Gas Tankless Water Heaters

Therm 660 EFO

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Outdoor model with freeze protection
Therm 660 EFO

Product Overview

Eligible for up to $300 Federal Tax Credit

The Therm 660 EFO is our most compact outdoor model and is loaded with features you’d expect from Bosch, including freeze protection and built-in high temperature capability (160°F).

Features & Benefits

Outdoor installation with freeze protection
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
Can be used in recirculation and space heating applications
Backed with 15-year warranty
Available in NG and LP models

Warranty

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

Bosch Warranty Details

Product Warranty

Therm 660 EFO	Specifications
Condensing/Non-Condensing	Non-Condensing
Application	Residential or Commercial
Max Input (BTU)	140,000
Min Input (BTU)	20,000
Capacity at 35°F Rise (gpm)	6.6 gpm
Capacity at 55°F Rise (gpm)	4.2 gpm
Intelligent Cascading	No
Min Flow Rate	0.5 gpm
Temp Range (°F)	100 - 160
Temp Stability (°F)	+/- 2
Default Temp (°F)	122
Energy Factor	.82
Thermal Efficiency	83%+
Installation Options	Outdoor
Dimensions (w x h x d)	14" x 20½" x 7"
Weight (lbs.)	67
Inlet Connection	¾" NPT
Outlet Connection	¾" NPT
Gas Connection	¾" NPT
Max Water Pressure	150 psi
Min Water Pressure	30 psi
Min NG Presure	4" WC
Condensing Heat Exchanger	n/a
Venting Options	n/a
Vent Maximun Run	n/a
Energy Star Rated	Yes