Heated Driveway

[rogerg]

Here on the west coast it is not uncommon to have EXTREMELY steep driveways for some reason. One customer of mine, who had a real screamer of a driveway also had it electrical heated. "Had" is the key word.
Concrete does what it wants to do on really steep inclines inclines : it wants to move down hill a little bit. Even maybe a hair.
Apparently the wire in the concrete couldn't move.


roger

[Ted S.]

I think I'd go out an buy a brand new fully loaded F350 and have it outfitted with a comercial grade plow and spreader before dropping that kind of cash.

[parkwest]

I like Ted's suggestion!

I was going to suggest checking out some snow plowing forums online there and getting leads for that as a "green" alternative to heating a driveway with a boiler or electric mats, etc.

[Loren97]

We just installed some electric heat in a sidewalk. I heard the system cost about $15k, plus labor to install. It had a temperature sensor and a moisture sensor tied to a controller with ground fault sensors and temp control. The old electrician who worked on it didn't think it would last the year. It went under concrete at a commercial property. He hasn't had many good experiences with it...said he did an install several years ago that was messed up when a loaded triaxle turned around in the clients driveway, an another neighbor who can't even turn his driveway on because it has a dead short. Proper installation is tedious and it would seem the ROI is just about non-existent. Sell your client a skid-loader and tell them to have fun.

[clydewater]

I installed over 50,000 sq feet of pavers at an office park and it is all hydronic. We used the materials from Heatway with the rubber tubing. The detail in their catalog is one that I came up with back in 1994 for pavers.

The boilers are now hot water, originally they were steam with a flat plate heat exchanger. We do have one section of approx 150' x 6' heated with electric boilers and they do not perform as well as the natural gas / oil fired boilers.

As I recall it takes approx 100 BTU / SQFT to melt the snow at up to 2" per hour.

Doing that drive in electric would be very expensive to run.

I would go with pavers because and Propylene Glycol (not the same stuff you put in your car, but is used in food as a sweetener), and an oil or gas fired boiler. If you use Ethylene Glycol and have a leak you have an environmental issue that you do not have with the Propylene Glycol.

I liked the Heatway 3/4" inside diameter rubber tubing embedded in 4" of DGA aggregate, then 1" of sand, then the pavers. The rubber is more flexible than the PEX. We used 6x6 WWF and wire ties to secure the tubing in place while installing it in the DGA., Pressurize the tubing, then put the 4" lift of DGC well compacted.

It is like a many layer cake. Starting at the earth, install a stabilization fabric, then 4" of 3/4 clean stone with a 4" perforated drain running down the center with taps every 100 feet or so run to daylight to drain this layer (prevents frost heaves when the system is off and drains the water away, then another layer of stabilization fabric, another layer 4" of DGA, well compacted, then the 6x6 WWF, the tubing, 4" more inches of DGA, well compacted and leveled to 1/4" of final elevations, 1" of sand, then the pavers.

This system was installed in 1994 in NJ. In 1996 we had a 26" plus snow fall in less than 18 hours and the system kept the sidewalks clear.

The trick is you need to start the system 12 hours before the snow starts to get it up to temp or it will have a hard time keeping up

Just as a quick calc. 700' drive x 12' wide = 8400 sq ft x 100 BTU = 840,000 BTU Net so if you get a boiler that is 84% effic. then you are talking 1 Million BTU boiler, min, plus add another 10 or 15% for losses in the piping etc since you will have to have multiple distribution boxes along the way. As I recall I think there is approx 120,000 BTU / Gal of #2 heating oil so this will use 10 - 12 gals per hour to run. Just ballpark numbers here.


Send me an email if you want more details.
Rich

[cvandoren]

A reminder to consider and design for runoff. All the melted water will go downhill and when it hits the edge of the heated section it will re-freeze - and could cause the mother of all ice dams. I have read that this is especially a problem where only the 2 tracks where the tires run are heated rather than the full width.