The cost to install a tankless water heater is going to vary with the type of installation that is needed. Some of the biggest factors in determining the cost to install a tankless water heater are going to be the unit itself, gas line requirements, and venting requirements.
Tankless water heater are becoming more popular and easier to purchase than ever before. Home Depot actually sells some tankless water heaters that are as little as $1000. These on demand units usually don’t have a high output so they are not ideal for most residential households, especially for families. We don’t buy our tankless units from Home Depot just like many other plumbers. Most of the tankless water heaters that we purchase will go for around $1500-$2000 with the flushing kit sold as an accessory.
Materials to install a tankless water heater include copper supply lines and fittings that feed off the water heater from the existing supply. Depending on the type of unit that you install, you may also need a condensate line that runs to the nearest floor drain. Each unit will also require special vent pipe and fittings for both intake and exhaust. Additional materials may need to be purchased to setup up the gas lines. Most tankless units will require a 3/4″ gas line feed. Traditional water heaters will typically be powered fro a 1/2″ gas line.