anyone here use... heating loops in concrete driveway/sidewalk?

We're out here in flyover country where the snows are deep and cold, and getting real, real, tired of shoveling out the driveway and clearing the sidewalk.

Even with a contractor handling it, that often means waiting a day or so because of their other work.

So... we'll be needing some concrete work on the driveway in a few years, and I was looking into tapping off our home heating boiler (baseboard, hot water circulating) and running some loops in the concrete.

It would add between five hundred and a thousand to the basic concrete work, and cost, perhaps, ten dollars for the extra natural gas each time we'd use it.

It would also mean changing/adding an antifreeze mix to the boiler loop, which might reduce efficiency a notch (there's lots of argument...) and thus cost us another hundred, maybe, ech winter. Maybe.

So it's economically plausable.

Anyone have experience, thoughts, cautions, or even "you're absolutely crazy" warnings?

Thanks.

Reply to
danny burstein
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Way back when energy was cheap, the Gas company here in town had heated sidewalks and it worked well.

I think that it would cost a lot more than you think it would because if the Gas company here can no longer afford to do so it's got to be expensive.

Reply to
philo

The $500 to $1000 additional cost sounds low to me. Not only do you have the piping that has to go in the concrete, but you have plumbing back to the boiler, controller of some kind, etc.

The $10 cost for the energy to melt deep snow in a cold place, also sounds low to me, even if it's nat gas. Where did that number come from? I don't have experience using such a system, but I would think it would typically go on as snow begins to fall and it would have to keep the driveway above freezing for the duration. That would be a big concern, what it costs to run it when it's needed.

Also, can the existing boiler handle the increased load? Typically systems are sized to the house, with some reserve, based on the coldest days. If you then add in a whole new load, temps in the house may suffer, but maybe that's OK. Like if the system runs at night mostly.

I guess it could work out and be worth it. But I just use a $750 snow blower that's 20 years old. I do a 75 ft driveway plus larger parking apron typically in 15 mins for a snow of 5". If it's a big one, over a foot, probably takes 30 mins or so. If I could clear that with hydronic for $10 or $20, each time, it would be worth it on an operating cost basis. But then I have a furnace.....

Reply to
trader_4

Our local post office has a concrete ramp entrance done. I think it is electric though. It does an excellent job of keeping it clear especially since we've had over 8' of snow this year.

If you can operate it for less than $20 a snowfall, I'd say it is a good deal to save a lot of labor, either yours or a contractor.

Reply to
Ed Pawlowski

It's only a 20 foot run from the edge of the driveway to the boiler, and then figure 150 or so feet of coiled, err, whatever the flexible pipe is made of.

Actually make it a couple of smaller loops, but same concept.

I'm basing it on the amount of hot water I used one day when I _had to_ clear the driveway and shoveling wasn't an option. Used up the tank and had to wait for the water to reheat a bunch of times... but all in all it was about two hours. Water heater is something like 20,000 BTU/hr, so give or take a therm, ala a hundred cubic feet (more or less), which was umm, one or two dollars.

So I figure ten dollars of heat into the concrete should be a reasnoable back of envelope number.

(yes, some goes into the ground, etc., etc.)

System is spec'ed for, yes, a hundred degree differential between outdoor (it gets way subzero here) and indoor.

We retrofitted a higher efficiency, modulated controlled boiler five years ago. It typically runs at 25 percent (apparently its lowest setting) with a 30 or so percent duty cycle. Only time it's hit near 100 percent is when we've been gone and let the ouse drop to 50 degrees..

Alas, Father Time has gotten to us...

Reply to
danny burstein

What is the area of the driveway?

.> I'm basing it on the amount of hot water I used one day

I would think there must be some resource online from the companies that sell this stuff that would give you a better estimate. But I take it from the above that the driveway area is also small.

Sounds like it could be a viable option.

Reply to
trader_4

Many years ago, I heard that the Rochester, NY bus garage, maybe they call it RGRTA, can't remember, put in parking lot heaters. They found it cheaper and easier than plowing and snow moval.

I don't have any real data, your google fu might be far better than mine.

Reply to
Stormin Mormon

Where does all the water go after the snow melts? Will you wind up with a big ice dam along the edge of your driveway?

Reply to
Billy Bologna

Per danny burstein:

No experience... but I would have to think about where the melted runoff would go.

Slope: no problem, I would think...

Dead Flat: I'd worry about pooling and freezing - especially after repeated snowfalls with no thaws between.

Reply to
(PeteCresswell)

On the edge of my old failing memory, I think at the bus garage with the heated parking lot, the snow would turn to vapor, and so melt and run off wasn't an issue.

- . Christopher A. Young learn more about Jesus .

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Reply to
Stormin Mormon

It takes at least 1200 BTU to melt ice to 1 gallon of water. At 15 cents per kWh thats, about 5 cents of electricity per gallon of water melted. If you want it done in 1 hour, you need 350 Watts per gallon.

It takes at least 8000 BTU to evaporate 1 gallon of water to vapor. At 15 cents per kWh thats about 36 cents of electricity per gallon of water evaporated.

If you want it done in 1 hour, you need about 2300 Watts per gallon.

How many gallons of water do you suppose we are talking about on a typical driveway? It takes a lot more energy (about 7x) to evaporate the water than it does to melt the ice.

Mark

Reply to
makolber

Does snow melt quicker than a block of ice?

I would tend to think so since it's mostly air space. Just like a bag of crushed ice melts faster than a solid block of ice. Increased surface area.

Also, since it takes roughly 10 inches of snow to equal 1 inch of water (melted down), it seems like the run off would be minimal. Certainly no more than a typical rain shower.

Ideally, the driveway heating would be turned on when the snow starts so it never has a chance to build up in the first place. It would melt as soon as it hit the driveway.

Of course, even if you manage to keep your driveway completely clear, you'll still have snow out on the street. Even if the street is plowed, they're probably not going to clear the road right up to your driveway.

I live in a rural area and the snow plow usually creates a large berm of snow right at the top of our driveway. Some winters that berm has been as high as four feet. Even if my driveway was clear I would have to dig my way through the snow berm.

The best option is to simply avoid driving anywhere when it snows. Take a day off, or work from home if you can. Obviously, that's not an option for most people.

Otherwise, a snowblower has worked best for me. I started with a small electric model which worked great for the sidewalks and areas around the house. But I had to get a gas powered snow blower for my 200ft driveway and that berm at the top.

Thanks to a changing climate, we haven't had a significant snow fall in the last few years. I never even used the snow blower this winter.

Anthony Watson

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Reply to
HerHusband

That't the important issue, that 1 gallon of water will make a lot of snow. Also, somehow Mark segued into using costs for electric. OP has a boiler, IDK if it's gas or oil, but either would be significantly less to operate.

Reply to
trader_4

| It takes at least 1200 BTU to melt ice to 1 gallon of water. | It takes at least 8000 BTU to evaporate 1 gallon of water to vapor.

Interesting statistics, but how relevant are they? I assume those figures are for ice at a bit under 32F with little wasted energy. With a heated driveway, wouldn't most of the heat go toward "heating the whole outdoors"? That's not the same as cooking a block of ice in a pan. And of course snow is not ice, either. Wouldn't the difference also be significant between melting snow in -5F vs 31F air temperature? And how hot would it need to be in a blizzard, with 2-3"/hour falling? Also, "flyover country" could be anything but the east or west coast.

If it were me I think I'd get some estimates and then plan on a significantly higher figure. There's no sense doing all the work if it turns out too expensive to use. Especially for a luxury that's so notably unnecessary in the first place.

I also wonder about possible problems like frost heaves. If the heat is only on during snowstorms then what's to prevent a frost heave cracking the concrete and breaking the whole works?

Reply to
Mayayana

This is true.

How does that work? If I get 12" of snow and take the day off, does it just disappear by next morning? This winter, I'd be stuck for about three months waiting for it to melt.

Reply to
Ed Pawlowski

| > The best option is to simply avoid driving anywhere when it snows. Take a | > day off, or work from home if you can. Obviously, that's not an option for | > most people. | | How does that work? If I get 12" of snow and take the day off, does it | just disappear by next morning? This winter, I'd be stuck for about | three months waiting for it to melt. |

I'm surprised how many people here seem to find it unreasonable to consider shoveling snow. Does everyone havea bad back? I kind of enjoy it. It's good exercise. If you get 12" you're probably not going anywhere, anyway. So why not get out and shovel?

Reply to
Mayayana

No joy here to do 75ft of driveway, plus wider area in front of 2 car garage..... And if you're out of shape, which many of us are, it's a good way to have a heart attack. OP apparently is in the Midwest where cold and lots of snow are common too.

Reply to
trader_4

A cubic foot of snow can range from 5# to 25#. You can roughly figure a

6" snow is a half gallon per square foot. 600 Btu per sq. ft. A 35' x 9' driveway would need a minimum of 189,000 Btu 138.000 Btu per gallon of oil.

Add to that, the loses to the ground and the time getting the thermal mass up to temperature. The lower the ambient, the more energy needed.

Reply to
Ed Pawlowski

If you really want to do the job right, you'd put a couple of inches of foam board under the concrete. Otherwise, yes, you are trying to heat the entire earth. Foam is used on some highways in Europe and is becoming popular in garages here. I don't know, nor am I inclined to search for, the specifics of the construction.

Since the heat loss is both up and down, the cost could easily be double the BTU needed to melt the snow.

Reply to
Ed Pawlowski

+1

Putting some insulation under it sounds like a cost effective idea.

Reply to
trader_4

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