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A coil/Condensor sizing

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Originally posted by Terence McCann

Hi Kevin:

Look for the numbers like 024, 048, 060. These are short for the BTUS on the air conditioning. 024 being two ton, 048 being 4 ton and 060 being 5 ton. Just remember 12,000 BTUS per ton of cooling. Some manufacturer's like to be really cryptic though.

Thank you sir.

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LENNOX is one of the mfg's who like to encrypt. The FIRST TWO numbers after the model number represents the nominal tonnage. example CB10-41 or CB10-65 CB10 is STYLE AND SERIES MODEL, 41 INDICATES THE NOMINAL TONNAGE 3 TONS, 65 = 5 TONS. These can sometimes be difficult to interpret for example a heat / cool roof top unit GCS4-261-60

GCS4-261-60 would indicate GCS4 = Model 261 = 2 tons cooling 60 = 60000 BTU Heating

21 = 1 1/2 TONS

26 = 2TONS

31 = 2 1/2 TONS

41 = 3 TONS

46 = 3 1/2 TONS

51 = 4 TONS

65 = 5 TONS

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FWIW, I'm on a new home construction inspection out in the country. The HVAC guy was putting the finishing touches to the upper level Heat Pump air handler. He was even sealing all air leaks.

I asked him about miss-matched coils. His exact words, "I always try to match things up because I don't want the problems down the road. But, on a cooling system, you can have a larger evap coil by a 1/2 ton, no problem. But miss-matching coils on a heat pump will be a big problem on one mode or the other."

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  • 4 weeks later...
Originally posted by hausdok

Originally posted by mgbinspect

Hey, just for future reference, are there any licensed/certified HVAC Techs (past or present) that are members and regular contributors to TIJ?

Is there any such thing as a licensed and certified HVAC tech? I don't think they need any licensed or certifications to work out here?

OT - OF!!!


Licensing varies with locality. Illinois has no state wide licensing of HVAC contractors or building codes. Licensing is required in Chicago and other major cities and they have building codes as well. Though NIACCA is pushing for state wide licensing of HVAC contractors.

There is currently a certification program called NATE. Depending upon the manufacturer (Trane, Carrier, Lennox, etc.) any company that is a dealer will need to have a certain percentage of its employees to be NATE certified with eventual requirement of having 100 percent of installers and service technicians being certified. A phased in requirement. The talk is that any warranty work will also require the technicians NATE certification on the paperwork.

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  • 3 weeks later...

Courtesy of Home-Tech

BDP (Bryant, Daylight, Payne): Tonnage is in the model number

Example; Model# 324AC0042000B0 Model is 42 is size in thousands of Btu's. 42,000 = 3.5 tons.

Carrier: Tonnage is the last 3 to 5 digits of the model number.

001 = 1.5 T

002 = 2 T

003 = 2.5 T

004 = 3 T

004-5 = 3.5 T

005 = 4 T

006 = 5 T.

Climatrol: Model number shows size

Climate Master: Prior to '72 model number showed size, Example: V/H33 = 33,000 Btu/Hr

Post '72 the first two digits of the model number are the size Example: 10x = 1 T, 15X = 1.5 T, 20x = 2 T, Etc.

Chrysler Air Temp: Model number shows size.

Example: 1206 - First two number show type of system - 12 = split system; Third number shows manufacturer's - 0 in this example;

Fourth and fifth number show size - 6 = 5 tons (60,000 Btus)

0 = 1- 1.5 T.

1 not used

2 = 2T

3 = 2.5T

4 = 3T

5 = 4T

6 = 5T

Day-Night: (Now BDP brand) - Until purchased by BDP the size was indicated by hundreds of Btu/H in the model number

Fedders: Size is the last two digits of the model number = Btu/Hr; Example: CF30 = 30,000 Btu/Hr or 2.5T

General Electric: Size is the last 3 digits of the model number = Btu/Hr; Example WO048 = 48,000 Btu/Hr or 4 T.

Lennox: Size is in the model number. The model designation is followed by size in hundred of Btu/Hr; Example Mod. HSX-311 = 31,100 Btu/Hr = Approx 2.5T

Rheem/Ruud: Size is the last two digits of the model number. Size in thousands of Btu/Hr; Example AT38 = 38,000 Btu/Hr = Approx 3T.

Tappan: Size is the last two digits of the model number. Size in thousands of Btu/Hr; Example 0024 = 24,000 Btu/Hr = 2T

Trane: Size is the first digit of the model number; Example 3XXX = 3T



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I just knew that was coming.

Again, courtesy of Home Tech.

AMANA: For tonnage refer to FLA & RLA. For age use the serial number and the "B-L-A-C-K-H-O-R-S-E" code wherein S=1969, E=70, B=71, L=72.

B = 71, 81, 91, 01

L = 72, 82, 92, 02

A = 73, 83, 93, 03

C = 74, 84, 94, 04

K = 75, 85, 95, 05

H = 76, 86, 96, 06

O = 77, 87, 97, 07

R = 78, 88, 98, 08

S = 79, 89, 99, 09

E = 80, 90, 00, 10


Bryant:From 1964 to 1979 use the first two numbers of the serial number followed by a date code

1964 = R

1965 = S

1966 = T

1967 = U

1968 = V

1969 = W

1970 = X

1971 = Y

1972 = A

1973 = B

1974 = C

1975 = D

1976 = E

1977 = F

1978 = G

1979 = D

Example: 27Rxxxxxx = 27th week of 1964

After Bryant became Bryant, Day-Night, Payne the system changed. In the new systm the first and second digits of the serial number are the week and the last two are the year (Applies to all BDP).

Example: 2799xxxxxx = 27th week of 1999.


Carrier: Age is incorporated into the serial number. Through 1969, the first digit of the serial number indicates the year of manufacture. Example: 3xxxxxx = 1963, 4xxxxxx = 1964, etc.

1970 and later, a letter followed by a number indicates the month and year of manufacture. Example: A1 = January 1971, B1 = February 1971, C4 = March 1974 etc.

A = Jan

B = Feb

C = Mar

D = Apr

E = May

F = Jun

G = Jul

H = Aug

J = Sep

K = Oct

L = Nov

M = Dec


Climatrol: No known age code


Climate Master: Serial number indicates age from 1972 on


Chrysler Air Temp: Age is shown by the first digit of the serial number and correspons to the last number of the year of manufacturer. Example 0C893745 = 1970. 1 = 1971, 2 = 1972, etc. Use common sense and visual observation to distinguish decades from one another.


Day-Night: (Prior to BDP in 1979) Age coded into the serial number. First letter is the month followed by the second letter which is the year. A = 1970, B = 1971, Etc. Example: AAxxxxxx = January 1970, BExxxxxx = May 1971.


Fedders: Through 1977, the last two letters of the serial number show the month/year of manufacture, beginning with September 1964. Example: xxxxAA = Sept 66, xxxxBC = Oct 68.(I is not used)


General Electric: Age is the last 3 digits of the serial number. First digit being the year and the second and third digits being the month. Example xxxxx241 = 41st week of 1982, 92, 02 etc., xxxxx533 = 33rd week of 1985, 95, 05 etc..


Lennox: Before 1974 the first 2 digits indicated the year and the next digit the month. Example: 732xxx = February 1973.

After 1973, the first two digits indicate the plant, the 3rd and fourth indicate the year and the 5th is a letter month (I is not used). Therefore 5598C = March o 1998.


Rheem/Ruud: The age is coded into the last four digits of the serial number by week and year. Therefore xxxx2302 = 23rd week of 2002.


Tappan: Age is the last 3 characters (digits and letter) of the serial number for the year and month of manufacturer.

Example: xxxxx85C = March 1985. (I not used)


Trane: Begins in 1971. Age is a number followed by a letter in the serial number. Example: 1C-xxxx = March 1971, 81, 91, 01 (Use common sense to distinguish one decade from the next.) Beginning around 1982 the date of manufacturer is stamped on the ID plate.


Whirlpool: Begins in 1970. The letter indicates the decade followed by the week. G = 1970's, H=1980's, J=1990's, K=2000's Example: H416XXXXX = 16th week of 1984.


Hope this helps, but I can't guarantee that all will, because I've never worked with most of these brands.



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No, as I posted, from Home Tech.

About a year after I got into this business, I took one of Home Tech's 2-day inspection seminars just out of curiosity, to see how it compared to the training I'd gotten from the franchiser. The training wasn't much - a waste of time and a couple of hundred bucks really - but they provided some handouts that have proven useful over the years.

OT - OF!!!


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Thanks for that info Mike, that'll be going in the 'ol clipboard.

Update to my original post, Goodman was going to stand by their warranty, but turns out nothing was damaged and everything is operating correctly after servicing.

Interesting, since I started glancing at the tonnage on the spec plates, have had no fewer than 5 more instances of 4T condensors with 3 1/2T A-coils since this thread began.

Don't know if it's a regional thing or not, but several techs I've talked to here say it's very common and done all the time, others still say they never do it. I just put a BP in my report about it now.

I'll keep scratching my head. Thanks again to all that helped with the initial topic.

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Need help with these(age and tonnage):

BDP Evaporator:

518a024cc Model

18006725 Serial

Carrier Condenser:

38ckc024340 Model

1003e14328 Serial

The condenser is pretty new, while the evap look original with the home. The home looks to have been built early-mid 80's.

The unit was not cooling the home very well.

The #'s on the evaporator were pretty hard to read so they could be off, but hopefully not too far off.


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I showed you how to figure that out in my post of June 28th Above. if you copied that evaporator model number correctly, the evaporator is a 2 ton unit manufactured the 18th week of 2000. However, I don't think you've copied it right because the last two digits are supposed to be numbers, not letters and the 3rd and 4th digits after the letter are the BTU's in thousands. Since 4 is in the 3rd spot after the letter, I think it's possible that the 4th letter might have been a 3 and thus matched the condenser.

The condenser is a 43,000 Btu (Approx 3.5T) manufactured the 10th week of 2003.

You were there though, you should know better than me.

OT - OF!!!


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Whoops! I just realized that I was using the BDP key for both of those and wasn't looking at the Carrier key. You guys are right of course its a 24,000 Btu or 2 ton and it was manufactured in May 2004 if that key is correct and it runs a 20 year cycle beginning in 1970.

Sure would be nice if they'd just print the darned date and tonnage in plain English instead of encoding it.

OT - OF!!!


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Originally posted by hausdok


Sure would be nice if they'd just print the darned date and tonnage in plain English instead of encoding it.

OT - OF!!!


Nah, knowing this stuff makes us look smart.

That is why I carry half the meters and guages I do. ;)

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