Automatic RV generator

At first sight, an auxiliary contact on the demand control on the aircon operates the start circuit for the generator. Two wires?

Sounds like you need a load manager, auto- transfer kit for your particular generator brand...

http://www.electricgeneratorsdirect.com/standby-generator-accessories.php

One might do away with all that complication, and simply open the window...

Very good suggestion, it would really simplfy things. However, it wouldn't give much comfort on a 95 degree F day.

How about this?

A basic scheme would be a time delay relay on the AC circuit. Set up the AC thermostat to start the generator, with a short delay before starting the AC.

It seems I would have to change the existing thermostat to a temperature controller. When the desired temperature is reached, the relay would cut the power. When the temperature reached the "turn on" temperature, the controller would turn on the starter for the generator. After some reading that the generator was on, the starter would be cut off. Then, the AC would be powered by the controller via a relay.

I don't know if I can do this or not. To buy one, I'm limited to the number of generators it will work on. I'd like to use my Harbor Freight el cheapo electric start generator. I'll give it a try. I'm not very good at this. Yesterday, I fried an inverter because I got the "+" and "-" backwards. I wanted my refrigerator in my camping trailer to run while going down the road. I have a small, AC only refrigerator. Well, no guts, no glory.

Have some fun today,

PAPADOC

RMFR

I'll live life my way until Willie sings.

Onan has had a start on demand for generator sets since early seventies when I first encountered them. In essence a low voltage (12V)was run through the AC wiring and when any current flow was detected by a closed switch it triggered a start genset circuit on motor. I'm sure they have a much more sophisticated technique not that we have semiconductor chips. The ones I worked on back then were relay controlled.

Unfortunately most start on demand controllers in use today are simply triggered by battery voltage. Large inverters have a 'sense' circuit that kicks the inverter from standby into active mode when a load in excess of a few watts ( typically 10W) but not having been involved with inverter design I only know details second hand and as a user.

Depending on how much hands on you wish to get involved with, its relatively easy but as a black box off the shelf item, it may involve a bit more digging. There are such things as current sensing relays (adjustable threshold) that trip when a load current is sensed and the contact can be wired to the electric start circuit on a genset if so fitted. If the genset is not already equipped with an 'autosrtart' feature it will get somewhat more involved.

Some brands may offer it as a add-on feature at a price.