I have a Lennox Air Handler (CBX32MV i think) with electric heat. No heat pump attached at the moment. When I had it installed new a few years ago, the installer determined I needed 12.5 kWh electric heat for my house.
My power meter was recently updated to one of the smart meters. With it I can now look over the Internet at the wattage being used at any given minute, hour, or day
Using the smart meter's website, I've observed that when my furnace runs, it only shows around 8,600 watts being used. In the very first minute it turns on however, it shows a wattage of around 12,500, but then drops off in the next minute to the 8,600 where it stays. I thought this was odd as I had a 12.5 kWh furnace, and expected to see the wattage stay around 12,500. I called the company that installed it and had them come check whether everything was working properly.
The tech took the panel off and used his ammeter and determined that all three elements were drawing power. I don't remember the exact amps, but something like 40, 25, and 18 ( it's been a year since he checked, so I don't remember the exact values). He told me that likely what was happening is the furnace determines the airflow and will only turn on the elements it needs to.
He however couldn't explain why the power meter showed 8,600 watts being with all three elements working when it should be 12.5 kWh? It seemed to me that the 8,600 I was seeing would indicate only two of the elements were working (plus a few watts for other house items, which is usually around 200 watts without furnace running). When he checked the elements with the ammeter showing all three working fine, the cover was off, but when we would look at the power meter, the cover would be on. His other explanation was that it's possible the elements were rated at 12.5 kWh at a different voltage then the furnace is currently using, which could cause the difference in the wattage.
So my question is, is this normal behavior for my furnace? Even though it's rated for 12.5 kWh, would it be normal to see ~8.6 kWh being used on my power meter, or is there an issue with my furnace and I'm not getting full heat out of it? Even after running for 30 minutes, it will still be drawing around 8,600 watts.
Thanks in advance.