nc I just finished building a home in N. VA, Blueridge Mtn area - similar climate to yours. We live on the main level of the house - second level is just for guests like you plan. We have heat pumps (it's geothermal but still a heat pump) with electric auxilliary heat (what I call toaster mode). Here are some things we did and learned - hope they help: The new heat pump system works great but only because we were nuts about making sure the house was well insulated and sealed properly. We used 2x6 framing, blown cellulose insulation in attic & walls, added extra insulation in attic (R40), used high quality windows & doors. Pick an exterior door type that is designed to provide a tight seal all the way around the door - with 3 point latching. Caulk every nook and cranny on the inside of the house including at the floor and ceiling along the stud top and bottom plates and between butted wall studs where large air gaps are common. Use foam in areas where cellulose won't stick too well. Personally inspect every inch of the house after the insulatimg company says they are "done" - you will find holes that need to be plugged. I had an old lenox heat pump in the first home i bought and the emergency heat always came on - and the bills were out of sight AND the house was never comfortable. After I replaced the lenox with a high efficiency Amana heat pump, it was a huge improvement in both comfort and reduction of toaster mode. Heat pumps have come a long way and you are in a great climate to consider them. In my new home the toaster mode only comes on when a) it is below zero outside, or b) the heat breaks - both cases are rare. It is nice if you go with a second stage gas burner, but probably not needed if you do the insulation right. The main reason I wish I had seond stage gas heat is that you can run it off a backup power generator. Both my main and Aux Heat is electric and would need a massive generator to run it. So my backup heat is wood burning and gas firpelaces. If I could do it all over again, I would go with the second stage gas heater. If you go with that make sure that the second stage and the blower fan can be operated off a backup generator if the main power goes out and stage 1 heat is out and wire it that way, even if you don't do a generator right away. It takes a lot of power to start a compressor used in stage 1 but almost nothing to run the HVAC contols and start the second stage gas burners. We have separate heat pumps for the main level and the second story and I do recommend that. But I also zoned the second floor system because in my past homes, the second floor bedroom temps varried quite a bit depending on sun angle and season. Plus - when my parents come to town my dad likes to create his own tropical environment - and so I really put the zones in so he could do whatever he wanted in that 1 room and not mess up the rest of my house:) I have been doing a lot of experimenting with the tstats ans found that when I set the upstairs tstats to 62 and the downstairs to 65 - the upstairs HVAC system almost never turns on. In summer I set the second floor to 81, downstairs to 78, and again second floor HVAC almost never on. So that saves us money and we like that feature. Soon after we moved in, I added humidifiers to my heat pumps in the basement (but not on second floor unit). I had thought that with a heat pump I would not need these, but I was wrong. Bypass humidifiers are not expensive and well worth the money and effort to put them on. When you are planning out your plumbing, have them add a hot water pipe and valve near each of your your units. It won't cost much to do this and using hot water in the humidifier is better than cold, especially with a heat pump. With humidification, the house will feel warmer at a given temp than a dry house will. A few months after we moved in to our newly built, energy efficient humidified home - we started to sense a musty smell around the June time frame. Turns out that since our house was so tight, we had mositure building up in our basement on humid days and it had no place to go. Learned that I needed a whole house de-humidifier to fix that problem and so far that has worked great. You live in a humid area so you may want to have one of these incorporated into your system, or at least plan for one. We found that when we contolled the humifity level to within 45 to 55%, the house feels cooler and it allowed us to keep the tstat at 78 where we might have to run it at 76 to get the same level of comfort we like. I have also discovered that since my home is so tightly sealed, I need to add in an Energy Recovery Ventilator that will periodically bring fresh air into the home and exhaust stale air. You might want to think about the ventilation part of HVAC - it is important. There are a lot of good posts on this forum about how ERV's work and the benefits. As far as hot water, I have two LP Rinnai tankless units that are connected in series. Normally only 1 unit fires, the second is only for when the demand is higher than normal like when we have guests. I like the Rinnai's for a lot of reasons - but my favorite is that I can run them off my backup generator so we can have hot water when the power goes out (which it does quite a bit where we live). Placement of tankless generators is key, and you have to be very careful since the venting requirements for these things may limit where you can put them. If you are planning to use tankless, you need to think about placement very early in the design - especially if you are thinking about a finished basement. We chose to put our units in the basement, directly under the master bathroom so we get instant hot water there. However, the kitchen and several other sinks are on the other side of the house - 88 feet away. We discovered that it was taking almost 5 minutes to get hot water at those distant sinks (88 feet of pipe holds many gallons of water which takes about 5 minutes to bleed out of a standard sink running at 1.5 GPM). Unfortunately, we could not place a tankless unit in the basement at the other end of the house due to venting issues. I would have prefered a smaller thrid tankless system at the distant end but instead wound up putting in small hot water recirculating system to eliminate that 5 minute delay at those sinks. I recommend pre-wiring the house so that you can add in a small backup generator later - even if you don't plan to have one initially. Have the electricians install a sub-panel in the basement near the location where you would likely put the generator - preferably on a side of the house down wind and away from the master bedroom. Have them wire your heat pumps, refigerators, well pump, septic pump, tankelss hot water, TV, Internet, some lights and outlets, freplace contoles etc. - whatever else you need to survive in an extended outage off that sub-panel. The delta cost for them to wire it this way during construction is very small and you will love it later if you decide to put a generator in since the wiring will be much easier. Best of luck in your new build!

OK, I heard from the company offering the Trane system. He would insist on a 2 stage thermostat as well. He did say that this is the smallest unit they carry so it is oversized for the size of the house but he thought the first stage would meet be close to our size most of the time and then the higher stage would be available when we were heating both zones (the bonus room and the main house) to meet the larger need. Does that make sense? I'm surprised the choices seem so limited that we'd have to go significantly oversized because while our house is on the smaller side of houses being built new these days, I didn't think it would be so outsized. Is that due to the extra insulation reducing the heating need? I'm just worried about the impact of this on energy efficiency and comfort (we live in a drafty 1100 sq foot apartment right now with a 50 year old GE furnace that is surely way oversized and it gets really cold, heats up fast then gets really cold again during normal winter weather (not extreme cold)). Was hoping to leave such behavior behind! Would it be worth it to put in the XC 95 fully modulating furnace on the idea that it could adjust more smoothly given the system is oversized? It apparently has 60 speeds to choose from...

So, My dad wasn't worried about the efficiency or the comfort of 2-stage etc. His concern is that he wants the furnace in the basement and the builder doesn't want to do it. He says the basement will be too cold (which someone here said it will be colder). He is concerned with frozen pipes and I guess the coldness of the space in general. Frozen pipes might be a very small chance, but once he knows of a potential problem he doesn't take chances. He wouldn't buy the house they saw that had two sump pumps...... I explained to mom that the hvac contractor has probably engineered (or whatever it's called) the model with the unit in the attic and moving it would involve changing more than just the location of the unit. I suggested that maybe they can run a duct down into the basement for a couple of vents or maybe look into a gas fireplace down there that they could run when there is a vicious cold snap or he is doing stuff down there. Maybe they make a wall heater of some type that would be effective and would be less $ than an actual gas fireplace as they don't plan to finish the space. Not sure if a few vents or a separate heater, or getting them to actually move the furnace would be cheaper and/or most effective. They are extending their attorney review period until they get this sorted out, so it's a big deal to dad. If we can come up with a solution the builder will do that doesn't break the bank it would be great! Thanks for everyone's input.

Great units, for certain. Is this for one unit or two? Have you considered the possibility of insulating your hot water pipes and putting in ONE large hot water heater? This would reduce your standby loss (depending on your run length of your pipes). How about a tankless hot water heater? They use way less gas and they are so much easier to install now rather than later. If this is a two story home, you want to make absolutely certain of the following: You need either: (1) a zoned system with two different units. (2) one system with automatically controlled zones. (Carrier Infinity is known to be among the best with their zoned system and the price would be slightly less than for two systems--IF you do it now rather than later--drywall labor etc). Don't let anyone tell you that one unit can heat and cool a two story home. It needs to be zoned: either with one unit and thermostatically controlled dampers or two units. Don't take my word for it. Talk to any 2 story homeowner that has one unit for two floors. Too, I would seriously consider adding HVAC to the basement (especially if you ever plan on finishing the basement) Running the ductwork would only be a matter of a thousand bucks or two. Doing it now is a whole lot less expensive than later. Generally, the air conditioning and heating needs of a basement aren't all that significant and you can often use the same size unit depending on the outdoor exposure of your walls and windows/insulation etc. Another thing you may want to consider is having your ducts SEALED with a company that specializes in this. It is not uncommon to have brand new ductwork that LEAKS 20% of your system capacity. It is virtually impossible to get your ducts good and tight without this method. Aeroseal is a proven method which blows little particles into the "holes" and permanently seals them from the inside. Typical cost for this size home: perhaps $500-$750. They print the before and after results for you right then and there. It only takes an hour or two. Cold winters are no problem IF these unit(s) are correctly installed according to the heat load/heat loss of your home. On a twenty thousand dollar job, the HVAC contractor can take an hour or two and run a load for you. Insist on it. Before you go with American Standard/Trane (which are excellent units), check out the Carrier Infinity system with zoning. (You can have up to EIGHT individually controlled zones) Many professionals and homeowners testify that the Infinity system is the best. I should know as I have two of them! Good luck!