Airthereal Electric Tankless Water Heater 27kW - Endless Hot Water

In this review of the Airthereal Electric Tankless Water Heater 27kW, the bottom line is simple: this unit is best for homes that need reliable on-demand hot water for two to three showers and want to reclaim utility space. The reviewer found the heater heats quickly without a storage tank and that its endless hot water capability and self-modulating operation are the single biggest reasons to buy. Installation requires 240V and specific breakers and wiring, so plan the electrical work before purchasing.

Key Features

• Endless hot water: Heats water on demand so multiple showers can run without tank depletion, reducing interruptions during peak use.
• Quick heat-up: Reaches usable temperatures in under two minutes, allowing near-instant hot water at a minimum flow of 0.475 GPM.
• Space saving: Wall-mounted design uses about 90% less space than a traditional tank, freeing utility room or crawlspace.
• Energy saving: Self-modulating temperature technology heats only the water you use and can lower water heating energy compared with a tank heater.
• Safety protections: Built-in high temperature, dry-heating and electrical leakage protection separate electric and fluid systems for safer operation.
• Capacity for multiple showers: 27kW output supports roughly 2-3 showers depending on inlet water temperature and flow.

Who It's For

This unit is well suited to homeowners or renovators who need an efficient, compact water heater to serve two to three simultaneous showers or to add hot water to a secondary bathroom, kitchen, or small apartment. It appeals to those who value saved floor space and reduced standby energy loss from tank heaters.

It is not ideal for homes without 240V service or those unwilling to upgrade their breaker panel to accommodate 3x 40A double pole breakers and 3x 8AWG/2 wiring. Buyers who expect maintenance-free longevity should also consider that some users report mixed durability experiences.

Pros & Cons

Pros

• Provides continuous hot water on demand for showers and household use.
• Compact wall-mounted design saves significant space compared with tank heaters.
• Self-modulating heating reduces wasted energy and can lower operating costs.
• Includes multiple safety protections to reduce risks of electrical leakage and overheating.

Cons

• Requires 240V and specific electrical setup (3x 40A double pole breakers and heavy gauge wiring), which may add installation cost.
• Some customers report inconsistent temperature performance and durability issues over months of use.

Specifications

Our Verdict

The Airthereal 27kW tankless heater is a strong value for households that need compact, on-demand hot water for multiple showers and can provide the required 240V electrical setup. Its fast heat-up, space savings, and safety features make it a practical replacement for a small tank, though buyers should budget for proper electrical installation and be aware of some mixed reports on long-term durability.

Frequently Asked Questions

Can this unit run multiple showers at once?
Yes, the 27kW unit is designed to support about 2-3 showers simultaneously depending on inlet water temperature and flow rates.

What electrical work is required?
Installation requires access to 240V, 3x 40A double pole circuit breakers and 3x 8AWG/2 wiring; verify your breaker panel before installing.

How fast does it produce hot water?
The heater can reach useful hot temperatures in less than two minutes at its specified minimum flow.