HVAC Serial Number Decoder
Day & Night Serial Number Lookup
Find out exactly how old your Day & Night furnace, air conditioner, or heat pump is — and what size it is — in about 30 seconds. Then see what it costs to replace it factory-direct.
ICP brand — same as Heil / Tempstar / Comfortmaker
HVAC Decoder Hub › Day & Night
Decode your Day & Night in seconds
Day & Night is an ICP (Carrier) brand — Furnace Direct sells Day & Night coastal-grade equipment in Florida. It uses the standard ICP serial code.
Estimate only. Different eras used different formats — the definitive date is the MFG DATE stamped on the metal rating plate. Not sure? Call (888) 762-1334.
Day & Night serial number formats by era
HVAC makers change their date codes over the years. Match the start of your serial to the right row.
| Era | How the date is coded | Example |
|---|---|---|
| 2006–Present | 1st char = year letter, next 2 = week | T30… → week 30, 2021 |
Where to find the serial & model number
01
Find the rating plateA metal or foil label on the side of the outdoor condenser or inside the furnace cabinet door.
02
Read the serial (S/N)Use the format table above to turn it into a manufacture date.
03
Read the model (M/N)The model number tells you the size — see the tonnage guide below.
04
Know your optionsOver ~12–15 years old? Replacing usually beats repairing. We can price it.
Reading the Day & Night model number (size)
Almost every HVAC brand hides the tonnage in the model number as a 2–3 digit BTU code. N4A336GKA → 336 = 3-ton AC
| Model code | Size | Cooling capacity |
|---|---|---|
| 018 | 1.5 ton | 18,000 BTU |
| 024 | 2 ton | 24,000 BTU |
| 030 | 2.5 ton | 30,000 BTU |
| 036 | 3 ton | 36,000 BTU |
| 042 | 3.5 ton | 42,000 BTU |
| 048 | 4 ton | 48,000 BTU |
| 060 | 5 ton | 60,000 BTU |
1 ton = 12,000 BTU/hr. Gas furnaces instead show input BTUs (e.g. 060 = 60,000 BTU input).
Frequently asked questions
How old is too old for a Day & Night unit?
Furnaces typically last 15–20 years and ACs/heat pumps 12–15. Once yours is in that range and needs a major repair, replacing it factory-direct is usually the better spend.
Can I just replace the Day & Night unit myself and save?
Yes — that's exactly what Furnace Direct is built for. You buy the same Day & Night-class equipment at factory-direct pricing and hire any licensed installer, skipping the contractor's equipment markup. Call (888) 762-1334.
My serial number doesn't match any format above.
Older or imported units used other codes. The definitive answer is the plain-text manufacture date on the rating plate — text us a photo at (888) 762-1334 and we'll read it for you.
Does the model number tell me efficiency too?
Usually yes — a 2-digit SEER/SEER2 or AFUE number is embedded near the size code. N4A336GKA → 336 = 3-ton AC
Time to replace your Day & Night? Skip the markup.
Get the same equipment factory-direct and save 40–60% versus a contractor quote. No salesperson — just a price.
Call (888) 762-1334Serial/age estimates are provided as a convenience; the manufacturer's rating-plate date governs. All brand names are the property of their respective owners and are used for identification only.