Plan a new home in Central Pa. and I am sold on geothermal. The 30% tax break makes payoff easy and I plan to live there for 30+ years. I'm sorta locked on a company, Bryant, because that's what our home builder subcontracts. Here are the details of the home:

2100 sq. ft. (30 by 36 ft.) two-story home. R23 walls, R50 roof, good windows. Basement unfinished but plan to finish.
.6 acre of land

I plan to get Bryant's most efficient geo pump because it is a two-stage unit and has a very good thermostat and features (and uncle sam is covering 30% of it). I also want the desuperheater, humidity control and electric air purifier. Here is the unit: http://www.bryant.com/products/geoheatpumps/geo-gtpx.shtml

Installer says I need a 3-ton unit with 3 wells (each 150 ft deep).

1) Since I plan to finish the basement, is this enough?
2) Are the wells deep enough for the unit? He says he will go deeper or add more but at a cost, of course
3) He plans to connect the desuperheater to a 80-gallon electric water heater. Is it possible to use a propane heater with direct vent or better yet, a propane on-demand heater with the unit? Or do I need an auxiliary tank for the desuperheater to store the hot water? I'm trying to cut energy costs when possible. (solar water heat is out of my price range at this time and it's freakin cold around here.)
4) Am I missing anything else that I should ask for?

Thanks for the help. Any advice or links to more info would be appreciated.

Your contractor should have done a heat loss/gain calculation for whole house to make sure system is sized properly, so ask for that if you're wondering if it's sized properly. Find out what % of heating and cooling loads they are sizing for, ask them why. Can't speak for the loop side of things, you'll have to see what is standard for your area, will depend on soil types etc.

I like going with an auxiliary tank for the hot water. You can hook that up to whatever type of hot wate heater you choose to use after that. Why is contractor using an 80 gallon? Could you maybe get by with a 50?

I double posted this thread so there's another one out there with more info. I thought that too about the massive water tank. It will be electric now but I will soon switch to propane. They don't give much rebate if you decline the tank and I want to wait for a possible tax rebate (I'm using all I got with geo for one year). Electric is slow so I will switch to a smaller propane tank. Family of four with two small kids. 2.5 baths but not a terrible amount of hot water needs. Have 30 gal. natural gas now and it rarely runs out. Plan on third kid (all girls so far!!) so my water needs will be high, and also the lesser of many worries. ;-)

The HVAC contractor said the builder would upgrade to 80 gallon tank as soon as I mentioned geo. Not sure why but maybe he plans to pump the desuperheater water right into the larger water tank and not use an aux. tank. Not sure if that is what he meant or even if that is possible.

To be effective, desuper needs its own upstream, unfired, unenergized storage tank. If that isn't included, it is unlikely the increased cost of the desuper option will ever be recovered.

I disagree, A buffer tank is ideal for sure. But my desuperheater keeps my normal 50 gal DHWH hotter than it does by itself. I normally keep the breaker turned off a large part of the year. That means I'm not buying any additional heat for my DHWH. That's true payback. My DSH only cost me $400. As a matter of fact I do understand the big tank(85 gal) as my DSH seems to be limited by the amount of water it has avail to heat. 50 gals stays hot and often the circulater won't come on as the tank is already heated to temp. If I had a bigger tank I would have more water sitting ready to be used at 140*. Ideal would be a large tank heated by desuper heater feeding a smaller DHWH. In the buffer tank scenario even in heating mode if the DSH wasn't heating the water in my case just having the well water going into the buffer would raise it from 50-55* to room temp before feeding the cold side of DHWH. That much less temp difference for the electric elememnts to raise in the DHWH. I'm not familiar with how much heat is avail in a waterbased sys. I have a DX system and I can see the diff on the elec bill when I'm using the DSH. it pays for itself with just a single DHWH a buffer tank would just make it even better. 

While you are correct that some people have had success wthout a buffer tank, I have a documented case where operating a system without a buffer cost my customer money. He had a seperate meter for the warter heater and noticed kw usage rose after dsh was piped in but was half his hisrtoric usage after buffer installaton. So if you think there's benefit to a buffer and know there could be cost to not using one, you would never recommend a system without (f you sold this stuff for a livng).
Joe

Joe, I'm curious what was the issue in the (Doc case)? Defective DSH? I understand in theory that the sys could use the hot water in tank as heat source. However the heat exchanger surface is not huge in the DSH and there are check valves to keep the circulater from moving water unless the refridge temps are HIGHER than the water in the tank. At least in both of the DSHs that I've owned. Both of which are add on type units. Was this a water based system? Can you tell me are the refridge temps similar in a water based system VS my DX. I've been curious about that. Seems several things work differently with WB systems and I've been curious if this is because of temp differences. I've found my DX system is easy to compare with conventional heat pump type systems. They are basicly the same except where the condenser tubes are located. Under ground instead of in the air in back yard. My DX system works pretty much the same except that the temp differences have always been higher because the efficiency of the buried tubes in my DX sys. Higher heat temps in plenum, lower cold temps in plenum, And it is my understanding the same with refrdge lines because the dx moves heat so readily. Is the refridgerant in a WB system carrying similar temps as CONV/DX between heat exchanger and A-coil?  
You are correct I'm a user/owner not an HVAC professional. I would always recommend the most efficient system as well. However just making the point MINE works fine as it is and this was the common way to install these when my sys was new. There are always improvements to be made.

I'm pricing the only hot water storage tank I know of (Rheem Marathon) and it's about $1000 to $1200 for the 50 and 75 gallon models. The homebuilder includes an 80-gallon electric water heater in the price and other options as upgrades. You generally win with the standard and lose with an upgrade because they are a volume builder. Is it possible to just have two hot water tanks installed and just not power one? Since they are costing me about $250 each, that seems like the most cost effective solution. I'm sure the Marathon tank is superior, but it's MUCH more money and I can insulate the crap out of these electric heaters myself. They are energy star models. Also, if that sounds like it will work, what sizes should I get? 80 gallons seems like too much for me, but 50 might be kinda small.

Hi everyone. I'm new to this forum. I see Marathon and 1 tank versus 2 water tanks being discussed and wanted to add my 2 cents. Please forgive some cutting and pasting, but much of what I am about to say was just said (by me) in another geothermal forum today.

I agree with squatch in that you will get the most DSH benefits by having a buffer tank. We didn't want a second tank in the house. Instead, we went with one 85 gallon Marathon and installed a water heater timer. The timer setup allows us to get DSH benefits at least 20 hours per day. We have the timer set so that the heating elements of the Marathon are provided with power long enough (about 4 hours) to heat the entire tank. This provides us with enough hot water for the day (your hot water needs may differ). As soon as we start using hot water, colder water enters the water heater allowing the DSH to heat the colder water. When the DSH operates, it reduces the amount of time the Marathon's heating elements need to be on the following day to fully heat the tank (assuming the DSH doesn't fully heat the tank). We are very happy with this setup so far. Our 2 Envision units with desuperheaters were just installed in April, and we look forward to seeing what the desuperheaters do this winter.

The owner of the company that installed our geothermal unit has just one tank and a water heater timer in his house too. He doesn't have a Marathon though. Our digital programmable water heater timer cost $75 + roughly $50 for installation.

Yes, the Marathon is expensive, but remember the tank has a lifetime warranty and heat loss is very low. I'm not saying buy one, just saying compare the overall cost of the Marathon (unit, electricity cost, etc.) to a conventional steel tank (unit and replacement units, installation cost of replacements, gas cost, etc.) to make the best decision you can.

Also, the recovery rate of electric water heaters can be much lower than gas water heaters. Remember this when determining the water heater size if you go with an electric model.

Installing 2 standard electric hot water tanks and only powering one works fine. The unpowered tank just works as a buffer tank. You may want to consider having the buffer on a switch and turning it on if you have a lot of people in town and need extra water for a day(such as for a PSU football game!).

-Adam

I 2nd Adam's point - it is an extra feature of a dual tank system and may allow downsizing both tanks a bit for the price of an additional 30 amp circuit. Empty nesters with kids who return on holidays or weekends can select a primary tank just large enough to meet their low day to day needs while enjoying the ability to accommodate guests with the flip of a switch or breaker. This saves space, first cost, and operating cost (smaller tanks have lower standby losses)

The problem with the timer method is a loss of flexibility. Time of day of peak desuper HW generation varies by season - summer it is late afternoon, winter it is late at night. The operational goal is to ensure users have plenty of HW whenever they need it, but that the desuper has plenty of cold water awaiting it just before its peak hours. This is extremely difficult to dependably make happen in a single tank system.

It is a popular myth that equipping storage electric water heaters with timers saves significant electricity or money. The "only heat water when you need it" mantra fails to account for the low standby losses of modern, well-insulated storage tanks - many, if not most lose only a few degrees per day.

As much as I dislike tankless demand heaters, in cases where there is absolutely, positively room for only one tank it may make sense to use the space for an unpowered dsh tank and take advantage of the small physical volume of a tankless unit as the finishing heater. Be certain to select one able to accommodate a wide range of entering water temps.

All good points! Thanks. I have a growing family so my water needs are on the rise. I'll go with the two hot water tanks, maybe an 80 gallon and a 50 or 60 gallon and kill the breaker on the 80 gallon. I like the "added bonus" of being able to kick on the second heater. My family now has an energy star 30 gallon natural gas water heater and it almost never runs out. But with girls comes great water usage, I know.

About the warranty on the Marathon: I'm sure it performs well and is well built. But the warranty on the heating element is only 6 years. Kenmore and others go 9 year warranty on some, and I think I even saw a 12 out there. The lifetime warranty on the tank is nice, but I can't see cashing in on that one during the life of the tank. Maybe I'm wrong there but I never had a water leak from a water heater before.

oh, and new house = no basement full of useless crap yet so I've got room, for now.

Thank you.

However, your concern / priority on tanks vs element warranties is misplaced. Resistive heating elements are somewhat prone to failure owing to thermal cycling and sedimentation from hard water. Fortunately they are cheap and easy to replace. A long element warranty leads you to believe the whole unit is of the highest quality, but is in fact a cold calculation by marketing folks who know that if the element dies during the warranty interval it'll be cheap to repair.

That means they can jack the price of a conventional heater by pushing a longer warranty while knowing they'll only have to make good on a relatively low number of unit failures - the price jack covers the warranty costs especially given the frequency of house sales (warranties typically not transferable, and even if so, who actually hands over the water heater warranty paperwork at a house closing?)

A tank leakage warranty is another matter entirely. If the tank leaks, the whole unit will have to be replaced, no ifs, ands or buts. That's expensive, 10-20x replacing an element. Marathon's lifetime tank warranty means you have bought your last water heater as long as you live in your current home (though I suppose you could drag the thing to your next house)

All steel tank water heaters will eventually rust and leak, though you can stave off the day with periodic sediment flushing and proper regular attention to the anode (how many people actually inspect and assess the condition of their water heater anode rod???)

So, a tank warranty has value. An element warranty does not.

I don't have a Marathon now, though I've had one in the past. I won't argue that the much greater cost of one is justified, but I firmly believe there is simply no comparison between a Marathon and a conventional steel tank storage electric water heater. BTW, I believe Marathon is now made by / owned by Rheem, the vast majority of whose water heaters are of the conventional steel variety. In other words, Rheem is happily serving the 5,8, 10, 12 year and lifetime warranty markets. You get what you pay for, just know what the real issues are.

Makes sense. Consumer Reports recommends the longer warranty models but also because features generally improve on the longer warranteed models. For example, a Kenmore 6 model, the base model, has 1 inch of insulation but the others have two inches. I don't work on water heaters, so I don't know the facts for sure but I still never heard of someone having one that leaked. Common problems I hear of are elements and gas leaks or malfunctions in the valves and plumbing. But again, if you see a lot of them leaking then maybe it's an issue. For the most part, water heaters in general have been problem free for me and I could buy 4 steel tanks for the price of a Marathon. And it 20-30 years, I might be heating my water with something different altogether.

Not sure about Rheem, but most hot water heaters are made by the same three companies, pretty much like everything else nowadays.

Just looked at the Geothermal Survival Kit pdf linked on this site and was shocked to see my annual space heating costs for a 2,200 sq. ft. home in Central Pa. cost about $364. Is this anywhere near correct? I planned for saving a few bucks each month but I usually pay $1,200 to $1,500 for natural gas. (The new house will only have oil, LP, electric options.) I'm trying to budget for a mortgage and knowing my bill will stay under $800 a year even will be a huge plus for me. I was factoring on it costing about $1000 to $1200. House will be caulked, sealed and very well insulated. R23 walls, R49 roof, as mentioned. Energy star windows.

Also, I'm getting Bryant's most expansive thermostat and I plan to not use the electric backup heat often. Never if possible. I don't adjust the thermostat much but I do turn it down when we leave the house for long periods of time and program it to drop down at night. I don't want it to jump up in the morning and think it's got to get warm fast. Are geothermal thermostats better at dealing with such cases?

No, a geothermal heating cost of 1/4 of nat gas is not anywhere near correct. 3/4 is possible.

That's about what I figured.

If I use a standard water heater for my unpowered tanks, however, will it have the correct fixtures to recirculate through the desuperheater? I talked to Marathon and they plan a 4-valve system coming out soon. I saw the tank accessory water furnace sells looks like it has four connects. Two for recirc and I guess one to head to the water tank and another one for something else.

Alton. I'm pretty sure it's fiberglass. R23 walls, R49 roof. I'm assuming there's better stuff out there but that's what comes standard and I'm on a tight budget.