I think jackta's been hitting the medical weed too much. I see that the Lorax statue was stolen from Dr. Seuss' house. I wonder if it was a ride share by you know who?

Oh, sorry for hijacking the thread.

Well the thread is about radiant heating. Some genius is going to put pex in the slab. I don't have confidence in that technology. I have wacked away at too many walls with a sledge hammer in search of leaks caused by frost damage. I couldn't sleep at night if I ever leave the house for longer periods of time and I have to depend on some automated system to keep the temperature of the house above freezing or else. But that's just my personal take on this technology.

As for my ICF house project. An ICF manufacturer would do well to allow me to scam them or be able to acquire their blocks for my project. The engineer who is going to inspect/approve my house is preparing plans for an shopping center outlet center 5 minutes down the road. I have heard that ICF manufacturers don't care much about residential anyway. The big bucks these days is in commercial.

The likelihood of the PEX in a slab freezing in western WA inside an R20+ ICF home is probably about the same risk as seeing that house accidently shipped overnight to Kansas by express tornado. Design temps at anywhere near sea level there are ~20ish F, and extremely rare is the week where it doesn't break freezing outdoors. With literally any amount of solar gain, it's inherently freeze protected there. (People have uninsulated plumbing in vented crawlspaces there, with only once a decade freeze-up problems.)

That's not to say radiant would be the best approach, (even if it's the most-comfortable approach), but freeze-up risk isn't a reason to avoid it. Hydronic baseboards would be far more likely to freeze up if the place went unheated for the coldest month since the last ice age, but even that's pretty low risk in any ICF house if you're willing to close the windows & doors.

But any propane burner would be a poor choice here, given the none-too-cold climate and the wide availability of high efficiency air-source heat pumps. In WA (and much of the US) the three vendors that collectively dominate the market are Mitsubishi, Fujitsu, and Daikin (with Sanyo & LG vying for 4th place) and they all have pretty-good products & support.

In dmaceld's analysis, if you spent the extra $20K+ on photovoltaics instead of geothermal, the lifecycle costs of ductless air source + PV with the same cash is a dramatically better deal, and the net annual operating costs will be much lower. Even without subsidy you'd get at least a 3kilowatt PV array out of it, which would deliver more than 4000kwh/year (about $500-worth, at typical western WA rates) if it has minimal shading factors.

Pex is spec rated at 35F. Conveniently 35 is above freezing (32F).

Posted By jacktca on 31 Mar 2012 02:38 PM
Pex is spec rated at 35F. Conveniently 35 is above freezing (32F).

Is there a pipe that is rated below freezing??  Pipe is one thing, but as long as you use fittings and manifolds, which are made of plastic or brass, the freeze protection is limited to the weakest link.

Don't get me wrong. This technology is accepted even in climates far colder than Pacific Washington. On the Polish/Czech border they even retrofit houses with automated equipment used for installation after the fact of this type of in-floor heating system. Let's say you have a room in a house. You lay the plastic pipes down on the floor. In comes a machine. You stick a monitor into the room. It uses a transducer of some sort to take measurements. Tells you how many bags of cement to put into the machine. How much sand. How much gravel. How much water. Shines a laser level on the four walls of the room to help guide the concrete smoothing/finishing process. Voila. On my ranch east light snow in February is knee deep. Average waist deep. In a good year shoulder deep. I wouldn't want this kind of heating because like I said earlier. I have seen too much damage caused by frost in my day. But if you're into it more power to you.

Please don't worry about the 'if' it can be installed in my area, as my brother already has it installed and has no issues with his. (6 years ago) My only question is that if it is a wise choice with the ICF home. Propane is our only fuel source, leaving few options. Electric, Propane, Heat Pump (not comfortable with this one, as we are right on the water and in a flood zone and not sure if that matters) or Hydronic.

Thank you for all the concern, though.

You're mixing up heat source with heat distribution mechanism. The heat source can be gas (natural or propane), wood, solar, ... , or a combination. The distribution mechanism is radiant heating. I am assuming you're referring to floors. I can't see how radiant heating could possibly come into play with ICF walls.

Radiant heating as a distribution mechanism is more efficient and no energy is lost through air ducts (the alternative). If you have allergies they might be aggravated by moving air (the alternative). The downside (as I see it) is you have to worry about freezing in case a fluke perfect storm occurs when you're away. Also as with everything $$$ cost $$$ may be a factor.

Yes, in the floors. My apologies, as I was attempting to say the heat source would be propane or electric, but you were able to figure that out.

And yes, $$$, but when you get it at a better rate having relatives in the Radiant heat trade... it helps.

The downside (as I see it) is you have to worry about freezing in case a fluke perfect storm occurs when you're away.

That's not a worry here.

If you are worried about water in PEX freezing, use antifreeze. Works well far below freezing (for example, snow melt applications).
Personally, I would put tubing in any new slab - it's inexpensive.

Posted By jacktca on 31 Mar 2012 08:01 PM
Radiant heating as a distribution mechanism is more efficient and no energy is lost through air ducts (the alternative). If you have allergies they might be aggravated by moving air (the alternative). The downside (as I see it) is you have to worry about freezing in case a fluke perfect storm occurs when you're away. Also as with everything $$$ cost $$$ may be a factor.

Ductless air source heat pumps have no duct losses.

Freezing basement slabs simply isn't going to be a problem in that climate in any house that has glass in it's windows, and doors that stay closed when locked.   A hurricane taking the roof off just before the cold-snap of the decade might put it at risk though. It's literally that level of "fluke" that would be required.  East of the Cascades, different story.

The system cost of air-souce ductless is less than radiant, and can even less than higher-temp hydronic heating.  In the past year I ran the numbers on a real application a mini-split solution vs. a 140F baseboards running off a gas-fired hot water heater for a low heat-load application.  Upfront cost on the mini-split won hands down on the heating system alone, without including the combined cost of separate heating + air conditioning systems.  comparing it to small ducted (and 2-3x oversized) smallest-in-class condensing gas hot air furnace it was comparable, but the cost of separate air-conditioning still tipped the balance heavily toward the mini-split.

Mini-splits with continuously variable speed blowers have remarkably little air-movement & noise aggravation at low to mid speed-  comparable to continuously variable ECM-drive air handlers on multi-stage gas furnaces of comparable cost.

Dana- do you have stock in the mini split industry?

I agree with Jonr I put pex in all my ICF homes in New York including both of mine and have had no problems, I have an antifreeze mix of 30% and make sure that loop is under 300' and no joints in concrete.
I generally use Unico heat pumps called Unichillers which do both the heating and the cooling.
The cooling is done via forced air 4" ducts from ceiling this keep dust from being blown into the air from floor registers and if you use a concrete floor system like Insuldeck you hear nothing. Radiant is without a doubt the most efficient as it heats thermally not through the air, it seems a couple of people on this thread don't understand the technology and should do some reading.
The system on my 7300sq ft house is just 5Tons and does both heating and cooling, I also used designs from a NASA engineer in Texas that I'm sure a few of you know of he is brilliant....literally a rocket scientist :-)

Posted By lzerarc on 02 Apr 2012 12:06 PM
Dana- do you have stock in the mini split industry?

Not yet. (D'ya think I oughtta? )

Five years ago I would have thought you could only get good performance out of ANY air-source in US climate zone 3 or lower, but the ductless air-source industry has proven me wrong.  There has been ample 3rd party evidence documented by the Bonneville Power Administration's ongoing ductless heat pump program that they work and work WELL in climate zone 4 (western WA) even at design temp, and shown to deliver winter-average COPs of at least 2.5 even on the cooler east side of the Cascades (US climate zones 5 & 6.) 

The results of the BPA work establishes a basis for the subsidy levels at which the utilities gain more profit from paying for site-reductions of load than from building new generating capacity.  For example, the $1200 kickback from Puget Sound Energy isn't "free money",  it's an investment in "negawatts" to keep the rates lower for the ratepayers in general than if they had to build more even generation & distribution capacity to accomodate regional growth, while allowing the utility to profit.  It's a triple-win, the biggest slice going to the mini-split owner, but the utility & ratepayers at large gain from this as well.

I've also gotten private feedback from multiple relatives in that area (none of whom are energy nerds) at how well they are performing, and these are in houses that aren't even up to current code-min for R & U values.  In a moderate-R code x 1.5 house like an R22 ICF with decent windows ductless systems should do even better on both comfort & efficiency.  In a Puget Sound climate they can approach geothermal-type efficiency in a low-load house.