iQ Series

When space is at a premium, you can count on our wall-hung iQ251 units for superior performance and reliability. Ideal for highly variable applications using potable hot water, these innovative on-demand, water heaters provide 96% thermal efficiency and are constructed for maximum durability – even in the most demanding commercial applications

iQ251 Key Features:

Masterless Cascading – Cascade up to 10 units for 2,510,000 BTU/ hr capacity for larger applications. Eliminate single-point failure with our patented Masterless Cascading technology. If one cascaded unit is offline for servicing, all other units regroup and continue to operate.

Eliminate Mixing Valves & Lower Legionella Risks –With no storage tanks, there’s a lower risk for Legionella growth. By eliminating the need for mixing valves, this feature also reduces their associated unreliability and costs.

Full Modulation – Smart units deliver maximum BTU/hr input when needed and zero BTU/hr the rest of the time.

Low Gas Pressure Operation – System requires very low gas pressure to operate, down to 2.5” WC.

Common Venting Capabilities – The iQ251 units transform common venting into smart–common venting. Accommodates 3” PVC exhaust venting up to 130 feet (power vent).

ASME-HLW Compliant – Suitable for applications managed by engineers, specifiers and contractors.

Factory Supplied Strainer – iQ251 units deliver debris-free inlet water to the system.



Ideal for hotels, schools, hospitals, restaurants, laundromats and other commercial applications.



Eliminates the need to oversize an installation with redundant equipment.


Better ROI

Lower capital and operating costs compared to boilers and tank-style water heaters.



Commercial-grade, expandable 316L stainless steel heat exchanger with proven durability.

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Sizing On-The-Go

Entering simple measurements and the number of fixtures and can get the exact water heater requirements within minutes. This includes an email with detailed schematics. 

TelliSize is available in the App Store to help you work efficiently.