HOUSING INDUSTRY RESEARCH CENTER

Day & Night – 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

Day & Night – 1980 thru Present day

Serial Number format:  3784C47010

(This serial number is from a furnace transcribed during a home inspection).

Using the first, second, third and fourth digits 3784C47010 you will find the week and year of manufacture.  The first and second digits are the week of manufacture and third and fourth digits are the year.  This unit was manufactured the 37^th week of 1984.

Year of Manufacture:  3784C47010

Week of Manufacture:  3784C47010

Day & Night – 1970 thru 1979

Serial Number format:  M4234567

(This serial number is fictitious).

Using the first and second digits M4234567 you will find the month and year of manufacture.  The first digit is the month and is expressed in letter format and the second digit is the year of manufacture during the decade of the 70’s.  This unit was manufactured in December of 1974.

Year of Manufacture:  M4234567

Use the following chart to determine year.

0 = 1970

1 = 1971

2 = 1972

3 = 1973

4 = 1974

5 = 1975

6 = 1976

7 = 1977

8 = 1978

9 = 1979

Month of Manufacture:  M4234567

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

Day & Night – 1960’s

Serial Number format:  2123456

(This serial number is fictitious).

Date of Manufacture:  Through the 1960’s the first digit of the serial number 2123456 indicated the year of manufacture.  This unit was manufactured in 1962.

Year of Manufacture:  2123456

Use the following chart to determine year.