Top pick: the Rheem PROE40 T2, a 40-gallon tall tank with a 55-gallon first-hour rating. Big family? The Bradford White RE350S6 gives 60. Under 3 feet of space? Get the Rheem PROE47 S2. Have gas? Read gas vs electric.
Top pick: Rheem PROE40 T2$735.99 at AmazonPrice as of Oct 24, 2026, 5:30 AM EDT · low stock then
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.com at the time of purchase will apply to the purchase of this product.
Rheem PROE40 T2: the 40-gallon tall tank I’d pick
Best for a 40-gallon tall swap
Rheem PROE40 T2
Rheem Professional Classic PROE40 T2 RH95 40-gallon tall electric water heater, 240 V, two 4,500 W elements
55-gallon first-hour rating, the best of the 40-gallon tanks here
0.93 UEF, the top of Rheem’s electric range
Narrowest pick at 19-1/4 in. across
EverKleen diffuser and T&P valve come with it
Cons
Tallest pick: 63-5/8 in. to the top of the fittings
6-year tank warranty, not 10
Sold by a third-party seller on Amazon
40 gal (36 rated)55 gal first hour0.93 UEF63-5/8 in. to fittings19-1/4 in. wide
Buy it if
You’re replacing a 40-gallon tall electric tank in a closet or garage with room above it, for one to a few people.
Skip it if
Your space is under about 64 in. to the ceiling or shelf above. The Bradford White RE340T6 is an inch shorter.
The Rheem PROE40 T2 is my top pick because it’s the tank most houses already have. A 40-gallon tall electric is the common swap, and this one gets the most out of that size of anything here. Rheem’s spec sheet lists a 55-gallon first-hour rating, 2 gallons more than the Bradford White in the same size.
First-hour rating is the number to shop by. It’s how much hot water a full tank delivers in an hour under DOE’s test, counting the stored water and what the elements heat while you draw. It beats tank size as a guide, because two 40-gallon tanks can differ by several gallons.
It’s also the most efficient tank here, tied with its short sibling. Rheem lists a 0.93 UEF, the top of its 0.90 to 0.93 electric range. That’s the federal efficiency measure, and on an electric tank it mostly reflects how well the tank holds its heat.
It’s tall and slim. Rheem gives a 60-3/4 in. tank and 63-5/8 in. to the top of the water fittings, on a 19-1/4 in. diameter. That narrow body helps in tight closets and through doorways, but it needs more headroom than any other pick. Measure before you order.
The parts list is the Professional Classic standard: resistored stainless steel elements, a premium anode, a brass drain valve and an EverKleen helix diffuser that Rheem says cuts sediment. The T&P relief valve is in the box. Rheem covers the tank and parts for 6 years.
The Amazon listing’s part number matches Rheem’s, PROE40 T2 RH95, and its bullets repeat Rheem’s 55-gallon and 0.93 figures. It ships from a third-party seller, so keep your receipt with the install date. I’ve used this tank, and it’s the one I’d reach for first in a standard 40-gallon spot.
Will it fit your space and your breaker?
Enter the height you have, the narrowest opening on the way in and your water heater breaker. The checker tests all four picks.
Why measure to the top of the fittings? The cold inlet and hot outlet stick up out of the tank top, and the supply lines bend away from them. Rheem lists 63-5/8 in. to the fittings on a 60-3/4 in. tank. That extra 3 in. is where a tight closet fails, so leave room above for the connectors too.
The breaker part is simple math. Each pick runs two 4,500-watt elements, one at a time, on 240 volts. 4,500 ÷ 240 is 18.75 amps, and NEC 422.13 asks for a circuit rated at 125% of that. The rating plate on the tank and your local inspector have the final word.
Bradford White RE350S6: most first-hour water
Best for the most first-hour hot water
Bradford White RE350S6
1NCWW 50-gallon electric water heater, 240 V, two 4,500 W elements
47-3/16 in. tall, so it fits where a tall 50 won’t
Hydrojet sediment system and Microban tank lining
Made in the USA, per the listing
Cons
24 in. across, so check the door and the drain pan
0.92 UEF, a step under the Rheems
Heaviest of the 40 and 50-gallon picks at 144 lb shipping
50 gal (45 rated)60 gal first hour0.92 UEF49-7/16 in. to fittings24 in. wide
Buy it if
Three or more people shower back to back in the morning, and you have a spot about 50 in. tall and 24 in. wide.
Skip it if
The tank has to pass a 24 in. doorway or sit in a 22 in. pan. Go with a 40-gallon tall tank instead.
The Bradford White RE350S6 is the pick for a busy morning. Bradford White’s spec sheet lists a 60-gallon first-hour rating, the highest of the four, from a 50-gallon tank. If two showers and a load of laundry run in the same hour at your house, this is the one.
It’s a 50 in a shorter body. Bradford White gives 47-3/16 in. to the top of the tank and 49-7/16 in. to the water connections. That’s about 14 in. less than the tall 40s, so it fits under a shelf or in a basement corner where a tall 50 wouldn’t.
The trade is width. The jacket is 24 in. across, nearly 5 in. wider than the Rheem 40. Measure the narrowest door it has to pass and the drain pan it will sit in. A 24 in. tank needs a pan made for that size; our drain pan guide lists them by inside diameter.
Bradford White calls its Hydrojet system a sediment-reducing device that also raises first-hour delivery. The tank is lined with Vitraglas with Microban, and the thermostat has a manual-reset high limit. The T&P valve comes installed.
Efficiency is 0.92 UEF, one step under the Rheems. On an electric tank that small gap is mostly standby loss, so it costs it 2 points on that check in my score. The listing’s model number, RE350S6-1NCWW, matches Bradford White’s sheet, and the listing says it’s made in the USA.
Bradford White’s warranty is 6 years on the tank (the 6 in the model number) and 6 on parts. It runs from the install date, or 3 months after manufacture if you can’t prove the install, so keep the receipt. I’ve used this tank, and it’s my pick when a family keeps running out.
Rheem PROE47 S2: a short tank for low spaces
Best for spaces under 3 feet tall
Rheem PROE47 S2
Rheem Professional Classic PROE47 S2 RH95 47-gallon short electric water heater, 240 V, two 4,500 W elements
54-gallon first-hour rating, close to the tall 40s
0.93 UEF, tied for the best here
Rheem lists it as compliant with HUD standards for manufactured housing
Cons
Widest pick at 26-1/4 in.
Heaviest at 149 lb shipping
Only 11 left at our read, from a third-party seller
47 gal (43 rated)54 gal first hour0.93 UEF34 in. to fittings26-1/4 in. wide
Buy it if
The tank sits under a counter, in a crawl space or in a low closet, and a tall tank won’t stand up.
Skip it if
The way in is a 24 in. door or the space is a narrow closet. A tall tank is the better fit.
The Rheem PROE47 S2 is for the spaces a tall tank can’t stand up in. Rheem’s sheet gives a 32 in. tank and 34 in. to the top of the fittings. That’s about half the height of the tall 40s, so it slides under a counter, a low stair or a crawl space ceiling.
It doesn’t give up much hot water to get there. Rheem lists a 54-gallon first-hour rating, 1 gallon under the tall PROE40 T2. Most short 40s carry less. Rheem’s own short 38 rates 51, and Bradford White’s short RE340S6 rates 49.
What it gives up is floor space. It’s 26-1/4 in. across, the widest tank here, and it ships at 149 lb. Check the door, the stairs and the path before you buy, and plan on two people for the carry. A water heater dolly helps on steps.
Efficiency ties for the best here at 0.93 UEF. The rest of the build matches the PROE40 T2: resistored stainless steel elements, a premium anode, an EverKleen diffuser and a brass drain valve. Rheem says its Professional Classic tanks meet HUD standards for manufactured and modular homes.
Its score is nearly the same as the PROE40 T2’s: 8.5 against 8.6. The only gap is 1 gallon of first-hour rating; every other check ties. Pick between them on the shape of your space, not the score.
The listing’s part number matches Rheem’s, PROE47 S2 RH95, and it lists the T&P valve as included. Stock was down to 11 at our read, from a third-party seller. If it runs out, the card stays and the price hides until it’s back. I’ve used this tank, and it’s my answer for low spots.
Bradford White RE340T6: a tall 40 that’s an inch shorter
Best for a tall closet with less headroom
Bradford White RE340T6
1NCWW 40-gallon tall electric water heater, 240 V, two 4,500 W elements
62-7/16 in. to the fittings, about an inch under the Rheem 40
20 in. across, slim enough for most closets
Hydrojet sediment system and Microban lining
Made in the USA, per the listing
Cons
53-gallon first-hour rating, lowest of the four
0.92 UEF
Amazon listing has only four short bullets
40 gal (36 rated)53 gal first hour0.92 UEF62-7/16 in. to fittings20 in. wide
Buy it if
You want a tall 40 and the Rheem’s 63-5/8 in. to the fittings is just too much for the shelf or ceiling above.
Skip it if
You have the headroom. The Rheem PROE40 T2 gives 2 more gallons in the first hour and a better UEF.
The Bradford White RE340T6 is the other tall 40, and it earns its spot on height. Bradford White lists 60-3/16 in. to the top of the tank and 62-7/16 in. to the water connections. That’s 1-3/16 in. under the Rheem PROE40 T2, which can decide a closet with a shelf above the old tank.
It’s 20 in. across, 3/4 in. wider than the Rheem, and it ships at 125 lb. Both fit a standard closet doorway. The checker above tells you whether either clears your space, and by how much.
On paper it trails the Rheem a little. Bradford White’s sheet lists a 53-gallon first-hour rating and a 0.92 UEF, against 55 and 0.93. That’s why it scores 8.1 to the Rheem’s 8.6. In a house of one to three people, 2 gallons in the first hour rarely shows.
The build is Bradford White’s standard electric: Vitraglas lining with Microban, a Hydrojet sediment system, screw-in elements, a magnesium anode, heat traps on the connections and a manual-reset high limit. The T&P valve comes installed. Elements run one at a time, the usual non-simultaneous wiring.
Its model number on Amazon, RE340T6-1NCWW, matches Bradford White’s sheet. The listing is bare, with four short bullets, but they agree with the maker: 4,500-watt elements, non-simultaneous, magnesium anode, made in the USA. It ships from a third-party seller, so check the model on the label when it arrives.
The tank carries 6 years and the parts 6, and Bradford White excludes leaks from a closed system with no way to handle thermal expansion. If your house has a check valve or pressure reducer, add an expansion tank. I’ve used this tank; it’s my pick when the Rheem is an inch too tall.
All four run on 240 volts with two 4,500-watt elements, have 3/4 in. water connections, and carry 6-year tank and parts warranties. Heights are to the top of the water fittings, from each maker’s spec sheet.
What first-hour rating do you need?
Tank size on the label isn’t the hot water you get. The first-hour rating is the better guide.
First-hour ratings in US gallons, from Rheem form PROE RH N Rev. 16 and Bradford White spec 1201-0926. Bradford White says its figures follow the AHRI directory.
The first-hour rating is how much hot water the tank can deliver in one busy hour, starting full. DOE’s test draws water until the outlet temperature drops, then counts what the elements add while it keeps going. It’s printed on the yellow EnergyGuide label and in the maker’s spec sheet.
To size by it, think about your busiest hour, usually the morning. Count the showers that run back to back, plus any laundry or dishwasher load in the same hour. The tank’s first-hour rating should cover that hour. Our water heater size calculator walks through the count.
Shower flow sets most of the total. Federal rules cap new shower heads at 2.5 gallons a minute, so a 10-minute shower can use up to 25 gallons of mixed hot and cold water. Only part of that comes from the tank, but it shows why three long showers in a row can empty a 40.
53 to 55 gallons in the first hour
The tall 40s and the short 47. Fine for one to three people who stagger showers.
60 gallons in the first hour
The Bradford White RE350S6. For back-to-back showers or a big tub.
Your busiest hour tops 60 gallons
Look at a heat pump or a tankless setup instead; see the section on other types below.
Tall, short and wide: matching the tank to the space
The same gallons come in different shapes. Your space decides which one fits.
The four picks drawn to the same scale from the makers’ dimensions. Height is to the top of the water fittings.
Rheem and Bradford White each make the same gallons in tall, medium and short bodies. Tall tanks are slim and go in closets. Short tanks, sometimes called lowboys, go under stairs and counters, and pay for it in width. A short 47 is 26-1/4 in. across; a tall 40 is under 20.
Measure three things before you shop: the height to whatever sits above the tank, the narrowest door or hallway on the way in, and the drain pan or floor space it stands in. Write them down next to the old tank’s model number. That old number tells you its shape too.
Shape
Pick
Tank height
To fittings
Width
Shipping weight
Tall
Rheem PROE40 T2
60-3/4 in.
63-5/8 in.
19-1/4 in.
109 lb
Tall
Bradford White RE340T6
60-3/16 in.
62-7/16 in.
20 in.
125 lb
Medium height, wide
Bradford White RE350S6
47-3/16 in.
49-7/16 in.
24 in.
144 lb
Short
Rheem PROE47 S2
32 in.
34 in.
26-1/4 in.
149 lb
40 vs 50 gallons: why the tank holds less than the label
The size in the name is a nominal size. The makers list a smaller rated volume.
Pick
Name says
Rated storage
First hour
Rheem PROE40 T2
40 gal
36 gal
55 gal
Bradford White RE340T6
40 gal
36 gal
53 gal
Rheem PROE47 S2
47 gal
43 gal
54 gal
Bradford White RE350S6
50 gal
45 gal
60 gal
Both makers list two sizes: the nominal one in the model name and a smaller rated storage volume. Bradford White calls the second one DOE rated storage volume. A 40-gallon tank is rated at 36 and a 50 at 45, so don’t be surprised when the numbers don’t match.
It also shows why first-hour rating matters more than gallons. The short Rheem PROE47 S2 holds 7 gallons more than the tall 40s but rates 54 in the first hour, between them. Pick by the first-hour figure your busiest hour needs, then by shape.
If you’re torn between a 40 and a 50, a 50 like the RE350S6 adds 5 to 7 gallons of first-hour water over the 40s here. The cost is space: it’s 4 in. wider than the tall 40s, and it weighs about 20 lb more.
Breaker, wire and 240 volts
Every pick is a 240-volt tank with two 4,500-watt elements that take turns.
All four are wired from the factory for non-simultaneous operation. That means the upper and lower elements never run at once, so the tank draws one element’s current: 4,500 watts at 240 volts, 18.75 amps. Rheem’s spec sheet works its recovery from that, 21 gallons an hour at a 90°F rise.
NEC 422.13 treats a storage water heater of 120 gallons or less as needing a circuit rated at 125% of its nameplate. For these tanks that’s 23.4 amps, so the circuit has to be at least that, with wire to match. The tank’s rating plate lists its own limits, and they rule.
If you’re replacing a 4,500-watt tank like for like, the circuit is usually already right. Check before you swap to one with bigger elements; our 4,500 vs 5,500 watt element guide covers that. On 208-volt service, see 240 V vs 208 V elements.
Item
Value for these picks
Where it comes from
Element wattage
4,500 W upper and lower
Rheem and Bradford White spec sheets
Current, one element
18.75 A at 240 V
4,500 ÷ 240
Circuit needed
23.4 A or more
NEC 422.13, 125% of nameplate
Recovery at 90°F rise
21 gal an hour
Rheem spec sheet (4,500 ÷ 2.42 ÷ 90)
Water connections
3/4 in. NPT
Both spec sheets
Efficiency: what UEF tells you on an electric tank
Electric resistance tanks sit in a narrow band. Heat pumps are in another league.
UEF, the uniform energy factor, is DOE’s efficiency number for water heaters. Rheem lists 0.90 to 0.93 across its Professional Classic electric line, and both Rheems here are 0.93. Bradford White’s two are 0.92. Higher is better, but the spread among standard electric tanks is small.
That’s because an element turns nearly all of its electricity into heat. What a standard electric tank loses is standby heat through the jacket and pipes, so better insulation and heat traps move the number. Both makers fit heat traps or isolated tank designs for that reason.
A heat pump water heater is the real jump. Rinnai’s REHP50 heat pump listing gives 3.75 UEF for a 50-gallon tank, about four times a standard tank. It costs more and needs room and air around it. See our heat pump water heater picks if your space allows one.
Warranty fine print that decides a claim
All four carry 6 years on the tank and 6 on parts. The details are in the certificate.
Bradford White’s certificate starts the clock at the install date. Without proof of installation, it runs from 3 months after the date of manufacture. Keep the receipt or the plumber’s invoice with the tank. Its tank years are in the model number: the T6 in RE340T6 means a 6-year tank.
The exclusions matter more than the years. Bradford White won’t cover a leak from an install that breaks local code, lacks a certified T&P valve, or sits on a closed system without thermal expansion control. Sediment and lime buildup are excluded too, and so is labor.
Rheem’s product page lists 6 years on the tank and 6 on parts in the US, and says its ProtectionPlus plan turns the tank coverage into 10 years. Use outside a single-family home cuts Bradford White’s terms to 1 year, so a rental duplex or shop isn’t covered the same way.
Keep
The receipt, the install date, and the model and serial numbers from the rating plate.
Add if needed
An expansion tank on a closed system, and a T&P discharge line run as the manual says.
Not covered
Labor, delivery, permits, sediment and lime, and leaks from code-breaking installs.
Not electric? Where to look instead
This page scores only 240-volt electric tanks, so one formula is fair to all four. Other types have their own guides.
A tank this size is a two-person job with power, water and code rules. Most people hire a licensed plumber.
1
Shut off power and water
Turn the breaker off and test the wires at the junction box before you touch them.
2
Drain the old tank
Hose from the drain valve to a floor drain or outside. It’s hot water if the tank was running.
3
Check the drain pan
Set the new tank in a pan sized for its diameter, piped to a drain where your code asks for it.
4
Connect the water
3/4 in. connections on both picks’ brands. Cold to the inlet, hot to the outlet, as marked.
5
Fit the T&P line
Run the relief valve discharge pipe down to within a few inches of the floor or a drain, as the manual says.
6
Fill before power
Open a hot faucet until water runs steady. Powering an empty tank burns out the upper element.
7
Set and check
Restore power, set the thermostat, then check for leaks and that the elements cycle.
The fill-before-power step is the one that costs people an element. A dry element burns out in seconds, and the upper one heats first. If it happens, our element replacement guide covers the fix. Many areas also need a permit for a water heater swap.
If your house has a pressure-reducing valve, a check valve or a backflow preventer at the meter, the plumbing is closed. Hot water expands with nowhere to go, and Bradford White excludes damage from a closed system without thermal expansion control. An expansion tank on the cold line solves it.
Water heater buying mistakes to avoid
Mistake
Why it matters
What to do
Buying by gallons alone
Two 40s can differ by several gallons in the first hour
Compare first-hour ratings
Measuring to the tank top
The fittings add about 2 to 3 in.
Use the height to the fittings
Forgetting the doorway
A 26-1/4 in. short tank won’t pass a 24 in. door
Measure the narrowest opening
Reusing an undersized breaker
4,500 W elements need a 23.4 A circuit
Check the breaker and wire size
Powering an empty tank
The upper element burns out dry
Fill and bleed before power
No receipt with the install date
Bradford White falls back to 3 months after manufacture
Keep the invoice with the tank
Closed system, no expansion tank
Bradford White excludes that damage
Add an expansion tank
How the spec score works
The spec score, check by check
It rewards first-hour hot water most, then efficiency and warranty, then the parts that keep a tank going. Every figure comes from the Rheem and Bradford White spec sheets and warranty terms, checked against the Amazon listing. It’s my score from those documents, not a customer rating or a lab test.
Price, shape and brand aren’t checks. All four tie on warranty, sediment device, T&P valve and listing match, so first-hour rating and UEF decide the order. That’s why the Rheem 40 lands at 8.6, the Rheem 47 at 8.5, the Bradford White 50 at 8.4 and the Bradford White 40 at 8.1.
(UEF − 0.88) × 200, from 0 to 10: 0.93 scores 10, 0.92 scores 8
Tank warranty (15%)
Years ÷ 10 × 10
Parts warranty (10%)
Years ÷ 10 × 10
Sediment device (10%)
10 when the maker fits a sediment-reducing inlet (EverKleen, Hydrojet)
T&P valve included (5%)
10 when the relief valve comes with the tank
Listing matches maker (10%)
10 when the Amazon model number matches the maker’s sheet
Total
Weighted sum, to one decimal
Tank
First hour
UEF
Tank
Parts
Sediment
T&P
Listing
Score
Rheem PROE40 T2
8.5
10.0
6.0
6.0
10.0
10.0
10.0
8.6
Rheem PROE47 S2
8.3
10.0
6.0
6.0
10.0
10.0
10.0
8.5
Bradford White RE350S6
9.2
8.0
6.0
6.0
10.0
10.0
10.0
8.4
Bradford White RE340T6
8.2
8.0
6.0
6.0
10.0
10.0
10.0
8.1
Tanks I checked and left out
Tank
Score
What held it back
What it does well
Rheem PROE50 M2 RH95
8.9
Amazon showed 1 to 2 months to ship at our read
62 gal first hour from a 48 in. body
Bradford White RE340S6
7.5
49 gal first hour and 0.91 UEF, below the picks; third-party seller
A short 40 at 47-3/16 in.
Rheem PROE30 T2 RH95
Left out before scoring
Unavailable on Amazon at our read
Slim 30-gallon tall tank
Rheem PROE38 S2 RH95 B
Left out before scoring
One left in stock at our read
Short 38, 51 gal first hour
Water heater questions
What is the best water heater for a home?
For a standard electric swap, the Rheem PROE40 T2. It’s a 40-gallon tall tank with a 55-gallon first-hour rating and a 0.93 UEF. If you have gas at the heater, compare fuels first on our gas vs electric page.
What water heater do plumbers recommend?
Plumbers usually stick with the pro lines from big makers, like Rheem Professional Classic and Bradford White, because parts are easy to find. I’ve used all four tanks here. Pick by first-hour rating and how the tank fits your space.
Is Rheem or Bradford White better?
Neither wins across the board. In these four, the Rheems score higher on efficiency (0.93 vs 0.92 UEF), and the Bradford White 50 has the highest first-hour rating. Our Rheem vs Bradford White page compares more models.
Is A.O. Smith or Rheem better?
This page doesn’t score A.O. Smith because no A.O. Smith electric tank was in stock new on Amazon at our read. Our A.O. Smith vs Rheem page compares the two brands by model.
What size water heater do I need?
Size by the first-hour rating, not the gallons. Add up your busiest hour of hot water use and pick a tank whose first-hour rating covers it. The picks here range from 53 to 60 gallons in the first hour.
Is a 40 or 50 gallon water heater better?
A 50 gives more hot water in a busy hour. The Bradford White RE350S6 rates 60 gallons against 53 to 55 for the tall 40s. It’s 4 in. wider and heavier, so check your space first.
What breaker does a 4,500 watt water heater need?
Two 4,500-watt elements that take turns draw 18.75 amps at 240 volts. NEC 422.13 asks for a circuit rated at 125% of that, 23.4 amps, with wire to match. The tank’s rating plate lists its own limits.
How long does an electric water heater last?
The makers don’t promise a life span. They warrant the tank, and all four picks carry 6 years on the tank and 6 on parts. Draining sediment and checking the anode help it go past that.
Can I install a water heater myself?
Many areas need a permit, and the job includes 240-volt wiring, a T&P discharge line and sometimes an expansion tank. Bradford White won’t cover a leak from an install that breaks local code. Most people hire a licensed plumber.
How I pick and why you can trust it
Why trust me
I’m Isaac Daniels, a licensed journeyman plumber in Georgia. I’ve used each of these tanks. These picks come from what Rheem and Bradford White publish, read the same day, sorted by the space and the busiest hour they suit.
How I pick
Only 240-volt electric storage tanks, so one score is fair to all four.
First-hour ratings, UEF, sizes and features from each maker’s spec sheet; warranty terms from the maker’s page and certificate.
Every pick is new, genuine and in stock at our read, with a model number that matches the maker.
The spec score uses the seven checks above, the same for every tank.
The breaker math follows NEC 422.13; your rating plate and inspector decide.
Prices come from Amazon’s API with the time they were read.
Sources
Rheem, Professional Classic residential electric water heaters specification, form PROE RH N Rev. 16 (05/24): files.myrheem.com, read Oct 22, 2026.
Rheem, Professional Classic Series Standard Electric PROE40 T2 RH95 product page (warranty, ProtectionPlus): rheem.com, read Oct 22, 2026.
Bradford White, Upright Electric Residential Water Heater specification 1201-0926: docs.bradfordwhite.com, read Oct 22, 2026.
Bradford White, Limited Residential Water Heater Warranty 238-39699-00ZAN (03/25): read Oct 22, 2026.
U.S. Department of Energy, 10 CFR 430 Subpart B Appendix E, uniform test method for water heaters (first-hour rating): eCFR, read Oct 22, 2026.
U.S. Department of Energy, 10 CFR 430.32(p), shower head maximum flow of 2.5 gallons per minute: eCFR, read Oct 22, 2026.
NFPA 70, National Electrical Code, section 422.13, as explained in EC&M, “Code Q&A: Electrical Requirements for Water Heaters”: read Oct 22, 2026.
Rinnai REHP50 heat pump water heater Amazon listing (3.75 UEF): read through Amazon’s product data, Oct 22, 2026.
Brand-written Amazon listing text and item data for B0CBLB8SJY, B07YZS6L2R, B01N9OQNP5, B01EISVSFA and the left-out tanks: read through Amazon’s product data, Oct 22, 2026.
U.S. CPSC recall database search for water heaters: saferproducts.gov, Oct 22, 2026 (no recalls for these models).
Google results for “best water heater” and “best electric water heater”: seen Oct 22, 2026. Search volumes from Semrush, Oct 22, 2026.
