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Driveway good, Snow bad!

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Hey /diy/kes! I'm finally putting in a proper driveway to my garage instead of just gravel. My question is this: I live in the snow belt, and I've always herd stories of some old plumber putting in tubing in the concrete of his driveway, hooking it up to a small water heater with a pump in a closed loop and using that to melt snow and ice off. Anybody ever really seen this in action, or is it total horse shit? The company I work for used to do everything, but we have gotten out of plumbing and now just do electric and HVAC, so my boss has about a 1000 ft. of pex he will let me have for the reel deposit. Will pex work in concrete? No experience at all with plumbing, so I don't have a clue. It's 1/2 inch btw if that makes a difference.
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>>902456

basically the same technology as radiant floor heating... some systems use hot water and plastic tubing, some use electrical heater wire
only problem I see is with the extreme cold of the snow on the concrete, chances are the plastic tubing will burst if the system is ever off and filled with water when it snows. the cold will make the water expand when it freezes. so unless you plan to run this 24/7 during the winter, or have a failsafe in case the pump fails or the electricity goes out, it probably isnt a cost effective option. now, if you embed electrical heating wire into the concrete at least you dont have the problem of possible broken tubing spewing water under the driveway foundation.. but your electric bill will be horrific to run an electrical heater for the whole driveway for the entire winter 24/7

sometimes nothing beats a good ole shovel, or a snow blower....
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>>902460
Weeelllll, Since it is a closed loop, I was going to use either a methanol/water mix like in geothermal, or just plain 50/50 antifreeze and water so I wouldn't have the freezing problem. I'm leaning more towards the methanol/water mix becuas of better heat transfer.
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>>902460
To add to this, I highly doubt it'd actually properly melt existing snow.
Say it falls over night and you're dealing with a meter of snow.
You ain' gonna melt shit. Atleast not in a respectable amount of time. I'd imagine you'd need to run it 24/7 to melt down snow and ice as it starts to form on the ground.

I would consider a snow blower like the Anon suggested.
I'm considering buying one myself since the ATV has trouble pushing heavy snow.
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Yeah, I figured it was horseshit. I'm just a lazy fucker. lol Seriously though, I'm seriously considering one of the belt-drive units that mount on the front of my lawn-tractor anyway. That way I can just drive it to my dads a half mile away and use it on his too.
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Could always try it and report back, I'd be interested. If it doesn't work just drain it, flush it and pump it full of screed
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In ski villages in colorado, montreal and other places that are cold/snowy, this sort of thing is done for the entire road and sidewalk surface. It's definitely technically possible and no *too* cost prohibitive if they're doing it on such a grand scale.

However what you consider cost prohibitive might be very different, since you probably don't have the same formula they have, e.g. 'We can spend $2million to snowproof this 3 miles of road, compared to our average personal injury settlement fund each year of $5million!'

Literally googling 'heated driveway' will show you most of what you need to know in terms of how the pros get the job done. Adding antifreeze to radiant heating solution alters the thermal loading characteristics of the water you're circulating, in ways that are often not advantageous, while it won't freeze it may also be less efficient of a vehicle for transferring heat and cut down on overall efficiency of the system.
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>>902497
>Adding antifreeze.. alters the thermal.. often not advantageous..

- yeah, does AF not work both ways, ie also prevents boiling? Not that OP was aiming for that level of temp, but, I think you correct, it is designed to prevent both (over) heating and freezing.
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>>902456
Before you get too attached to the pex, has it been exposed to the sun while in storage? UV exposure on job sites leads to damage you can't detect for several years.
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>>902501
Of course, that's why it's called anti-freeze/coolant interchangeabley.
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>>902469
why not use glycol?
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>>902561
This.

I work in oil and gas in Northern Alberta. -50C winters. They use glycol heat exchangers for the plant. It's extremely efficient and quite hardy.

I'm not sure if the corrosive properties of concrete will fuck with your pex anon. Also the heat transfer of pex itself is not the best.

I'm an Electrician so for me heat trace would be the way to go.
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>>902566
Concrete doens't mess with pex. Pex is put in concrete all the time in radiant floors.

OP, as another anon has said, people do this all the time, but it costs money. It melts fine, but you have to have it on AS the snow is coming down.
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>>902456
This Old House did a driveway like that.

http://www.thisoldhouse.com/toh/article/0,,198277,00.html
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Shovel and snow tires and shut the fuck up
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These systems are more for getting rid of ice. They're not supposed to melt the snow in your driveway
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>>902460
Second. water pipe radiant heating is used indoors when you don't have to worry about freezing, because it is slightly more efficient that radiant electrical heating. However, it's a bitch if it breaks because leak.
Unless you're going to setup a water heater to run it constantly at ~50 degrees, don't do it.
Besides, the real use for those systems is >>902797, and for <2in. of snow. So you run it on mornings so that the snowmelt runoff from the day before that froze into ice on your driveway turns back into water and you don't crash. Or so that you can run a snowblower and leave that last half inch of snow on the driveway and melt it without worrying about packing down layers into ice under the snow over the winter.
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Concrete finisher from a cold ass state here. Those heated driveways cause so many issues. The tubing in them creates thin spots that can result in cracks. A driveway needs to be at least 5.75 inches thick to really withstand vehicles, plows, your fat mother in law. Okay all that aside, have you never seen how much concrete heaves during the freeze/thaw? Do you guys honestly think anything can withstand that much abuse without having to put in a new 20 grand driveway every 6 years?
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>>902820
This. I am no expert, but my understanding is that concrete likes to heave due to thermal gradient (top gets coolder than the bottom). This tends to cause cracks which will expose the reinforcing steel to corosion. I would suggest that you use an 8" thick slab with rebar as your reinforcement (maybe 2 layers of rebar). This will hopefully help the concrete from developing serious cracks. And dont put the pex near the top surface (try putting it in the middle). You may also want to carve some gutters down the middle of the driveway to help the snowmelt drain. What range of ambiant temps are you expecting?

I live in texas so i dont really have a whole lot of experience dealing with the snow. So take this with a grain of salt
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>>902860
the problem is that concrete, like stone, has high thermal mass. so the farther down you place the heat the more energy it takes to warm it through the 'blanket' of concrete. Well, unless he plans to have it run all winter.
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>>902456
>I'm finally putting in a proper driveway to my garage instead of just gravel.
What's wrong with gravel and why do you want no drainage through your driveway?
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>>903007
Not op, but I hate gravel because I can't use my snow blower without hitting rocks all summer with the lawn mower, and there isn't a solid flat surface for shovels to ride along, creating more work.
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Have you read the threads about "solar roadways"?
They had a similar idea; the panels would melt the snow.
Some people brought up that by melting the snow instead of pushing it away, all you would do is create ice somewhere else.
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Up here in the canada eh, alot of my buddies have radiant heating using pex in their shop floors. all using premixed coolant, just incase they want to shut the system off, or the heater dies. they work AWESOME. As far as im concerned it will work on a driveway no problem, considering how fast snow/ice from vehicles and machinery melts when it hits the floor.

No idea on operational costs though, I know building it isnt too bad though, if youre getting the PEX for free it will definitely be cheaper than buying a blower for your tractor!
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>>902501
>>902553

While anti-freeze does have a higher boiling point than pure water, the engine is more than hot enough to boil either. The thing that keeps the coolant from boiling in your engine is the fact that the radiator is a pressurized system.
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>>902456

It's a technically feasible goal, but it's going to take a horrendous amount of energy to power.

For reference, 1000kg of snow at -10°C would need ~42,000kJ _just_ to get it to 0°C. That's over 11.5kWh, or, conveniently enough, about 1kg of gasoline.

But water also requires a monstrous amount of energy to actually undergo a phase change, roughly 80x what it takes to heat it just 1°C. That tacks on a whopping 334,000kJ, or nearly 93kWh.

All of this is assuming 100% efficient transfer of energy, which of course is foolish. Given that snow is a decent insulator and concrete doesn't conduct heat that well, I'd fudge it at around 66% efficient. So, basically, 150kWh to melt a reasonably heavy snowfall off your driveway. Equivalent of over four gallons of gasoline, which is probably the cheapest way you're gonna get that energy. Probably over $30 worth of electricity if you go that route.


Again, doable. But that shit's for richfags with more money than sense. Might be more reasonable if you only ever got light snowfall and had a small driveway/walkway, but you appear to have neither of those...
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>>903850
I'm soon going to start building a house for myself. I'd love to have a setup like this. As I'm going to heat the house and garage (workshop) with wood anyway so it could be a possibility to install a secondary circuit to melt the driveway. To ease the burden I'm thinking that I'd move most of the snow myself and just let the heater melt and dry the remnants. Just need to figure out where the water would go!
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>>903821
Not to mention constantly circulating through the cooler
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>>902456
we had this on a 150ft walkway at work, It works wonderfully for snow, but when you get sudden heavy snow, or the temperatures drop to low you get a large layer of ice on the path, that wouldn't have been there otherwise. we eventually tore it out, and instead just clear the paths with a mini-plow.
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>>902501
AF has a very low specific heat capacity compared to water. You will not be able to carry as much heat away with the same volume.
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>>903850
How d'you reckon melting something can be inefficient? Is the heat wasted as heat or something?
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>>902561
Glycol is a nightmare to deal with. I'm not sure an average joe can buy the shit.
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>>902456
i've only ever seen steel pipe used in this application. if you use pex then you need to run conduit first and fish it through after you tie the conduit to the rebar and probably after pouring. pex is fairly reliable in regards to expansion and contraction, but check the writing to make sure you're getting the good stuff (wirsbo, pex/al/pex). make sure you have the conduit openings accessible in the garage so you can pull it out and fish in new pipe in case it breaks down
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>>906843
edit: after googling it i'm seeing bare pex being run in this application. i'd still probably put it in conduit because i don't like the looks of it, but i may be wrong
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>>902456
This is entirely feasible, but, some of the details getting the thing running smooth can be a pain. For the whole system there is three basic parts, the tubing in the drive, the pump, and the heating system.

>the heating system - difficulty: easy
Probably the easiest part, a regular home hot water heater will work just fine. Just be sure to clearly label it that it is NOT for potable water

>the tubing - difficulty: medium
What size is the tubing you can get? How big is the area that will be covered? Knowing these will help you estimate how much fluid you will need to fill the loop.
When laying it out, you can space it anywhere from 6" to 9" centers, it will just take longer to heat up at a larger spacing. Just be aware with tighter spacing you will need to make sharper curves, which increases the chance of kinks in the pex tubing.
You will wan to put down a layer of foam insulation over the base before you lay the pex to help direct the heat into the concrete slab, otherwise you are just wasting your money heating the dirt.
While not required, putting some wire mesh down and just ziptying the pex to the wire helps keep the pex much neater. Especially once you start pouring the concrete.

>the pump - difficulty: hard
The pump is where things can really get complicated. Either you get an automated pump and controller, or you just have a manual switch. Manual is definitely cheaper and a lot simpler to set up. You want the driveway heated, you flip the switch, it heats. The obvious problem with that is you need to be there to turn it on. The automated systems while much nicer, are more expensive. Most often the include a remote sensor you pour into the driveway that detects the slab temperature and moisture, and when it falls below a certain temperature threshold with moisture, it will start the pump and circulate heated fluid through the loop.

A water/glycol mix is your best bet, just be sure to get propylene glycol, as it is non-toxic.
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>>906873
here's a pretty good overview of setting up a system
http://www.radiantec.com/pdf/Installation_Closed_Radiant_Heating_System.pdf
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>>902460
You don't use water in these systems.

These systems do exist, I recently finished up a house where it was basically an extension of the infloor heating system, however it only did a small patch in front of the garage because of how cost intensive it would be (and this was for an 8mil house)
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>>902456
In-ground heated driveways are amazing. You turn them on when there's snowfall and they barely use up wattage. However! If you turn them on AFTER snowfall they will eat up tons of wattage and money. Most use restive wire, not tubing.
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>>907165
>restive

Resistance wire, wtf browser.
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>>902456
Heated driveway huh? That's a great idea in theory, but I don't really see the point if you're just using your heated driveway to get to snowy roads.
Also, if your driveway happens to end at a public road or sidewalk (and doesn't have a heated french drain at the bottom), prepare to be sued when they're shittons of ice on the road/sidewalk where all the extra water flows off your driveway and then freezes onto the frozen road.
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>>907177
That is what road salt and cinder is for. The road crews use salt trucks to spread it.
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It might not work as well but I know of people who keep their koi ponds somewhat warm with a close loop very long geothermal setup. Its cost very little to run beyond the initial setup. But somehow you would have to run the pipe much deeper and then up to the driveway.
Thread posts: 42
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