What will it cost me?

Elliot,
First take a step back and look at the system in total. Co you really need air cooling in Kalispell?
I checked my design book and no cooling degree days were listed for that area, but they
show 7200 to 9000 heating degree days (HDD). Where I am from we only have 5500 HDD per year.

A geothermal heat pump system is like any other refrigerant system, there is a hot side and a cold side.
In heating mode, the indoor unit is hot, and the ground loop is cold. in cooling mode, the indoor unit is cold,
and the ground loop is hot. You can pick air or water for the indoor unit, but not both. If the indoor unit is in cooling mode, there is usually a coil to pre-heat the domestic hot water, this is sometimes called a de-superheater.

Assuming that you do not need air cooling, (big assumption on my part- I have never been to Kalispell in the summer)
I would eliminate the air system all together. If you have a good southern view, I would eliminate the geo-thermal and install solar and a wood gassifier for your radiant heat and domestic hot water, and a gas or oil automatic boiler in case all else fails.

A geo-thermal system is only as good as the wells, in my area, they are expensive.

The price discussion comes after the overall plan is kicked around a bit, otherwise there are too many possibilities.

cheers!

I looked into geothermal, but we have no need for cooling and the ball park figure was $40,000.

So unless we find we are sititing on a hot spring, just not logical.

With a new build, I would look to design to minimise your need, I have seeen it argued that with a well designed house even radiant is overkill.

My house is 2400 sq ft. 10 years ago I was told that with state rebates geo would cost me over $30k. At the time, the state was kicking in 40%. I'm not sure I would live long enough to pay that back. Or that the house would stand that long.

Take a hard look at all your options - geo, solar, wood, fossil (for backup), and maybe even electric for backup. Pick what makes the most economical sense, and put the money saved into insulation.

There is a guy on another forum in Alaska. His design day temp is -47 deg F. Mine is -5. Same sq footage. His heat load is half mine.

I'd recommend doing your heat load calc to try to determine your ongoing costs for heat. You can use current prices for oil or LP just to get a rough idea. Then play with the heat load to see what happens to your ongoing costs if you add insulation to the roof? The walls? Basement walls? Higher quality windows? If you are using software to do this, it's pretty easy to save it with different insulation configurations. You might find a sweet spot where x dollars of more insulation saves you x dollars of ongoing costs over the next 5 or 10 years.

I think we can help you narrow down your boiler selection options with a little more information.

First, you should decide if you want the boiler inside or outdoors. An indoor installation is a lot cheaper and probably more efficient, since you won't be piping any hot water underground and any standby losses will be in your house, not outside. The downsides to an indoor install include: wood mess and probably some smoke in the house on occasion when loading; noise from the blower (if you buy a boiler with a blower); wood handling and storage can be more complicated. All of these factors can be mitigated with the right forethought and design. Since you're building the house, you can design an ideal boiler setup.

Wood supply is important. If you're shopping for a gasifier as you mentioned in your initial post, you're going to need dry firewood. That usually means having enough space to accumulated and store at least a year's worth of wood (preferably more) on your property. Covered storage is best, but most of us get by to some extent stacking on the ground and covering with tarps. I try to get a winter's worth of wood into my barn in the spring, so that it can finish drying over the summer. That works well for me, but it's not essential.

A 3,000 or 4,000 square foot in Kalispell can probably be easily heated with a boiler in the 25-40 KW range (80 to 140K btu/hour). For an indoor unit, you're going to have to decide if you want a Seton-style refractory-based boiler or a Tarm-style European-type downdraft gasifier. The former design relies on natural draft, while the latter has a blower. Plenty of opinions on which is better. Our two sponsors, Cozy Heat and Econoburn both sell the Euro-style forced-downdraft gasification boilers. The Garn is another design to consider, and it has a passionate group of users who I'm sure will share their ideas with you as you begin your research.

I am in Colorado, why do you need air con in Montana?

A properly designed home would not need it, and woud have a low heating requirement. First find out your demand, then look for a solution.

Elliot,

I am/was in your same situation 3 years ago. I built my own home mostly by myself. It ended up being a 4600+ sf insulated concrete home with radiant floor heat throughout with 11 heat zones. I researched about every avenue for heat/AC and found that the best investment was in insulation and windows (so surprise here). I decided to use all radiant floor heat with the pex tubes on top of the subfloor and embedded in gypcrete (lightwgt concrete). This supposedly helps with heat mass and coasting etc. After completing my house, there is no doubt that it is extremely efficient. Our highest natural gas bill was $165 for a month of which ~$30 was delivery and fees/taxes. By the way we have an instanteous gas hot water heater and do all of our cooking with gas. During the summer we have elect bills that hoover around $150 for 2 months and our gas bills are around $20 (of which ~14 is delivery and fees!). We have a 1.5 ton central AC unit (which is equivalent to the largest window AC units available) in the attic that cools the majority of the house for all but 2 months/year. Then the downstairs AC comes on to help when it;s 95 degrees for may days in a row, etc.

All things done, I can now offer my (for what its worth) advice. I would still use radiant floor heat over any other form of heat. It is very efficient and very even in its heating. BUT, I would defineatly not ever do the gypcrete again. There are a number of reasons for this that I won't get into but trust me the heat mass-thing does not offset the troubles associated with it. The other thing is that My system was allot more expensive than originally projected. Direct cost were nearly double at $20K for heating alone. INdirect cost were cost to that much again. If I had to do it over again I would defineatly us Warmboard as my subfloor. It would seem more expensive up front but you will have far less problems down the road. Espcially concidering that if you are building your own house you may do things that require a retrofit later (ex I forgot to run a elect line thru th efloor to my island in the kitchen- how do I find the water line now that it is in gypcrete, etc). I also would defineatly use www.radiantec.com and there systems, except for maybe I would add a wood boiler as Primary heat source and use the Polaris as a backup/vacation use. There "boiler in a box" systems are MUCH more simple and a reasonable DIY'er can do this without a plumber/HVAC guy. They also are much cheaper overall. Just my 2 cents but good luck. It will be a great learning experience.

Yes I can. First of all, I have 42,000lbs of the gypcrete on the 2 levels (1.5 inch thick times 2850 sf (above ground) times 15 lbs/sf).
#1 In lieu of this, I had to have much larger floor joist and they had to be closer together. For example, I have a 18' span in my living room that had to have 2X4 web joist that were spaced one per every 12 inches! That means that there is 8.5 inches in between each joist. This did not seem to be a problem to me when I built the house frame UNTIL I tried to run my plumbing and electrical. How do you put 4" waste water lines perpendicular to the joist? This was the same for the rest of the house where they were 2X4 joist on 16" centers. Also, think about holes/channels thru your floor to put drains, domestic water lines, electrical. If your wall on the upstairs floor is over a floor joist or that joist is over a downstairs wall, it is very difficult to get the lines up and down.
#2 Similar to #1, how do you run Air conditioning returns inbetween the joist? This is actually the reason we have 2 AC (note more money) units. I put the smaller in the attic and the second in the basement and had to "box" around the returns (does not look good). FORETUNEATLY, I indirectly discovered HIGH VELOCITY AC units that use flex-coil ducts that are phenominally easy to install and fit in very small spaces (<4").
#3 If you forget to put an electric line thru a level pre-pour, it is more difficult to do since you are unable to actually see the pex tubing (see example in previous post)
#4 Framing. You have to add a 2x4 to the bottom of every wall in order to get the 1.5" extra height for the concrete. Not a big expense but when framing you have to make an extra 1.5" calculation in all your measurements. ALSO, your load bearing walls have to have much more bracing and "beef" to hold all that weigth. A normal 2X6 can carry ~5000lbs of vertical load BUT it will break like a toothpick if it bows/bends even slightly. Therefore you must either place a 2x4 perpendicular and attach it to the load baring stud or place a sheet of plywood on the wall before sheetrocking and screw in every 2' on each stud so that they can not bend.
#5 In spite of what the manufacturer states the gypcrete does NOT form a completely level surface. It is NOT 100% self-leveling. And no I did not have variation in my framing to cause unlevel floors. What you get is slight variations in the gypcrete thickness that cause problems when you put in your finished floor.
#6 Flooring. How do you install carpet and especially real hardwood flooring? You have nothing to tack of nail into. Carpet was easier since all you need to do is nail an extra ripped 2x4 along the outsides of each carpeted room, but once again more time/money/effort. In addition, waht if the wife wants to change from carpet to hardwood in 10 years? Hard wood installation is even worse because you would have to place a "nailer" every 18 inches throughout each room so that you don't nail into a tube.

I am not a salesperson for warmboard but would have gladly paid for there product which would have solved 90% of the above problems and only cost directly about roughly the same direct cost. In the lng run, using warm board or even a hanger type system would have been far cheaper. Gypcrete should be reserved for commercial applications or aparment complexes where there needs to be fire barriers b/w floors.

the air conditioning doesnt have to be a big deal, especially since you will use it only once in a while. since the floor plan is open you could put in a wall unit or a mini split. The wall unit will be less that $1000 installed. The mini split, maybe 2,200.

for heating, its radiant all the way. in my house I installed 1.5" concrete thin slabs and acid stained them for finishing. even on the coldest day, here maybe 10 f, the floor water isn't over 82.

Desigining a house from scratch is pretty cool. The ideal situation for the wood boiler is in the basement. (my wife would say outside) You need direct access to outside, preferably not too many stairs, if any. The wood storage for the current year should be as close to that basement door as possible. A masonry chimney going up the core of the house would also be good. It will need 2 separate linings, 1 for the wood boiler, the other for the "automatic boiler".

Slab you say? I put a radiant barrier done, then 2" of high density foam before we poured the slab. If you do not do this you will lose alot of heat going down. Just my 2 cents

To answer Biomass's questions about hardwood flooring. I build lots of house with radiant in concrete and we just add a 2x4 perimeter with 2x2 sleepers 12" on center for nailing. It's quick and we use up whatever framing scraps are left.

As for AC the mini-split option is a good idea.