Every tank and tankless water heater carries a label with its make, model, serial number, fuel type and ratings. On a tank it is usually a metal or foil plate on the side of the jacket, often near the controls. On a tankless unit it is commonly on the side or under the front cover area, and the manual will show where.
Copy the details below while the heater is working normally. If the label is behind straps or in a tight closet, a phone photo is fine, but write the key numbers down too in case the photo is lost.
Your heater's details
| Item | What to look for | Your heater |
|---|---|---|
| Brand | Manufacturer name on the label | ______ |
| Model number | Often labeled Model or M/N | ______ |
| Serial number | Often labeled Serial or S/N; may encode the manufacture date | ______ |
| Manufacture date | Printed date, or decoded from the serial using the maker's guide | ______ |
| Fuel | Natural gas, propane or electric | ______ |
| Capacity | Gallons for a tank | ______ |
| Input rating | BTU per hour for gas, watts and voltage for electric | ______ |
| First-hour rating or flow | On the EnergyGuide or spec label | ______ |
Reading the label safely
- Do not move the heater.Read the plate where it is. Never unstrap or shift a tank to see behind it.
- Keep clear of hot surfaces.The vent and flue area on a gas tank get hot. Stay at the side, not over the top.
- Use a light and a photo.A phone flashlight and a quick photo save time in a closet installation.
- Decode the date if needed.Many makers encode the year and month in the serial number. The manufacturer's site or a plumber can explain the format.
Label terms
- BTU/hr input
- How much gas a heater burns at full fire. Relevant to gas line sizing.
- First-hour rating
- Hot water a full tank can deliver in its first hour of use.
- Recovery rate
- How many gallons a tank can heat per hour at a stated temperature rise.
- Wattage
- Electric element rating, which together with voltage determines the circuit needed.
Also note
- Where the heater is: garage, hall closet, outdoor wall
- Whether it has two seismic straps
- Whether the gas and water connectors look flexible
- Any rust at the fittings or burner opening
- Date of the last flush or service, if known
Common questions
- I cannot read the label. What now?
- Photograph what you can and give the plumber the brand and any partial numbers. They can often identify the unit from those.
- Does the serial number really show the age?
- On many brands it does, in a code. The manufacturer's information or a plumber can decode it.
- Is the BTU rating important for a replacement?
- For gas heaters, yes. It affects whether the existing gas line and venting suit a new model.
General information for Fullerton, not a quote or professional advice. In an emergency, call 911.