Recommendations on HVAC for new construction

[Nissan197]

Well I am in the process of obtaining bids to start building our new house. I am trying to get at least three bids in each area. Right now I am stuck checking out HVAC systems. I would love to go with a geo thermal unit, but the dealers are calling for a 6 ton unit for 2750 sq feet of house (ranch). Best bid so far is a little over 22K (Vertical). Wow!!!! Heat pump route is around 11.5K. Planning on using foam insulation in all exterior walls. Area I am building on has electricity only. If I want propane I would have to haul in a tank, which is not a big deal if it will be more efficient. The thing is there are so many different variations of systems with one differing from another by just one little thing. Decisions, decisions. If I had only won the Lottery the other night. Opinions on HVAC systems......

 

[kmdigital]

What do you want? Comfort, efficiancy or cheap? You might be able to pick 1-1/2 or 2 of these, but you sure can't have all three!

Put radiant heat in the floor if it's slab, either the basement or main level if no basement. If it's in the basement, you can either power it from a Geo or a simple water heater, and you won't ever regret doing it.

As for Geo, where would you dispose of the water? Is there a pond, or were they quoting a buried loop system? Or a second disposal well? Obviously, a pond or ditch is the cheapest and easiest, and the other costs much more.

What does your electric cost per kWh? What does LP gas cost? I don't like Air-to-air heat pumps, but depending on your electric rates and winter design temp it may be a good option. Be assured, if it gets cold outside you will need to use the resistance heat unless you have something like radiant heat to supplement the heat pump. And of course, you have to heat the water somehow, so electrically heated hot water isn't a great deal better then a regular electric furnace.

But with Geo you can also heat your water for cheaper than just an electric water heater. Usually, LP gas will be cheaper than electric for a water heater or electric heat.

LP gas has 92,800 BTU per gallon, but you need to figure that a water heater is only about 80% efficiant, unless you have a high efficiancy unit. And the best you can get from a gas furnace is about 92%, when properly sized and isntalled, but that doesn't include the cost of electricity to run the furnace, nor any heat losses from any duct that may be in an unoccupied space. Trust me, the vaaaaaassssssstttttttttt majority of high efficiency furnaces actual operating efficiencies are considerably lower than there rated efficiencies. That is because they are often oversized, improperly installed, have duct leaks, aren't properly maintained, etc. The posted ratings are under ideal conditions, in a laboratory.

Electric has 3412 BTU per KWH, so it isn't hard to figure out which is more expensive, based on what you pay for each. Electric baseboard is 100% efficient, but an electric furnace normally isn't, unless the duct work is entirely within the heated space so that any heat lost through the duct isn't wasted.

Hope that helps.

 

[toolaholic]

My son in law and Daughter have a Geoexchange buss in Wash. state.

Please name another heat source that will pay for it self. Borrow the $ ,You'll never regret it !

 

[mrkool]

Sounds like someone hasn't run a load calc on your ranch house.
I have about 3000 sq ft on one level, metal roof and I replaced the propane
package with a Hi-Eff Amana split heat pump with variable speed blower,
I also have a 2000 sq ft 2 story separate garage with 3 ton split heat pump.

And since I live in the country, with a lot of spare wood, I got a Hardy wood furnace in case a heat pump/electric heat break down or even no electricity, I can fire up the hardy and generator and have as much heat and hot water as I want.

I ran a load on my house, and it came up to 57,500 Btu gain, so 5 ton is a bit over, but I have some hot women living here.

Geo-thermal is nice, if you've got the money, I've done residential & light commercial central heat & air in middle Tenn for 28 years, and just installed
2 - 3 ton heat pump systems across the street for the builder, and I charged him $11,500 for both systems, and I was the high bidder, he said he like the Amana units better than Rheem/Ruud and Carrier.

If you want, I can send you a CD I picked up at the dealer that let's you do a load calculation, then you'll know how much heat and cool you really need.

Later,

 

[BarryinMN]

Find your cost per KWH to figure payback differences per system. The HVAC contractors should be able to show you their heat loss & AC assumptions.

My cousin installed a geo thermal system ~ 15 years ago & his heat bills average $30-40/mo & he keeps it pretty warm.

Here the electric Co-op has a remote demand shutoff electric heating cost of $0.04 per KWH, (1/2 regular rate) but requires a dual fuel setup unless it's in floor radiant.

Might consider a corn burner, with all the corn being planted this Spring, the bottom may fall out of the market at harvest. It's cheaper per therm anyway but might be a real bargain later this year. Adding a 500 bu silo to the house should be less than $3K.

Look at different water heater systems as well for total costs.

 

[Kevin22]

First of all, a heat loss calculation is in order. Free software is available from slantfin.
Have you ever visited HeatingHelp.com You can post any questions on the "wall" and receive answers from heating proffessionals. They don't discuss price and are not advocates of DIY heating. But you can get honest advice on what is best for your situation.
From the home page of heatinghelp there is a link for the free heat loss calculation software from slant fin and there is also a "find a professional' search function for contractors in your area.

The heatinghelp community are mostly "wetheads" (hot water) guys, radiant, fin tube, and panel radiator advocates. Gas Modulating-condensing boilers with outdoor temperature reset seems to be the latest and greatest in new technology for both comfort and efficiency.

The principal of operation for the outdoor temperature reset is such that the boiler controls limits the heating of the water in the boiler based on the outdoor temp and corresponding higher heat loss.

IE: I have fin tube heating elements. In my area the design temperature (coldest temp of the year) is 5*f, I would need 180*f water to maintain a room temp of 70*f. However when the outdoor temp is 40*f, the boiler water needs to be only maybe 135*f, to obtain a room temp of 70*. This control technology saves energy because it limits the water temp to what you need based on the heat loss according to outdoor temp (which is always changing).

By using radiant hydronic heat stapled up under subflooring or embedded in concrete, even lower temperatures (100 - 110* f) can be used with favorable results.

I believe that oil gives you the most therms per energy dollar but, I cannot quote you numbers. That may be an option if that is available in your area.

Another website: hvac-talk.com

Good luck!

 

[_RaT_]

Find your cost per KWH to figure payback differences per system. The HVAC contractors should be able to show you their heat loss & AC assumptions.

My cousin installed a geo thermal system ~ 15 years ago & his heat bills average $30-40/mo & he keeps it pretty warm.

Here the electric Co-op has a remote demand shutoff electric heating cost of $0.04 per KWH, (1/2 regular rate) but requires a dual fuel setup unless it's in floor radiant.

Might consider a corn burner, with all the corn being planted this Spring, the bottom may fall out of the market at harvest. It's cheaper per therm anyway but might be a real bargain later this year. Adding a 500 bu silo to the house should be less than $3K.

Look at different water heater systems as well for total costs.

Wow, the regular rate is only .08 cents KW? Any transmission/distribution charges on that? Do you guys have tier pricing? Out here, you simply do not use electric anything (especially resistance heating) when you can avoid it. On the other hand, it makes solar panels very easy to recover the cost on. My NG gas bill for January was $48 that includes a Rinnai water heater, stove and our std efficiency furnace. Electricity on the other hand would have been unthinkable. It makes me wonder if a GeoX could do it cheaper? The AC out here is what hurts. Could GeoX beat any other method for cooling?

 

[Bill Barrett]

Geo is great for cooling, plus thats when you get the most free hot water. I'm with everyone else on the heat loss, heat gain, it sounds off for 2700 sq ft and foam insulation, unless you have lots of glass. Look at two stage equipment its the best for comfort. Also electrical rates are going up in most areas. I've installed Geo for 20 some years.

 

[KentT]

Seeing that we have geothermal intallers responding here, I have a couple of related questions. I'm also considering geothermal for my new house in a rural area w/o natural gas service (leaving electricity or propane as the energy sources). The area is serviced by TVA-generated power so the electricity is affordable, in comparison to some other areas. I'll need both a septic system and a well dug.

a) Is it possible/practical to combine the trenching done for the septic system with the ground loops needed for a horizontal-loop geothermal system?

b) Is it possible/practical to combine the drilling done for a water well with the drilling done for a vertical loop geothermal system?

It just seems that there might be some efficiencies here, and some ways to reduce installation costs...

I hope this doesn't turn into a t/j, but it seems related to the original question. Thanks!

 

[Birdhunter1]

One piece of advice I'll give: on your duct system do multiple returns and not just one in the center of the house, use all metal pipe and insulate it for your runs to your rooms instead of using flex duct(espcially on the return duct system) and put a good quality media air filter like an Air Bear on it. A HVAC system with a crapy duct system is like a deisel with bad fuel and a clogged filter.