When a homeowner weighs an all-electric heating and cooling swap, the first question is usually whether the new equipment will cut the cooling bill. Manufacturer ratings give a starting point, but they come from standard test conditions that your house will not match. Your attic temperature, your duct leakage, your window orientation, and your thermostat habits all shape the real result. ACHR News reports on a Transaera installation that will operate alongside a conventional system in the same building, and the report says its "performance data will be published for building owners" who are evaluating all-electric options. For a homeowner, that kind of setup is more useful than any single efficiency figure on a spec sheet.
Two Systems Share One Weather File
Two systems in one building see the same weather, the same occupants, and the same sun exposure. That is the closest thing to a controlled test a homeowner can get. A brochure comparison cannot do that. A before-and-after comparison across a season does not do it either, because the weather changes between the two periods and you cannot separate the equipment from the conditions. The parallel setup described in the ACHR News report is worth borrowing as a model, even if your project replaces a single system.
Log the Old System Before It Leaves
Start the log before the first day of the change. Record the outdoor high and the indoor setpoint each day, the runtime hours if your thermostat reports them, and the monthly kilowatt-hours from your utility meter or smart meter portal. If you are trained and comfortable working near live equipment, you can clamp the outdoor unit feed at the disconnect while it runs and note the amps at a steady load. If you are not, let a licensed electrician take that reading. Volts times amps times hours gives a rough energy figure for a run period. For example, a unit drawing 14 amps on a 240-volt feed for 3 hours uses about 10 kWh. Treat that as a sanity check against your bill, not as a billing estimate. Also write down the model and serial numbers of the old condenser and air handler, since you will want them later for service history.
Three Questions for the Installer
Before you sign, ask the installer three things. First, will the old and new readings cover the same weather window, and how will that be verified? Second, who receives the data, in what format, and on what schedule? Third, if the new unit falls short of its estimate, who runs the retest and who pays for the adjustment?
If an installer resists a side-by-side period, that is information too. A short trial with shared data costs a contractor little when the equipment is sound, and it protects you when the numbers arrive later.
Where a Parallel Test Misleads
Thermostat setpoints can drift between two units if one person keeps adjusting the wall control. Occupancy matters as well. A house with a home office all day and a house that sits empty on weekdays will not share a load profile, so a comparison between them tells you little. Shoulder-season days often favor neither system, which means a short test in spring says less than a full cooling period. Treat the parallel data as one input, and weight the metrics you can reproduce on your own schedule.
Keep the Old Unit's Paper Trail
Even after the old equipment leaves, keep its model and serial numbers, its service history, and your log together in one folder. If a problem appears later, that record shows whether the change, the house, or the way the house is used is the more likely cause. Ask the installer to deliver the new unit's data in the same format so the two sets can be compared directly. The goal is not to prove one brand right or wrong. It is to know, with your own numbers, whether the swap did what the bid said it would do.