This digital guide can be used with the printable checklist version of Pearl's Buyer Guide. If you are in the home and able to access the home's water heater, click here to access the checklist so you can write down key features of the water heater.
Two water heaters in the home?
Some homes have more than one unit — sometimes in different locations, sometimes serving different parts of the house. If the home has multiple water heaters, work through this guide once per unit.
In this guide:
In HubSpot, link each item below to the corresponding H3 anchor. See Manual Steps for how to set up anchors.
- Identify the water heater
- Find the nameplate
- Find the EnergyGuide label
- Check the other features
- Understand your SCORE
- Look at the connections. Electric units have thick electrical cables or conduit at the top or side. Gas, oil, and propane units have a pipe with a shutoff valve — the fuel supply line.
- Look for a flue. Electric units have no exhaust vent. A metal pipe leading up through the ceiling, or PVC pipes going out through the wall, means a combustion fuel: gas, oil, or propane.
- Check the nameplate. The label on the unit will often list the fuel type directly.
- Plain top, no extra components → standard electric storage water heater
- Large unit on top with a fan or air intake → heat pump water heater. It runs on electricity but pulls heat from the surrounding air — similar to how a refrigerator works, but in reverse. Heat pump water heaters are significantly taller than standard electric units.
- Brand — the manufacturer name (e.g., Rheem, Bradford White, A.O. Smith)
- Model number — used to look up specifications, UEF, and warranty details
- Serial number — used to determine the manufactured date (see below)
- Manufactured date — if listed separately from the serial number
- First four digits as year and week (e.g., 2318… → manufactured in week 18 of 2023)
- A letter followed by a two-digit year (e.g., F18… → manufactured in 2018; the letter encodes the month)
- Storage tank (electric or gas): 10–15 years
- Tankless: 15–20 years
- Heat pump: 10–15 years
- Pearl's Automated Virtual Assistant — call 800-888-8888. Have the manufacturer name and model number ready. We need both.
- AHRI Directory ahridirectory.org — search by manufacturer and model number.
- Smart thermostat compatibility — connects to a smart home system to schedule heating during off-peak hours, when electricity rates are lower
- Leak sensor — detects water at the base of the unit and can alert you before damage spreads
- Remote monitoring and app control — lets you adjust settings or check status from your phone
- Early life — typically full useful life remaining; standard maintenance applies
- Mid-life — plan ahead for replacement; watch for early signs of wear (corrosion, inconsistent temperatures, unusual sounds)
- Later life — replacement is likely in the near term; evaluate repair vs. replace carefully
Identify the water heater
Before you can evaluate a water heater, you need to know what type it is. The answers to these questions determine the fuel source, the vent setup, and which efficiency standards apply.
Storage tank or tankless?
The most visible difference is shape. A storage water heater is a large cylinder — usually 4 to 5 feet tall — standing on the floor. It heats water and keeps it hot until it is needed. A tankless water heater is a flat box mounted on a wall. It heats water on demand only. Both types can be electric or gas.
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Caption: A storage water heater holds heated water in a tank until it is needed. |
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Caption: A tankless water heater heats water on demand. There is no storage tank. |
What fuel does it use?
The clearest way to identify fuel type is to look for three things:
For tankless units, the same logic applies: electrical conduit only means electric; a gas supply pipe plus vent pipes means gas.
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Caption: Electric: no vent pipe. Look for electrical wiring or conduit at the top or side of the unit. |
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Caption: Combustion fuel: a vent pipe will be present — either a metal pipe going up or PVC pipes going out through the wall. |
Electric conduit vs. gas line
A flexible metal conduit on an electric water heater can look similar to a flexible gas supply line. When in doubt, look for the vent pipe — that is the clearest indicator of a combustion fuel system. Electric units have no vent.
Electric — standard or heat pump?
If there is no vent pipe, look at the top of the unit.
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Caption: Standard electric storage water heater — no extra components on top. |
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Caption: The heat pump unit sits on top. It is taller than a standard electric water heater. |
Combustion — what type of vent?
If the unit uses gas, oil, or propane, the next step is to identify the vent type. Vent type affects how combustion gases leave the home — and how safely.
Typical. Hot combustion gases rise naturally through a metal flue pipe and exit through the roof or an exterior wall. This is the most common setup in older homes.
Power vent. A fan pushes combustion gases through a horizontal vent pipe to the outside. The exhaust pipe is usually smaller-diameter metal.
Sealed combustion. The burner draws outside air through a dedicated intake pipe, and exhaust exits through a separate pipe. The home's air is never used in the combustion process. This is the safest type.
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Caption: Typical: metal flue pipe going straight up through the ceiling or out through the wall. |
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Caption: Power vent: a fan and horizontal vent pipe, usually exiting through a side wall. |
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Caption: Sealed combustion: two pipes — one intake, one exhaust — both going outside. |
Not sure what you're looking at?
Some setups are more complex — including water heaters connected to a boiler, a ground-source heat pump, or solar collectors. A tankless water heater can also look similar to a wall-mounted boiler. If the piping looks unusual or you can't identify the type, ask your home inspector. You can also contact our team for help. [ADD LINK TO CORE SUPPORT]
Find the nameplate
The nameplate is a label affixed directly to the unit. It has the information you need to determine age, look up efficiency, and check warranty status.
Where to find it
On a storage tank, look on the upper third of the tank — usually at eye level or just below. On a tankless unit, it may be on the front, inside a panel door, or on the back of the unit.
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Caption: The nameplate is usually on the upper portion of the unit. It includes brand, model number, serial number, and often a manufactured date. |
What to record
Four fields matter most:
How to decode a serial number
Most manufacturers encode the date of manufacture in the first few characters of the serial number. The format varies by brand. Common patterns include:
Pearl's digital guide includes a decoder for major brands. If the serial number alone isn't enough, the model number lookup through the Automated Virtual Assistant (see the EnergyGuide section below) can also return the manufactured date.
Estimating lifespan
System life varies by type, water quality, and maintenance history. Typical ranges:
These are general ranges. A unit with documented annual maintenance may reasonably exceed them. A unit in a hard-water area with no maintenance history may fall short.
Find the EnergyGuide label
The EnergyGuide label is a large yellow label required on most new water heaters sold in the United States. It shows the unit's estimated annual energy cost and efficiency rating.
Where to find it
On storage tanks, look on the front or side. On older units or units installed in tight spaces, the label may have been removed or covered. That's not a problem — the model number from the nameplate is all you need to look up the rating.
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Caption: The EnergyGuide label shows estimated annual energy cost and the UEF rating. It is usually yellow and prominently placed. |
What is UEF?
UEF stands for Uniform Energy Factor. It is the U.S. standard for measuring water heater efficiency. A higher UEF means the unit produces more hot water per unit of energy it consumes. A heat pump water heater with a UEF of 3.5 uses about 70% less energy than a standard electric unit with a UEF of 0.95 — often a difference of hundreds of dollars per year.
How to interpret your UEF
UEF thresholds differ for electric and combustion systems because the energy sources are not directly comparable. Use the table below to find your rating:
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Typical |
Good |
Very Good |
Excellent |
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⚡ Electric |
< 1.0 |
1.0–2.0 |
2.0–3.2 |
3.2+ |
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🔥 Gas / Oil / Propane |
< 0.58 |
0.58–0.69 |
0.70–0.87 |
0.88+ |
What if there's no label?
You can look up UEF by model number. Two options:
Need help finding UEF?
Call Pearl's Automated Virtual Assistant: 800-888-8888. Have the manufacturer name and model number ready — we need both.
Check the other features
Beyond type and efficiency, a few other characteristics affect the Pearl SCORE and the system's overall value to the household.
ENERGY STAR certification
ENERGY STAR is a voluntary certification program run by the EPA. For water heaters, it marks units that significantly exceed federal minimum efficiency standards. Heat pump water heaters almost universally qualify. Most standard electric and conventional gas tank units do not.
Look for the ENERGY STAR label on the unit itself. If it's not visible, search the model number at
Look for the ENERGY STAR label on the unit itself. You can also verify at energystar.gov using the model number.
Is the tank firmly strapped?
A storage tank that is firmly strapped to a wall stud or masonry surface can resist tipping in earthquakes and flooding events. An unstrapped tank can fall, rupture supply lines, and cause significant water and structural damage.
Look for metal straps or brackets securing the tank — typically in two places: upper third and lower third. Strapping is required by code in seismic zones (including all of California) and is good practice everywhere.
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📷 FPO: FPO_tank-strapping.png Caption: Metal straps secure the tank to the wall at the upper and lower thirds. Both straps should be present and tight. |
Installation date
The installation date is different from the manufactured date. A unit may have been built in 2018 but installed in 2021. The installation date is what starts the warranty clock and the useful life estimate.
Installation date is most reliably found in seller documents: the purchase receipt, warranty registration card, or service records. Ask the seller for these documents before the inspection. If none are available, the manufactured date is a reasonable fallback.
Smart and connected features
Some newer water heaters include features that can reduce operating costs over time:
These features don't change the UEF rating, but they can meaningfully reduce long-term energy costs for households that use them.
Understand your SCORE
Pearl evaluates water heaters across five dimensions. Here's what each one measures and how to read your results.
S — Safety
Safety reflects the risk of combustion gas exposure based on vent type. Electric systems have no combustion process, so they carry the lowest risk. For combustion systems, the vent type determines how reliably exhaust gases are kept out of the home.
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Vent type |
Safety rating |
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Electric (no combustion) |
Excellent |
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Sealed combustion |
Very Good |
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Power vent |
Good |
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Typical flue |
Typical |
O — Operating Cost
Operating cost reflects how efficiently the system produces hot water, as measured by UEF. The higher the UEF, the less energy the unit consumes for the same output.
A heat pump water heater with a UEF of 3.5 uses roughly 70% less energy than a standard electric unit with a UEF of 0.95. Over a 10-year period, that difference often represents $3,000–$5,000 in utility costs, depending on electricity rates and usage.
Use the table in the EnergyGuide section above to look up your operating cost rating.
R — Resilience
Resilience reflects how well the system is protected from physical hazards. Two factors matter:
Strapping — a tank firmly strapped to the wall resists tipping in earthquakes and flooding events. This is the single most effective physical protection measure for a storage water heater.
Elevation — in flood-prone areas, raising the unit above the base flood elevation (BFE) prevents water damage during a flood event and may be required by local building code. Even outside flood zones, a unit elevated above floor level has a practical buffer against minor water intrusion.
E — Energy
Energy reflects whether the system is optimized for efficient operation. ENERGY STAR certification and smart control features are the key indicators.
A certified heat pump water heater with smart scheduling can shift water heating to off-peak hours — reducing both operating costs and grid demand. This is especially valuable in households on time-of-use electricity rates, where the price difference between peak and off-peak hours can be substantial.
Age
Age isn't a performance score — it's context. A system in its early life is a different proposition than one approaching the end of its expected lifespan, even if both have the same UEF.
Determine age by installation date if available. If not, use manufactured date.
Maintenance records matter here. A well-maintained system in later life may outlast an identical unit with no maintenance history.