# Thread: Old Lennox Heatpump # size question

1. Professional Member
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## Old Lennox Heatpump # size question

Have an old Lennox heatpump to change out and me and the boss whose been in the industry much longer than me but not a Lennox dealer disagree on the size. He says a M/n 10HP48-1p, S/n 5193E32877 is a 5 ton because Lennox used odd numbering back in the day but it sure looks like a 4 ton to me by those numbers. Can a Lennox guy chime in and settle this ? Thanks

2. first to # are the series, (10) next two are the type (hp) heat pump the next two are the btu (48k) the next number is the revision (1) and the last letter is the voltage (p) 208-230 1 ph that unit is a 4 ton

3. Originally Posted by westmorelnd
Have an old Lennox heatpump to change out and me and the boss whose been in the industry much longer than me but not a Lennox dealer disagree on the size. He says a M/n 10HP48-1p, S/n 5193E32877 is a 5 ton because Lennox used odd numbering back in the day but it sure looks like a 4 ton to me by those numbers. Can a Lennox guy chime in and settle this ? Thanks

Send me an email (address is in my profile), and I will forward you the Lennox Nomenclature to show your boss.

It is a four ton unit as hvacman14 said. In the old days the 5 ton was listed as a "65".

4. For old Lennox, round down. The 5 ton 65 dawg mentions, round down from 65 to 60,000 BTUs. Or an old 4 ton would be a 51 which rounds down to 48K. So simple.

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Thanks a bunch guys. great help and knowledge always hanging around here.

6. old numbers

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

dogboy

7. whats the indoor model # ???

8. Originally Posted by DOGBOY
old numbers

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

dogboy
these numbers as in HS19-311-2P or HP18-411-7P the 3rd number like 411 or 413 stands for single or 3 phase.

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