Hi, sorry first post.

I am trying to keep my dogs water bowl outside from freezing up. I know there are commercial products that can do this, but most of these are either very expensive, or they only hold a small amount of water.

I use this,

https://www.lowes.com/pd/Behrens-5-5-Gallon-Residential-Bucket/3452176

as his water bowl, its a 5 gallon, metal water bowl. I was under the impression, that i could use this

https://www.amazon.com/NTE-Electron...UTF8&qid=1481215322&sr=1-1&keywords=nte+dto60

inline to open or close a circuit that contained just a resistor and I could use thermal paste to attach the thermostat and the resistor to the bottom of the water bowl.

Then when temp falls, the circuit closes, the resistor gets hot, and heats the water bowl, then when water heats up, circuit opens. Rinse and repeat.....

Question is, what resistor should I use, or should I use multiple resistors.


Sorry for the very basic and laymans terms, but trying to get this solved before the really cold temps get here.

 

How much power you'd need to apply would depend on where you are and what freezing conditions you encounter, and could range up to several hundred watts (or even more). Rather than trying to rig something up with resistors (expensive, prone to failures and possibly dangerous), why not just use an immersion heater?

 

Question is, what resistor should I use, or should I use multiple resistors.

I suggest a proper immersible heater (of such design that, by virtue of resistance alone, will not burn-out if continuously run dry) -- Pursuant to the safety of yourself and your pets redundant grounding and GFCI protection is imperative!

Best regards
HP

 

Rather than trying to rig something up with resistors (expensive, prone to failures and possibly dangerous), why not just use an immersion heater?

Exactly! Which is to say Ditto!!!

Best regards
HP

 

i actually had considered an imersible heater as my first option, my tendancy to go another route is two fold.

1. This is for a lab. He often chews anything he can. The water bowl is staked to the ground and I could run a cord under the water bowl so that he can not chew at it. But running one into the water bowl would be exposed to him.

2. Secondly, all the immersible heaters I have found appear to be of two variety. Aquarium heaters, and camping heaters for boiling water. I do not want to boil the water, simply keep it from freezing, and I am worried an aquarium heater would bust, or the dog would chew it, and I believe those have chemicals in them that are very hazardous.

 

I am most definitely open to any suggested products that might work however.

 

The control part is easy enough. "How much heat" is the second level of difficulty. The safety aspect is an absolute, no fakes allowed, necessity. Trying to do a home-made heater causes the safety aspect to be in great danger.

Now, "how much heat"? How cold is it? How much insulation does the bucket have? What temperature is warm enough?
With no clue as to where you are, it's all guessing from here.

ps, A dog only chews an electric cord once. After that, he knows the cord can defend itself.

 

You know, I thought the same thing about the chewing an electric cord, but I have replace 3 extension cords in the last 12 months.


I live in arkansas. It is never below 0 F. But often below 32F. The bucket is metal, with no insulation. Any temperature to keep the water in liquid state would be fine.

I was basing all of this thought process off of this website

http://blog.mydbsupply.com/how-to-make-a-heavy-duty-chicken-water-heater/

 

40 watts is the rough calculation, so try 80 watts to 120 watts with a thermostat.
Sorry about your extension cords. It worked with my puppies.
A litter of 9 never destroyed an electric cord in 5 years.

Labadors have wonderful personalities, but they are almost as stupid as an Irish Setter.

 

That thermostat should work but 60°F is a little high for the temperature as the heater will cycle for any temperature below that.

You might want to insulate the outside of the bowl (place it in a styrofoam cutout for example) to minimize the power consumption.

You will need a transformer or power supply to power the heater to avoid the electrocution hazard (for both you and the dogs) of having mains voltage near the metal bowl.

The size of the resistor needed is the question.
It will depend upon how cold it gets and how well you insulate the tub.

I would consider a cattle tank de-icer such as one of these (see bottom of page).
It gives you a chart to determine the heater size required depending upon the tank size and your location (it doesn't go down to your small tank size but you can roughly extrapolate from that).
It includes a built in thermostat.
For safety from electrocution in case of an accidental short (say a dog decides the cord is a good chew toy ) I would power it only from a ground-fault-interrupter (GFCI) socket (if the available socket isn't GFCI you can add a plug-in one such as here).

 

https://www.amazon.com/Green-Alumin...979&sr=8-3&keywords=100+ohm+100+watt+resistor

in series with the thermostat? If i remember my ohms law correctly, that would be 200 ohms, at 120 volts, .6 amps, 72 watts. But the heat would be dissapating from two separate points.

Thoughts???

Of course this is going to be plugged into a gfci.

 

But the heat would be dissapating from two separate points.

Thoughts???

Why would the heat magically not be heat if it arrives at two separate points?

 

I assumed, trying to heat a metal container from a point of heat, that more surface area for heat transfer, the more efficient that heat transfer would be

 

I assumed, trying to heat a metal container from a point of heat, that more surface area for heat transfer, the more efficient that heat transfer would be

Irrelevant. The total heat introduced within the boundaries of a closed system is the total heat. The only thing that changes is the temperature gradient at the point of entry. As long as you limit the heat to x number of watts, you could heat this bucket with an oxy-acetylene torch or your own belly and the only difference would be the temperature at the interface.

 

Point taken

 

https://www.amazon.com/Green-Alumin...979&sr=8-3&keywords=100+ohm+100+watt+resistor

in series with the thermostat? If i remember my ohms law correctly, that would be 200 ohms, at 120 volts, .6 amps, 72 watts. But the heat would be dissapating from two separate points.

That would work; mount the resistors onto aluminum heat spreader plates perhaps a few inches square, and mount the plates to the underside of the tank. But I would opt for lower value resistors, and power them from a 12V or 24V transformer for safety's sake.

 

https://www.amazon.com/gp/aw/d/B01G...r+100+watt&dpPl=1&dpID=51odQi2RgQL&ref=plSrch


One of these, with the thermometer placed on the bottom?

I do think I will get a block of Styrofoam and make a cut out for the bowl to sit into. Insulate the bowl, and protect the resistor from the elements.

 

1) Insulate the bucket. Even a little bit would help a lot. Setting it where it is out of the wind and sees sunlight (and painting the outside black) would go a long way as well.
2) Some here may groan that I'm a one-trick pony on such things but I'd just put a lightbulb underneath it. No thermostat. Obviously you'd want a wooden box or such that would protect the bulb.

One reason I love lightbulb heaters is the visual feedback. You could look out into the yard in the middle of the night and know in a second if the heater was running.

I doubt the bulb would really need to be turned off by a thermostat. You could probably just do that manually if the weather has warmed up so much that the extra heat is making the water too warm. I do the same with my boat in my garage. If the weather outside falls below 0°F, my garage will eventually head below 32°F. I just click on a 100W bulb inside my engine compartment and turn it off when the temp outside comes back up.

I have no idea what wattage you'd need but I'd experiment with 100W. That may be too much, so be prepared to back off to a 60W or less.

 

While I'm on a roll, the thermostat might not be very important. What you're doing is raising the water bucket by about 40F above ambient. At zero F, the water will be 40F. At 70F, the water will be 110F. If you are able to unplug the heater on days when the temperature will be above 32F, you don't need a thermostat.

Oh...wayneh just said that while I was typing.

 

holy geez, i just googled styrofoam block, wth is it so expensive?