The 2 questions were:
1. The MTU appears to transmit its output via the circuit breaker it's connected to, but that would present the data on one leg only of the household wiring. How then could the receiver work if it were plugged in to a receptacle on the other leg?
2. How are major loads detected for logging in Footprints? It looks like current is only measured at the service entrance -- I don't see how specific loads are identified. I would like to look at two major loads -- AC and water heater -- for sure, and possibly others, at the same time.
Their (prompt) answers were:
1. In some cases it doesn't receive data consistently...but in some cases it doesn't affect it (if the secondary transformer is nearby). A solution to the opposite-phase-issue (if you plan on moving the display all the time to places all over your house) would be to put in a phase-coupler....which you can get at RadioShack.
2. That's what Footprints does. Among other things, it is designed to recognize major loads.
And my folllow-up was:
1) is no problem, probably, since the transformer is on a pole in my front yard.
I'm still puzzled about 2). How does Footprints differentiate among several "major loads"? For example, suppose I had 2 identical water heaters -- could Footprints distinguish them and report them separately? My real "major loads" right now are the water heater, HVAC, well pump, and irrigation pump. Does this imply that I couldn't elect to define and track "minor loads" using Footprints? For example, I have several outside lights triggered by motion sensors; could I log the times they were on?
I'll continue to report back. I just got a Kill-a-Watt, or whatever it's called, and plan to monitor our garage fridge for a week or so. I'm kind of scared what the numbers might look like. Like most garage fridges, it was moved from the kitchen when we bought our new (10/97) one, whose EnergyGuide claims 762kWh/year. The garage fridge is probably 25 years old.