Anyone ever use an oil/water temp sensor to turn off oil/block heaters?

[Hammer]

Been thinking about this one a bit more lately.
It wouldn't seem to be too difficult of an issue to setup a temp cutoff switch for either the oil or water heaters.
These heaters can take a LOT of electricity if you leave them on!
But if you set a temperature for them to come off/on at, it would save a bit of electricity AND keep the motor ready to go.

Most people wouldn't need this really. But I run tow trucks, and the trucks have to be ready to roll 24/7. So when the temps stay below 30 in the day, and single digits at night (I know, not nearly as cold as some people have it here), I leave one truck plugged in at night.
That is what really got me to thinking about this.
But I also figured there would be people here who would be interested in this.
Heck, even if you have your heaters on a timer, it could still save some $ but shutting the heat off when it's not needed.

 

[OPCOM]

The idea would also be to avoid boiling the coolant..

If you found a switch that turned off at a low temp, less than 200 degrees. Good choice would be a common 12V automotive one of the kind that turns electric fans on and off.

A relay or contactor with a 12V coil could be used to control the 120VAC to the heater. You would need a 12V power supply (1 amp wall wart size) and then the relay, a surplus 20 amp one would do, make sure its contacts are rated for at least 120VAC.

It is a good idea, lots of ways to get it done.

A key construction factor would be to make sure that when the coolant is properly warm, the switch actually does cut off. The switch's sensor would have to be in good contact with the coolant or coolant vessel surface.

There may be no need to heat it all the way to 160 degrees, as 100 degrees migh be fine for starting and getting moving and that would save electricity as well. It might be worthwhile to see if a waterbed thermostat which is ajustable from 60 to 100 degrees or so would do the job if its probe were clamped to a warm piece of metal like the side of the block. That will always be cooler than the inside, so a lower activation temperature on the sensor is OK.

I keep my standby generator at 60 degrees in the winter (although the heater is out of order now) but that's another story as it starts up full throttle and it's made for that-so no problems there with difficult starts!

 

[Hammer]

Yeah, I wouldn't really be worried about heating it to 160°.
That makes it nice for turning the heater on as soon as you start the vehicle. But that does take a bit more electricity then what is really needed.

Hmm, water bed thermostat. Interesting idea in that it would be a pretty easy install, and still adjustable. Getting the probe to be remotely accurate might be difficult though.
Doubt it would handle the amps for the heater itself though, so one more relay I guess.

 

[rmgill]

There have to be some process control thermostats on McMaster Carr's site that would work for this just fine.

 

[Hammer]

Yeah, about 50 bucks for a 25 amp, surface temp controller, 240v though.
Everything else they have goes up from there.
Would get kind of spendy if you use one for the coolant and another for the oil pan (don't forget the fuel )

 

[cranetruck]

The fuel burning coolant heater is thermostatically controlled between 120 and 175°F. It automatically switches between "HI" and "LO" to keep the coolant within that range....

For an electric heater, I'd use a simple timer.

 

[yeager1]

I really like the thermostate idea because it's variable. In the last month in Colorado we've had nights in the 30's and in the -20's and you never really know. With 5 trucks plugged in, we use a lot of electricity, but it's cheaper then having 5 people stand around because a truck won't start. The variable system would probably run all out on a really cold night, but the trucks would start, on a mild night, your electric bill would probably be cut in half.

 

[Hammer]

Ah, searched around some more, and a darn simple surface mount thermostat switch would seem to be VERY easy to wire into either the coolant or oil pan heater setup.

http://cgi.ebay.com/12x-Temperature...Automation_Components?_trksid=p3286.m20.l1116

Cheapy version, but the idea is there.

 

[Hammer]

And yes, the differing temperatures could save some money when you keep trucks plugged in all the time.

 

[mangus580]

They actually make thermostats special for this. Check the ZeroStart website....

 

[yeager1]

The zerostart looks nice, but I haven't found a price. Here's anoth one, it's not a block heater, but it is a coolant heater.

http://www.amazon.com/HOTSTART-TPS101GT10-120V-Coolant-Heater/dp/B0006TPJYC/ref=sr_1_30?ie=UTF8&s=automotive&qid=1233436790&sr=1-30

 

[n3sq]

Sensor

Why not just use a temperature controller from a heat tape? They are a little thing that sells for $9 at Home Depot. You plug it into the wall and plug your extension cord into it. It will turn on the block heater when the air gets cold. You could even attach the sensor to your bottom coolant hose from the radiator - when the hose gets hot it will turn off

 

[Hammer]

The Zerostart is nice. But I am not going to replace all the heater setups on my tow trucks. The surface mount thermostat I posted a link to earlier would work very well for my setup.
And it is rated for switching under full load.

Big thing about all these other ideas is that they don't seem to be rated for enough amps.

 

[mangus580]

Zerostart (or one of the block heater companies) makes a t-stat you tape to a radiator house, plug the block heater into, and plug the t-stat into the wall....

 

[mangus580]

http://www.zerostart.com/UserFiles/File/08%20ZEROSTART%20GUTS%20US.pdf

See around page 77. I always wanted the fancy plate with lights on page 78... but I am too cheap!

 

[rmgill]

To get the best efficiency, you want to turn on and off with the temperature of the block, NOT the air or based on time. The Zero Start using would be good.

 

[Hammer]

A well done surface mount thermostat should be fairly close to accurate on the block temperature.
That IS what they were made for after all.
Might take a little work to find a good spot to mount it though.

Now, on the deuce, seeing as I don't have a block/coolant heater on it, getting a zerostart might be a good option for me.