The issue is moisture going through the wall and condensing on exterior sheathing. The key is 1) minimize the moisture in the house through good building practices and ventilation, and 2)make the house air tight.

Posted By rgonyer on 09 Dec 2015 12:10 PM
I will definitely take a look at that, thank you.

It's unfortunate that I can't simply rely on a building contractor to know these things, isn't that why a general gets paid? It seems around here, they earn their percentage just by managing subs.

Amen.

Once you have a set of prints the Manual 'J' can be done and HVAC system options can be intelligently considered from an informed perspective.

I like the 2x4 wall with Thermax on the exterior. In fact I used Thermax on the interior of my retrofit master suite in a recent remodel. The comfort level improved dramatically from the 1978 2x4 wall it was.

We design many radiant floor systems for SIP, ICF and stick built homes, but hyrdonic radiant floors are but the first step. If you have enough heat load to warrant a condensing boiler and you have natural gas, then an indirect-fired water heater is in order.
Then you need to consider ventilation. We use ERV's most of the time in our Midwest design.
Finally, cooling and humidity control.

In my own house I opted for the iSeries from Unico giving me the advantage of easy ducting with fresh, filtered, humidity controlled air to all habitable rooms and the efficiency of the air-to-air heat pump Dana so astutely promotes.

If you are not melting snow/ice in the driveway and walk and the loads are low enough, you might find a properly sized sealed-combustion, direct vent water heater such as Vertex, Polaris or Phoenix will take care of all of your spacer heating and domestic hot water needs.

People who have natural gas can rarely afford to use electricity for primary space heating, no matter how much they want to use electricity...

PS I have not seen your plans. www.BadgerRadiantDesigns.com

PSS. My dad grew up in Potosi. I live in Minneapolis, MN

You can build a 2x4 wall, a double wall or a 100% foam insulated wall that will have moisture problems. It's more about choosing/designing/executing it right than any one being consistently superior.

@BadgerBoilerMN - I should have an updated set in the next day or so, I will be happy to supply them and would even like to hire your design services.

@jonr, I agree - the question is how do I make sure they are doing it right. In my case, getting it designed right is most of the battle. My friend and I may be framing it ourselves- and if not, I currently live within walking distance of our new site so I can easily check things out daily.

To jonr's point. It is relatively easy to visually inspect a isopropyl application making sure the manufacturers' recommended tape and general installation instructions are followed. Windows and doors become the tricky parts.

Borst Building Assembly Moisture Analysis Software

This software is based on the 2013 American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Fundamentals Handbook historical steady-state dew-point or Glaser methodology for evaluating moisture accumulation and drying within building envelopes.

Really no reason to reinvent the wheel.

http://www.acca.org/standards/approved-software

@Badger, another piece of info- I'm fairly sure I'm going to be putting solar panels on the south roof, and there will be a lot of room there. Does that lean me any more towards electric, or is the equipment just not there yet? I do have natural gas available. I would LOVE to have snow/ice melt capability on the driveway, but it's going to be a fairly big driveway so I'm afraid it won't be affordable or sensible. Maybe just doing the landing pad in front of the garage will make sense.

Whether or not solar is for you depends first on the climate then on the construction with everything weighted by available fuel.

If the bulk of your energy load is in the heating season, as it is here in the upper Midwest, and you have natural gas, the PV can be used for lesser loads but I'm sure Dana will chime in the with particulars.

Having the first 20 feet of the garage drive snow melted is a blessing.

Unfortunately, ACCA doesn’t get involved with moisture analysis software, only simplified heat loss analysis software for HVAC technicians. Fortunately, ASHRAE does understand moisture analysis and makes the analysis methodology available to building engineers. If you are constructing an unconventional building assembly that has not been tested and proven in your area, you will want to accomplish a proper moisture analysis. Perhaps too late, perhaps not, here’s also some good advice on selecting contractors:

Consumer Reports - Selecting a Contractor

I use a lot of AC, it's 90+ and humid here way too often. I'm soft in my middle age. Haha.

Do be careful of those simple HVAC contractors and their silly ACCA approved software, such as Wrightsoft.

ftp://ftp.wrightsoft.com/pub/rst/PDFManual/Tools30Manual.pdf

ASHRAE is an association and as such, not a sentient being capable of understanding anything.

Further, the volumes of useful information, available to anyone with a credit card, is of little use without the proper training and experience, thus the HVAC industry standard called ACCA Manual 'J' for residential work.

Most modern construction will need humidity control beyond a properly sized and installed AC unit especially with the addition of an ERV. ICF and SIP's are a good example. The heating and cooling loads may be so low that proper dehumidification and warm floors are not possible. Thus the modeling using radiant specific software.

Sent you our most recent floor plan.

Actually, ACCA (Air Conditioning Contractors of America) is an Association of HVAC (heating, ventilation, air conditioning, building performance) contractors.

ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) is a professional Society to advance the arts and sciences of heating, ventilation, air conditioning and refrigeration to serve humanity and promote a sustainable world.

We do not put much credence in Alliances/Associations (e.g., Radiant Professionals Alliance, Radiant Panel Association, etc.) because they typically just sell memberships to any company that pays their membership fee. Alliances/ Associations are more about marketing and making the companies that purchase their memberships appear competent. This is not to say that all companies that are members of these Alliances/Associations are incompetent. It is just that these Alliances/Associations do not have any membership acceptance criteria that actually evaluates HVAC competence and experience.

In lieu of Alliances/Associations, we prefer and recommend professional Societies like the American Society of Mechanical Engineers (ASME) and the American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE), which have strict and vigorous membership acceptance criteria.

When it comes to building analyses, it is usually best to hire an independent third party professional to accomplish just the analysis who is licensed to operate in the State where the building will be constructed. There is nothing wrong with the ACCA Manual J analysis methodology. However, there is risk that the person hired to accomplish this analysis may be less than competent and may be more motivated to sell their services and products. If there turns out be a problem, a consumer usually has more legal recourse if they hired a company that is licensed to operate in their State.

You really want to do this...again?

"may be motivated to sell their services and products. " ?

Who would know better?

Still knitting?

That Unico system looks pretty neat. From some of the pics on their site, it looks like they have the unit and ducting in unconditioned space in the attic, I thought all the ducting would have to be in conditioned space?

I love Unico.

The new iSeries air-to-air heat pump is spectacular. We finished a new 6000 sq.ft. house this spring, wherein we placed two 3-ton units running cold-weather backup off the indirect water heater, all driven by condensing boilers.

I am about to replace my marginal mini-split with a Unico iSeries system for better control of humidity, filtration, fresh air, improved comfort and lower noise during the peak cooling season...now in Minnesota.

Many high velocity systems are installed in an attic, but unlike conventional low-velocity duct, the typically 9" profile of the insulated Unico plenum will neatly fit below the attic insulation. In my book it is "in" the envelope.

What's more; my hum-drum Manual 'J' heat load program allows me to design with Unico and radiant floors, walls and ceilings using all the information generally available from ASHRAE, but otherwise useless without dedicated software specific to the task.

Posted By BadgerBoilerMN on 12 Jul 2016 09:37 AM
I love Unico.

The new iSeries air-to-air heat pump is spectacular. We finished a new 6000 sq.ft. house this spring, wherein we placed two 3-ton units running cold-weather backup off the indirect water heater, all driven by condensing boilers.

I am about to replace my marginal mini-split with a Unico iSeries system for better control of humidity, filtration, fresh air, improved comfort and lower noise during the peak cooling season...now in Minnesota.

Many high velocity systems are installed in an attic, but unlike conventional low-velocity duct, the typically 9" profile of the insulated Unico plenum will neatly fit below the attic insulation. In my book it is "in" the envelope.

What's more; my hum-drum Manual 'J' heat load program allows me to design with Unico and radiant floors, walls and ceilings using all the information generally available from ASHRAE, but otherwise useless without dedicated software specific to the task.

You don't have to sell me I'm already sold. I do believe I sent a current floor plan your way but didn't get a reply. Right now our floor plan is essentially complete, and we're working on getting the remaining plans detailed. I still have time to decide on the exterior wall construction method. I'm leaning towards 2x4, OSB, and 2" foam, but my contractor is kind of scared to do that since it's not typical around here. Easiest for them is to do plain 2x6 exterior walls.

Sorry, I'm not sure I got your plan. I like the OSB Thermax stack-up and wouldn't back off.

Looking for a new message from you now.

Best of luck.