Heated driveway???

[stltreedr]

If the weather ever breaks this spring I'm going to have a concrete driveway installed. I was thinking that since I already have the OWB, why not run a few lines inside the concrete and have on demand driveway clearing in the winter when needed. I know some people with radiant heat in their shops, but noone with the driveway done. Anyone on here with an experience in this??

 

[jimbojango]

dude... call mel's heater service in contraception PA, he actually installs waste oil heaters but its the same idea. A boiler is a boiler once the water is up to temp. They run them at like 41 degree's water or something and the spacing is different than for heating. but he knows EVERYTHING about the actual "water line" part of a boiler system

 

[stltreedr]

I appreciate the info. I don't usually call to ask for advice for free, but maybe he sells some hardware and I could buy some stuff off of him. Thanks again.

 

[Sawyer Rob]

I have a friend with his sidewalks and drive heated, some towns have their sidewalks heated... All I know is you have to run antifreeze to keep it all from freezing up...

SR

 

[stltreedr]

All I know is you have to run antifreeze to keep it all from freezing up...

Yeah, I know that. I ran antifreeze in my system last year until it melted down. I had to replace my lines this year, so I'm running straight water now, but planned to fill with antifreeze next year anyway.

 

[Dan_IN_MN]

Search the web for earth tubes.

 

[Rookie1]

Man how I would love a heated driveway. Ill be jealous when you install it.

 

[dave_dj1]

Here's what I would do, run the loops for walkway to a plate heat exchanger, keep the walkway loops separate from the heating loops and filled with anti freeze, turn on circulator as needed for walkway. This way you wouldn't be heating it 24/7 and wasting wood.

 

[Iska3]

I know the heated drive does not work in our area. When we would get 3 or 4 inches of snow, I had piles of slush to clean up and when the winds blew at night I had another mess. This guy had 4 feet of sand under his drive to act as a heat sink and foam all around the sides and entending 4 ft out along the top to keep back the frost. After a few weeks he turned off that zone and only used the one under the overhead door. We found out that the sun would melt the snow almost as fast and his heated drive with less of a mess.

 

[jimbojango]

I appreciate the info. I don't usually call to ask for advice for free, but maybe he sells some hardware and I could buy some stuff off of him. Thanks again.

Buy the blend valve from him. He gets an auto-valve from a company i won't say (that is VERY GOOD) so your driveway water doesn't get "too hot" and most of your heat goes to the house. He's got all the piping, valves, EVERYTHING lol

 

[hupte]

I know a guy who put in lines for a heated driveway. he used it one year and never used it again. cause the water would melt and run down to the end of his driveway and freeze then he had a big pile of ice to drive over.

 

[Joesell]

I have to put I new sidewalks next year and I was thinking about heating them. Now I'm not so sure it's worth the money.
Does anyone have good results?

 

[cre10]

I know the heated drive does not work in our area. When we would get 3 or 4 inches of snow, I had piles of slush to clean up and when the winds blew at night I had another mess. This guy had 4 feet of sand under his drive to act as a heat sink and foam all around the sides and entending 4 ft out along the top to keep back the frost. After a few weeks he turned off that zone and only used the one under the overhead door. We found out that the sun would melt the snow almost as fast and his heated drive with less of a mess.

Sand is poor for thermal conductivity so it won't hold heat. Look at outdoor ashtrays, they are filled with sand because they won't hold heat.

 

[Sawyer Rob]

I have to put I new sidewalks next year and I was thinking about heating them. Now I'm not so sure it's worth the money.
Does anyone have good results?

My friend I mentioned above likes his, but of course he poured his cement so all the water runs away from his drive and he pushes the slush back too. His walks ect. dry right out, and makes it really nice for walking. His garage floor also is "pexed", and this is all in Alaska, so he does have cold....

SR

 

[taskswap]

I researched this a lot myself - if you Google it you'll find all sorts of information online, including instructions, guides on pipe spacing and depth, how many / long / kind of loops you need, etc. I backed off. The consensus was it takes an enormous amount of energy - like, my boiler puts out 125kBTU/hr and heats my house fine, but a calculator I found said I'd need like 2 MILLION BTUs to melt 8" of snow off a driveway with my dimensions. That's a 16-hour burn without even giving the house any heat.

It seems like the trouble is the depth. Anything can melt an inch of snow - I don't even shovel that much, just drive over it. But to melt 6-12" you really need to pour on the BTUs. It's a linear relationship with depth. 6" is like six 1" snowstorms in terms of the heat you need it. It's not like once it gets melting it stays going - as @hupte pointed out above, it can turn back to ice really easy if it doesn't melt enough to flow all the way off your driveway. And let's not forget what the plow is going to do to the end by the road...

I concluded that the amount of wood it would use wasn't justified. It's cheaper to have it plowed than to buy that much cut/split, and if you get your firewood for free, it's still faster to snowblow yourself than to cut/split enough wood to melt it.

Put another way: if I had the kind of coin to not care about the math, I probably wouldn't be heating with wood.

 

[Sawyer Rob]

I think we are talking about two different things here. I, nor do I think my friend, or other people I know with heated drives/walks, thought it was to melt large amounts of snow that falls on the drive. The folks I know, still plow them, they just want the small amount that snows, or the ice that builds up to be gone and the drive/walks to be ice/snow free and safer. They plow them off and let what's left, melt/evaporate away...

It takes MUCH less to get rid of that much snow and it creates much less water to deal with.

SR

 

[taskswap]

@Sawyer Rob That's a fair point - several of the guides online do discuss bulk removal to "help" the system out. I have a gravel driveway and it's a trick to snowblow it without eating up the auger, so a good packed "base" is actually an advantage for me.

The math is all about BTUs to melt height * width * depth, outside temp at the time, whether it's insulated underneath or not, etc. One interesting use is if you have a long sidewalk or front walk - they're narrow enough that they don't take much work to melt. That sounds like a good compromise - put the loops just in the critical / high-value spots and you need far less energy to run it.

So... while we're on the topic, what about doing the same along a roof-line? I've seen all those electric systems, but if I have a boiler running, why pay for that? I wonder if I could run like 1/2" UV-resistant tubing in the same zig-zag pattern, filled with antifreeze, with a heat-exchanger on the loop, and drive that? It's the same concept, this time for ice dams. Any thoughts?

 

[Sawyer Rob]

I sno-blow too and my drive is gravel as well. I don't think anyone is talking about "pexing" a gravel drive, and if it's paved/cemented, it's a non issue.

BTW, I have pretty good skid shoes on my blower, it really helps a lot to keep the stones out of it.

SR

 

[UpOnTheHill]

Either put in trench drains or pitch it to run off the water slightly. The key is to keep the slab above freezing whenever the outdoor temp is below freezing. I have done the controls for a bunch of sidewalk systems. Buy a mixing valve and pump so you can run that loop at a lower temperature. You don't want to send 180 degree water into 20 degree concrete with the flip of a switch - bad things can happen. One system I just finished runs the glycol mix at 135 degrees, which is the highest temp I've ever done one. Usually they are set for about 120 or 125. I had the mason put a concrete box in the middle of the slab and I had the electrician run 3/4 inch PVC stub into the building from the box. I can monitor the slab temp and control the automated mixing valve to keep the slab at 42 degrees. I also installed a sensor outdoors that tells my system when its snowing so i can drop the slab a couple degrees if its not snowing. I have yet to see snow come down hard enough that it builds up on the stamped concrete or stairs. It melts immediately and it drys fairly quickly once the snow stops (an hour or two). It does take a tremendous amount of energy to keep a concrete slab up to temperature though. The heating system at this particular building can produce 10 million btu's per hour. That's for the whole building of course, domestic hot water, heated Olympic size pool, etc. Something you could try would be to watch the forecast and start heating the slab a day ahead of time before a snowstorm. It WILL take a huge amount of heat from your OWB depending on the slab size, amount of tubing, temperature of the slab at start-up. It's a super cool idea though!

 

[homemade]

I often thought of the same possibilities with the new house I would be building. I only planed on doing an apron of 20ft or so out from of the garage and wondering if it was worth it to heat that. Of course I would be plowing/snowblowing it like the rest if the driveway but it would be nice to always have that clean with out having to salt or scrape the snot out of it. I will be heating the garage floor. So just extending it outside a few feet???