How to solve the following practical problem that I currently have in my "food bike" design in a practical manner:
Power supply (AC):
- Generator: 800W
Loads (AC, purely resistive, each controlled with its own thermostat):
- water heater: 750W
- syrup heater: 517W
- The available power may never be exceeded. If so, a breaker trips, which must be avoided.
- The syrup heater load demand must always be satisfied.
- The water heater load demand is allowed to be interrupted in order to satisfy the syrup heater load.
Edit 1: Additional rules to narrow the solution space:
- Human intervention is not allowed to achieve the desired result because the food bike operator is too busy serving his customers.
- I prefer to keep both heaters unmodified so their certification remains valid. Therefore both heaters (including their thermostats) are considered as "black boxes" with only their power cords as the "interfaces" to an external circuit.
Additional system details: This is a real-world problem that I try to solve in order to design a food bike for myself in order to have my own small business, in contrast to food-trucks, and in the long term to be powered with PV-charged LFP batteries. For now, I use a noisy and stinky generator. Each thermostat switches its heater on to keep it at a given temperature. Assume, for the sake of conversation, that this happens randomly at intervals of roughly a minute or so. The water heater is expected to demand power predominantly after the food bike operator washes his hands because that heater serves the hand-washing station. The budget to solve this specific problem is in the order of $100. Weight is an issue, so a lightweight solution is desired. Fictitiously, an "XOR" power strip with an configurable socket prioritization (the syrup heater socket would get priority) would solve the problem, by that I mean a pair of AC power sockets that mutually exclusive provide power without temporal overlap that would trip the generator's breaker. You could also see this as a "power strip with load-shedding".
Project's geographical location: California, USA (needed for appropriate certifications / regulations).