I'll be building a timber frame home enclosed with SIPs. I've recently started looking for an HVAC contractor and all those I've spoken do not know how to get the heat/AC ducts up to the second floor. All 2x4 interior room divider walls will have a timber frame beam at the top of the wall. Anyone know how to run HVAC ducts in a timber frame home? Thanks.

1. Build some walls which are not under beams.
2. Use mini splits - in a SIPS house they'll work great, they're less expensive than typical HVAC systems, and quieter.

where are you running plumbing? Whoever designed the frame should have planned these things out; most do. you can always run things in the corners of closets, but that may or may not work.

Bob: Can you tell me what a mini split is. Thanks.

Air Source Heat Pumps.
We've used them in all our superinsualed homes for several years.

http://www.mitsubishicomfort.com/articles/ductless/5-advantages-of-ductless-cooling-and-heating-systems?gclid=CjwKEAjw19vABRCY2YmkpO2OzTsSJAAzEt8sXkX7Epw0xNUlZgfZHRGFGPxPltTKbJoxs8SgCr3IMRoCXyDw_wcB

and
http://www.greenbuildingadvisor.com
enter "mini split" in the search box - lots of articles about them.

Then run your whole house off PV panels!

Bob, I'm familiar with Daikin mini splits and like them very much.

What were the deciding points that pointed you to Mitsubishi mini splits? Are they as good, trouble free?

Very few Daikin units have specified outputs below 0F outdoors, some don't even have a spec for +5F (though some do.) Both Mitsubishi & Fujitsu have units designed for temps of -13F or lower. They also include things like automatic pan-heaters for managing defrost ice build-up issues, features not found in any of Daikin's offerings (that I'm aware of.)

With Mitsubishi the pan heater is an optional accessory on their cold-climate models, but it's really not an option for US climate zone 6, (or even the cool have of zone 5), since they won't warranty against damage from ice build up without it.

Mitsubishi has pretty good reliability record, and very good local support in most of New England (more local support than Daikin), which is another reason Bob (who is out of New Hampshire) is probably more familiar with Mitsubishi than Daikin.

Just did some reading on mini splits. Sounds like it might be a good solution.

Dana, Do you know if a person in zone 8 (10F - 15F winter) were to use a Mitsubishi unit that can work at -13F, even though zone 8 never gets that cold, would the minisplit work more efficiently?

The DOE US climate zone 8 is the middle of Alaska- it definitely gets that cold- and colder (a lot colder!)! You must be talking about plant hardiness zone 8 or something?

http://www.greenbuildingadvisor.com/blogs/dept/building-science/all-about-climate-zones

All minisplits have lower capacity & efficiency at lower temperatures. The published HSPF efficiency numbers are in a heating zone IV climate (not to be confuse with US climate zone 4), with a 99% outside design temp of +17F (which might be in US climate zone 4A or 4B, or some other zone.)

http://www.fsec.ucf.edu/en/publications/html/FSEC-PF-413-04/images/Figure5_lg.gif

http://articles.extension.org/sites/default/files/7.%20Outdoor_Design_Conditions_508.pdf

If you are in a lower heating zone than IV or have a 99% outside design temperature warmer than +17F you will usually beat the HSPF efficiency if the thing is sized correctly for the load. Being modulating equipment you want to have sufficient capacity at your 99% outside design temperature, but not so oversized that it won't modulate during the shoulder seasons. Mini-splits are tested for both max & min output at +47F, so it's useful to have calculated the heat load of the house at that temperature, as well as at your 99th percentile temperature bin.

In general, the cold-climate Mitsubishi & Fujitsu units will outperform their published HSPF numbers in locations where it only drops to high single-digits during the coldest days/nights of winter, but only if sized correctly. In those locations you can probably skip the pan heater too, since in places that temperate it's unlikely to see several days in a row where it literally never breaks freezing outdoors, allowing defrost cycle ice to build up in the bottom of the pan.

deciding points that pointed you to Mitsubishi?
first, they are excellent machines; well built with new advances coming out at least annually. The deciding factor was that most HVAC contractors had heard of ASHPs but few had used them, except for a small heating store near the big lakes. They started selling Rinnai units for space heating, but latched onto mini splits early for their AC capabilities, and sold them like hotcakes. So when I was looking for a contractor, they had installed dozens or hundreds when most contractors hadn't done any. With a unit like this, the quality of installation and the knowledge of the units trumps (sorry) all else.

We are doing a house where the home owner has called for Daikin. I'll read up on Mitsubishi for the future. Thanks for the info.

What is your 99% outside design temperature?

What are your 99% heating & 1% cooling loads?

"...a house that calls for Daikin..." isn't something that a house usually does. There is more than meets the eye for picking the optimal mini-split, and even within a manufacturer's line up there are enough differences in models of similar tonnage that one can be considerably more appropriate than another.

Local support & expertise will often narrow the choice between manufacturers, but there are few US markets where Daikin is hands down the local leader on that front.

I have nothing against Daikin- they are the world's largest manufacturer of variable refrigerant volume HVAC equipment and a high quality vendor, but they are not head & shoulders above the rest by any means. (I'm a fan of Daikin's Quaternity series for high-R /low-load homes in humid climates like the southeastern US, but would have no problem specifying something from another vendor's lineup if it were more appropriate.)