Tankless Gas waterheaters are great for the family of 4 or more. They are high efficiency and provide for endless hot water. Keep in mind these important factors when considering them. 1) How far apart are all the hot water outlets and/or appliances. The father apart they are the more water you will go thru to get the hot water at the source. Centralizing the water heater is important. 2) How far from the gas meter is the water heater going to be? An on demand uses 4 to 5 times more gas than a tank type when it is running. Therefore the gas line must be increased in size. A qulified mechanical contractor shoul be used to size and install this gas pipe. A contractor with Process piping catagory is required. (HVAC equipment is not a qualified license.) 3) venting distance should be taken into account. These vent out the side wall for the 90%plus models and thru the class B venting for the 80% models. None should vent into clay tile flue without approval from the manufacture. 4)Condensate drainage must be handled to code. 5)An electric service will be required to provide power to code. 6) Inpectors will require proper sizing to home use. 7) A Mechanical Permit is required for gas piping in excess of 8 ft and for the venting and drain pumps. Plumbing is required if the water heater is relocated and more than the usual recconection piping is needed as in replaceing a standard water heater. The local plumbing inspector should be asked regarding the amount of re-piping. Call Mark Grant Mr Heat and Cool for further details a free estimates. 231-955-8780 firstname.lastname@example.org. A plumbing permit is usually required. I will use another highly trained plumber to assist and pull that part of the permit.