Quote:
Originally Posted by John Mercier
brk-Int,
The relative concept working in my head is that the incandescent bulb and the convection heater use the same basic technology.
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The incandescent bulb, convection heater, and IR heater all use the same core principle - resistance of current flow. All 3 of those (and while we're at it, every other form of electric heater) produce the desired output (heat, or light) by exploiting the basic rules of physics and electricity as needed to produce what is really just a convenient side effect (heat or light) of electron flow through various materials.
In the context of these threads, SailinAway appears to be concerned not just about
feeling warm, but about ensuring her house is sufficiently warm enough to prevent damage from things like frozen pipes. So, we need to advise in the context of heating a room or dwelling, not just creating a perception of increased comfort.
As I mention in another thread, and I think you are aware, heat is a physical object. For these conversations we can draw a lot of analogies using water instead. People can see water, whereas they can't see heat, so it's sometimes easier to understand.
Instead of heating a room, imagine filling a swimming pool with water.
Let's say we have a 15,000 gallon swimming pool (room) and two hoses with nozzles (heaters) that we can choose from to fill the pool. Both hose/nozzle combos have an output flow rate of 1500 gallons per hour (watts). One nozzle has a large spray pattern, and one has more of a concentrated stream output, but it is important to note, they both deliver the same amount of water over a given time period. If it's not clear, the spray nozzle is the convection heater, and the stream nozzle is the IR heater.
If we want to take our swimming pool from empty to full, and the pool is 15,000 gallons, and either nozzle option delivers 1,500 gallons per hour, we can see that it's going to take us 10 hours to fill the pool either way.
Now, if we don't want to go swimming (heat the entire room) and we just want to cool off (warm up) quickly, using the nozzle with the stream output to hose yourself down will cool you down pretty quickly because you can direct all of the output just where you want it, instead of in a large spray pattern. This is the primary benefit of the IR heater, it is producing the exact same amount of output, but directing it in a smaller area. It won't heat the room/fill the pool any better, faster, or cheaper overall, but it can give a
perceived level of working better via the directed output.
If we have another source of water/heat, like a wood burning stove, then an IR heater might be a better choice for auxiliary heat than a convection heater because it would let us focus the additional heat just on ourselves, instead of spraying it around the entire room, with only a little bit directed to us.
However, if we are filling a pool/heating a room, both are going to take the same amount of time, and have the same operating costs, for a given output rating.
If you are heating with electricity, the only way to save money is to use less heat. You can make the room temperature lower, or you can heat less area (eg: close doors to unused areas), but until our laws of physics change, all your options or form factors are exactly the same.
The above examples are based on using electric heaters, essentially creating heat from "nothing". This is in contrast to a heat pump, which moves heat instead of creating it.
We can belabor our swimming pool example by envisioning that we have access to a large body of clean water someplace, and we have a giant sponge. You can use the sponge to soak up this "free" clean water, and then squeeze it out into the pool, repeating the process until the pool is full. This is the basic principle of a heat pump.
If we have plenty of free water available, this process works well and it will use less energy (water) than buying water from a supplier via a hose (buying power from the electric company). We can automate this sponge squeezing with a couple of motors, and while the motors cost money/electricity to operate, 1500W of motors might be able to squeeze sponges equivalent to 5000W of the direct method. (I know, it's getting weird with motors squeezing sponges, I said it was going to be a bit of a belabored example).
As our free water supply diminishes, it becomes harder to fully saturate the sponge, and it takes more work to squeeze all the water out and into the pool. We might got from using 1500 watts of motors to get 5000 watts of equivalent output to only getting 3000 watts, and then 1500 watts, and then even potentially only 500 watts, making the sponge/free water example MORE costly to operate when the water supply is down to the last few drops.
Similarly, with a heat pump, as the outside temperature drops, there is less "free" heat in the air, and the equipment has to work harder and longer to extract it. At some point it becomes impractical to move this free heat/water effectively and we have to resort to hoses/resistive heaters. This is why your cold weather climate heat pump will often have an emergency/aux heating option to resort to heat
creation instead of heat
movement when it is too cold outside and/or the demand for heat inside is greater than what the pump system can provide.
Apologies for the long response, hopefully it helps clarify some of the concepts.