Hey all,
I've ordered my SIPs, have been very happy with the communication from my designer.
Excavator is scheduled for Sept. 17, ICF foundation to follow.
My trouble is with my trades... I found an electrician willing to try SIPs, no big deal there.  My local plumbing supply shop took a month to get my radiant heat design back and I just don't feel like they paid any attention to the 5" of closed cell foam  on  the roof deck, the R-26 EPS SIP wall, or the closed cell foam  on everything I can't SIP.  I'm putting out some big bucks for insulation here, where's the downsized heating and cooling equipment savings I'm supposed to be seeing?  The house is only 30'x 32', full 8' basement with heat in the slab (poured over 2" of closed cell foam for $1800), 2 story with attic trusses.  I'd like radiant heat on the main and second floor, and in the basement slab, and nothing in the attic. 
And all this is before I  bring in the A/C guy (do I really need an auxillary heat pump to heat in the spring and fall here in Iowa?)


Time's draining away, I need to get a handle on these things pretty soon.   I've looked at the A/C direct site, I may try installing a spacepak and HRV myself.  I was planning on running 3/4" PEX on a 16" spacing stapled up with a reflective barrier below and heating it with a water heater.

Anyone got any ideas? 

Ben

So far so good...

Insist that a Heat Loss calculation be performed. Many HVAC people are infamous for just using a 'canned' loss per square foot. I can give you pointers to a DIY one if interested.
Auxiliary Heat? In a SIP house? Ouch! I'm willing to bet that a high efficiency 40k/BTU modulating/condensing boiler(think Munchkin) could easily heat the space and your DHW. For efficiency purposes, I would go with a small boiler instead of the W/H.

I am in the process of building a SIP/Timber home, and will admit that I let the plumber figure out the radiant heating needs (no AC here since I'm at 9000 elevation).  Here is what he (or his supply company) came up with:

215 KBtu LP gas boiler with Indirect Fired water heater.  This will supply heat to:

1500 ft^2, 9' high basement (not ICF) with radiant tube in the slab
1500 ft^2 1st floor living area with radiant tube stapled underneath the first floor
1200 ft^2 2nd story with Baseboard Hot water heaters in the bathrooms and bedrooms.  I could not use radiant heat in the 2nd floor because there is no subfloor

Does anybody think that's overkill on the boiler size?

How can there be no subfloor?

It sounds like it. But then again w/o a Heat Calc I don't know what your loads are.

For comparison, my house is at 8,900', 4,000 sqft, and copious amounts of South facing windows on 2 floors, with 2"x6" stick framed construction. My Heat Loss is calc'd at 140k BTU/hr. I'm heating it, and an 80 gal sidearm with a 140k BTU Munchkin Boiler. Last winter the house was comfortable when it hit -10.

JC -

Indeed there is no subfloor between the 1st story and 2nd story.  I had to design it this way because of a height restriction in the county where I am building.  Electrical is coming through interior walls as is plumbing.  Because this is a timber frame home, the timber floor joists are the structural 2nd floor members.  The timber joists are covered in the 2nd story w/ 2x6 T&G, serving as the first floor ceiling.

Yea, after I posted, I started thinking about it, and that's what I came up with. Never-the-less, have a Heat Loss Calculation performed, and it will tell you what you need.

Also, you might check out Runtal baseboard radiators. They are pricy, but sweet. And, you'll have more heat output and be more comfortable than with H/W convection baseboards.

Good Luck!

An interesting thing I just discovered when looking at the boiler manufacturer's site (Slantfin.com). At 2000' elevation, the boiler's capacity is reduced by 4%, and an additional 4% for every 1000' rise in elevation. For my site (9000'), that means a 32% loss in rating. Makes sense since there's less oxygen at that elevation, and therefore less combustion.

You have a keen eye! That is what's called Altitude Deration and it's calculated on the Heal Loss Calculator that we designed as well as the spreadsheet provided by the Pikes Peak Building Department.

So when all is said and done, your heating plant must provide at least the number of BTU's calculated. The calculations do vary, for instance our calculator, for an elevation of 9,000', uses 70.25% as the deration factor.

Ben:

Check a product called Crete-Heat for installing pex tubing under concrete, go to website www.sipenergysystems.com and go to the link for the Crete-Heat.  This company can supply you with it,  a 30' x 32' =960 sq. ft. @ $1.40 per sq. ft.

There are several companies that will design your radiant heat system for free over the internet if you will send them your plans