Selecting a Tankless Water Heater

Selecting a Tankless Water Heater

Fuel Type

The first thing that you'll need to decide when selecting a Tankless Water Heater is the fuel type. You will need to select between an Electric Tankless Water Heater (like Eemax Tankless Hot Water Heaters or Siebel Elton Tankless Water Heater) or a Gas-Fired Tankless Water Heater (like Rheum Tankless Hot Water Heaters). Fuel Choice and Sizing

Fuel Options

The most efficient systems available are generally gas-fired. If you currently have an oil-fired boiler, your best options are to purchase in indirect tank that connects to your boiler or an integrated unit that provides space heat and hot water in one. Electric water heaters are not recommended.

If you currently have an electric water heater and natural gas is available in your area, a switch might save you a lot of money. Even though electric models have a higher energy factor than fuel-burning models, electric resistance is a very expensive way to generate heat. It does not have great environmental benefits either, since electricity is only as clean and efficient as the fuel (often coal) that generates it. Before you rule out electricity, though, check with your utility company. It may offer special off-peak rates or options for purchasing renewable power that may make electricity a more attractive option for you.

Sizing a Water Heater (hot water furnace)

The capacity of a water heater is an important consideration. The water heater should provide enough hot water at the busiest time of the day. For a storage water heater, this capacity is indicated by its "first hour rating," which accounts for the effects of tank size and the speed by which cold water is heated. First hour rating is included in product literature and on the Energy Guide label alongside efficiency rating. To determine your family’s first hour rating, use the Peak Water Demand Worksheet

For tankless heater, solar and indirect water heaters, sizing requires a few other calculations that your installation contractor can help you with.

Tankless Heater Installation and Maintenance

Problem: Not enough hot water or water temperature too low.

When the top of the tank is hot the upper thermostat removes power from the upper heating element and transfers the power to the lower thermostat and heating element. If the lower thermostat is defective, then the lower portion of the tank will not be heated and the supply will be greatly reduced.

Check for power at the upper thermostat terminals where the power is sent to the lower thermostat and heating element. If there is no power then the upper thermostat should be replaced. If there is power then check for power at the lower heating element. If there is no power at the lower heating element then replace the lower thermostat.

If there is power to the lower heating element then it should be getting hot. If it is not, replace it. Another possibility is a broken dip tube. Check for a broken dip tube and replace if necessary.

Problem: Water is too hot.

A likely cause is one of the thermostats. Check for power at the top heating element. If power is present at the top heating element, the top thermostat is defective. If power is present at the lower heating element then the lower thermostat is defective. Another possible cause is if the thermostats are not pushed firmly against the tank.