12 Best Tankless Water Heater For Washing Machine of 2026 To End Lukewarm Wash Cycles

1

Stiebel Eltron Tankless Water Heater - Tempra 20 Trend –

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  9.2
• Brand
  Stiebel Eltron

Key specs2

Electrical Service Requirement

125A minimum recommended service at 240V

Temperature Control Range

Output water adjusts between 68 and 140 degrees Fahrenheit using an electronic switch and digital display to match specific wash cycle demands.

Pros & cons42

Pros

• Delivers high 19.2kW heating output at 240V for continuous hot water during laundry cycles
• Digital display allows precise temperature setting from 68 to 140 degrees Fahrenheit
• Auto-modulating technology adjusts energy consumption to match incoming flow rate
• Backed by a 7-year leakage warranty and a 3-year parts warranty

Cons

• Demands a minimum 125A dedicated electrical service that may require panel upgrades
• Requires hardwired 240V installation with substantial electrical capacity

2

Kelaro Tankless Water Heater Flushing Kit with Flow-Aide Biodegradable Descaler

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  9.2
• Brand
  Kelaro

Key specs2

Descaling Cycle Duration

45 minutes or less

Included Maintenance Hardware

• 1/8 HP utility pump
• 6 ft stainless steel color-coded hoses
• 3.5 gallon bucket with EZ-Off lid
• Flow-Aide biodegradable descaler

Pros & cons42

Pros

• Includes a 1/8 HP utility pump and 6-foot stainless steel color-coded hoses for descaling
• Flow-Aide biodegradable descaling solution flushes mineral scale in 45 minutes or less
• Complete DIY maintenance package comes with a 3.5-gallon bucket and EZ-Off lid
• Compatible with major tankless water heater brands featuring standard isolation valves

Cons

• Serves strictly as a maintenance descaling kit rather than a water heating appliance
• Requires tankless heater to already have compatible isolation service valves installed

3

Chromex Tankless Water Heater Flush Kit with Certified Liquid Descaling

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  9.2
• Brand
  Chromex

Key specs2

Pump Power Rating

1/6 HP utility pump

Flush Cleaning Time

Circulates citric acid solution through heater coils to strip mineral deposits in 30 minutes or less using elevated pump filtration.

Pros & cons42

Pros

• Features an upgraded 1/6 HP pump and an elevated grate to circulate descaling fluid
• Citric acid descaling solution clears mineral deposits in 30 minutes or less
• Comes with a 5-gallon bucket with lid and two 6-foot PVC coated hoses
• Backed by a 1-year manufacturer warranty

Cons

• Functions exclusively as a cleaning kit and cannot heat water for a washing machine
• Requires existing service isolation valves on the water heater plumbing line

4

EcoSmart ECO 11 Electric Tankless Water Heater, 13KW at 240

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  8.8
• Brand
  EcoSmart

Key specs2

Flow Rate Capacity

1.3 to 3.1 GPM based on inlet water temperature

Heater Dimensions & Weight

Measures 11.5 x 8 x 3.75 inches and weighs 6.5 pounds for tight wall installations near laundry machines.

Pros & cons42

Pros

• Delivers 13kW of heating power at 240V to maintain hot water within 1 degree of set point
• Provides flow rates between 1.3 and 3.1 GPM depending on incoming groundwater temperature
• Compact 11.5 x 8 x 3.75-inch wall-mounted footprint frees up laundry utility space
• Lifetime warranty covers electronics, heat exchanger, and heating element

Cons

• Output flow drops to 1.3 GPM in colder climates with low inlet groundwater temperatures
• Requires 240V electrical connection that may exceed standard 120V outlet wiring

5

Electric Tankless Water Heater, ECOTOUCH 14kW Instant Hot Water Heater

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  8.6
• Brand
  ECOTOUCH

Key specs2

Electrical Hookup Specs

240V, 1x 60A double-pole breaker, 6 AWG wire

Plumbing Port Size

1/2 inch NPT

Pros & cons52

Pros

• Delivers 14kW heating power at 240V to produce water at 120 degrees Fahrenheit or higher
• Self-modulating heating automatically matches power draw to current flow rates
• Uses standard 1/2-inch NPT plumbing fittings compatible with common laundry hookups
• Touch control screen and digital display provide real-time operating status
• Certified to ETL standards and qualifies for UL safety requirements

Cons

• Requires a dedicated 60A double-pole breaker and 6 AWG wiring
• Operates on 240V service only and will not run on standard 120V wall receptacles

6

Camplux 2.64 GPM Propane Portable Gas Water Heater, Outdoor Tankless

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  8.6
• Brand
  CAMPLUX ENJOY OUTDOOR LIFE

Key specs2

Heating Capacity & Fuel

68,000 BTU/hr on Liquid Propane

Water Pressure Operating Range

3.6 to 110 PSI

Pros & cons42

Pros

• Produces up to 2.64 GPM of hot water fueled by liquid propane with 68,000 BTU/hr output
• CSA certified safety design includes flame failure and automatic high-temperature shutoff at 176°F
• Operates across a wide water pressure range from 3.6 to 110 PSI
• Portable 18-pound build mounts with rear bracket for off-grid or garage laundry setups

Cons

• Requires liquid propane fuel and adequate outdoor or ventilated exhaust arrangements
• Manual warns never to wrap Teflon tape between gas regulator and gas inlet pipe

7

Airthereal Electric Tankless Water Heater, 9kW, 240Volts - Endless On-Demand

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  8.4
• Brand
  AIRTHEREAL

Key specs2

Breaker Panel Requirement

240V, 40A dedicated circuit breaker

Chassis Profile

Measures 16.14 by 9.84 inches with a 2.6-inch depth for mounting directly adjacent to laundry supply valves.

Pros & cons42

Pros

• Consumes a moderate 9kW at 240V, fitting homes with smaller 40A double-pole breakers
• Self-modulating heating adjusts power automatically to avoid temperature swings
• Slim 2.6-inch profile allows flush mounting directly behind or alongside laundry equipment
• Separate fluid and electrical channels protect against internal leakage and corrosion

Cons

• Lower 9kW output produces less temperature rise during high flow rates in cold weather
• Requires 240V electrical connection and will not function on standard 110V lines

8

Gateenon 3.2GPM 12L Tankless Water Heater Propane Outdoor - Liquid

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  7.8
• Brand
  Gateenon

Key specs2

Max Propane Flow Rate

3.2 GPM (12 L/min)

Heat Exchanger Construction

Built with tinned pure copper heating coils and copper valves to accelerate thermal transfer during cold water intake.

Pros & cons52

Pros

• Delivers high 3.2 GPM flow rate using liquid propane for rapid washing machine tub fills
• Equipped with a CSA-certified quick gas connector and solid copper heat exchanger
• Safety features include automatic 20-minute shutoff and 167°F overheat cutoff
• Lightweight 12-pound chassis with LED display simplifies remote or outdoor mounting
• Backed by a 1-year product warranty

Cons

• Designed for outdoor or well-ventilated propane setups and cannot vent indoors without ducting
• Shuts off automatically after 20 continuous minutes of operation as a safety measure

9

Tengchang 10L 2.6 GPM LPG Gas Propane Instant Tankless Hot

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  7.8
• Brand
  Tengchang

Key specs2

Thermal Rating & Efficiency

20kW thermal input at >= 80% efficiency

Minimum Water Pressure

0.025 MPa operating threshold

Pros & cons42

Pros

• Produces 2.6 GPM with a 20kW thermal rating running on liquid petroleum gas
• Operates at a low minimum water pressure threshold of 0.025 MPa
• Delivers a rated 25-degree Celsius water temperature rise at 80% thermal efficiency
• Uses standard G 1/2-inch gas and water inlet connections

Cons

• Requires dedicated 4.2 vent piping for safe exhaust gas discharge
• Water outlet uses a 20.96mm connection that may require plumbing adapters for laundry lines

10

Nannday Mini Tankless Instant Hot Water Heater, Household Electric Dual-Use

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  7.6
• Brand
  Nannday

Key specs2

Operating Voltage

110V standard US power supply

Verification Notice

Kilowatt rating, minimum water flow activation, and fitting dimensions are unlisted by the manufacturer and must be verified before connecting to a washer.

Pros & cons32

Pros

• Operates on standard household 110V electrical lines without requiring 240V rewiring
• Ultra-compact mini footprint installs in tight spaces under laundry sinks or behind washer units
• Integrated indicator light visually signals when the heating element is energized

Cons

• Power draw and exact flow ratings are omitted in manufacturer specifications and must be verified
• 110V mini electric units typically lack heating capacity for rapid high-volume washer fills

11

Thermoflow 110V~120V Mini Tankless Water Heater Electric Point of Use

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  6.8
• Brand
  thermoflow

Key specs2

Power & Wiring Specs

3.5kW at 110-120V, 30A breaker, 12 AWG wire

Intended Application Limit

Designed primarily for low-flow handwashing sinks, producing limited heat rise during rapid laundry fill bursts.

Pros & cons42

Pros

• Runs on 110V to 120V electrical supply using a 30A breaker and 12 AWG wiring
• CSA certified unit features smart modulation to maintain temperatures between 95°F and 122°F
• Rotating digital LED display provides real-time water temperature feedback
• Uses standard 1/2-inch NPT pipe fittings and handles water pressure up to 115 PSI

Cons

• Manufacturer specifies point-of-use sink duty, so 3.5kW will struggle with cold washer fill cycles
• Requires dedicated hardwired 30A circuit rather than plugging into an existing wall outlet

12

Harbin-Star Tankless Water Heater Electric, 4500W Electric Water Heater with

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  6.4
• Brand
  HarBin-Star

Key specs2

110V Electrical Draw

4500W at 29.5A rated current

Safety Cutoff System

Shuts down automatically and displays error E1 if outlet temperature exceeds 131 degrees Fahrenheit to prevent scalding.

Pros & cons42

Pros

• Provides 4500W of heating power on a 110V line with a rated 29.5A current draw
• Digital touch panel displays operating status with automatic shutoff when exceeding 131°F
• IPX4 water resistance rating and tempered glass front panel resist laundry room splashes
• Compact 11.02 x 7.48 x 2.56-inch housing fits neatly in cramped washer alcoves

Cons

• High 29.5A current draw on 110V requires dedicated wiring to avoid tripping laundry circuits
• 4.5kW output provides modest temperature rise during high gallon-per-minute washing machine draws

Last update on 2026-10-09 / Affiliate links / Images, Product Titles, and Product Highlights from Amazon Product Advertising API

Can a compact 110V tankless water heater supply enough hot water for a washing machine?

A compact 110V or 120V water heater generally struggles to heat the fast water intake of standard laundry cycles. Units operating on 110V to 120V power, such as 3.5kW hard-wired models or 4500W units, are primarily designed for point-of-use hand sinks. Washing machines draw water quickly, which means lower-wattage elements cannot raise incoming water temperatures fast enough before the tub fills. If you are pairing an on-demand unit with a washing machine for a small household, higher-output 240V heaters rated at 9kW, 13kW, or 14kW provide the self-modulating heating capacity needed to keep wash cycles warm.

What electrical service and voltage does an electric laundry tankless heater require?

Dedicated electric point-of-use laundry heaters generally require a 240V electrical connection. Compact wall-mounted heaters such as 9kW, 13kW, and 14kW models run on 240V power to continuously warm water on demand. Smaller point-of-use models operate on 110V or 120V circuits at 3.5kW or 4500W, but they deliver significantly lower heat output. Breaker amperage requirements and wire sizes vary by model, so verify your electrical panel capacity and check the specific manufacturer specifications before installation.

Will a portable propane tankless water heater work safely for a garage or off-grid washing machine?

Yes, portable liquid propane water heaters can supply hot water to off-grid or outdoor laundry stations if used according to manufacturer safety ratings. Units producing 2.64 GPM or 3.2 GPM come equipped with CSA-certified gas connectors, flame failure devices, anti-freezing protection, and overheat protection. Because these models burn liquid petroleum gas, they require proper outdoor placement or approved venting to prevent combustion hazards. Confirm that your water pump or supply line provides enough flow to activate the gas burner reliably.

What flow rate is needed to trigger a tankless heater during washer fill cycles?

The incoming water stream must meet the heater minimum activation flow rate when the washer valve opens. Tankless models list flow capacities such as 2.64 GPM or 3.2 GPM for propane, while electric models feature self-modulating technology that adjusts power output based on real-time flow rate. If a washing machine draws water in brief, low-volume spurts below the unit activation threshold, the heater will not turn on and the tub will fill cold. Check your washing machine inlet flow requirements and compare them to the minimum activation rate listed on the heater product page.

How do you protect a laundry water heater from mineral scale buildup?

Regular descaling flushes protect internal heating elements and heat exchangers from hard water mineral buildup. Complete homeowner flush kits include a 1/6 HP pump, hoses, a 5-gallon bucket, and biodegradable descaling solutions that clear scale in 45 minutes or less. Performing these flushes on a routine schedule maintains heat exchange efficiency and extends the operating lifespan of both electric and gas tankless units. Check your heater manual to determine the recommended flushing schedule based on your household water hardness.

How much wall space do you need to mount a point-of-use heater by a washer?

Most electric point-of-use heaters require minimal wall space and mount directly to the wall without venting pipes. Dimensions vary by model, with 13kW units measuring 11.5 by 8 by 3.75 inches and 14kW units measuring 15.87 by 11.14 by 3.46 inches, taking up roughly 90 percent less space than conventional tank heaters. When planning the layout around your laundry hookups, leave adequate clearance for plumbing lines and consider adding a washing machine automatic shut-off valve to guard against leaks.