Heat pumps put out large volumes of warm air. New heat pumps put out 97-degree air at 40F outside temp, 93-degree air at 30F outside temps. Heat pumps produce cheap heat.

If you go dual-fuel (heat pump plus gas back-up), you have the option of switching to gas heat in case you still do not like the temps that the heat pump puts out, or if fuel prices flip-flop.

Whichever route you decide to go, make sure you know the model numbers of the condenser (outside unit), air handler (or furnace), and inside a/c coil (if you go with a furnace). Once you have the model numbers, you can go the the ARI (American Refrigeration Institute) website and confirm system BTUs as well as SEER/EER. Some mfrs systems don't measure up to their stated ratings and you can check it only if you have the model numbers.

I would go with 2x6 framing and insulate as best you can. Insulation is a one time investment that pays for itself many times over the life of the home. Fuel costs will continue to rise, so insulate well.

Best to you.

ncamy

First of all, one has to assume that your home will have excellent new home construction/insulation qualities in walls,attic, floor, windows/doors, etc.

The South has very reasonable electric rates. This would lead to consideration of a geothermal heat pump system. Downside is that it will cost two to two and half times a normal conventional system. If that is not within your budget, then go straight high eff heat pump system with var sspd air handler. Second choice would be a dual fuel system which is a high eff heat pump paired with a var spd backup gas furnace. Do you plan on using gas for other purposes like cooking, clothes drying, etc? And this would be nat gas not LP gas? Dual fuel works and is worthy of consideration.

Since your home is a story and half, I would definitely have zoning controls between the two separate living areas. No reason to heat/cool an area that will not be used continuously.

I am attaching a fuel comparison calculator. Run the numbers. Keep in mind, it is very likely for this area that electric rates will remain more stable and reasonable than nat gas rates.

IMO

Here is a link that might be useful: Fuel Comparison Calculator

Thanks for the advice. Yes, we will be cooking and most likely drying with Natural Gas. We're not sure about the hot water yet. I would like to go tankless but we haven't fully compared costs yet. I'm not sure about the geothermal system. Doesn't that involve digging pretty deep on your land? We have a teeny tiny in town lot in a historical area so I doubt they would approve of us disturbing the earth, roots, etc. too much. The historical commission is rather picky about that sort of thing!

ncamy

Since you plan on using nat gas for cooking and drying clothes, then you are a great candidate for dual fuel.

But definitely plan on zoning controls for the two living areas. Without them would be a mistake.

My opinion.

When I use the fuel calculator above, how do I convert the natural gas cost to cubic feet. The company we will use has it listed as "per therm."

I think I figured it out. I divided it by 100 to get the cubic foot rate. The natural gas rate and the electric came out within pennies of one another.

ncamy

Your computation of therm to cubic foot is correct.

I recommend you check with your electric utility about any special rate for heat pump heating.

I suggest you recrunch your fuel comparison numbers. My outcome was entirely different from yours favoring HP. I used a COP of 3 for HP and a 94% eff for natural gas furnace. Keep in mind that you must average in these base charges for both electric and nat gas into your usage. And it is highly probable that electric rates will be more stable vs nat gas rates.

Dual fuel is your best outcome.

IMO

Be sure to research well before you commit to a tankless water heater. We have a Rinnai tankless & have been quite happy with it. However, there are only 2 of us thus relatively low demand at @ given time & the water intake temperatures are higher than what Asheville will be.

We went with a natural gas tankless as our low-boy gas unit in the crawlspace developed a leak & no manufacturers made low-boy gas versions anymore. We could have gone electric tank but preferred natural gas. The only other option was moving the gas & water lines to the garage which was on the other side of the house which would have significantly increased the time to get hot water to the master bath area. Thus we opted for an exterior tankless unit.

The initial costs are definitely higher. We would have gone with a conventional tank natural gas water heater had we had the space.

For a new build I'd go w/ a natural gas tank water heater & size it such that you don't worry about running out of water when you fill up the whirlpool tub while someone else is taking a shower. YMMV as it depends on # of people in the house & the number of appliances that you would run simultaneously & the incoming water temperature.

I usually take Tigerdunes advice without question but I've never been totally sold on HVAC zoning systems. In some cases I agree that makes a lot of sense & with this being a 1 1/2 story maybe so. My reservation on zoning systems is that typically it is implied & customers assume that 1 system w/ zoning is cheaper than 2 independent systems. The zoning equipment is fairly expensive & I have seen it priced such that they are equal to or exceed 2 systems.

On a small lot as you mention a single system w/ zoning may make sense but don't automatically assume it will save you the costs of another whole system.

I definitely agree you don't want to use only 1 system w/o zoning for anything over 1-story. Either go w/ 1 system w/ zoning or 2 independent systems. Heat pumps definitely provide better heat today compared to 20+ years ago. It still is not the same feel as natural gas but its not bad. As garyg said, dual fuel is probably a very good option for your area.

We currently have a 50 gallon gas water tank which I was assured would be sufficient for a family of three. Well we run out of hot water every single day! My daughter's idea of a "short shower" is twenty minutes. In this next house we will have a 130 gallon tub and multiple shower heads in the master in addition to the teenager bathing/showering upstairs.

I appreciate the advice so far!

ncamy

Mike makes a valid point about zoning. Generally, I prefer having separate systems for separate floors/zones. While you didn't mention the size of the main floor and the guest quarters, I suggested one system with zoning controls for your complete home which you described as a 1 1/2 story. However be clear. Do not even attempt one system by itself without zoning controls. It will leave you with a bad taste and disappointment with poor comfort. I still believe a two stg high eff heat pump with var spd gas furnace and zoning controls is your best choice.

IMO

It's a 1900/700 split between the first and second floors. And let me just add that I love gaining all this knowledge so that I actually sound smart when I talk to my GC (and even husband for that matter!)

You might want to consider a small dedicated tankless water heater for the 130 gallon tub. And put everything else on a conventional tank 80 to 100 gallon water heater.

Or depending on the location/distance figure out the optimum split between a conventional tank & tankless or the optimum split between 2 tank water heaters.

And keep in mind Governor Easley is asking every household to keep their water consumption down to 25 gallons/day during this drought. That means you could fill your tub about every 5 days without any other water consumption.

Back to the HVAC...

You need to have a Manual J load calculation done for your house. This will tell you what size units you should have. A rough rule-of-thumb (DISCLAIMER before everyone goes off on this... I mentioned the Manual J above, it depends on a lot of factors such as window thermal performance, size of windows, which way they face, where you live, insulation in the house, etc, etc so no one rule of thumb applies, etc.) is 1 ton per 500 to 700 sq ft. That means for your 700 sq ft upstairs you may only need a 1 to 1 1/2 ton unit.

The point to make here is that many HVAC manufacturers don't make units that small (depending on SEER rating, etc) so a single system w/ zoning may make more sense in this case even if it does turn out to be the same or more upfront costs.

You don't want to oversize the system as it will cycle too quickly & most likely not remove the humidity as one that is appropriately sized for the space. Also make sure the duct design is done properly per a Manual D.

ncamy:

I found your post on a search. I am getting ready to build in Burnsville, about 40 miles north of Asheville. If you don't mind, please email me at david(at)etheridgelawfirm.com and let me know who you ended up using for your HVAC. Thanks.

I'm not sure if it's just me, but I don't get notifications for posts. Hopefully the OP will check back. If not, mtnlaw, you can always feel free to start your own thread to compare your HVAC options.

I wish you all the best with the house you are building. I just want to mention have you considered geothermal heating and cooling. It's initial cost is high due to the drilling needed but it can save you alot of money down the line. Check out the Econar website for an introduction as to how it works. As for the question of 2x4 verses 2x6 exterior walls definitely go with the 2x6. Very soon with energy star houses becoming mandatory It will be standard procedure. Good luck

Feedback on HVAC bids received for new construction in southern Idaho with cold winters and hot summers (low humidity) would be so appreciated!

House is river-side in the country with 2052 sq feet on main level with vaulted ceiling in great room & open loft of 800+ sq ft. Loft is Game/Media room, bathroom & small bedroom primarily for guests and grandchildren.

In great room, there will be a gas fireplace and possibly a free-standing small wood stove (old, dead firewood is plentiful locally). Floors will be concrete (poured over foundation/crawlspace) so radiant heat is being considered.

However, we want AC to complement the radiant floor heat but installation cost of central air + ducting minus furnace is practically equal to installation of a dual-fuel system.

There's the current dilemma. If radiant heat, then what for AC? If Dual-fuel, which system?

Of course, of 5 HVAC contractor-proposals, none have completed a Man J or Man D which I requested. I'm still considering those calculations with inexpensive online programs; however, conscientious HVAC contractors should gladly complete that process.

The bids on Lennox, York, Tempstar and Bryant proposed a variety of equipment and sizing. Only the following proposal priced equipment separate from ductwork & labor.

This is the only contractor who priced a Bryant system (preferred given information gleaned from y'all). Another, verbally stated a quote of $13,000 but would not provide that in writing (probably was for Legacy equipment).

1 large HVAC contractor said single stage HP w/o zoning was adequate; others felt 2-stage HP was required.

Please review the following, latest proposal:
(of course, more info including model #s would be required before accepting any proposal)

Equipment Temp Star
1 100,000 BTU 92% Gas Furnace (N9MP2100j20)
1 5 ton 13 SEER R 22 Heat Pump (N2H360)
1 Digital Heat Pump Thermostat
1 30 ft line Set
Total $3400.00

Equipment Bryant Legacy
1 100,000 BTU 92% Gas Furnace (352 AAV)
1 5 Ton 14 SEER 410 A Heat P:ump (214 ANA)
1 Digital Heat Pump Thermostat
1 30 ft Line Set
Total $5400.00

Equipment Bryant
1 100,000 BTU 92% Gas Furnace (355 CAV)
1 4 Ton 410 A 16 SEER Heat Pump (288ANA)
1 Evolution Digital Thermostat
1 30 Ft Line Set
2 zone
Total $7200.00

Duct
All Main Strunk Line Metal and Insulated with R8
20 Heat Runs all heat runs will be metal
with 5 feet of flex on ends
4 Return Air Vents

Gas Piping
Furnace, bbq, range, boiler and water heater

Venting
bath fans, range, dryer, furnace

Bid includes : labor, parts, permit and tax
Total $10,700

After reviewing months of threads on this website, I value opinions, expertise and experience of participants.

You're all outstanding for the time & thoughtfulness you provide to home-owners who just want a fair deal on an appropriate heating and cooling system.

Thanks!
Idaho Cowgirl

Cowgirl

with good new home construction, I suspect you are oversized both heating and cooling especially first two quotes.

I strongly recommend you insist on seeing the load calculations in writing from your HVAC dealers as well as performing one yourself for comparison purposes.

BTW, what is your electric rate? If you decide on radiant heat, I would consider pairing with a high eff HP. If you select a furnace,I would want at least a var speed two stg model.

The Bryant Evolution is top of line equipment.

IMO

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!