Ultimate Guide in Choosing the Best Tankless Water Heating System

Household Size (Usage)

The size of your home will help determine what size and style of tankless water heater is best suited for your needs. An even better indicator than size though, is how often you will be using hot water and at how many points. A large home using only one shower at a time will need a smaller system than the same large home that uses several showers simultaneously.

Indoor or Outdoor

Many tankless water heaters have the capacity to be installed either outdoors or indoors, and this is often decided on how the unit fits into your plumbing the best. For homes that are replacing a conventional water heater, it makes most sense to install their new tankless system in the same location. Outdoor tankless heaters are made to stand up to the elements of both rain and sun, and even freezing temperatures in most cases. These units often have freeze protection and small internal heaters to keep their parts running smoothly. The danger in this instance is a power outage, which might have the capacity to freeze your unit and cause permanent damage. If you plan to use an outdoor tankless heater during freezing weather, it would be pertinent to have a back-up generator to run it in case of an outage.

Fuel Type

The fuel type that you choose for your tankless water heater will be much up to your preference. Electric units are about half the size of their gas-powered sibling units and they do not require any additional ventilation to the outdoors. Gas-powered units do require ventilation and will need to be hooked up to either natural gas or propane. Many of the differences between electric and gas tankless water heaters are charted here at the Go Tankless website.

Temperature Range (BTU)

The general temperature range for all tankless hot water heaters is about 80F to 140F. Some commercial models will go slightly hotter than this for sanitation purposes. For gas-powered units only, you will also see a BTU indicator.

BTU stands for British Thermal Units. Each BTU is the quantity of heat that is needed to make one pound of water increase by one-degree Fahrenheit. The larger the BTUs, the more heating power – but in general the average shower temperature is 105F, so you can feel confident that your hot water heater will provide the temperature that you need.

Flow Rate (GPM)

GPM simply stands for Gallons Per Minute, and this is the output that you can expect when using your tankless water heater. Usually the GPM listed indicates the maximum flow output. If you are running more than one shower or sink simultaneously, this flow rate will be slightly decreased because the areas are sharing hot water.

Energy Efficiency & Certification

Tankless water heaters can be up to 99% energy efficient, and about 24%-34% more energy efficient than traditional water heaters. If you install several tankless water heaters in your home instead of one, this can also make the system more energy efficient. In terms of certification, even though electric and gas-powered models are both great energy savers, only gas-powered tankless water heaters have the capability to be certified with Energy Star. We go into the reasoning behind this further on in our article.

Installation & Maintenance

For the best outcome, we at Plumbing Lab always recommend that you have a professional install your new tankless water heater. For electric tankless heaters, this is a pretty straightforward process and can be done easily in about an hour’s time. For gas tankless heaters the proper ventilation will need to be built-in as well to ensure that you don’t have carbon monoxide coming into your home. The same applies also to maintenance. New boiler costs can vary widely so always shop around for quotes. Electric tankless heaters are maintenance free – we just recommend that you check the filter several times a year to make sure there isn’t any debris blocking your water. Gas-powered tankless heaters require an annual inspection to ensure proper gas flow and upkeep.

Lifespan & Warranty (Durability)