Lennox
model hp26-030-12p
serial 5803a 35663
Thanks!
Lennox– How to determine the age or manufacture date
Every effort is undertaken to offer you correct and concise information to assist you in determining the age or manufacture date of HVAC equipment. Anytime anyone is dealing with numbers and letters in determining data, mistakes and misinterpretation are bound to happen. For this reason if you find during your research that we may have erred please contact us. In addition perhaps you have come across a brand, model or serial number format that we have not addressed. Email us information or pictures of data/nomenclature plates of the unit and we will attempt to assist you in your determinations. Email
This page was last updated: 25 July 2009
Lennox
Serial Number format: 5896A 36571
(This serial number is from an actual furnace unit transcribed during a home inspection).
Using the third, fourth and fifth digits of the serial number 5896A 36571you will find the year and month of manufacture. The third and fourth digits are the year and the fifth digit is the month expressed in letter format. This unit was manufactured in January, 1996.
Year of manufacture: 5896A 36571
Month of manufacture: 5896A 36571
Use the following chart to determine month.
*A = January
B = February
C = March
D = April
E = May
F = June
G = July
H = August
“I” was not used.
J = September
K = October
L = November
M = December
2.5 ton
Thanks Wayne 
model hp26-030-12p
30,000 btu/hr (12,000 btu = 1 ton) so 30K = 2.5 ton
No problem