Low-voltage low-amperage Induction Heater (HVAC)

Thread Starter

Dave Gambino

Joined Jan 7, 2017
6
Hey guys. Non-engineer here. 20 years experience as a general contractor. I can build a hell of a custom bathroom, but not so much engineer things...

Here's my idea.

I'm building an enclosed travel trailer that will function as a living space as well as, possible mobile business. I've watched youtube videos on how to assemble Tesla powerwall style battery banks using tons of 18650's. So I have a power supply sorted out, but I got to thinking, I wonder if I could take a heater core for a vehicle, since it already has a radiator style to it, fill it 80% with anti-freeze, and heat it with a simple, low-voltage, low-amperage induction heater. Heat the internal anti-freeze just as you would in a vehicle, and then blow the heat off with a 12v computer fan.

I'm thinking, a heater core comes with an inlet and an outlet. If I fill the core with anti-freeze, and then solder on end caps to the inlet and outlet or join them together with a few 90 degree elbows to make it a closed circuit, and of course solder in a overflow nipple similar to what you would find on an actual radiator to make an allowance for expansion, (so the thing doesn't explode as it expands). Then wrap the joining piece of copper with an induction coil to heat the internal fluid.

I like the idea of low-voltage low amperage for the sake of having a standalone enclosure being run by a combo of solar panels, battery bank. I prefer electric over gas anything. Just trying to make it as standalone as possible.

My question is, is there such a thing as a low-voltage low-amperage induction coil, or do those things just run rampant until they explode into fire? I have no idea how they work or where I would even start on limiting the voltage. I don't care if it takes 15 minutes to get warm. I'm talking about 100sq ft space that needs to be heated, so it's not like it needs to be 5 million BTU.

Thanks for any help!

P.S. Of course, the ideal solution would be a 12v heat-pump that could be used as either an AC or a heater, but I have yet to find one that is low-voltage low-amperage and would punish my battery bank
 

#12

Joined Nov 30, 2010
18,210
5 million BTU.
That's 1.465 million watts. In terms of 12 volts, that needs 12,208 amps.
This is not low current in my frame of reference.

It doesn't matter whether you use DC or some megacycles per second. 1 watt hour = 3.413 BTUs.
Making a Rube Goldberg contraption won't change that. A Freon pump will.
A Freon heat pump can produce 3x the BTUs per watt compared to burning pure electricity.

Also, your 5 million number is very wrong. Most 3 bedroom homes are heated with 2% to 3% of that.
 

Thread Starter

Dave Gambino

Joined Jan 7, 2017
6
That's 1.465 million watts. In terms of 12 volts, that needs 12,208 amps.
This is not low current in my frame of reference.

It doesn't matter whether you use DC or some megacycles per second. 1 watt hour = 3.413 BTUs.
Making a Rube Goldberg contraption won't change that. A Freon pump will.
A Freon heat pump can produce 3x the BTUs per watt compared to burning pure electricity.

Also, your 5 million number is very wrong. Most 3 bedroom homes are heated with 2% to 3% of that.

lol I jokingly was saying, "It does NOT need to be 5 million BTU" because it is such a small space.

I don't really have a target BTU. But if the heater core itself was able to reach a temperature of 150 degrees, I suspect that would be beyond warm enough. I just wouldn't want it to keep heating and keep heating until the point of failure. I suppose the real question is, how would I limit amperage to the coil to something like 2 amps? And at some point, I would have to use a temperature sensor to cut the coil on and off.
 

Thread Starter

Dave Gambino

Joined Jan 7, 2017
6

#12

Joined Nov 30, 2010
18,210
No offense man, but if we all went to school and knew how to do this stuff already, there wouldn't really be a need for a forum like this lol. Was just looking for a simple "this is how you limit the amperage/voltage on an induction coil".
OK. So don't read the tutorial. Just use the simple answer I gave you: 24 ohms.
 

MaxHeadRoom

Joined Jul 18, 2013
21,639
You won't do that by induction with low current.
Besides if the tube is copper is going to heat very little, if at all, it requires ferrous metal, plus it is full of fluid.
Max.
 

Sensacell

Joined Jun 19, 2012
2,634
I don't see what "induction" has to do with your requirement.

You need to convert electrical energy in to heat? right?

There is nothing more efficient and inexpensive than a resistor for this purpose.
That's what electric space heaters are - resistors.

Add a thermostat and a fan, and... done.
 
The problem is you need power (Watts) to produce heat. More importantly, you need BTU's/hr of heat. This almost sounds like the USB powered cup warmer. USB is capable of 1 Amp at 5V, so about 5 Watts tops. USB3 has more of a chance to keep a cup warm.
 

Thread Starter

Dave Gambino

Joined Jan 7, 2017
6
Gotcha. I appreciate all the replies. Again, Im very obviously not an engineer. This was just an idea that came to mind and I was wondering if it was a practical approach towards a small heater. Thanks again!
 

Alec_t

Joined Sep 17, 2013
11,755
Have you ever sat in front of a single-bar (1kW) electric fire in a small room? It takes a long time to get the room moderately warm and it's barely comfortable. With that in mind, I think you would need a similar power for your trailer heater. That implies drawing around 80A from a 12V supply :(.
 

Thread Starter

Dave Gambino

Joined Jan 7, 2017
6
Funny thing is, I have a 27" iMac late 2009, and the internal heat in there is right at about 105 degrees. I cut out the vent a bit more with a dremel, as these model computers were notorious for frying harddrives due to bad ventilation design. I bet that could function somewhat as a heat probably lower voltage and amperage than a heating coil anyways lol
 
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