....quite a long time ago with a "decoding" chart for lennox model numbers, and how they relate to equipment size. Specifically, I'm looking at a HS29-261-3P condensing unit.
What is the BTU rating of this unit???
14= 1 ton
21= 1-1/2 ton
26= 2 ton
31= 2-1/2 ton
41= 3 ton
46= 3-1/2 ton
51= 4 ton
65= 5 ton
So, your unit is a two ton model.
The HS stands for high side, HP for heat pump. The next two numbers are the series of unit, they generally work up as they introduce new models. Then a dash and the next two digits which are the capacity, see above. The third number between the dashes indicates single phase or 3 phase, a single phase unit in your case. And the last numbers after the next dash will be the series number and sometimes a letter which indicates the voltage
So an HS29-261-1P is an air conditioner, 29 series, 2 ton, single phase, first revision (we call that the dash number, important when ordering parts) and the P stands for 208-230 volts.