Suit yourself of course.
What I can tell you is that except for very small areas in public places I have
never known anyone to use heat to remove snow. A decent snow thrower here uses
between 8 and 12 horsepower and costs upward of $1,200 to purchase, fuel to
operate and a frozen operator and until very recently we paid less than 3 cents
per KWH. I think now we pay 5 cents per KWH for the first 750 and 7 cents above
that. Perhaps we are all too stupid or just enjoy freezing our buns off but I
am pretty sure it is the economics of it.
I do know that trying to meld ice with a propane torch from around a drain in
spring above freezing temperatures is simply a waste of time. I don't have any
idea what the BTU yield is from my torch but it sure boils water in a hurry.
By the way, the frost below the ground does draw off heat. It is how the ground
freezes.
There is another problem too, just what happens to the water which melts from
the snow and ice? It flows until it freezes forming an ice dam. that can me
mitigated by installing a drain at the low end of the walk or drive or path
provided it is deep enough not to freeze as well. In the spring we do send
trucks around steaming out drains of course to carry away melt water.
Where one receives trivial amounts of snow melt systems can work and maybe even
economically enough however I would have thought that trivial snow
accumulations hardly warrant the capital costs.
Do keep us informed though about your experience with electric snow and ice
melting. I would well appreciate a real life example of where it works.
We had a couple of systems at our hospital when it was built a little over
thirty years ago. One was installed in a set of 6 or 8 steps at the rear door
coming up from the parking lot. It worked for about 10 years , this stair well
is recessed into the basement wall and covered, mostly it kept snow and ice
from what ever drifted in there. It burned out. There was another small pad
under a canopy at the front entrance where cars pull up to disembark, I don't
remember how many years it operated but not many and I don't know why either.
They solved the problem at the ambulance entrance buy covering it with a drive
through garage with automated doors at each end. Now I assume the architects
knew something about these systems so probably they work somewhere, somewhere
in the south no doubt but they don't work here.
If I was Han Solo I'd probably pet my wookie
----- Original Message -----
From: Michael baldwin
To: blindhandyman@yahoogroups.com
Sent: Thursday, February 25, 2010 5:01 PM
Subject: RE: [BlindHandyMan] Radiant floor heating.
The ground does not need to be heated 4 foot deep to melt the snow on the
side walk. this is a snow melt system, not a keep snow off my walk system,
so in really cold snows, or fast, deep accumulations, there will be build up
on the sidewalk or drive, but the system will get it all melted.
The heating wires are put in the concrete about 1.5 inches below the
surface.
50 watts is about 170 BTU. 1 watt is 3.412 BTU.
1 sq/ft of concrete that is 1.5 inches deep is about 11.1 pounds.
it takes 0.2 BTU to raise 1 pound of concrete 1 degree F.
To raise the temp to 32 degrees F from 0 degrees F, it would be 71.04 BTU's
Okay, that leaves us with 98.96 BTU's
Going with a medium snow, not real wet and heavy, but not real light and
fluffy, the snow would weigh about 10 pounds per cubic foot.
and if we get an inch of that in 1 hour, that would be 0.83 pounds.
it takes 0.5 BTU's to heat ice by 1 degree f.
To bring the snow from 0 to 32 degrees f, it would take 13.28 BTU's
Now, this is the real BTU hog, it takes 144 BTU's to go from ice at 32
degrees F to water at 32 degrees F, per pound.
That would be 119.52 BTU's in our example.
The total BTU's so far is 204.38, so that puts us into our second hour,
cause we only have 170 BTU's per hour.
In the second hour, we wont' need the full 71.4 BTU's cause the concrete is
already warmed to 32 degrees F, but it will take some BTU's to maintain that
temp, lets say 30% of the original to make it 21.31 BTU's to maintain the
concretes 32 degree temp.
total 225.69 BTU's.
Because heat moves to cold, we will waste BTU's heating the concrete below
the wires as well. Lets say we use another 100 BTU's to heating the
concrete below the wires during the time it is melting the snow on top.
Total 325.69 BTU's
go with 340 BTU's to add some extra in for the heck of it.
So 2 hours to melt 1 inch of snow, and the use of 100 watts per sq/ft.
15000 watts for a 3 by 50 sidewalk.
15 KW times $0.12 per KW, and you get $1.80 to remove 1 inch of snow.
If 1 inch takes 2 hours, and if 8 inches would take 16 hours, then we would
be talking about $28.80 to have a snow free sidewalk.
Then, if the average snow fall is 60 inches for the year, that would be
about 120 hours of use, and $216.00.
of course, there are other variables that you would need computer modeling
to take into effect, like speed of winds, and the thermal loss of the
concrete, and insulation value of snow after it starts to accumulate, rate
of snow fall, etc... but if it costs lets say even $400 a year to remove 60
inches of snow for your sidewalk, that is cheap compared to being in eh
hospital because of a heart attack from shoveling that much.
Possibly cheaper then paying someone to do it as well, not to mention,
waiting on them to get it done.
Oh, best I could find was raw turkey rolls being0.81 BTU's to heat by 1
degree for 1 pound.
Michael
_____
From: blindhandyman@yahoogroups.com [mailto:blindhandy...@yahoogroups.com]
On Behalf Of Dale Leavens
Sent: Wednesday, February 24, 2010 10:16 PM
To: blindhandyman@yahoogroups.com
Subject: Re: [BlindHandyMan] Radiant floor heating.
Well, it takes half a day to thaw a 20 pound turkey in my house at 72
degrees F. My patio weighs about 11 tons and is sitting on frost that
penetrates about 4 feet and just now it is 0 degrees F out there with a
slight breeze. That would require a load of heat to melt the snow even if
the patio was laid on insulation.
If I was Han Solo I'd probably pet my wookie
----- Original Message -----
From: Michael baldwin
To: blindhandyman@ <mailto:blindhandyman%40yahoogroups.com> yahoogroups.com
Sent: Wednesday, February 24, 2010 10:44 PM
Subject: RE: [BlindHandyMan] Radiant floor heating.
Then go to
h <http://www.suntouch <http://www.suntouch.com> .com> ttp://www.suntouch.
<ttp://www.suntouch.com> com
click on the ProMelt Mats link
read the info, and download or open the pdf link SunTouchR ProMeltT
Brochure, and see what it says for yourself.
it is possible I miss read 50 watts on 240 volt systems, and 36 watts on 120
volt systems.
Michael
_____
From: blindhandyman@ <mailto:blindhandyman%40yahoogroups.com>
yahoogroups.com [mailto:blindhandyman@
<mailto:blindhandyman%40yahoogroups.com> yahoogroups.com]
On Behalf Of Dale Leavens
Sent: Wednesday, February 24, 2010 9:27 PM
To: blindhandyman@ <mailto:blindhandyman%40yahoogroups.com> yahoogroups.com
Subject: Re: [BlindHandyMan] Radiant floor heating.
I don't believe that for a moment.
If it is below freezing it is going to take a lot of heat just to raise the
temperature of the surface above freezing. A cement walkway has a lot of
mass to bring up to temperature. Then there is the latent heat. it takes
something like 40 calories of energy to change the state of water from solid
to liquid alone without actually raising the temperature.
finally, you need to heat enough area to keep the snow and ice liquid
distant enough for it to run away and not just freeze again.
In locations where one only gets occasional snow and ice and the ambient
temperature does not drop much below freezing then electric may be
effective. Other locations like small areas, steps which are sheltered for
example may be cost effective. Even the hot water systems aren't widely used
except under a loading area like for example an ambulance entrance and that
usually under a roof and behind a wall. The ambient atmosphere will draw
huge amounts of heat off a surface very effectively.
If I was Han Solo I'd probably pet my wookie
----- Original Message -----
From: Michael baldwin
To: blindhandyman@ <mailto:blindhandyman%40yahoogroups.com> yahoogroups.com
Sent: Wednesday, February 24, 2010 9:17 PM
Subject: RE: [BlindHandyMan] Radiant floor heating.
I installed the SunTouch brand in our last house, and it was great on the
feet. It didn't raise our electric bill by any noticeable difference. I
installed 45 square feet on a 120 volt system. After the tiles were warmed
up, it never really ran that much.
I am now installing it here at our new place, under the tile. it is
expensive to install. I think it was over $300 for the 30 inch wide by 14
foot long mat. i tried to find the watts per square foot on there site, but
was unable to. I know i saw it there before.
So, there is my recommendation for a brand if you want to do this.
It does look like they have heating mats for the snow. 120 volt mats draw
36 watts per square foot, and 240 volt ones draw 50 watts per square foot.
There is a sensor, so they only operate when it is snowing, so unless you
get a lot of snow, or are doing a large drive way, the cost would not be
all that bad.
Michael
_____
From: blindhandyman@ <mailto:blindhandyman%40yahoogroups.com>
yahoogroups.com [mailto:blindhandyman@
<mailto:blindhandyman%40yahoogroups.com> yahoogroups.com]
On Behalf Of Dan Rossi
Sent: Wednesday, February 24, 2010 7:03 PM
To: blindhandyman@ <mailto:blindhandyman%40yahoogroups.com> yahoogroups.com
Subject: [BlindHandyMan] Radiant floor heating.
I've been doing a lot of research into heated floors. There are two main
kinds of radiant floors, electric or hydronic (water). You can bury pipes
in the cement floor, or place them in the joist bays beneath a wood floor,
then use hot water flowing through the pipes to heat the floor.
You can also use electric mesh mats under a layer of cement or cyramic
tile to heat the floor. Depending on where you live, this could be pretty
expensive.
Heating a floor inside a house is a lot less expensive than heating a
driveway or sidewalk. Electrically heating a driveway to melt snow would
be for the rich only I would expect. heating the floor in the house would
be much more cost effective.
--
Blue skies.
Dan Rossi
Carnegie Mellon University.
E-Mail: d...@andrew. <mailto:dr25%40andrew.cmu.edu> cmu.edu
Tel: (412) 268-9081
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