Most all of the Bosch gas tankless water heaters come with built in freeze protection. The heaters listed below have built in freeze protection and are approved to be installed in some outside installations.
Our Bosch Outdoor Tankless Water Heaters (Bosch 2700ES with AQOK Outdoor Cap / Bosch 2400ES with AQOK Outdoor Cap/ 125BO / 425HNO / 2400EO / 250SXO) have built in freeze protection and are designed to handle an occasional overnight freeze. They plug directly into the wall and provide freeze protection down to 5 deg F above zero. In order for the freeze prevention kit to provide adequate protection,120V AC must always be supplied to the water heater.They are approved for use in the following areas:
Florida, Georgia, North Carolina, South Carolina, Alabama, Mississippi, Arkansas, Texas, Virginia (only in zip codes beginning with the first three digits 233-237), Arizona (in zip codes beginning with the first three digits 850-857 and 864), Oregon (in zip codes beginning with the first three digits 970-975), Washington (in zip codes beginning with the first three digits 980-986), California (except in zip codes beginning with the first three digits 935 or 961).
Installation instructions state that the water heaters must not be installed in a location where it may be exposed to prolonged freezing temperatures. If the heater must be left in a space which is likely to experience prolonged freezing temperatures, all water must be drained from the heater. If precautions are not taken, resulting damage will not be covered under the warranty. NOTE: Use of agents such as anti-freeze is not permitted as they may cause damage to the water heater's internal components. The freeze prevention will not protect plumbing outside the appliance from freezing. Precautions should be taken.
The Bosch 250SX/2400E/2400ES and 2700ES come with built in freeze protection and these units are for inside installation only. The freeze protection helps the unit if it is installed on the inside of an outside wall where it may be cooler than normal.