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

"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

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

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!

"Dennis Pogson" wrote in
news
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

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

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

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?

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).

"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