Insulate for snowmelt or not?

Kevin O. Pulver_2

Hello, I'm a hydronic radiant heating contractor and a firm believer in underslab insulation. But I've been re-thinking insulation under snowmelt. Mark Eathertons article in Contractor magazine talked about measuring an insulated slab with an IR thermometer. The ground temp was 34, and the slab was only 25 degrees, due to being un-coupled from the earth, and night sky re-radiation.  I'm thinking that snowmelt may be a little different than say heating a basement or slab home, and that it could be an advantage to have the slab in contact with the earth.  I understand heat goes down as well as up and sideways. I understand insulation saves fuel cost etc.... but since we're only running the system occasionally, and since we're only needing a temp slightly above melting point, wouldn't being thermally coupled to the ground be an advantage more times than it would be a disadvantage? I think the complete answer could depend on your area of the country, ambient temps, and days of precipitation. What do you think? Kevin

Paul Rohrs_14

I think......

I think the Huskers have an excellent chance at dominating the Big 10 this year!



Hey old friend.  Got to remember those cold Nebraska winters and how much NG it takes to bring a cold slab up to temp in the winter.   I think your idea is plausible but the response time and expections might be grounds for litigation.



Get an understanding from your end-user as to what kind of recovery they want/expect from the snowmelt.



Let me know if I can help further but I am a huge proponent of using insulation in all snowmelt projects.



Paul

Kevin O. Pulver_2

Hey Paul...

Did you know?... ;-)

I'm with you Paul, but if "bringing the slab up to temp" means only 34 degrees rather than 80 degrees, and if ambient air temp is 25 to 35 and if the slab start point is possibly colder WITH insulation than without it...

and the few times the snowmelt needs to run depends upon  BOTH precipitation AND icing temps, I was just wondering if on the average it would be favorable to not have insulation.  What we need is black concrete. Look how quickly highways melt with just a little free solar! (and earth-coupled with  no insulation)



What started me thinking about this was an electric cable supplier. (The heavy  Nexxans stuff) Apparently there is a contractor in Idaho who does a lot of electric snowmelt jobs without insulation- not out of trying to be cheap, but rather trying to couple the slab to the ground, which would typically be warmer than ambient air temp. Googling the subject brought up MEs article in contractor mag, which got me thinking further.  I was wondering if anyone else does it that way?



 I know I only have ONE chance to get insulation in there, and I've NEVER done one without it.. But it appears that at least under some conditions, it would work against you rather than for you, at least for some period of time.



(a little trivia; Paul used to be my wholesaler, and while he may have taught me everything I know, the problem is he definitely did not teach me everything HE knows!)

Mark Eatherton

As with any hydronic/water related question, the only correct answer is...

It Depends!



What is the soil structure? How conductive is it?



How often will the system be running, and for how long?



Will the system ever be idled?



What are the consumers expectations as it pertains to reaction times?



And for the record, I too have never performed an installation without insulation. It just does not make sense to heat mother Earth without some means of controlling it.



I suspect our highly paid nannies (U.S. Government) will soon outlaw snowmelt systems, or at least require the use of non fossil fuel resources in their operation, at which point insulation will be REQUIRED.



I am aware of at least a couple of systems that utilize the heat of the Earth, and a small circulator to provide snowmelt. One of them is in Osaka Japan, and does a huge parking lot. We may have to start thinking outside of the box on this stuff if it is going to stick around.



Thanks for reading the article Kevin.



ME

Kevin O. Pulver_2

Thank YOU

Thanks for writing the article Mark. I've quoted you a lot over the years.  Ah, yes, "IT Depends" Your questions about soil conductivity, idle times etc... etc... remind me that I learned  that here as well.

 I think I'll end up using insulation. I believe it's sorta like seatbelts... SOMEtimes they can work against you, but as a rule it's much better to have them on than not.

And the subject of seatbelts (or legislation of the use thereof)  ties right in with your "nanny state" comment Mark, and possible coming mandates for snowmelt.

And concerning, "nanny state" I watched a really great video debate again today. It's called, "The Great Civil War Debate" with two presbyterian ministers- Peter Marshall and Steve Wilkins. Wilkins took the side of the south, and utterly crushed Marshall. (which was really hard on me until I switched sides) Wilkins said that we ALL lost the civil war, and if anyone disagrees, just look at the monster Federal govt. which controls and dictates everything, all the while telling us we're "free". He said the Civil War didn't stop slavery, it just extended the plantation.