The EZ Ultra is a natural gas or propane (LPG) condensing water heater that offers all the features our customers have grown to expect. The unit uses exhaust gas to preheat incoming water for added efficiency. It can be vented horizontally or vertically using a 2" Solid Core Schedule 40 PVC/CPVC anti-back draft vent device included. Stainless Steel Horizontal Vent Pipe is included and the heater can also be used to vent the water spigots and showers. " No pilot light" design is safe and convenient, using automatic ignition to further your energy savings. EZ Ultra condensing tankless water heater can be installed anywhere with an adequate air supply. With the ability to vent using 2" Sch. 40 PVC, this unit can also be used for vertical venting, horizontal ventilation, or diagonal vents, just keep the overall length less than 30ft. Asking yourself a few simple questions can help you decide which water heating system is best for you. This EZ Ultra is designed for use with Natural Gas Only. It can be vented Horizontal or Vertical using SCH 40 PVC - the cheapest way to vent is through an exterior wall to the outside or must you vent vertically through the roof to your home?