ATMOR Tankless Water Heaters: 2 Picks Ranked by Specs

Quick picks

Our 2 picks

1 Best overall

ATMOR PRO XTP 18kW 3.8 GPM

Best for: Small households with proper electrical setup

Fuel Type

Electric

Flow Rate

3.8 GPM

Wattage

18kW

Temperature Control

90°F–125°F, 1°F increments

Certification

cETL

Dimensions

15.6 x 4.49 x 14.3 inches

View on Amazon: ATMOR PRO XTP 18kW 3.8 GPM Affiliate link

The ATMOR PRO XTP is an 18kW electric tankless water heater delivering 3.8 GPM. It features precise digital temperature control from 90°F to 125°F in 1°F increments. This compact unit supports 1–2 bathrooms in warm climates. It includes dual safety cutoffs and stainless steel internals. The self-modulating technology saves energy by heating water only when needed.

Pros

• Precise 1°F temperature increments for consistent output
• Self-modulating technology eliminates standby energy loss
• Dual over-temperature protection safety system
• Compact wall-mounted design saves space
• 7-year leak-free warranty coverage

Cons

• Lower flow rate limits use to 1–2 bathrooms
• Requires two 40-amp double pole breakers
• Needs specific 8/2 AWG wiring installation

Good fit if

• You need precise temperature settings for comfort
• You have the required electrical capacity installed
• You want a compact unit for small spaces

Skip if

• You require high flow for multiple bathrooms
• You cannot install two 40-amp breakers
• You need a gas-powered heating solution

Verdict: ATMOR PRO XTP 18kW Electric Heater suits homeowners with adequate electrical infrastructure who value precise temperature control. It fits small households in warm climates needing efficient, space-saving hot water.

2 Best budget

Atmor 36 kW 6.2 GPM Electric Tankless Water Heater

Best for: high-flow electric tankless needs

Fuel Type

Electric

Flow Rate

6.2 GPM

Wattage

36 kW

Voltage

240V

View on Amazon: Atmor 36 kW 6.2 GPM Electric Tankless Water Heater Affiliate link

The ATMOR 36 kW unit delivers up to 6.2 GPM of continuous hot water. It operates on a 240 V electric supply without gas lines or venting. This high-output model suits homes needing strong flow for multiple fixtures. It reduces standby heat loss by heating water only when needed. The system requires four 40 amp double-pole breakers and specific wiring for installation.

Pros

• 36 kW power output for high flow
• 6.2 GPM flow rate
• No venting or gas lines required
• Reduces standby heat loss
• 7-year leakage-free warranty coverage

Cons

• Requires four 40 amp double-pole breakers
• Needs four 8/2 AWG wires with ground
• Limited to electric installation only

Good fit if

• You need high flow for multiple bathrooms
• You have the required 240 V electrical capacity
• You want to avoid gas line installation

Skip if

• You lack space for four 40 amp breakers
• You cannot install 8/2 AWG wiring
• You need gas fuel type

Verdict: ATMOR 36 kW Electric Tankless Water Heater provides strong 6.2 GPM flow for busy households. It fits homes with adequate 240 V electrical infrastructure seeking vent-free electric heating.

Specifications side by side

ATMOR Tankless Water Heaters Ranked

ATMOR offers two electric tankless models that differ primarily in power and flow capacity. Both units operate without venting and require 240 V electrical infrastructure. You choose based on your household’s hot water demand and available amperage. The ATMOR PRO XTP 18kW delivers 3.8 GPM in a compact 9.5-pound frame. It suits small households with limited electrical capacity. Its dimensions are 4.49 by 14.3 by 15.6 inches. This model provides precise temperature control for efficient daily use. It is ideal for warm climates or single-fixture applications. The ATMOR 36 kW model provides 6.2 GPM for higher demand. It fits busy households needing strong continuous flow. This 36 kW unit is best for whole-home supply. You should verify your panel can handle the higher wattage. Both models share the same electric fuel type and vent-free design.

Who ATMOR Heaters Suit

ATMOR targets electric-only homes needing compact, vent-free units. The range spans from the 18 kW PRO XTP to the 36 kW model. You pick based on flow needs. The 18 kW fits small households with proper electrical setups. It delivers 3.8 GPM in a small gray box. The 36 kW handles higher demand at 6.2 GPM. Both require 240 V infrastructure. Neither model offers gas options or outdoor ratings. You avoid these if you lack sufficient amperage. The lineup is strictly electric with no gas alternatives. Choose based on your peak hot water usage.

How to choose the right ATMOR heater

1. Check your electrical capacity

   Both ATMOR units require a 240 V electrical supply. The 18 kW model draws less power than the 36 kW version. You must verify your home panel has enough amperage for your choice. The 36 kW heater demands robust infrastructure to operate safely. If your electrical setup is limited, the 18 kW PRO XTP is the safer option. Ensure your wiring meets local codes for high-wattage appliances. Proper installation prevents tripping breakers and ensures consistent performance.

2. Match flow rate to usage

   Flow rate determines how many fixtures run simultaneously. The 18 kW model provides 3.8 GPM, suitable for small households. The 36 kW unit delivers 6.2 GPM for busy homes. If you need hot water for multiple showers at once, the higher capacity model is necessary. Consider your peak usage times. A smaller unit may struggle if many taps are open. Choose based on your actual daily hot water demand rather than maximum potential.

3. Consider climate conditions

   Incoming water temperature affects performance. In warm climates, the 18 kW heater works efficiently for small households. Cold groundwater reduces output for all electric units. The 36 kW model compensates better for cold inlet water. If you live in a region with freezing winters, the higher wattage provides more reliable hot water. Check local average ground temperatures. This spec helps you predict real-world flow rates during the coldest months of the year.

4. Verify venting requirements

   Both ATMOR heaters are vent-free electric units. You do not need to install flues or exhaust pipes. This allows flexible installation in closets or utility rooms. You save space compared to gas models. Ensure the installation area has adequate airflow for cooling. The compact design fits tight spaces easily. This feature simplifies retrofitting in existing homes. You avoid the complexity and cost of venting systems. Check local codes for clearance distances around the unit.

5. Assess physical dimensions

   Size matters for tight installations. The 18 kW PRO XTP measures 14.3 inches high and 4.49 inches wide. It weighs 9.5 pounds. The 36 kW model is larger but still compact. Measure your available wall space before buying. Ensure you have clearance for maintenance access. The gray finish blends with most utility areas. Check the mounting requirements for your specific location. Proper spacing ensures longevity and easy servicing. Compare these dimensions to your planned spot carefully.

Frequently asked questions

See also

• best ATMOR 36 kW tankless water heaters
• atmor pro xtp 18kw tankless review
• best tankless water heaters with tankless
• apec water apec tankless ro water review