Clean vents and ensure there’s no debris, particularly if the return is positioned near other exhaust vents, Fleming advises. You can also use compressed air for any buildup on the fan and door.
For gas units, schedule burner check and evaluate the vent for cracks as a safety precaution, Houston recommends.
Some facilities have oversized water heaters in the first place. Tankless can be scaled to your actual water demand.
“You don’t replace a water heater with a tankless unit based on the original storage capacity – you size the tankless model based on your hot water demand,” Fleming clarifies.
Sizing evaluates a number of factors, says Houston. Look at the number of fixtures that use hot water, their gallons per minute rate, and peak demand. You also need to know the groundwater temperature coming in through your pipes, which affects how much energy is needed to raise the temperature to the setpoint.
Installing a tankless heater as close as possible to the point of end use is best as less energy will be lost as water is transported throughout your building. Otherwise, you need a recirculation pump and line, which will keep the water at the correct temperature, says Fleming. You can also add a timer and aquastat for additional control.
For gas units, anticipate a slightly larger fuel bill, particularly if your hot water demand was never satisfied with your original heater.
“For example, you may currently have a 199,000 BTU water heater but are always short on water. It could take a 380,000 BTU tankless unit to meet your demand fully,” says Fleming.
You may also need to expand the size of your incoming gas line, Stebbins suggests, though gas companies typically offer deep discounts to help you with upgrades. Vents are another consideration as tankless heaters use concentric vents to dissipate carbon monoxide rather than a standard V vent, Fleming says.
“Electric units are simpler to retrofit as there are no venting requirements, though you might need to increase the size of your breaker in the main panel and have a larger electrical feed wire running to the unit in many applications,” says Stebbins.
Lastly, shop around for installation costs, stresses Houston. The plumbing technician should also have familiarity with these units, otherwise improper installation could negate future savings.
Jennie Morton email@example.com is senior editor of BUILDINGS.