In addition to the operational energy savings, the condensing water heater is less expensive to install. The installation of the heaters exhaust venting carries a substantial part of the overall cost of the installation. The conventional tankless water heater venting, usually exceeds $30.00 to $45.00 per foot. This high cost is due to the cost of the special vent pipe, the time it takes to engineer, and the time to install the special venting.
Venting a condensing water heater is substantially less expensive. If the outlet water temperature is 150F or less, PVC pipe can usually be used to vent the heater. If the water temperature is greater than 150F the manufacturer will recommend a specific type of pipe to be used. Installing PVC pipe usually costs between, $2.50 to $4.50 per foot to install.
Virtually every service tech I know knows about PVC pipe and how to install it.