30 amp variac instead of an autoformer?

pianotuna wrote:
Hi Gde,

I am not looking for "over parity" devices. I'm looking for a voltage boost. I know that costs more amps.

Sure you can boost the voltage going to the A/C which would reduce the current draw of the A/C. BUT the device boosting the voltage would then in turn demand more input current..

Even worse is the boosting device will insert considerable line loss of energy in the form of heat.. That loss also means that the booster is consuming some energy in the process adding that loss to the input current of the booster.

In the end, the A/C draws some less current, the booster draws more current and add the loss in heat of the booster and the over all result is a net loss.

Putting it another way.. boost 108V at 30A, 10% increase of voltage gives you 118.8V but now the booster will add 10% MORE current to the input which would be 3A of additional current PLUS what ever loss due to the transformer losses in heat say 1A.. You are now 34A of current..

Keep in mind that you could set your fridge to propane, that would free up 275W-325W depending on the fridge.. That just may be enough to stop the tripping breaker..

Thinking outside of the box, perhaps consider a window A/C unit?

RV A/C units are terrible for efficiency, window A/Cs reuse the condensate water by splashing over the condenser coils. This effectively allows the A/C to give more cooling power per watt than a non splash A/C which is what a RV unit is.

I use two window A/Cs in my 26ft TT, a 10K BTU and a 6.5K BTU, combined I get 16.5K BTU but they use a little less wattage than the 13.5K RV A/C unit they replaced..

Having two allows me to only cool part of the trailer if I want or if limited power (20A) I can turn on the 10K BTU and allow it to run to get trailer somewhat cool then turn the 6.5K on to get it to comfy temps.. I am able to do that when I stop at my Cousins house with 100F to 110F outside temps and not pop their 20A breaker..