Tankless Water Heater Size Requirements

For both gas and electric models a tankless water heater s overall energy efficiency is measured using an energy factor ef rating.

Tankless water heater size requirements.

This ef rating is based on test procedures developed by the u s. Tankless water heaters are rated by the maximum temperature rise possible at a given flow rate. Below we ve highlighted what size water heater you would need in our example of 6 5 gpm at a 63 f temperature rise. For example an electric tankless heater that is rated at raising the water temperature 55 degrees at 1 5 gpm will supply you with a 120 degree temperature if the incoming water is 65 f or higher.

How much does a water heater permit cost. The first permit is for the water heater itself. Today tankless water heater energy factors range between 64 and 91 for gas fired models and up to 99 for electric models. This is as easy as heading down to the local planning or building department to ask for one.

Therefore to size a demand water heater you need to determine the flow rate and the temperature rise you ll need for its application whole house or a remote application such as just a bathroom in your home. The initial cost of a tankless water heater is greater than that of a conventional storage water heater but tankless water heaters will typically last longer and have lower operating and energy costs which could offset its higher purchase price.