lot of that in IT ironically enough.

Yes, although design days can be selected at 2.5%, 1% or .5%. I believe the standard for residential is the loosest - 2.5%. I imagine that for critical institutional designs (hospitals, for example), it would be much tighter.

The hack tendency to oversize has very real negative consequences beyond high first cost - noise, efficiency and comfort all suffer.

Yep. You'd be much better off with a system that's a half ton short rather than oversized.