The Tankless Water Heater Buyer Guide


The Basics

While there certainly are many pros and cons to installing a tankless water heater in your home, this is a product that any homeowner (and home builder) should at the very least consider. Tankless water heaters are a large investment and can even outlast the time you spend in your house. Not only can your choice of water heater affect the resale value of your home, it impacts your daily life; check out our tankless water heater buyer guide to select which heater is best for you (or click on the graphic below for quick overview of everything you need to know).

The Tankless Water Heater Buyer Guide from SUPPLY.comTypes of Tankless Water Heaters

When selecting a tankless water heater, there are a couple choices you need to make before doing anything else. First, you must decide whether you want your heater to be condensing or non-condensing. These two terms derive from the fact that steam is a natural byproduct of the tankless water heater process, due to the high temperatures of the water passing through. Condensing heaters, like the Ultra Series from Rinnai, keep this steam within the unit, retaining the heat associated with the vapor in an efficient manner. However, the vapor can act as a corrosive agent, slowly eroding the inner workings of the heater and necessitating more frequent repairs. Non-condensing heaters, like the Rinnai Luxury Series, release this heated vapor outside of the system, usually by way of a channel to the outdoors. This method allows the unit to last longer, but wastes heat in the releasing process.

Bottom line? The condensing tankless water heater is more efficient and effective, but is usually more expensive to maintain, while the non-condensing unit is more affordable, yet less efficient in terms of retaining heat.

The second choice you need to make is where in the home your heater will be installed. Internal heaters are inside the home and usually reside in basements and closets. These heaters require venting pipes and are usually routed through a vent in the side of the home. External heaters are hung outside the home, eliminating the need for venting pipes. External heaters are very popular, but they are not recommended for parts of the country with very cold temperatures and many freezing nights.

Water Heater Flow Rate

After you have figured out what type of tankless water heater is best for your situation, you need to consider your heater’s flow rate. Flow rate refers to the amount of hot water the heater is able to produce within a certain time (often stated as gallons per minute, or gpm).

When calculating your ideal water heater flow rate, a good rule of thumb is to add up the flow rates of any devices in your home that produce hot water. For example, if you have a shower that produces 3 gpm of hot water and a sink that produces 1.5 gpm, and you want to be able to operate these two devices at the same time, then you need a water heater with a flow rate of at least 4.5 gpm.

The Rinnai tankless water heater lineup contains units with flow rates ranging from 0.26 gpm to 9.8 gpm; check out the collection, and don’t hesitate to reach out to a SUPPLY.com representative for assistance when calculating flow rate.

Advantages of the Tankless Water Heater

There are several advantages to installing a tankless water heater, not the least of which is an endless supply of hot water. Tankless water heaters last an average of 20-25 years, twice as long as tanked water heaters, and they are also smaller and use less space than tanked models, resulting in a lower gas bill. And on the subject of money, the average energy cost to run a tankless water heater each year is over $100 less than that of a tanked heater. Finally, mostly due to the advantages listed here, tankless water heaters increase the re-sale value of a home.

Additional Information

Buying a tankless water heater involves higher purchase and installation prices compared to tanked water heaters (County and municipality tax breaks can sometimes counterbalance these costs; check out the Rinnai Rebate Finder to see if you are eligible for any rebates). Additionally, tankless water heaters must be vented, meaning they need venting pipes, a vent added to the home, and possibly a new gas line added as well. However, exterior tankless heaters cut the cost of venting pipes and a vent. Regardless, we suggest installing a water heater as close to the home’s gas meter as possible.

Tankless heaters must be serviced annually, to a cost of $79-$100 per year, but homeowners are usually able to service the heaters themselves, taking around four hours once per year. Additionally, tankless water heaters take more time to send hot water to your faucet than tanked heaters. However, tankless heaters also do not run out of hot water, allowing for longer showers and more water consumption. The key, therefore, is to time your showers and be conscience of your water usage.

We have presented the pros and cons of purchasing a tankless water heater, but it ultimately comes down to your personal judgement and living situation. If you have any additional questions about tankless heaters, contact our team of product experts at 888-426-2323.

Want to see some more tankless water heater models? Check out our entire Rinnai collection at SUPPLY.com!