Ruud 88H40*
0.81 UEF DOE CCD · 2026-09-19No A–G grade: Fewer than 8 models share this heater type, fuel and draw pattern, too few for a fair A-G scale.
A short tank built to sit under a counter, low draw pattern (a one- or two-person household).
You are checking a Ruud 88H40* against its registry entry. At the low draw pattern, the standard daily hot-water usage DOE tests against, it uses 2,771 kWh of electricity a year. This site calculates that figure, and no class median comparison is shown because too few models share the class.
Energy use per year
2,771 kWh a year
Computed by this site from the registry's UEF and the federal test's daily hot-water draw for this draw pattern. What it costs depends on the electricity rate where you live.
Not published: Class comparison
Too few models share this heater type and draw pattern for a fair class median, so no comparison is shown.
The yearly energy figure above stands on its own and does not depend on the class.
What it costs to run where you live
What the registry files
- UEF (Uniform Energy Factor) how much hot water you get for each unit of energy the heater uses
- 0.81 DOE CCD · 2026-09-19 Compared only with other models registered as a short tank built to sit under a counter at the low draw pattern.
- Draw Pattern the standard daily usage profile DOE tests the unit against
- Low DOE CCD · 2026-09-19
- First Hour Rating how many gallons of hot water the unit can deliver in one hour, starting from a full tank
- 50 gal DOE CCD · 2026-09-19
- Rated Storage Volume the tank size in gallons
- 36 gal DOE CCD · 2026-09-19
What it costs to install
Not published: Installed cost range
This model's UEF lies outside the range NLR REMDB's cost model was fitted on, and the range is not stretched past it.
The annual energy figure on this page does not depend on this range and is unaffected.
Safety record
No CPSC recall names this model.
Checked against the CPSC recall database. CPSC does not publish a model-level match for this product category, so this list is curated by hand from the manufacturer's recall filings.
CPSC · 2026-09-24What these figures mean
How this compares
The closest models in the same class — same fuel, type and draw pattern.
Keep going
How every figure on this page is calculated
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Find what replaces your water heater
Enter the model number off your old unit and see what is on file today, with the yearly cost difference.
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What a water heater costs to run
Prices a unit's efficiency against your own utility's filed tariff for your ZIP code.
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Is a 40-gallon water heater enough?
Answered from what models in this size actually file.
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Water heaters
Every model on file with the Department of Energy, by heater type.
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Every Ruud model on file
What this brand files, by heater type.
UEF 0.81 Price it on your ZIP
The figure of 2,771 kWh is electricity use per year for the Ruud 88H40*, a short tank built to sit under a counter. It applies only to the low draw pattern, which represents a one- or two-person household. This site computed it, not the registry, from the registry's UEF and the DOE test's daily hot-water draw for that pattern. UEF, the ratio of hot water delivered to energy used, is listed as 0.81 for this model. The source is DOE CCD, retrieved 2026-09-19. A different draw pattern or a different daily use would give a different annual figure, and this page does not calculate one.
The rated volume is 36 gallons. The first hour rating, the gallons of hot water available in the first hour from a full tank, is 50 gallons. Together with the low draw pattern, these ratings match a one- or two-person household with modest hot-water demand. They do not show that the unit meets the demand of a larger household, and the 2,771 kWh figure would not describe that use. Readers who want to filter by fuel, space and size can use the water heater selector. As noted above, no class median or rank is available for this model, so the page makes no claim about how it compares with similar units.
Running cost is not stated in the text because it depends on your own utility electricity tariff. Multiply 2,771 kWh by your rate per kilowatt-hour to get the yearly cost at the low draw pattern, or enter your ZIP in the cost calculator to have it done for you. The steps behind that calculation are described in how the annual cost is calculated. An installed price range is not published for 88H40*. Its ratings, including the 36 gallon rated volume and the 50 gallon first hour rating, lie outside the range the cost database's model was fitted on, and that range is not stretched past its limit.
DOE CCD · 2026-09-19