Weird I haven’t seen a modulating setup without a W2 before. That’s a new one for me. I guess they’re really aiming for those rebate programs and making them pretty bare bones but still modulating.
I’d say it’s probably using the same logic as the single stage control from the graph. It might be a little different curve but you could check it for yourself.
It has bluetooth diagnostics you can watch the static pressure or blower motor rpm go up the longer it stays on to see how it increases output as it runs longer. I think that’s a pretty clear way to see how it is working. The quick and dirty formula for BTU output is:
BTU = CFM x ∆T (deg F) x 1.08
If it provides you with cfm and temp rise you can calculate the heat output if you’re really determined.