How Many Tankless Water Heaters Does Your Home Need?

These days everyone is looking into tankless water heaters. That’s because they’re more energy efficient than conventional reservoir water heaters and provide virtually endless hot water on demand, when and where it is needed. There is a caveat that comes with tankless water heaters, however. While a reservoir water heater can provide hot water to an entire home, it’ll take more than one tankless water heater to supply the same home with enough hot water. This begs the question: how does Fsi Oil and Propane determine the right number of tankless water heaters for a home? Continue reading to find out.

Many considerations go into deciding how many tankless water heaters to install: the number and type of fixtures throughout the home requiring a hot water connection, the duration and frequency they are being used – including peak demand rates, and how cold the area’s groundwater gets. A tankless water heater’s capacity is found using two main factors. The first is expected water use in gallons per minute (GPM) at peak demand. The second is how much that water will need to be heated compared to its incoming temperature. For example – if groundwater temperature is 50ºF and the amount of water delivered from a showerhead, which outputs 2.5 GPM, needs to be heated to at least 120ºF, the tankless unit needs to be able to heat 2.5 GPM by 70ºF. On average, propane or natural gas tankless water heaters can handle a rate of 5 GPM at a 70ºF rise, so as more fixtures are added to the tankless system, the tankless unit can quickly become overwhelmed.


Determining peak demand is done simply by adding up the GPM rates of all the fixtures in the house and determining the temperature rise needed during winter in the area and comparing that to manufacturer specs. This will help prevent us from installing an under-sized water heating system. Another benefit of tankless water heater systems is that an over-sized system isn’t going to waste energy like over-sized reservoir water heating system. This allows proper hot water distribution, without causing energy bills to rise.


Do you feel like your water heating system is wasting energy? Are you unhappy with the temperature of your hot water? Fsi Oil and Propane can help determine if your water heating system is as efficient as it can be. Whether your reservoir water heater is throwing your energy dollars out the window or your tankless system isn’t supplying enough hot water, we can help! Contact us today and improve your water heating system.