Water heaters
Heat pump water heater installation: what to check on site and how to quote it
Heat pump water heaters are coming whether customers ask or not: a DOE standard requires heat pump technology for most electric tanks from 2029. Here is what the manufacturers require for space, air, condensate and power, what changed with the tax credit and rebates, and how to price the job.
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A heat pump water heater (HPWH, also sold as a "hybrid") moves heat from the surrounding air into the tank instead of making it with an element. It also asks more of the install site than a standard tank: enough air, somewhere for condensate to go, the right circuit, and room for a taller, heavier unit.
Plumbers will see more of them. The U.S. Department of Energy's 2024 water heater standard requires heat pump technology for most electric storage water heaters from 2029, and in parts of California, zero-NOx air rules push gas customers the same way. This guide covers the site-visit checks, using what Rheem, A. O. Smith, Bradford White, ENERGY STAR and DOE publish, and how to put it all on the quote.
The site visit checklist
| Check | What the sources say |
|---|---|
| Air space | Most 240 V models need about 700 cubic feet (ENERGY STAR). A. O. Smith's Voltex AL is rated for a 450 cubic foot room; Rheem's ProTerra runs down to 450 at reduced efficiency |
| Room temperature | DOE: a location that stays between 40°F and 90°F year-round. Heat pump operation ranges: 37 to 120°F (A. O. Smith 120 V, Bradford White), 37 to 145°F (Rheem) |
| Condensate | A drain within reach, or a condensate pump; ¾ inch connections on Rheem and Bradford White models |
| Power | 240 V on a 30 A circuit for most full-size models (ENERGY STAR); some 120 V plug-in models run on a shared 15 A circuit |
| Clearance above | Bradford White recommends 12 inches above for air discharge and service; Rheem 6 inches minimum on top |
| Weight and height | Rheem's ProTerra weighs 166 lb (40 gal) to 261 lb (80 gal) empty; the 80 gallon is over 74 inches tall |
| Noise and cooling | 45 dBA (A. O. Smith), under 50 dBA (Bradford White G2), 55 dBA (a Rheem 120 V model); the unit cools and dehumidifies the room |
Air space, louvers and ducting
This is the check that decides whether the job works. ENERGY STAR's installation guide says most traditional 240 V models need at least 700 cubic feet of air space; DOE's guidance has been at least 1,000 cubic feet. Manufacturers now go lower:
- Rheem ProTerra (240 V): 700 cubic feet is best; it "will operate in rooms less than 700 ft3 down to 450 ft3 but at reduced energy efficiency." A smaller room needs a fully louvered door or two louvers (top and bottom) with at least 3.25 square feet of free area.
- A. O. Smith Voltex AL (240 V): a 450 cubic foot enclosed room, 84 cubic feet with a louvered door (130 square inches of free area per louver), or no minimum space when it's ducted in and out.
- Bradford White AeroTherm G2: at least 700 cubic feet, or louvers with 240 square inches of open area each.
- ENERGY STAR: a closet of at least 84 cubic feet can work with a fully louvered door.
Measure the room (length × width × height) on the first visit and write the number on the quote. Bradford White and Rheem give a useful field test afterwards: if the room's air temperature drops more than 15°F while the unit heats, it isn't getting enough air.
Tell the customer about the cooling effect up front. DOE notes that heat pump water heaters "tend to cool the spaces they are in" and don't run efficiently in a cold space. In a garage in Phoenix that's a bonus; in a heated basement in Minnesota, it's part of the conversation.
Condensate
The heat pump pulls water out of the air, so every unit needs a condensate path:
- Bradford White wants a floor drain or other drain no higher than 36 inches above the floor; if there isn't one, a condensate pump rated for at least 1 gallon a day.
- A. O. Smith: if there's no floor drain, or the drain is above the level of the condensate line, a condensate pump must be installed.
- Rheem's ProTerra has ¾ inch condensate drain connections.
The model codes we read handle condensate in their mechanical sections: the IRC requires condensate from cooling coils and evaporators to go to an approved place of disposal (M1411.3 in 2021, M1411.9 in 2024, with a slope of at least 1/8 inch per foot), and the UPC (814.1) to an approved plumbing fixture or disposal area, with condensate pumps installed per the manufacturer where the authority having jurisdiction approves them. Neither names heat pump water heaters specifically, so ask your inspector how they apply it. A condensate pump and its line are a line on the quote, not an afterthought.
Electrical: 240 V or 120 V plug-in
| Type | Circuit (manufacturer) | Notes |
|---|---|---|
| 240 V full-size | 30 A breaker, 10-gauge wire typical (ENERGY STAR); 30 A (A. O. Smith Voltex AL); 25 A minimum (Bradford White G2) | Rheem also sells 15 A versions with smaller elements and a lower efficiency rating |
| 120 V plug-in, shared circuit | 15 A shared circuit (A. O. Smith Voltex 120 V; Rheem ProTerra Plug-in with HydroBoost) | Plugs into a standard outlet; no new circuit |
| 120 V plug-in, dedicated circuit | 15 A minimum breaker (Rheem ProTerra Plug-in, dedicated) | Check whether the outlet must be dedicated |
The 120 V models are what make gas-to-heat-pump swaps possible without a panel upgrade. ENERGY STAR's guide adds a sizing rule for those swaps: 120 V units typically need to be "sized-up two sizes from a gas water heater," for example a 40 gallon gas tank to a 65 gallon heat pump. A bigger tank changes the space, weight and drain pan, so check them together.
If you don't do electrical work, line up an electrician before you quote, and decide whether their work sits on your quote or theirs.
Modes, efficiency and what to tell the customer
All three brands have similar modes: heat pump only, a hybrid default that uses the elements when demand is high, electric only, and vacation. Hybrid is the default on A. O. Smith's Voltex AL. Show the customer the mode on hand-off, because a unit left in electric mode loses the savings they paid for.
Efficiency is rated as Uniform Energy Factor (UEF). ENERGY STAR's Version 5.0 criteria, in effect since April 18, 2023, require a UEF of at least 3.30 for integrated heat pump water heaters, 2.20 for 120 V / 15 A models, a first-hour rating of at least 45 gallons, and a sealed system warranty of at least 6 years. Current spec sheets list UEFs of 3.45 to 4.20 for 240 V models from the three brands, and 2.8 to 3.46 for 120 V plug-ins.
Heat pump tanks also have anodes. A. O. Smith's heat pump manual says to inspect the anode after the first six months and then yearly; our water heater anode rod guide covers the rest.
Tax credit, rebates and the 2029 standard
The 25C tax credit has ended
The federal Energy Efficient Home Improvement Credit gave homeowners 30%, up to $2,000 a year, for qualifying heat pump water heaters. Public Law 119-21, signed July 4, 2025, ended it: the IRS says the credit "will not be allowed for any property placed in service after December 31, 2025." Don't promise it on a 2026 quote.
State Home Energy Rebates
The federal Home Energy Rebates program funds a rebate of up to $1,750 for an ENERGY STAR certified heat pump water heater, for households under 150% of area median income. States run the programs and decide which products qualify, and DOE recommends waiting for your state's program to launch before starting a project that counts on it. Check your state energy office's site, and put the rebate on the quote as the customer's possible saving, not a price reduction you guarantee. Check the local utility for its own rebates too.
The DOE standard from May 6, 2029
DOE's final rule of May 6, 2024 sets new standards for consumer water heaters, with compliance required from May 6, 2029. For electric storage water heaters, it sets standards for larger products "that are met through the use of heat pump technology," while smaller ones (20 to 35 gallons, with a first-hour rating under 51 gallons) can still use electric resistance. A. O. Smith reads it as: tanks over 35 and up to 120 gallons will require heat pump technology. DOE's page lists no change to this rule. Start building your heat pump install experience now, while it's still a choice.
How to quote a heat pump water heater
The unit is only part of the price. Give each site-dependent item its own line in your price book:
- The heat pump water heater, by size and voltage (240 V and 120 V plug-in are different products)
- Installation labor, with removal and haul-away of the old tank
- Condensate: drain line to an existing drain, or a condensate pump and line
- Air: louvered door, louvers or ducting kit when the room is under the manufacturer's minimum
- Electrical: new 240 V circuit, or confirming a 120 V outlet (yours or the electrician's line)
- Drain pan, expansion tank, T&P discharge and the permit: the same items as any tank swap, covered in our guide to water heater code requirements
- Gas cap-off, when it replaces a gas heater
For gas customers in South Coast or the Bay Area, quote the heat pump next to the gas option, with the electrical line visible; our guide to ultra low NOx water heater rules explains why that choice is coming up more often.
Plumbo builds the water heater quote from your own price book, so the condensate pump, the louvered door and the electrical line come out at your prices, and Quote Guard checks water heater quotes for forgotten items like the expansion tank and the permit. Plumbo is on the App Store and Google Play. Try the 60-second demo →
Questions plumbers ask
How much space does a heat pump water heater need?
Most 240 V models need about 700 cubic feet, according to ENERGY STAR; DOE's guidance has been 1,000. Some current models go lower: A. O. Smith's Voltex AL is rated for a 450 cubic foot room, or 84 cubic feet with a louvered door, and Rheem's ProTerra runs down to 450 at reduced efficiency.
Does a heat pump water heater need a drain?
Yes, for condensate. Bradford White wants a drain no higher than 36 inches above the floor; without one, A. O. Smith and Bradford White require a condensate pump.
Can a heat pump water heater plug into a regular outlet?
Some can. A. O. Smith's Voltex 120 V and Rheem's ProTerra Plug-in with HydroBoost run on a 15 A shared circuit. Full-size 240 V models typically need a 30 A circuit.
Is there still a tax credit for heat pump water heaters?
Not the federal 25C credit: it doesn't apply to property placed in service after December 31, 2025. State rebates of up to $1,750 may be available through your state's Home Energy Rebates program, for eligible households.
Tax and rebate information is general, not tax advice. Program rules and availability change; check the IRS, your state energy office and your utility.
Sources
- ENERGY STAR, Heat Pump Water Heater Installation Guide (air space, 240 V and 120 V, sizing), checked October 20, 2026.
- U.S. Department of Energy, Building America presentation on heat pump water heaters (2020) (40–90°F, 1,000 cubic feet, cooling effect), checked October 20, 2026.
- Rheem, ProTerra heat pump water heater spec sheet, ProTerra Plug-in with HydroBoost (shared circuit) and ProTerra Plug-in (dedicated circuit), checked October 20, 2026.
- A. O. Smith, Voltex AL spec sheet, Voltex 120 V spec sheet and hybrid electric heat pump manual 100379653, checked October 20, 2026.
- A. O. Smith, DOE residential regulations, checked October 20, 2026.
- Bradford White, AeroTherm G2 installation manual and spec sheet 1903, checked October 20, 2026.
- UpCodes, 2021 IRC M1411.3 condensate disposal (Utah adoption), 2024 IRC M1411.9 and UPC 814.1, checked October 20, 2026.
- IRS, Energy Efficient Home Improvement Credit and FAQs on Public Law 119-21, checked October 20, 2026.
- U.S. Department of Energy, Home upgrades and rebates and Home Energy Rebates FAQ, checked October 20, 2026.
- Federal Register, Energy conservation standards for consumer water heaters, final rule (May 6, 2024), and DOE, Consumer water heaters, checked October 20, 2026.
- ENERGY STAR, Residential water heaters key product criteria and tax credit dates, checked October 20, 2026.