The Bosch 2700ES is available in both natural gas (Bosch 2700ES-NG) and liquid propane (Bosch 2700ES-LP). The 2700 ES direct vent tankless water heater requires special 3" or 4" stainless steel vent pipe and can be vented either through the roof or out the side wall. In approved areas the 2700ES can also be mounted outdoors as it comes with freeze protection that is good down to 5 degrees F above zero and provides protection against occasional overnight freezes.
In addition to coming with built-in freeze protection, the AquaStar 2700ES also comes with a pressure relief valve (PRV) and an external water filter.
Like the 2700ES, the Evolution 500 direct vent tankless water heater also comes with built-in freeze protection, a PRV and an external water filter. It requires the same Z-Flex Z-Vent 3" or 4" special stainless steel vent pipe.
So, if you intend to have your tankless water heater installed professionally, have your installer visit www.prowaterheatersupply.com and check out the Evolution 500. These heaters are specially priced while supplies last.