Below is a pic of someone cutting down a tree using a manual chain saw. The hands go back and forth. Each tooth on the saw oscillates back and forth, and thus the net distance each tooth moves is essentially zero. Yet the saw still cuts through the tree.
For this saw, the energy is transferred from the chest, arms, and hands to the tree through the back-and-forth movement of the teeth in the saw. Also notice that the energy from the hands is transferred to the tree extremely quickly (almost instantaneously), much faster than the average speed of each tooth in the saw.
The same goes for an AC circuit: you can think of the energy as being transferred from the source to the load through the back-and-forth movement of the electrons in the wires. Like the teeth in the saw, the back-and-forth movement of the electrons is pretty slow, while the transfer of energy from the source to the load is very fast. (In reality, however, the energy is really in the electric and magnetic fields surrounding the wires, not in the electrons. But that’s a different discussion.)
Now some people will say, “But if the electrons are just vibrating back and forth in an AC circuit, why do you also say current must flow in a loop? Isn’t that contradictory?” No. For the manual chain saw analogy, the saw, hands, arms, and chest definitely form a loop, yet particles are not flowing around the loop.
I know that a fan though the wall of the bathroom would be enough. It’s a 1-Ton heat pump, and will have more than enough capacity for the bedroom and bathroom. The issue is - my wife refuses to let me put a cross-ventilation fan in the bathroom. I’m not 100% sure of the issue, but it’s some noise thing. She’s a very sensitive individual.
We usually limit the term resistance to the kinetic effects, the Ohmic component of the circuit. Impedance is that resistance plus reactive effects that occur when the conductors are implemented in certain geometries that generate significant electrical and magnetic fields. Hopefully, OP’s electric heater is purely resistive and algebraic. We even sometimes use the term ‘ac heater/ing equivalent’ for shorthand to represent a black box load that isn’t very reactive.
Sometimes, it’s only the reactive component that is of interest like for coaxial cable which is rated in characteristic impedance (such as 75 Ohms) but measures ‘a dead short’ with a multimeter. Similarly, audio gear has impedance which is understood to be the equivalent resistance at 1000 Hz but measures almost zero Ohms.
I know this is way OT, but it is sort of a misconception that a coax cable is an open circuit (if the other end is an open circuit) or a short circuit (if the other end is a short circuit) when measured with a regular ol’ multimeter. During the first few nanoseconds, the multimeter will read 75 ohms, or whatever the characteristic impedance is. But then after a few microseconds, the meter will read an open or short circuit, depending if there’s an open or short on the other end. And since the meter can’t respond so quickly, and does lots of averaging, all you see is the open or short circuit displayed on the LCD.
If an ideal coax cable stretched from Earth to Pluto, the multimeter would read 75 ohms for about 13 hours.
Yes and no.
You can extract energy by approaching a static electric field, or by a varying electric field, but if nothing is changing, than now energy can be extracted.
Electrostatic fields are how DLP ICs work in video projectors.
There’s no way that a fan will maintain a higher temp in the bathroom than in the rest of the space warmed by the heat pump. So I’m not sure i would agree that it’s “enough”.
But I’m sympathetic to it being a noise thing. I hate the sound of fans, too. I never turn on the bathroom fan until i leave the bathroom.
Right, that’s why the fan won’t be able to keep the bathroom warmer than the bedroom. And my preference, both summer and winter, is for the bathroom to be warmer.
But her objection is different, and also valid, imho.
I’ve seen electric baseboard heaters that are designed to be primary heat sources and left on all night on a thermostat.
I just noticed a video on YouTube (didn’t watch) where a guy is so proud that he fools his Tesla charger into operating a 7.5 Kw heater. Probably the least efficient heater ever.
I saw that come past as well. Didn’t watch it either. If that was here, it would be an interesting proposition, as most electricity suppliers are offering significantly discounted power for charging an EV. How this is managed varies and continues to change. A while ago my supplier was offering a deeply discounted overnight (12-6am) rate so long as it was only going into your EV. They insisted that they install the charge controller along with current sense transformers to directly meter the power going into your car. Only that power was cheap. Now they are just saying 12-6 is cheap, and please put it in your EV. But if your use pattern is suspicious they will terminate the deal. The up front cost of having their specific charge controller installed, by them, made the deal quite uneconomic. About 4 years of car charging at off peak rates. Which is why I never went with it. Seems others made the same decision.
So if one was on such a metered cheap EV plan, fooling the charge controller would be something some idiots would consider. I can’t see the value in it, and the usual outcome is people becoming greedy and having the contract voided. Running a 7.5 kw resistive heater is just nuts. Burning the garage down is probably the likely outcome.
Power companies are still looking at selling excess overnight capacity, which I had thought would be a thing of the past, but not, so it seems. Very region dependent.
One of the competition electricity companies uses a system where the car reports the electricity use via the usual car companies integrated internet connectivity. So they trust the car reporting, and don’t need external metering of the charge controller. Tesla were the first company they supported through this system. They have added BMW and Mercedes Benz since. So a way to go. But no way to fool an EV special plan with silly hacks. This may well become a favoured mechanism for providing such rates.
I don’t understand how it is inefficient. Stupid, yes, he says that right in the video. Just as up thread describes, though, you have electricity, but you want heat, so nearly all of the electricity is converted to heat. What is inefficient about that?
He’s using an off the shelf 7.5Kw electric heater, designed to be mounted in a fixed location. Dangerous if you throw dryer lint at it, or something, but otherwise a readily available consumer product.
One of the main points of the video is that level 2 chargers are nothing more than fancy plug converters. All the charger does is listen for a signal from the car, and when it gets it, close a switch to start the power flowing. He recreates the signal from the car by installing a resistor (and maybe something more) across the signal lines in the heater side of the connector.
Now this is an interesting scenario. If it’s simply time of use electricity, then it doesn’t matter if you’re charging, running an electric dryer, or electric heater, it’s all the same price.
But if there is a special discounted rate for power that flows through the level 2 charger, then connecting it to an alternative device is an interesting cheat. Seeing how easy it is to convert from a J1772 or J3400 (aka NACS aka Tesla) connector to a 10-50 or 10-30 receptacle, it would be easy to misappropriate electricity for an electric furnace or AC.
Well, I figured a charger has to have internal losses… If it doesn’t work that way and just gets a signal to route house power to the car (or heater) then maybe it is just a fancy switch.
It does at first but it’s only about two household electric ovens. Just imagine all the, um, bootleg smelting and kiln firing you’ll get done before the garage becomes fully engulfed.
Come to think of it, I wonder if covert cannabis grows and crypto mining are legitimate concerns.
Keeping a multi-car garage at a decent temperature to do car maintenance when it’s 0C outside consumes a lot of energy. Be that energy from electricity or from gas.
