thermostat
 

Can anyone recommend a thermostat that does not require a power supply and
can switch a 12v heater?

thermostat
 

"Neil" wrote in :

Can anyone recommend a thermostat that does not require a power supply
and can switch a 12v heater?



12V heater??

Please tell me you're not trying to heat a boat with a 12V
heater....please?

A bathroom heater is 1500 watts, about. If we do a little math, 1500 watts
divided by 12V = 125 amps! That might work overnight with a set of 6250 AH
submarine batteries...(c; But, alas, they're about 4 ft X 5 ft X 7 ft high
and weigh a couple tons per cell....(sigh)

Sorry, doesn't float. A boat doesn't have anywhere near enough battery
power to heat anything more than a quick cup of coffee or a soldering iron
for a few minutes.

I also have a joke that goes along with that....

"Nothing is funnier than a boater with a new 4000 watt inverter carrying
his electric heater down the dock with a big smile on his face."

I'm not trying to make fun of you, really. There's a hundred boaters at
City Marina who bought one of those damned 12V heaters Waste Marine sells
in every store. I'm convinced they sell them so they can sell more
batteries, but can't prove it. By the way, they don't need a thermostat.
They barely get warm!

Sorry if it bothered you. You're not alone. Go plug the boat back into
the dock. Thanks. If your boat is gasoline powered, please don't use any
thermostat-controlled 115VAC heater, either! Any gas fumes that get sucked
into that heater at the moment when the points in the thermostat open may
blow up your whole end of the marina! Run the heater in the dark and turn
the thermostat until the heater shuts off. Big spark at 15A off
115VAC....BOOOM!

--
Larry

thermostat
 

On 2005-11-20, Neil wrote:
Can anyone recommend a thermostat that does not require a power supply and
can switch a 12v heater?
t
Thare exist mains rated bimetallic thermostats that can be used to
switch a relay to control your 12V load.

what is it you want to take the temperature of?

what is it you want to heat, and what is your heat source.

--

Bye.
Jasen

thermostat
 

Now I know why insurance is so expensive.

"Larry" wrote in message
...
"Neil" wrote in :

Can anyone recommend a thermostat that does not require a power supply
and can switch a 12v heater?



12V heater??

Please tell me you're not trying to heat a boat with a 12V
heater....please?

A bathroom heater is 1500 watts, about. If we do a little math, 1500
watts
divided by 12V = 125 amps! That might work overnight with a set of 6250
AH
submarine batteries...(c; But, alas, they're about 4 ft X 5 ft X 7 ft
high
and weigh a couple tons per cell....(sigh)

Sorry, doesn't float. A boat doesn't have anywhere near enough battery
power to heat anything more than a quick cup of coffee or a soldering iron
for a few minutes.

I also have a joke that goes along with that....

"Nothing is funnier than a boater with a new 4000 watt inverter carrying
his electric heater down the dock with a big smile on his face."

I'm not trying to make fun of you, really. There's a hundred boaters at
City Marina who bought one of those damned 12V heaters Waste Marine sells
in every store. I'm convinced they sell them so they can sell more
batteries, but can't prove it. By the way, they don't need a thermostat.
They barely get warm!

Sorry if it bothered you. You're not alone. Go plug the boat back into
the dock. Thanks. If your boat is gasoline powered, please don't use any
thermostat-controlled 115VAC heater, either! Any gas fumes that get
sucked
into that heater at the moment when the points in the thermostat open may
blow up your whole end of the marina! Run the heater in the dark and turn
the thermostat until the heater shuts off. Big spark at 15A off
115VAC....BOOOM!

--
Larry

thermostat
 

Larry wrote:
"Neil" wrote in :

Can anyone recommend a thermostat that does not require a power
supply and can switch a 12v heater?



12V heater??

Please tell me you're not trying to heat a boat with a 12V
heater....please?

A bathroom heater is 1500 watts, about. If we do a little math, 1500
watts divided by 12V = 125 amps! That might work overnight with a
set of 6250 AH submarine batteries...(c; But, alas, they're about 4
ft X 5 ft X 7 ft high and weigh a couple tons per cell....(sigh)

Sorry, doesn't float. A boat doesn't have anywhere near enough
battery power to heat anything more than a quick cup of coffee or a
soldering iron for a few minutes.

I also have a joke that goes along with that....

"Nothing is funnier than a boater with a new 4000 watt inverter
carrying his electric heater down the dock with a big smile on his
face."

I'm not trying to make fun of you, really. There's a hundred boaters
at City Marina who bought one of those damned 12V heaters Waste
Marine sells in every store. I'm convinced they sell them so they
can sell more batteries, but can't prove it. By the way, they don't
need a thermostat. They barely get warm!

Sorry if it bothered you. You're not alone. Go plug the boat back
into the dock. Thanks. If your boat is gasoline powered, please
don't use any thermostat-controlled 115VAC heater, either! Any gas
fumes that get sucked into that heater at the moment when the points
in the thermostat open may blow up your whole end of the marina! Run
the heater in the dark and turn the thermostat until the heater shuts
off. Big spark at 15A off 115VAC....BOOOM!

Er.............I think he means a 12-volt Eberspacher or similar, using
diesel to heat the boat? If I'm wrong, your maths is correct, but but I
would find it difficult to believe that anyone could be so mad!

thermostat
 

Jasen Betts wrote:

On 2005-11-20, Neil wrote:

Can anyone recommend a thermostat that does not require a power supply and
can switch a 12v heater?

t
Thare exist mains rated bimetallic thermostats that can be used to
switch a relay to control your 12V load.

what is it you want to take the temperature of?

what is it you want to heat, and what is your heat source.


A regular household thermostat comes it two basic styles: 220 vac,
or 12 volt.

The 220 v stat cannot take a lot of current as required usually by
12v equipment, but they can still handle current sufficient to
operate a headlight relay or battery solenoid.

A 12 v stat ususally has a sealed explosin proof mercury switch, but
cannot handle a lot of current either, though it can operate the
same relay or solenoid.

Don't let the gas explosion hype terror mongers get to you, they
probably own diesel stocks. Put the relay in a closed fume proof
box, if it worries you.

What you gonna control?

Terry K

thermostat
 

You can use old car a/c temperature control switch. It designed for high
current and 12 V, all you need to do is adjust the temperature setting on
the switch. There is a small screw for adjustment. By default it is set for
74-76 F to turn the AC compressor on and off.


"Neil" wrote in message
...
Can anyone recommend a thermostat that does not require a power supply and
can switch a 12v heater?

thermostat
 

Thanks for the replies.
Heater is a 12v 100watt ceramic heater, power supply 4x120AH leasure
batteries (shore power will not be installed at my berth this side of
Winter).
Trying to raise temprature a few degrees in a compartment contaning water
tank and pipes, for ice protection (nowhere near any diesel).

thermostat
 

"Dennis Pogson" wrote in
:

Er.............I think he means a 12-volt Eberspacher or similar, using
diesel to heat the boat? If I'm wrong, your maths is correct, but but I
would find it difficult to believe that anyone could be so mad!



Not mad at all. Non-electrical boaters buy 12V heaters by the hundreds
from Waste Marine...who also sells amazingly expensive batteries these
heaters destroy. Many people do not understand how LITTLE power a large
golf cart battery actually can store.

--
Larry

thermostat
 

"Neil" wrote in :

Heater is a 12v 100watt ceramic heater

Make a little test before going farther down this slippery slope.....

Put a 100W lamp in the boat at dusk. Measure the temperature when you
start. Come back in the morning and see how hot it is inside the boat from
this 100 watt heat source. I doubt it will raise the boat 1 degree. That
will make it 11F inside when it's 10F outside....unless the wind is blowing
through any hatches not hermetically sealed.

If you can't try this on the boat, try it in your garage WITHOUT parking
the warm car in there. Set a 100W lamp on the center of the floor at dark
and check it in the morning. The boat isn't insulated like the garage,
either.

--
Larry

thermostat
 

"Larry" wrote in message
...
"Neil" wrote in :

Heater is a 12v 100watt ceramic heater

Make a little test before going farther down this slippery slope.....

Put a 100W lamp in the boat at dusk. Measure the temperature when you
start. Come back in the morning and see how hot it is inside the boat
from
this 100 watt heat source. I doubt it will raise the boat 1 degree. That
will make it 11F inside when it's 10F outside....unless the wind is
blowing
through any hatches not hermetically sealed.

If you can't try this on the boat, try it in your garage WITHOUT parking
the warm car in there. Set a 100W lamp on the center of the floor at dark
and check it in the morning. The boat isn't insulated like the garage,
either.

--
Larry

The ceramic heater is not a lamp, it will in 15 minutes defrost all the
glass in a Mercedes Estate car and raise the interior temperature to
acceptable before starting. Trying to source an appropriate thermostat to
operate it in the boat's water tank compartment.

Neil

thermostat
 

"Neil" wrote in :

The ceramic heater is not a lamp, it will in 15 minutes defrost all the
glass in a Mercedes Estate car and raise the interior temperature to
acceptable before starting. Trying to source an appropriate thermostat to
operate it in the boat's water tank compartment.

Neil



100 watts is 100 watts is 341.29 BTu/hr no matter what the resistive
element looks like. The bulb does convert a small amount of it to light
because it gets hot enough to incandesce, but the heat from that light is
absorbed by anything it lights up.

In spite of the ad hype, the BTU output of a cheap nichrome heater is
exactly the same as the same wattage amazingly expensive ceramic heater.
Buried inside the ceramic, by the way, is a nichrome wire, which is what
heats it. The ceramic heater does concentrate its BTu output into a nicer
stream of hot air, making it feel like it's putting out more heat, which
it's not. My old "milk house heater" has a metal case that gets warm, but
it heats the room just as good.

Oil heaters that look like old radiators heat the same, too, once the oil
get warmed up. Go figure...nostalgia?

All these heaters with open thermostats will make a boat explode in the
presence of gasoline or propane fumes in explosive concentrations.
Luckily, I've seen some upper-end heaters coming out with solid state
thermostats that have no contacts, but triacs to control them.

To convert watts to BTu, the formula is:

BTu/hr = Watts x 3.4129

Find other interesting conversions on:
http://www.simetric.co.uk/sibtu.htm

Any heater whos outlet gets hot enough to ignite cotton, like those damned
radiant heaters, should be BANNED with the kerosene heaters. People are
too stupid to use these heaters.

The leakage from the boat is lots more than 341 BTu/hr, I'd bet raising the
temperature only slightly and just killing the batteries.

--
Larry

thermostat
 

"Neil" wrote in message
...

"Larry" wrote in message
...
"Neil" wrote in :

Heater is a 12v 100watt ceramic heater

Make a little test before going farther down this slippery slope.....

Put a 100W lamp in the boat at dusk. Measure the temperature when you
start. Come back in the morning and see how hot it is inside the boat
from
this 100 watt heat source. I doubt it will raise the boat 1 degree.
That
will make it 11F inside when it's 10F outside....unless the wind is
blowing
through any hatches not hermetically sealed.

If you can't try this on the boat, try it in your garage WITHOUT parking
the warm car in there. Set a 100W lamp on the center of the floor at
dark
and check it in the morning. The boat isn't insulated like the garage,
either.

--
Larry

The ceramic heater is not a lamp, it will in 15 minutes defrost all the
glass in a Mercedes Estate car and raise the interior temperature to
acceptable before starting. Trying to source an appropriate thermostat to
operate it in the boat's water tank compartment.

Neil

Granted your ceramic heater puts out more heat than a 100 watt light bulb I
still think Larry has a point. You'd never warm up a whole boat with this
but I guess you might raise the temp above freezing in a smaller
compartment. How often is it going to cycle on though? Might end up
running almost continuously. A real nuisance as you don't have AC to
recharge your batteries.
Why don't you just pump out the water tanks, add some RV-type antifreeze
(pink stuff, propylene glycol) and pump that through the system. Now you
don't have to worry as much about the charge of your batteries, about high
currents periodically running through wires or the whole system failing and
the water freezing.

thermostat
 

On 2005-11-21, Neil wrote:

Thanks for the replies.
Heater is a 12v 100watt ceramic heater, power supply 4x120AH leasure
batteries (shore power will not be installed at my berth this side of
Winter).
Trying to raise temprature a few degrees in a compartment contaning water
tank and pipes, for ice protection (nowhere near any diesel).

hmm, if for example in cold wether heater was to run full time it'd deplete
those batteries in only 57 hours...

anyway it's be approximatley an 8 amp load, so a relay (eg automotve headlight
relay) would be a good idea to save wear on the expensive thermostat
contacts.

something like a refrigerator thermostat would probably cover the temperature
range you're interested in, but the contacts are backwards (open when cold)

the easiest fix would be to use an automotive horn relay anstead of a
headllight relay, but this would waste a small amount of electricity
(15ma - about what a LED uses) holding the relay contactts open.

If it's possible to attach heating wire to the pipes and then insulate
them that may use less electricity...

--

Bye.
Jasen

thermostat
 

In article NvIgf.127275$S4.46489@edtnps84,
"Gordon Wedman" wrote:

Granted your ceramic heater puts out more heat than a 100 watt light bulb

On what planet do your Laws Of Physics, reside...... 100 Watts is 100
Watts.... it doesn't matter if that comes from a light bulb or a ceramic
heater.....Ok now you say that the light output must be subtracted from
the 100 Watts, BUT, so does thew glow from the ceramic heating element
as well. Both are RESISTIVE Loads, both produce 100 Watts of energy
into the enviorment...Again 100 watts is 100 Watts...... back to High
School Physics for you.....

Me

thermostat
 

Me wrote in
:

In article NvIgf.127275$S4.46489@edtnps84,
"Gordon Wedman" wrote:

Granted your ceramic heater puts out more heat than a 100 watt light
bulb

On what planet do your Laws Of Physics, reside...... 100 Watts is 100
Watts.... it doesn't matter if that comes from a light bulb or a
ceramic heater.....Ok now you say that the light output must be
subtracted from the 100 Watts, BUT, so does thew glow from the
ceramic heating element as well. Both are RESISTIVE Loads, both
produce 100 Watts of energy into the enviorment...Again 100 watts is
100 Watts...... back to High School Physics for you.....

Me


Actually, unless the light from the bulb escapes through an opening, its
light output (and the radiation glow from the heater) will both be
converted back to heat as soon as they bump into something in the boat,
anyways...(c;

Of course, physics is meaningless when faced with a good ceramic heater
advertising program convincing them their tiny heater will heat a 3BR, 2BA
house on 1500 watts...hee hee.

--
Larry

thermostat
 

"Me" wrote in message
...
In article NvIgf.127275$S4.46489@edtnps84,
"Gordon Wedman" wrote:

Granted your ceramic heater puts out more heat than a 100 watt light bulb

On what planet do your Laws Of Physics, reside...... 100 Watts is 100
Watts.... it doesn't matter if that comes from a light bulb or a ceramic
heater.....Ok now you say that the light output must be subtracted from
the 100 Watts, BUT, so does thew glow from the ceramic heating element
as well. Both are RESISTIVE Loads, both produce 100 Watts of energy
into the enviorment...Again 100 watts is 100 Watts...... back to High
School Physics for you.....

Me

Since the heater is designed to put out HEAT and the light bulb is designed
to put out LIGHT I suspect there could be some differences. Go back to your
own high school class and learn some manners.

thermostat
 

In article PH3hf.126316$y_1.29970@edtnps89, "Gordon Wedman" wrote:

"Me" wrote in message
...
In article NvIgf.127275$S4.46489@edtnps84,
"Gordon Wedman" wrote:

Granted your ceramic heater puts out more heat than a 100 watt light bulb

On what planet do your Laws Of Physics, reside...... 100 Watts is 100
Watts.... it doesn't matter if that comes from a light bulb or a ceramic
heater.....Ok now you say that the light output must be subtracted from
the 100 Watts, BUT, so does thew glow from the ceramic heating element
as well. Both are RESISTIVE Loads, both produce 100 Watts of energy
into the enviorment...Again 100 watts is 100 Watts...... back to High
School Physics for you.....

Me

Since the heater is designed to put out HEAT and the light bulb is designed
to put out LIGHT I suspect there could be some differences. Go back to your
own high school class and learn some manners.

I was at Walmart about a month ago, on the Chinese side, the side
with no food. Can you buy Chinese food at Walmart? Well back to the story,
I was looking for a heater. If you want to have some fun, stay awile and ask questions
and make comments about heating. You will hear all kinds of things. Oh, this
heater will heat a whole trailor. I mean, a 1000 watts is a 1000 watts. Most people will
have a story to tell. Just like there is a low efficiency of producing sounds from a speaker,
its not efficient at producing light from resistances wiring.
I ended up buying an oil filled radiator, and also a quartz radiant heater. They
both work great. Need to buy another 1000 watt quartz for the basement. You can't feel that
radiator across the room though.

greg

thermostat
 

In article PH3hf.126316$y_1.29970@edtnps89,
"Gordon Wedman" wrote:

"Me" wrote in message
...
In article NvIgf.127275$S4.46489@edtnps84,
"Gordon Wedman" wrote:

Granted your ceramic heater puts out more heat than a 100 watt light bulb

On what planet do your Laws Of Physics, reside...... 100 Watts is 100
Watts.... it doesn't matter if that comes from a light bulb or a ceramic
heater.....Ok now you say that the light output must be subtracted from
the 100 Watts, BUT, so does thew glow from the ceramic heating element
as well. Both are RESISTIVE Loads, both produce 100 Watts of energy
into the enviorment...Again 100 watts is 100 Watts...... back to High
School Physics for you.....

Me

Since the heater is designed to put out HEAT and the light bulb is designed
to put out LIGHT I suspect there could be some differences. Go back to your
own high school class and learn some manners.



It really doesn't matter WHAT the device is "designed" to do, what
matters IS, that the total power output of the device (heater or light
bulb) is going to be HEAT, unless, as it has already been pointed out,
some of the light leaks out thru a hole in the container, or room.
So far your whole premiss, is flawed, and your conclusions are BOGAS.
Like I stated before, best you go ask for a refund on your High School
Diploma, because you certainly didn't learn what they had to teach.....


Me could this guy be a Leno JayWalker Wannnabe..........

thermostat
 

The watt input between a bulb and a heater may be similar, but the
efficiency of heat transfer is related to surface area that can
radiate. A bulb has a tiny area compared to the surface area of an
electric heater and in a finite time will distribute its heat energy
less efficiently than a larger surface area heater.
In an infinite time span in a closed environment, the bulb and heater
will achieve almost a similar heat distribution. Since we don't have
infinite or even long time spans, a large surface area heater wins
everytime.

thermostat
 

On 2005-11-26, nollaigoc wrote:

The watt input between a bulb and a heater may be similar, but the
efficiency of heat transfer is related to surface area that can
radiate.

how is it related to that?
what are you proposing happens to the "extra" energy?

A bulb has a tiny area compared to the surface area of an
electric heater and in a finite time will distribute its heat energy
less efficiently than a larger surface area heater.

lightbulbs (and other radiant heat sources) tend to heat opaque objects
faster than they heat the air.

a heater with a large hot suurface puts most of its energy into the air.

In an infinite time span in a closed environment, the bulb and heater
will achieve almost a similar heat distribution. Since we don't have
infinite or even long time spans, a large surface area heater wins
everytime.

no, it depends what you are trying to heat.

Bye.
Jasen