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Thermostat set-back
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Tom Gardner
Nov 11, 2013, 5:05:40 PM11/11/13
to
How low should I set my thermostats at night in the shop? The goal of
course is to minimize the gas bill.
course is to minimize the gas bill.
Richard
Nov 11, 2013, 6:31:44 PM11/11/13
to
On 11/11/2013 4:05 PM, Tom Gardner wrote:
> How low should I set my thermostats at night in the shop? The goal of
> course is to minimize the gas bill.
OFF - max minimization
> How low should I set my thermostats at night in the shop? The goal of
> course is to minimize the gas bill.
Jim Wilkins
Nov 11, 2013, 7:02:48 PM11/11/13
to
"Tom Gardner" <Mars@Tacks> wrote in message
news:VIqdnVjeof0qyRzP...@giganews.com...
I'd creep them down until the building begins to take too long to heat
back up in the morning.
news:VIqdnVjeof0qyRzP...@giganews.com...
> How low should I set my thermostats at night in the shop? The goal
> of course is to minimize the gas bill.
Some of mine have an "off" position that could let the pipes freeze.
> of course is to minimize the gas bill.
I'd creep them down until the building begins to take too long to heat
back up in the morning.
Gunner Asch
Nov 11, 2013, 7:33:25 PM11/11/13
to
On Mon, 11 Nov 2013 17:31:44 -0600, Richard <cave...@earthlink.net>
wrote:
On the other hand..the next morning...max maxification. It is an
interesting question when one thinks about it actually.
--
Liberals want everyone to think like them.
Conservatives want everyone to think.
wrote:
interesting question when one thinks about it actually.
--
Liberals want everyone to think like them.
Conservatives want everyone to think.
Bob Engelhardt
Nov 11, 2013, 7:34:13 PM11/11/13
to
Are they programmable? Mine are and if I program them for 68 degrees at
7:00 AM, they anticipate and have it AT 68 by 7:00. If yours are like
this, the set back can be as low as the thermostat goes.
If not, a major consideration is how long it will take to bring the heat
up in the morning. If they are strictly manual, you might not be able
to set them back much without having a lot of discomfort in the morning.
As Jim said, try creeping it down & see.
There is a middle-ground thermostat which doesn't anticipate, but just
switches to the higher setting at the programmed time. With this kind,
the set back can be as low as it goes, but you have to set the return
early enough for recovery.
I wouldn't go the "off" route - I envision your factory building as
not-too-modern, poorly insulated, and likely to freeze up if the heat is
off.
Bob
7:00 AM, they anticipate and have it AT 68 by 7:00. If yours are like
this, the set back can be as low as the thermostat goes.
If not, a major consideration is how long it will take to bring the heat
up in the morning. If they are strictly manual, you might not be able
to set them back much without having a lot of discomfort in the morning.
As Jim said, try creeping it down & see.
There is a middle-ground thermostat which doesn't anticipate, but just
switches to the higher setting at the programmed time. With this kind,
the set back can be as low as it goes, but you have to set the return
early enough for recovery.
I wouldn't go the "off" route - I envision your factory building as
not-too-modern, poorly insulated, and likely to freeze up if the heat is
off.
Bob
jim
Nov 11, 2013, 7:44:54 PM11/11/13
to
Gunner Asch wrote:
>
> On Mon, 11 Nov 2013 17:31:44 -0600, Richard <cave...@earthlink.net>
> wrote:
>
> >On 11/11/2013 4:05 PM, Tom Gardner wrote:
> >> How low should I set my thermostats at night in the shop? The goal of
> >> course is to minimize the gas bill.
> >
> >
> >OFF - max minimization
>
> On the other hand..the next morning...max maxification.
The amount of fuel used overnight plus what it takes
to warm it up in the morning will be minimized by turning
it off overnight.
Tom Gardner
Nov 11, 2013, 7:51:54 PM11/11/13
to
have mentioned that.
Tom Gardner
Nov 11, 2013, 8:01:25 PM11/11/13
to
thermostat. The building is old block with a tongue-and-groove wood
roof with modified bitumen membrane on top...no insulation to speak of.
So, I must maintain above freezing.
What I was thinking is is it cheaper to keep the building a bit warmer
that run full bore for a long time in the morning?
Lloyd E. Sponenburgh
Nov 11, 2013, 8:15:04 PM11/11/13
to
Tom Gardner <Mars@Tacks> fired this volley in
news:OKSdnQ_AZ5Z14BzP...@giganews.com:
> What I was thinking is is it cheaper to keep the building a bit
warmer
> that run full bore for a long time in the morning?
>
No. Heat loss is a function of the differential temperature between
inside and outside. The warmer it is inside, the more loss.
Although it's a little counter-intuitive, a heavy burst of fuel
consumption to bring it up from too-cool to comfortable will cost you
less than running it warm all night. It always runs "full bore" when it's
on, anyway.
The heat mass inside the building requires the _same_ amount of energy to
raise from cool to warm, as it does to keep it warm. It's only the
losses through the walls and ceiling (and windows and doors) that make
the difference.
Remember, the warmer it is (on average) the higher the losses. So,
shutting down at night lowers the average temperature, thus lowering the
cost.
But to be honest, the difference is so small you probably wouldn't care,
even if you noticed.
Lloyd
Lloyd
news:OKSdnQ_AZ5Z14BzP...@giganews.com:
> What I was thinking is is it cheaper to keep the building a bit
warmer
> that run full bore for a long time in the morning?
>
inside and outside. The warmer it is inside, the more loss.
Although it's a little counter-intuitive, a heavy burst of fuel
consumption to bring it up from too-cool to comfortable will cost you
less than running it warm all night. It always runs "full bore" when it's
on, anyway.
The heat mass inside the building requires the _same_ amount of energy to
raise from cool to warm, as it does to keep it warm. It's only the
losses through the walls and ceiling (and windows and doors) that make
the difference.
Remember, the warmer it is (on average) the higher the losses. So,
shutting down at night lowers the average temperature, thus lowering the
cost.
But to be honest, the difference is so small you probably wouldn't care,
even if you noticed.
Lloyd
Lloyd
Richard
Nov 11, 2013, 9:40:21 PM11/11/13
to
So maybe Off is a bit extreme?
mike
Nov 11, 2013, 9:41:07 PM11/11/13
to
On 11/11/2013 2:05 PM, Tom Gardner wrote:
> How low should I set my thermostats at night in the shop? The goal of
> course is to minimize the gas bill.
Might be a good thing to consider other issues.
> How low should I set my thermostats at night in the shop? The goal of
> course is to minimize the gas bill.
If the temperature gets below the dew point, stuff happens
long before your pipes freeze.
Rust
Mildew
http://www.dpcalc.org/
Tim Wescott
Nov 11, 2013, 9:55:05 PM11/11/13
to
insulation there is between the pipes and your shop vs. the pipes and the
outside.
Really, this depends on your weather and how your shop is constructed.
--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com
pyotr filipivich
Nov 11, 2013, 10:07:05 PM11/11/13
to
Tom Gardner <Mars@Tacks> on Mon, 11 Nov 2013 19:51:54 -0500 typed in
rec.crafts.metalworking the following:
In that case, you now have a minimum temperature to keep - "above
freezing." What the thermostat has to be set to, in order to keep
that, is a variable that only you can be sure of.
Once upon a time, my brother worked the midnight shift at a gas
station in Minnesota. During "the coldest winter in fourteen years."
Sitting there all bundled up to keep from freezing when he went
outside to pump gas, he would turn the heat down to keep from
roasting. Until the first of the bottle pop in the stacks by the
window would break from freezing. "Ah, the sound of time to warm up
the place." You may want to find another means of determining if
you've set the thermostat too low than waiting to see if the pipes
freeze.
Not knowing where you are, I can but pontificate. It also depends
on "how cold is cold" and How long does it stay that cold?" I.e it is
one thing if it dips to the mid twenties at night, but warms into the
mid forties during the day, quite another if it stays below freezing
till spring.
It will also depend upon the level of heat retention in the place.
That is, how much insulation you have, and how fast does the heat
inside leak out.
Might want to consider insulating the pipes, or using the wrap
around pipe heaters to keep them from freezing. I dunno about your
specific situation.
Warming it in the morning is another question. Again, how fast do
the heaters warm it up, and to what temp? And how fast it exeunt the
building.. You probably know this already, but also "dress warm". Save
on heating costs if you don't have to heat the place "as much."
Ideally, you could program the thermostats to keep the place above
the freezing point at all times, and set to warm it up so that is it
is "comfortable" when you get there in the morning.
--
pyotr filipivich
"With Age comes Wisdom. Although more often, Age travels alone."
rec.crafts.metalworking the following:
freezing." What the thermostat has to be set to, in order to keep
that, is a variable that only you can be sure of.
Once upon a time, my brother worked the midnight shift at a gas
station in Minnesota. During "the coldest winter in fourteen years."
Sitting there all bundled up to keep from freezing when he went
outside to pump gas, he would turn the heat down to keep from
roasting. Until the first of the bottle pop in the stacks by the
window would break from freezing. "Ah, the sound of time to warm up
the place." You may want to find another means of determining if
you've set the thermostat too low than waiting to see if the pipes
freeze.
Not knowing where you are, I can but pontificate. It also depends
on "how cold is cold" and How long does it stay that cold?" I.e it is
one thing if it dips to the mid twenties at night, but warms into the
mid forties during the day, quite another if it stays below freezing
till spring.
It will also depend upon the level of heat retention in the place.
That is, how much insulation you have, and how fast does the heat
inside leak out.
Might want to consider insulating the pipes, or using the wrap
around pipe heaters to keep them from freezing. I dunno about your
specific situation.
Warming it in the morning is another question. Again, how fast do
the heaters warm it up, and to what temp? And how fast it exeunt the
building.. You probably know this already, but also "dress warm". Save
on heating costs if you don't have to heat the place "as much."
Ideally, you could program the thermostats to keep the place above
the freezing point at all times, and set to warm it up so that is it
is "comfortable" when you get there in the morning.
--
pyotr filipivich
"With Age comes Wisdom. Although more often, Age travels alone."
Ecnerwal
Nov 11, 2013, 10:28:23 PM11/11/13
to
In article <MY-dnRVPxfsUBRzP...@giganews.com>,
And, as someone else mentioned, condensation. One of the better
approaches to that (but I'm fairly sure Tom doesn't want to redo his
heating system) is to run some radiant floor heat, which couples to
cast-iron machines, keeping them warm - or actually run heat loops into
machines. It's not a responsive system (turns up/down poorly due to the
large coupled mass) but it can be used in concert with an air-heating
system for more rapid changes, and greatly reduces the odds of rusting
the ways.
The general generic assumption for most construction (may not apply to
Toms old factory, depending on location of heat, thermostat, insulation
or lack of it, and water/sprinkler pipes) is that 45 (or more
conservatively 55) is generally "safe" with respect to freezing pipes in
buildings that were not build insanely (which can freeze pipes when the
inside is 70F, due to terrible pipe location and lack of insulation.)
--
Cats, coffee, chocolate...vices to live by
Please don't feed the trolls. Killfile and ignore them so they will go away.
approaches to that (but I'm fairly sure Tom doesn't want to redo his
heating system) is to run some radiant floor heat, which couples to
cast-iron machines, keeping them warm - or actually run heat loops into
machines. It's not a responsive system (turns up/down poorly due to the
large coupled mass) but it can be used in concert with an air-heating
system for more rapid changes, and greatly reduces the odds of rusting
the ways.
The general generic assumption for most construction (may not apply to
Toms old factory, depending on location of heat, thermostat, insulation
or lack of it, and water/sprinkler pipes) is that 45 (or more
conservatively 55) is generally "safe" with respect to freezing pipes in
buildings that were not build insanely (which can freeze pipes when the
inside is 70F, due to terrible pipe location and lack of insulation.)
--
Cats, coffee, chocolate...vices to live by
Please don't feed the trolls. Killfile and ignore them so they will go away.
Tim Wescott
Nov 11, 2013, 10:44:48 PM11/11/13
to
rarely gets below 20F, and then only briefly; I remember one year where
we had a cold spell that stayed down in the single-digits or low teens
for a week. The water district lost several meters (the standard depth
here is just a couple of feet) and we lost a pipe in the wall behind the
washer.
Stormin Mormon
Nov 12, 2013, 7:23:30 AM11/12/13
to
On 11/11/2013 7:33 PM, Gunner Asch wrote:
>>
>>
>> OFF - max minimization
>
> On the other hand..the next morning...max maxification. It is an
> interesting question when one thinks about it actually.
>
At least, you're not paying for a lot of BTU
>>
>>
>> OFF - max minimization
>
> On the other hand..the next morning...max maxification. It is an
> interesting question when one thinks about it actually.
>
through the roof all night.
--
.
Christopher A. Young
Learn about Jesus
www.lds.org
.
Stormin Mormon
Nov 12, 2013, 7:25:11 AM11/12/13
to
On 11/11/2013 7:51 PM, Tom Gardner wrote:
>
> I'm worried about water and sprinkler
> pipes freezing. I guess I should
> have mentioned that.
I remember someone posting about a building
>
> I'm worried about water and sprinkler
> pipes freezing. I guess I should
> have mentioned that.
where they did the setback, and ended up
splitting a bunch of pipes. The repair
cost more than the saving.
Stormin Mormon
Nov 12, 2013, 7:27:23 AM11/12/13
to
On 11/11/2013 8:01 PM, Tom Gardner wrote:
> Yes, there are 6 overhead gas heaters, each with it's own programmable
> thermostat. The building is old block with a tongue-and-groove wood
> roof with modified bitumen membrane on top...no insulation to speak of.
> So, I must maintain above freezing.
>
> What I was thinking is is it cheaper to keep the building a bit warmer
> that run full bore for a long time in the morning?
The heat lost, is the heat you paid for. So,
> Yes, there are 6 overhead gas heaters, each with it's own programmable
> thermostat. The building is old block with a tongue-and-groove wood
> roof with modified bitumen membrane on top...no insulation to speak of.
> So, I must maintain above freezing.
>
> What I was thinking is is it cheaper to keep the building a bit warmer
> that run full bore for a long time in the morning?
any temp reduction is less heat lost.
Please consider calling in some estimates, for
insulation. That may pay for itself in a few years.
Jim Wilkins
Nov 12, 2013, 8:26:54 AM11/12/13
to
"Tom Gardner" <Mars@Tacks> wrote in message
news:OKSdnQ_AZ5Z14BzP...@giganews.com...
>
> What I was thinking is is it cheaper to keep the building a bit
> warmer that run full bore for a long time in the morning?
If you can read your gas meter you could compare consumption both ways
> What I was thinking is is it cheaper to keep the building a bit
> warmer that run full bore for a long time in the morning?
over similar cold nights. You might first find the lowest practical
setback temperature on an overcast night or weekend that won't drop
below freezing.
I just Alt+PrtScrn'd the clock at 08:09:10 on 11/12/13
jsw
Richard
Nov 12, 2013, 1:32:55 PM11/12/13
to
On 11/12/2013 6:23 AM, Stormin Mormon wrote:
> On 11/11/2013 7:33 PM, Gunner Asch wrote:
>>>
>>>
>>> OFF - max minimization
>>
>> On the other hand..the next morning...max maxification. It is an
>> interesting question when one thinks about it actually.
>>
>
> At least, you're not paying for a lot of BTU
> through the roof all night.
>
>
That would probably be worth correcting.
> On 11/11/2013 7:33 PM, Gunner Asch wrote:
>>>
>>>
>>> OFF - max minimization
>>
>> On the other hand..the next morning...max maxification. It is an
>> interesting question when one thinks about it actually.
>>
>
> At least, you're not paying for a lot of BTU
> through the roof all night.
>
>
Roof insulation? Is it possible?
dca...@krl.org
Nov 12, 2013, 2:26:25 PM11/12/13
to
On Monday, November 11, 2013 5:05:40 PM UTC-5, Tom Gardner wrote:
> How low should I set my thermostats at night in the shop? The goal of
>
> course is to minimize the gas bill.
If I recall correctly, you are going to have to move soon because of a new road being constructed. If that were not the case, I would say insulate.
> How low should I set my thermostats at night in the shop? The goal of
>
> course is to minimize the gas bill.
To keep water pipes from freezing, you might insulate the pipes first. And then make a low voltage high current transformer from a microwave oven transformer and connect the low voltage so the current circulates through the pipes. That is the cheapest thing I can think of to keep your pipes from freezing.
Dan
mike
Nov 12, 2013, 6:11:10 PM11/12/13
to
frozen pipes,
I think it's a bad idea for general use.
Pipe heating tape designed for the purpose will do a far more reliable job.
Just monitor it. Won't help if it breaks during a cold snap...or six
months ago cuz you never checked..
Just make an inventory of everything temperature dependent and take steps
to keep each item warm enough. Doesn't make much sense to keep the
whole building hot when the pipe nearest the soffit vent is the
thing that's gonna freeze.
google "fenestration". There are many programs that do more than windows.
I used an earlier version of this one
http://windows.lbl.gov/software/resfen/resfen.html
when I started thinking about weatherization.
Just remember that "averages" don't freeze.
Short exposed sections of pipe freeze.
And freezing ain't your only potential problem
when it's wet and cold.
Bruce L. Bergman (munged human readable)
Nov 15, 2013, 2:06:47 PM11/15/13
to
convert the sprinkler system over to a Dry Standpipe system with
compressed air in the pipes and a little dedicated Wob-L-Piston
compressor, then all you have to worry about is the Fire Water risers
and the water charging valve, and water mains freezing on you.
But for the machines you want to keep them above the dew point, I'd
say 45 or 50F. As others have mentioned, that's not the safest
because you'll get cold spots.
Are you going to be there a while? Do you Own or only Rent?
If you answer Yes, we own and we don't plan to leave anytime soon, I'd
look into adding insulation. wherever it can be done economically and
easily. And not just the radiant foil sheeting, considering it's
manufacturing and needs to be easy to clean I'd look into Fiberglas
batts and something to mechanically hold it in place. You wouldn't
want to hang and maintain Drywall, and I've seen a web of baling wire
fail to hold it in place...
I'd think either 1/2" welded wire mesh or the diamond Chicken Wire,
and furring strips along the joists to hold it up. Or perhaps a full
pallet of the factory-primed Tempered Hardwood Pegboard so the
backside is primed, and you bomb the face side with an Airless and
some gloss white enamel when you get done hanging it.
And nail the sprinkler pipes with Red, Water with Blue, Gas with
Yellow, Compressed Air with Sky Blue, and the electrical conduits
with Orange or Smoke Grey while you're at it. The holes allow a bit
of ventilation to let moisture out (or the roof leak to drain through
to find it easier...) and you can poke through the holes to locate
the joists before screwing in new pipe hangers.
But I would think NO vapor barrier below the insulation (toward
occupied space) since there's no attic, on a flat roof you won't be
ventilating the space above it. But you'd better get a few more
opinions on that.
(Unless you start drilling holes in all the fireblocks and the eaves
and putting in the round Mini-Vents all over the place, leave a
ventilation gap above the batts, and rig something to ventilate out
at the ridge. Then you could put Tyvek Housewrap under the pegboard.)
And/Or you do the foam spray on roofing - that's insulation too.
Tom Gardner
Nov 16, 2013, 3:13:12 AM11/16/13
to
anything physical to sprinkler system, they are rather picky. The
building is close to 20k' so doing anything would be expensive, but I
like heat tape. I wonder if it can be purchased in bulk?
Tom Gardner
Nov 16, 2013, 3:16:27 AM11/16/13
to
about the road, it could miss us by feet, ODOT won't tell us.
dca...@krl.org
Nov 16, 2013, 8:21:48 AM11/16/13
to
On Saturday, November 16, 2013 3:16:27 AM UTC-5, Tom Gardner wrote:
>
> I never heard of that, where can I learn more? We STILL don't know
>
> about the road, it could miss us by feet, ODOT won't tell us.
I do not know where you can find more information. You might find some info on welding sites talking about using a welder on the lowest amp setting to thaw out pipes. You can find out about rewinding microwave oven transformers on the internet. Using current to warm the pipes works well where you can not get to the pipes. You only need a couple of turns on the MWO transformer secondary.
>
> I never heard of that, where can I learn more? We STILL don't know
>
> about the road, it could miss us by feet, ODOT won't tell us.
If you can get to the pipes you can use heat cables but they are not super cheap. They consist of two wires with a semiconductor material between them and look kind of like 300 ohm twin lead. At room temperature the semiconductor material has high resistance so very little power in consumed. But at about 40 F the semiconductor material has lower resistance and so warms the tape and whatever it is in contact with.
Dan
Bruce L. Bergman (munged human readable)
Nov 16, 2013, 11:33:51 AM11/16/13
to
On Sat, 16 Nov 2013 03:13:12 -0500, Tom Gardner <Mars@Tacks> wrote:
>On 11/15/2013 2:06 PM, Bruce L. Bergman (munged human readable) wrote:
>> On Mon, 11 Nov 2013 19:51:54 -0500, Tom Gardner <Mars@Tacks> wrote:
>>>
>>> I'm worried about water and sprinkler pipes freezing. I guess I should
>>> have mentioned that.
>>
>> You can start with heat trace tape and insulation for safety - Or
>> convert the sprinkler system over to a Dry Standpipe system with
>> compressed air in the pipes and a little dedicated Wob-L-Piston
>> compressor, then all you have to worry about is the Fire Water risers
>> and the water charging valve, and water mains freezing on you.
>
>On 11/15/2013 2:06 PM, Bruce L. Bergman (munged human readable) wrote:
>> On Mon, 11 Nov 2013 19:51:54 -0500, Tom Gardner <Mars@Tacks> wrote:
>>>
>>> I'm worried about water and sprinkler pipes freezing. I guess I should
>>> have mentioned that.
>>
>> You can start with heat trace tape and insulation for safety - Or
>> convert the sprinkler system over to a Dry Standpipe system with
>> compressed air in the pipes and a little dedicated Wob-L-Piston
>> compressor, then all you have to worry about is the Fire Water risers
>> and the water charging valve, and water mains freezing on you.
>
>I'd have to check insurance and city regulations to see if I cam do
>anything physical to sprinkler system, they are rather picky. The
>building is close to 20k' so doing anything would be expensive, but I
>like heat tape. I wonder if it can be purchased in bulk?
You'd have to go to a Fire Sprinkler company to convert it over from
>anything physical to sprinkler system, they are rather picky. The
>building is close to 20k' so doing anything would be expensive, but I
>like heat tape. I wonder if it can be purchased in bulk?
the more common Wet Pipe system you have now to a Dry Pipe system, and
they have to recertify it. You might actually get a little break on
the fire & property insurance, less chance of water damage.
As I understand it, it should be fairly simple - the sprinkler piping
in the building wouldn't need to be changed, it's still got to meet
the same flow and coverage plans from before. Though it might call
for changing all the sprinkler heads.
But all the valve gear at the riser and the flow switch would need to
be replaced. And run two power circuits over for the little air
compressor and the Heat Trace on the stack. (I've seen these setups,
they put them on frozen food warehouses and huge walk-in fridges and
freezers. )
And no, they probably won't let you hook it up to Shop Air, it's
supposed to be totally independent.
They do sell the heat tape in bulk 500' rolls, but it's a bit tricky
to terminate. I know you enjoy the challenge, but for the less tech
inclined I'd say probably better off getting pre-made lengths.
And once you get the place freeze-proofed, then you just have to keep
it above dewpoint so the machines don't rust. And if the power and/or
heat fails, it's not nearly as big a disaster.
Bruce L. Bergman (munged human readable)
Nov 16, 2013, 11:41:41 AM11/16/13
to
On Sat, 16 Nov 2013 05:21:48 -0800 (PST), "dca...@krl.org"
<dca...@krl.org> wrote:
>On Saturday, November 16, 2013 3:16:27 AM UTC-5, Tom Gardner wrote:
>
>>
>> I never heard of that, where can I learn more? We STILL don't know
>> about the road, it could miss us by feet, ODOT won't tell us.
You need to get their attention and make them tell you, so you can
<dca...@krl.org> wrote:
>On Saturday, November 16, 2013 3:16:27 AM UTC-5, Tom Gardner wrote:
>
>>
>> I never heard of that, where can I learn more? We STILL don't know
>> about the road, it could miss us by feet, ODOT won't tell us.
make plans. Limbo is a bad place to be stuck in.
Hint, have your Lawyer write the letter, that might get a response. Or
try a FOIA Request.
>I do not know where you can find more information. You might find some info on welding sites talking about using a welder on the lowest amp setting to thaw out pipes. You can find out about rewinding microwave oven transformers on the internet. Using current to warm the pipes works well where you can not get to the pipes. You only need a couple of turns on the MWO transformer secondary.
>
>If you can get to the pipes you can use heat cables but they are not super cheap. They consist of two wires with a semiconductor material between them and look kind of like 300 ohm twin lead. At room temperature the semiconductor material has high resistance so very little power in consumed. But at about 40 F the semiconductor material has lower resistance and so warms the tape and whatever it is in contact with.
regular basis, you're going to set up a galvanic failure of some sort.
And you do NOT want Fire Sprinkler pipes popping leaks all over the
place...
Use regular heat trace tape and foam or Fiberglas overwrap insulation.
DoN. Nichols
Nov 16, 2013, 10:41:03 PM11/16/13
to
On 2013-11-16, dca...@krl.org <dca...@krl.org> wrote:
[ ... ]
> If you can get to the pipes you can use heat cables but they are not
> super cheap. They consist of two wires with a semiconductor material
> between them and look kind of like 300 ohm twin lead. At room
> temperature the semiconductor material has high resistance so very
> little power in consumed. But at about 40 F the semiconductor material
> has lower resistance and so warms the tape and whatever it is in contact
> with.
I hope that they are better than that used in some brands of
electric blankets. They use a two-conductor wire stitched into the
blanket in a zig-zag pattern so they don't cross. Hard outer jacket,
then a resistive inner insulation between and around the conductors. the
more you use them, the higher the resistance gets, and the higher you
have to set the temperature control (not a true thermostat) on the
blanket. I tend to use mine more than my wife does, and after a year,
there is an order of magnitude difference in resistance measured at the
connector at the foot of the blanket.
If the pipe heater has a similar lifetime problem, it will get
less efficient as it ages. If you install some, measure the resistance
just after you install it, and before you use it (and note the room
temperature), and check it annually at the same room temperature to be
sure.
There used to be another brand which had resistance wire, with
little safety thermostats every so often (you could feel the lumps as
you felt your way along the wire. But if you happened to tuck one of
the thermostats in at the foot or the side of the bed, that would open
up as that area overheated, and since it is a series string -- no heat.
This winter (the old resistive insulation one was too old, and
too expensive), I did some web searching, trying to find the old brand,
with no luck. But -- I found a new type -- A low voltage DC type. Each
side has its own controller and power supply, and after a couple of
weeks of use (only by me), both sides measure the same resistance, so I
have hopes of this one lasting.
Enjoy,
DoN.
--
Remove oil spill source from e-mail
Email: <BPdnic...@d-and-d.com> | (KV4PH) Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---
[ ... ]
> If you can get to the pipes you can use heat cables but they are not
> super cheap. They consist of two wires with a semiconductor material
> between them and look kind of like 300 ohm twin lead. At room
> temperature the semiconductor material has high resistance so very
> little power in consumed. But at about 40 F the semiconductor material
> has lower resistance and so warms the tape and whatever it is in contact
> with.
electric blankets. They use a two-conductor wire stitched into the
blanket in a zig-zag pattern so they don't cross. Hard outer jacket,
then a resistive inner insulation between and around the conductors. the
more you use them, the higher the resistance gets, and the higher you
have to set the temperature control (not a true thermostat) on the
blanket. I tend to use mine more than my wife does, and after a year,
there is an order of magnitude difference in resistance measured at the
connector at the foot of the blanket.
If the pipe heater has a similar lifetime problem, it will get
less efficient as it ages. If you install some, measure the resistance
just after you install it, and before you use it (and note the room
temperature), and check it annually at the same room temperature to be
sure.
There used to be another brand which had resistance wire, with
little safety thermostats every so often (you could feel the lumps as
you felt your way along the wire. But if you happened to tuck one of
the thermostats in at the foot or the side of the bed, that would open
up as that area overheated, and since it is a series string -- no heat.
This winter (the old resistive insulation one was too old, and
too expensive), I did some web searching, trying to find the old brand,
with no luck. But -- I found a new type -- A low voltage DC type. Each
side has its own controller and power supply, and after a couple of
weeks of use (only by me), both sides measure the same resistance, so I
have hopes of this one lasting.
Enjoy,
DoN.
--
Remove oil spill source from e-mail
Email: <BPdnic...@d-and-d.com> | (KV4PH) Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---
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