• Super compact 14" x 20½" x 7" size
• 83%+ thermal efficiency
• 140,000 BTU maximum input
• 6.6 gallons per minute capacity at 35F degree rise
• Minimum activation flow rate of 0.5 gallons per minute
• Electronic ignition
• Built in freeze protection
• Vents vertically or horizontally with 3” or 4” stainless steel
• Can be used in recirculation and space heating applications
• Backed with 15-year warranty
• Available in NG and LP models
• Also available as an outdoor model, 660 EFO

                  Eligible for up to $1500 Federal Tax Credit (30% of purchase price and residential installation)

The Therm 660 EF is compact enough to install virtually anywhere. But don’t let the size fool you. This model is loaded with features including freeze protection and built-in high temperature capability (160°F).

3" Stainless Steel Venting materials

 Frequently Asked Questions 

 Warranty Info 

 

15 year limited warranty on heat exchanger; 3 year warranty if used in direct recirculating applications

15 year warranty on heat exchanger if used if recirculated through a storage tank such as the Ariston mini-tank

5 year warranty on all other parts

 

Installation Manual

Brochure

Parts Diagram

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