Glad I found this forum, and I'd like to post my system specs:

My wife and I just moved to a house in southeastern PA. It's a 1959 cape with a vaulted ceiling single room addition on the back. The previous owners had hot water baseboard heating with an oil furnace, and a central a/c system with the compressor outside.

We were able to factor in the cost of a Geoexchange/GSHP into the mortgage of the house. The system is finally installed and I wanted to post what we have for any feedback, questions, comments, etc.
=====HOUSE=====
House: 2200 sq feet - House was energy audited and found to be in good shape, no obvious leaks, windows are all newer, no missing insulation, etc.
Zoning: 2 zones, upstairs, downstairs. (Basement is unfinished and unheated)
Previously, the owners were paying about $300/mo for oil.  My parents live in a very similar house not too far away, about the same age and square footage.  My mom said their oil bill is about $288/mo, higher in winter, lower in summer, but they are on budget pay where it's spread out across the year.

=====Our Geothermal System======
GeoMax 2 with desuperheater - 4 ton unit
Wells - Closed loop, 2 wells, each is 300 feet. Each well contains a double loop of PEX-type tubing for the ground loops, glycol.
Rehau is the mfgr of the tubing and the double loop system...some special "u bend". Rehau came out to supervise the install!
Oil furnace and baseboards removed, along with 275 gallon oil tank from basement.
40 gallon water heater installed, connected to the desuperheater, and also an AirTap.
AirTap - a mini-heat pump that sits on top of the water heater and pulls heat from the basement air to heat the water if the GSHP isn't on.  The Airtap is set to 120 degrees.  The electric coils in the water heater are set to 110.  Basement is not heated/cooled.

GeoMax 2 has a 2 stage compressor, plus the electric backup coil is also 2 stage (10 KW, and 15 KW), so basically 4 stage heating and 2 stage cooling.

Cost to install: $24,500 total - 8,000 (tax break) = $16,500

Presently, the thermostats are set to 68 when we're home, 57 at night, and 57 during the work day, 68 on weekends.
The electric backup coils are switched off at the breaker panel so they'll never come on.

Loop temperature reads 52 degrees.

Air temperature in the ducts is reaching 105 degrees. House warms up very quickly, and the system is very quiet...quieter than the original air handler for the a/c that was in the basement.

I did get 2 bids on the system, both wanted to put in vertical loops, but the other estimate was $32,000 and that was for a WaterFurnace.

Much of the original duct work was reused, although my HVAC guy did run a couple extra ducts to the bathrooms, added an upstairs return duct, and also patched some serious gaps in the original ducting (holes big enough to stick your fingers into!).

So far, it's working great...but it's only been installed a week.

=====PAYBACK Calculations:======
  If my electric bill goes up $50/mo, that would mean a saving of $250 per month over oil.  $16,500/250 = 5.5 years payback.
I realize that doesn't include yearly servicing, but I would have that with an oil heater.  I also know that the cost of electricity will probably go up, but even if the system adds $100/mo to my costs, my payback is only 11 years.  The system is supposed to last 25 years with the ground loops 50 years.

I'm a homeowner that previously lived in SE PA.  I have some thoughts (not regarding the Phillies) for you.

The savings comparison might make sense assuming your thermostat settings are similar to the previous owner's settings. Geothermal will also save on electricity in cooling mode compared to a conventional AC.

When it is very cold outside, geothermal systems can take a long time (without aux heat) to recover from an 11 degree setback. Smaller setbacks of 3-5 degrees may work better from a recovery standpoint. During recovery from a setback of more than a few degrees, your second stage will most likely be engaged. This isn't necessarily a bad thing from what I have read, just wanted to mention it.

We used uncomfortable thermostat setting before we went geothermal to save money. While we have not gone through a winter yet with our system, I can tell you that our electric bills in the summer have had only a small increase when we dropped the thermostat setting from 78 to 76-75. So far this heating season, I have already increased the thermostat settings significantly from where they were prior to us getting geothermal since I have more confidence in what the system can do (keep us more comfortable at a lower monthly utility cost than our previous systems).

Good point, Geome. It's hard to know exactly what I'll save because I didn't live in this house for long before I got the geo. My parents, though, tend to keep their (similar) house on the cool side (65) in winter, and I know we have ours set warmer. My parents, though, don't have central A/C, so that will "add" a little to the cost, I supposed. My monthly electric so far has averaged $125 since April and that was everything in the house, basically, except for heat/hot water, which up to now was oil. I'd love to hear from anyone who could help me estimate the costs and savings better, though. I remember touring the house when the previous owners were here, and it was quite comfortably warm. I also have a copy of their heating oil bills for the past 3 years, and they averaged $300 to $400 per month, so my guess is probably a thermostat of 70 degrees. It wasn't a smart thermostat either, so they either manually turned it up and down in the morning and evening (and they were retired, so they were home all day), or just left it at 70 all the time downstairs, and maybe cooler upstairs for sleeping...

11 degrees is a pretty big set back, but you did say the Aux heat is disabled and it heat up pretty quickly. Remember that any setback should be at least 8 hours to gain any benefits from a setback. Unfortunately I will not be ab out to take advantage of setbacks this year, we brought a parrot and I'll have to leave the temperature at one set level this winter.  

Yeah, we'll have to see as we get into real winter whether 55 is "too low". I'm assuming if it is, then setting the geo to something like 60 during the day would be better than leaving it at 55 but making the aux heat available?

We do have aux heat disabled. The HVAC guy showed me the breakers at the panel and they were the first thing I turned off. He was bragging that the system probably would only need the aux heat a couple times this winter, so I figured I'd turn it all off until I really needed it.

I'm wondering...and I know this sort-of defeats the purpose, but can you cool the rest of the house but have some sort of space heater in the parrot room? Those oil filled radiators, or even a small electric baseboard. I know the COP is 1. But would you gain anything by having that on instead of heating the entire house? Is the house zoned at all?

Unfortunately, I'm a data geek. I wish there was a way that I could feed all the thermostat, zone, ground loop, air duct temperature into one unit and then be able to pull up the data on my computer or on a single screen. As it is now, I have to check a little dial on the pipes for the ground loop temperature, the thermostat zoning panel for the duct temperature (which is in an awkward place) , etc. Oh, for a single location! Then I'd be able to tell if the system perhaps needed aux heat on for a brief time period.

Are there any outdoor temperature sensors that I could connected to the aux heat control so that only on the coldest days would aux be "allowed"?

I'm asking because on my old system at my old house (regular heat pump with aux heat) if I turned the thermo up more than 3 degrees, no matter what the outside temp was, the aux heat came on. I know that the pump itself could have done the 3 degrees, but by demanding it right away, the system would switch on aux. Does Geo do that? Is that a function of the thermostat programming?

I believe it is much more cost effective to have your setback at a point that your geothermal system alone (without aux heat) can recover from. Running aux heat is very expensive and will greatly diminish your savings from using the geothermal system. Better not to set back as much.

There is a possible problem with having some or all of the aux breakers turned off. If your geothermal system has a fault and locks out (shuts off to protect itself), it may have a feature that would ordinarily automatically engage the emergency heat so your house and pipes won't freeze in the midst of the winter (possibly when you are away). With breakers turned off, the heat strips will not go on. Of course, you may be in a climate where this is not an issue.

Someone else can better answer your questions on space heating for the parrot room (with electric you are counting on no power outages, and fumes may be an issue for the bird if fossil fuel heaters are used) and on data collection (devises do exist).

We plan to use the look and see approach to see when aux is needed. If at a certain outdoor temperature in the winter, your thermostat can't hold a set point, it is time for aux heat assuming the outside temperature is near the system design temperature. We will use the outdoor temperature at which the system can't hold a set point (without aux) to set the aux lockout (described below). I assume there are differences between paper calculations and real life situations with the design temperature calculation, but this may get you close.

Yes, there are outdoor temperature sensors that connect to certain model thermostats. Some thermostats have the additional feature that you are looking for called an aux or auxiliary heat lockout (or just aux lockout) (not to be confused with a compressor lockout which, from my understanding, you would never want to manually select with a geothermal system). The aux lockout used in conjunction with the outdoor temperature sensor will enable you to set an outdoor temperature. Above this temperature, the heat strips will not turn on (but they possibly will turn on if your system experiences a lockout condition and the breakers are on). Below this temperature, the heat strips can turn on if so instructed by the thermostat. Make sure the thermostat model you get has the aux lockout temperature range that you want/need. Ours is a Honeywell Prestige thermostat that goes from 5 to 65 degrees (I believe) in 5 degree increments.

I could be mistaken, but some thermostats may enable you to select at what difference in degrees the aux heat will engage (and possibly second stage too) but the window may be narrow (only a few degrees). My thermostat will not do this and I have limited experience with other thermostats. With the aux heat lockout, no worries about the aux heat going on as long as the outdoor temperature is above the lockout setting. You could even try the 11 degree setback without the aux coming on (again, as long as the outdoor temp is above your lockout setting). When it isn't that cold outside, your system may recover in a reasonable time frame, but when it is very cold outside, the recovery period may be too long. I have heard advise to not use much or any setback when it is very cold outside. Seems reasonable to me. If the outside temperature drops below the aux lockout setting, and you use a setback of more than a few degrees, there is a greater chance that the aux may come on. 11 degrees is still a huge setback to use with geothermal (although we did this when we had a furnace).

In my opinion, aux heat is fine when the outdoor temperature is close to design temperature, but I don't want it to come on at other times if I can prevent it and still be comfortable.

I did a study this past Winter, to see if a 3 - 4 degree setback routine would indeed be cost effective (for my GSHP system).  Indeed it was.  The study, though, did not include usage of Aux heat because I live in a hot weather climate (Dallas), and thus may not apply for you.

Data measuring, display and storing is not a problem.  Many systems are out there that will accomplish this for you very well.  I just posted in another thread, a response to the same questions.  A few contributors here have such a system.  See http://welserver.com/WEL0043/ for my system, http://welserver.com/WEL0114/ for Dwayne Dean's system ('geodean' here on this forum), and http://welserver.com/ww/ for many others (mostly not on this forum - a few are Dwayne's clients).

Best regards,

Bill

if you are a data geek you must get one of the welservers that Bill spoke about.  You can then obsess about the data like I do.  More importantly, you'll be able to keep track of any abnormalities that may crop up.

http://welserver.com/WEL0144

Travis

Right now, I have no plans to get a monitoring system (but probably will eventually). I'm currently at my limit of things to be obsessed about! 

Let me make sure I understand this (noob question alert!):
If the aux heat is physically turned off (breakers) and a lockout condition occurred, is there *any* chance of damage to the geothermal system itself? I mean, the loops aren't going to freeze or anything, right? The worst (and i know it would be bad) would be the house itself getting too cold and freezing up. But this lockout would really only happen if the geo loop pumps or compressor malfunctioned, correct?

I guess I need some sort of special (maybe I have it) thermostat/sensor that absolutely will not allow aux heat to come on unless:
* there is a lockout on the geo system which prevents any heat at all from the loop
* there is no way that the geo could ever maintain the requested temperature...due to a low loop temperature, I guess?

I'm assuming that the ground loop temperature will ALWAYS be around 50 degrees...that's the point of the ground exchange.... and pulling heat will ALWAYS be possible short of an actual equipment malfunction?

What would be best? Just turn on the aux heat breakers and keep the temperature changes moderate so as to not engage? I almost want some sort of RED FLASHING LIGHT on the thermostat to ALERT and WARN me of aux heat use. As it is now, it's just another little word that shows up on the big multi=touch display panel. Shouldn't aux heat use be something of concern?

Is there a way I could hook up a blinking red light or a siren or something to the aux heat switch so that if aux was called, I'd know it was happening?

Ok, maybe not a siren.

The experts will need to advise you on possible damage to the unit. As a homeowner, the only thing I can think of is that if it was cold enough, for long enough, where your unit is located, the desuperheater (DSH) plumbing could freeze possibly damaging the DSH pump and DSH lines inside the geothermal unit. When the pipes thawed you could have water everywhere inside the unit and the electronics probably wouldn't like that.  Isn't the possible downside of the pipes freezing up in the rest of the house enough to get those breakers turned back on (at least when you go away for more than 1 day in the winter)? 

Joe really needs to give you his "aux heat is not the end of the world" speech. It has helped me to understand aux heat usage better. Thanks Joe.

I'm happy with the aux lockout on our thermostat/outdoor temperature sensor setup. This way, our aux can't come on unless the outdoor temperature is below the system design temperature (if that is what you choose to set it at), or unless our geothermal system locks out. I asked Water Furnace (WF) about lockouts and aux heat (emergency heat in this case) operation. They told me that in the event of a lockout of our Envision units, one circuit board within the unit will tell the aux heat circuit board within the unit to turn on whenever there is a call for heat during a lockout event. For a lockout, it's not a thermostat trigger, it's all controlled from inside our Envision units. I have no idea if your unit functions the same way.

We opted for a thermostat that WF didn't offer. At least one of the WF thermostats has an error code display on the thermostat in the event of a problem. Since we have an "aftermarket" thermostat, I don't know if it will display a problem with the system (I assume not).  Again, I have no idea if your system and thermostat has this type of notification.

We changed our cycles per hour to "1" for auxiliary heat. For us, this will limit the number of times that the aux heat can turn on to "1" time per hour (when the outdoor temperature is at or below the aux lockout temperature we have specified).  I'm more concerned with lockout events than occasional aux heat usage (which should be infrequent with an aux lockout). I can always go into our basement and look at the indicator lights on our units to see if all is well. I suppose you could also monitor your electric meter from day to day looking for big differences. I hope to be able to not hear the geothermal compressor running if the unit locks out and engages emergency heat without my otherwise knowing about it. Thanks for making me paranoid!

I laughed out loud with the siren idea - imagining me ignoring it in the middle of the night until my wife kicks me out of bed to shut it off.

Does your thermostat currently display the outdoor temperature? What make and model of thermostat is it?

I know right now off the top of my head that the thermostat is a Honeywell, and it does have the option for an outdoor thermometer as well as a humidistat. I don't have an outdoor sensor though, although there are contacts to connect it on zoning control. I wonder if I can put a sensor in the air flow duct and wire that to the outdoor sensor just to get a reading on a convenient panel...or perhaps an electronic sensor (rather than the analog one) on the coolant pipe connected to the thermostat.

I have to see if I hook up an outdoor sensor whether the thermostat has a lockout feature. If it did, and as you write, aux would be called for emergencies only or extremely low temps, that would solve most if not all my concerns.

I suppose you could locate an outdoor sensor anywhere you wanted to (well, not anywhere), but it won't help the auxiliary lockout to function correctly unless it is outside.

The installation or setup manual to the thermostat should tell you if it has an aux lockout feature. If you don't the manuals, you should be able to download PDF's of the manuals from the Honeywell web site for your particular model.

It looks like I have the provision for an Aux lockout settable to the following outdoor temperatures:
40°F (4.5°C)
45°F (7°C)
50°F (10°C)
55°F (13°C)
60°F (15.5°C)
I guess that means that if I get an external sensor and set the lockout to 40 degrees, then the aux won't come on unless the temp is below 40 AND the thermostat calls for aux heat because the first 2 stages (ground source) can't achieve the required heating demand.

Now to find an external sensor!

And the aux may go on if you have more than a few degree setback that the system is recovering from and the outside temp is below 40 degrees.

Not a pro here but everything I have seen suggests that using setbacks with geo has more chance to cost you when the aux kicks in than whatever it might save you. As you guys are discussing I suppose a sophisticated system could be employed to try to control that but one benefit of geo seems to be the ability to forgo setbacks.

BTW, many parrots live in climates that cool off at night. I doubt that upper 50s/ low 60s nightime temps would bother most parrots. Check the books though.

gregj, if you mean forgo setbacks and still have reasonable, and not astronomical, utility bills, then I agree with you.

stuart.wyss, still be careful with setbacks if your aux lockout only goes as low as 40 degrees F. Depending on where you live it could drop below 40 degrees often in the winter and possibly engage your aux heat just as often when using a setback of more than a few degrees (possibly as little as 2 or 3 degrees). If you insist on a setback for comfort reasons, as we do, the purchase of a thermostat capable of lockouts lower than 40 degrees could be justified by a few (experts?) of winters of not having aux heat go on unnecessarily (i.e. when outdoor temperatures are above the design temperature of your geothermal system). The aux lockout of our thermostat goes as low as 5 degrees F, but there may be other less expensive thermostats out there that can suit your needs and not cost as much as a Honeywell Prestige.

Ok, to clarify: :-)
I'm am lowering the thermo at night just because we prefer it cooler at night, and during the day when we're not home. For those sorts of heating up cycles, the adaptive technology of the thermo itself should be taking care of heating the house up in the morning and evening, even from an 11 degree cooler point by using ground source heat. In theory, only when the thermo detects (because it will learn to turn on prior to my 4 pm arrival to heat the house up in time) that it won't be able to get the house to 68 in time for 4 pm with ground source only, then it will call for aux heat. If this is the true scenario of what happens, then I should be able to leave aux available all the time and know that the thermostat as-is with its adaptive learning will try its best to satisfy the heating without aux first. I can't believe that if aux was available, and the thermo was running its proper learning patterns, that it would call for aux unless 1) it was so cold that it sensed the house wasn't warming up fast enough to be ready, or 2) there was a lockout condition on the ground loop somehow and aux was the only heat available.

I guess my "concern" with aux heat is when one is home and randomly decides it a little chilly and cranks up the thermo 5 degrees. At that point, the system is going to try and get the heat up as fast as possible. Wouldn't it call for aux heat as that point? Would a 40 degree aux lockout help or hurt or have no effect? If I crank up the thermo 5 or 6 degrees on a whim, I don't care if it takes 1/2 hour to get to that temp, so aux doesn't need to come on....but I think it will. It wouldn't come on if I raised the temp 1 degree, went back 5 minutes later, raised it another degree, went back 5 minutes later, etc. But it's the immediate call for extra heat that is "out of programming" that would cause aux to come on.

Am I thinking this all through correctly? I don't have a problem with aux heat. I just want to know it comes on only when ABSOLUTELY necessary, and not for small on-a-whim changes if the system could make the change with ground source only.

Ok, I just tested it. It's Saturday morning here. Outdoor temp is 55 degrees. Group loop temp is 53. Indoor temp was programmed at 66 degrees. Thermostat called for 66 degrees around 6 am, and it's been 66 since then until now, 8 am. I'm in a t-shirt, feeling a little chilly, so I walked over to the thermo and put the temp up to 69 degrees....only a 3 degree difference.
First, stage 1 and 2 heat come on (ground loops). Within 30 seconds, the thermo is displaying "aux heat on". Fortunately, the breakers are off, so it never actually went on, but it was called for.
I'm going to wait and see how long it takes to get to 69 degrees. Okay, it took 8 minutes. Yes, with aux heat available, it probably would have taken 2 minutes, but I'm trying to prevent that.

In this situation, a 40 degree aux lockout would have helped. Since it's 55 outside, the aux would be prevented from coming on, and clearly the system can raise the temp 3 degrees in a very reasonable amount of time.

Maybe i just need a thermo that you can program to not engage aux unless, in this case, I raised the temp manually more than 5 degrees or 10 degrees from the normal programming.