Recommendations on HVAC for new construction

[thunderworks]

We built in the country in 2005 and installed a geothermal heat pump to supply radiant tubes in our floors, and standard air delivery for the summer a/c. Other than as a consumer, I have no expertise in HVAC, but after living with the system for a year and a half (we moved into the house in November of 2005), I am a huge believer in the efficiency of the geothermal systems. Our total electric bill is probably 2/3rds of energy costs had we used either conventional electric heat systems or propane. According to our contractor and his cost modeling, the payback for the installation up-charges was 100% in 6 years. IMO, it makes sense to spend the money up front, get a 6 year payback, then receive an on-going return.

We have a lot of land so our system used 5400 linear feet of line, trenched in our field. If you have to drill vertically, the costs are somewhat higher for installation.

Kent T: your questions about efficiencies of installation (doubling up digging for septics or wells) are probably county code dependent. In our county, there is no way we could have used any of the septic digging for geothermal lines. Don't know about the well . . .

 

[CurlyDave]

...on your duct system do multiple returns and not just one in the center of the house...

In our new house, I put a return air duct in every room. Otherwise you get no air flow to rooms with closed doors.

 

[BarryinMN]

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.

That is the raw rate. I happened to be talking to the area plumber at a trade show about a new controller for my propane boiler & the cheaper electric alternative came up. The energy source is MT coal and the power plant is in ND. The farm is pretty much at the end of the wire. The co-op team is extremely thrifty I saw something about starting to sell the coal ash residue vs pay to haul away.

The big city has always been significantly more expensive with more taxes, plus various riders, fuel adders, etc. Ends up about $0.11 KWH. AC peak demand has a remote switch that extends off times. NG heat is OMG.

MN is not great for solar & there is usually little wind at -30F.

 

[Birdhunter1]

You get airflow to the rooms the problem is it pressurizes the room and pushes all the air out, it will feel cold in a room in the winter time when you have an 8" round pipe suppling a 6x12 floor register. It literally pushes the heat out of the room.

 

[weedsportpete]

I am particularly dense in these topics - can you explain that in detail, a la Ductwork For Dummies? When does hot air going in or cold air going out force the hot air out of the room?

 

[Birdhunter1]

If there is no return in a room to circulate the air it is like blowing into a balloon, except the house doesn't expand so it forces the conditioned (heated or cooled) air out anywhere it can (around windows, doors, light fixtures etc).

Try this, go to a room in your house (if you have a return in each room) and block it completely off (use duct tape to seal the cardboard you put over the grille). Then close the door and do a test of it with just the conditioned air blowing into the room.

 

[kmdigital]

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 !

That is a blanket statement that may or may not be true. The only way to know is to make some calculations based on current energy prices, and what each may do in the future, which is certainly a crap shoot!

Also, be aware that a cast iron boiler, while it may not be as efficient as a geo unit will easily last 40 plus years, while anything with a compressor in, especially that is run year around, will be running on borrowed time after about 8 years or so. Sure many last much longer, but seldom will a compressor last much over 10-12 years when used for both heating and cooling. Also, a geo unit will need a lot more servicing if it uses well water, unless you have extraordinarily good well water, without high hardness and no iron. And that is hard to find in most areas of the country.

So you need to add the higher maintenance and repair costs into your equations also. Even a condensing gas furnace will usually cost less in to maintain than a well water geo. A closed ground loop geo will solve most of those problems, but the installation costs go up and the efficiencies go down, so they aren't the perfect solution either.

 

[Nissan197]

Thanks for all the replys. Yeah, I know the geothermal is the way to go, but that up front cost is what gets me, especially when I am trying to keep in budget. Electricity in my area is around 8 cents a kwh. I will have to call the installer back and see how much cheaper it would be going with a horizontal closed loop system. He priced it vertical. I also failed to tell him I was going with foam insulation not thinking it mattered. I also plan on going with radiant heat in the basement floor for sure and if not to much on the main level also. I have some friends who have installed radiant heat in their houses themselves and are willing to assist me in doing mine. Hopefully it will save some $$$.

 

[_RaT_]

That is a blanket statement that may or may not be true. The only way to know is to make some calculations based on current energy prices, and what each may do in the future, which is certainly a crap shoot!

Also, be aware that a cast iron boiler, while it may not be as efficient as a geo unit will easily last 40 plus years, while anything with a compressor in, especially that is run year around, will be running on borrowed time after about 8 years or so. Sure many last much longer, but seldom will a compressor last much over 10-12 years when used for both heating and cooling. Also, a geo unit will need a lot more servicing if it uses well water, unless you have extraordinarily good well water, without high hardness and no iron. And that is hard to find in most areas of the country.

So you need to add the higher maintenance and repair costs into your equations also. Even a condensing gas furnace will usually cost less in to maintain than a well water geo. A closed ground loop geo will solve most of those problems, but the installation costs go up and the efficiencies go down, so they aren't the perfect solution either.

Thanks for that comment KM, I think you are adding some perspective here that cuts through the hype. That comment Toolaholic posted made me curious to put it nicely. I think it may well depend upon your climate as to whether you can expect a payback in a reasonable period. Electricity out here hits .31 cents a KW at tier 3. Tier three is for those folks that use 2-60 watt light bulbs, 2 alarm clocks, drink coffee in the morning using electricty to make it and watch 6-8 hours of TV a week. I fall into that category. I have no clue how I could ever be in tier 1, thats about the energy it takes to run a wristwatch. Tier 2 is a wristwatch, a cordless phone and a 25 watt compact flourescent bulb. At tier one we are blessed with .13/KW. The other rates escape me. I do not know if their is anything after tier 3. Its a progressive structure. I am leaning more and more to getting back to NUCLEAR power. Am I wrong?

 

[davemhughes]

I am glad you posted up this question as I am in the same boat presently. My builder wants to use a 92% propane furnace. Been looking at the wood burner outdoor furnaces, looks like a lot of work on my part. Geo looks great but $$. Propane and electricity is getting more expensive all the time.

What I have decided to do at this point is put a good size pellet stove (corn/wood) in the walkout basement. Put ceiling fans in every room. Spend extra $$ on insulation during construction. Buy good windows and doors. Insulate all exposed pipes, ductwork, and the HW heater. The fireplace will be large with a good blower system in it. Also placing the house where a large row of trees will block the NW side from the wind.