Bosch Outdoor Tankless Water Heaters

Bosch offers four outdoor tankless water heaters that are approved for areas where it does not regularly freeze. The heaters are equipped with electric freeze protection down to 5 degrees F above zero and are capable of withstanding an occasional overnight freeze.

The following Bosch outdoor tankless water heaters come with this freeze protection:

Bosch AquaStar 2700ES-LP / Bosch AquaStar 2700ES-NG
Bosch AquaStar 2400ES-LP / Bosch AquaStar 2400ES-NG
Bosch AquaStar 125BO -LP / Bosch AquaStar 125BO-NG
Bosch GWH 425HNO-L / Bosch GWH 425HNO-N

LP stands for Liquid Propane and NG stands for Natural Gas.

In order for the Bosch 2700ES and 2400ES heaters to be installed outdoors they must have the Bosch AQOK outdoor vent kit. This optional vent kit attaches to the top of the heater and prevents water from getting into the heater.

The Bosch 125BO and the GWH 425 HNO do not need any additional accessories in order to be installed outdoors. Please note that while the Bosch 125BO and the GWH 425 HNO outdoor tankless water heaters come with 110 Volt plugs, these heaters do not have to be plugged in unless you desire the freeze protection. The Bosch 125BO has a pilot light and the GWH 425HNO uses Bosch's patented Hydro Ignition system.

Bosch has approved these four outdoor heaters for the following areas of the United States:

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).

Some people install these outdoor tankless water heaters for their summer homes or cabins in areas of the US and Canada that do freeze. When these heaters are installed in freezing locations the water heaters must be completely drained so that the heat exchanger and pipes do not burst. The Bosch warranty does not cover damage due to freezing.

The WebStone Isolation Valve Kits really make the task of draining these outdoor tankless water heaters easy, so they are especially recommended for this application.

There are two big advantages to going with an outdoor tankless water heater:

1. The water heater does not take up any space inside of your home; and


2. There is no venting required, thus reducing both parts and installation costs.

One possible disadvantage, however, is that you may have to pay an extra installation cost to get the gas line and water lines run to your installation point outdoors.

Steve