Tank vs. Tankless Water Heaters in Southern Utah: Which Is Right for Your Home?
For many Southern Utah homeowners planning to stay in their home long term, a properly sized tankless water heater is the stronger choice. Tankless systems can provide continuous hot water within their rated capacity, take up significantly less space, reduce standby energy loss and generally have a longer expected service life than traditional storage tanks. A conventional tank can still be the right choice when the goal is a straightforward replacement and the existing system already meets the household’s needs. [1][2]
The important part is properly sized.
Choosing a water heater should involve more than counting bathrooms or replacing a 50 gallon tank with another 50 gallon tank. Flow rate, temperature rise, water pressure, pipe sizing, recirculation, gas or electrical capacity, water quality and the way the home was originally plumbed can all change the answer.
That is especially important in Southern Utah, where hard water and large homes with long plumbing runs are common considerations.
Tank vs. Tankless at a Glance
Conventional TankTanklessHot water supplyLimited to stored volume and recoveryContinuous within the unit’s rated capacitySpaceRequires floor space for the tankCompact and typically wall mountedExpected lifespanCommonly about 8 to 12 yearsCommonly 15 to 20 years or more with proper maintenanceStandby heat lossYesMinimal because water is heated on demandRecirculationCompatibleAdvanced recirculation options availableHigh demand homesDepends on tank size and recoveryDepends on simultaneous flow and temperature riseHard water concernsSediment and tank corrosionScale inside the heat exchangerBest fitSimple replacement and predictable demandLong term ownership, continuous hot water, space savings and system upgrades
Expected life varies with equipment, installation, water chemistry, use and maintenance. Rheem currently describes traditional tank life as approximately 8 to 12 years and tankless life as approximately 15 to 20 years or more with proper care. [2] Rheem
Why Bathroom Count Is Not Enough
One of the most common ways tankless water heaters are marketed is by bathroom count.
A chart might suggest one size for a two bathroom house and another for a four bathroom house. That is useful as a rough starting point, but it is not how we want to make the final decision.
A four bathroom home occupied by two people may have relatively low simultaneous demand. A two bathroom home with a large primary shower, rain head, handheld shower, body sprays and a high flow tub filler can require considerably more hot water at one time.
The more useful question is:
How much hot water could this house realistically use at the same time?
EPA WaterSense showerheads are limited to 2.0 gallons per minute. Two showers operating simultaneously can therefore represent roughly 4 GPM before adding a kitchen faucet, another bathroom fixture or other hot water demand. Multiple showering devices can increase the total further. [3] EPA
That simultaneous demand matters much more than the number of bathroom doors in the house.
Tankless Sizing Is About Flow Rate and Temperature Rise
Gallons per minute are only half of tankless sizing.
The other half is temperature rise, or how much the incoming water must be heated before it reaches the desired outlet temperature.
If water enters the heater at 60°F and the system is set to provide 120°F water, the heater needs to produce a 60°F temperature rise.
The greater that temperature rise, the less water a given tankless unit can heat at one time.
Navien’s NPE 240A2 illustrates this clearly. Navien rates the unit at 11.2 GPM with a 35°F temperature rise, 7.1 GPM with a 55°F rise and 6.0 GPM with a 65°F rise. [4] It is the same water heater in every example. Navien
That is why the largest GPM number on a product page should never be treated as the amount of hot water a home will receive under every condition.
Actual tankless capacity depends on both demand and required temperature rise.
Water Pressure and Pipe Size Still Matter
A tankless water heater heats water. It does not create water pressure or correct restrictions elsewhere in the plumbing system.
If the house has undersized piping, a restrictive pressure regulator, filtration equipment, a water softener issue or another source of pressure loss, changing the water heater will not make those restrictions disappear.
There is also an important difference between static pressure and dynamic pressure.
Static pressure is what a gauge reads when the plumbing system is not flowing. Dynamic pressure is what the system can maintain while fixtures are actually running.
For a home with multiple bathrooms or high flow fixtures, what happens when several fixtures operate at once is far more useful than a single pressure reading with everything turned off.
The hot water distribution piping matters for the same reason. Pipe diameter, length and layout affect how much water can move through the system and how quickly hot water reaches distant fixtures.
Tankless Does Not Automatically Mean Instant Hot Water
This distinction is important.
Tankless means on demand heating. It does not necessarily mean instant delivery.
If the water heater is in the garage and the primary bathroom is on the opposite side of the house, the water sitting inside that hot water line has to leave before newly heated water arrives.
Installing a tankless heater does not eliminate the physical volume of water inside the piping.
This is where recirculation becomes important.
How Recirculation Changes the System
A dedicated hot water recirculation line returns water from the distribution system back toward the heater, reducing the amount of cooled water that has to be discharged before hot water reaches the fixture.
Some Southern Utah homes already have a dedicated return line. Others were not plumbed with one.
Those homes should not automatically be treated the same way.
For whole home gas tankless installations, Artisan Plumbing primarily installs Navien, and recirculation is one reason. Navien’s NPE A2 ComfortFlow system incorporates a small internal buffer tank, recirculation pump and controls into the tankless unit. Navien states that the system is designed to reduce the cold water sandwich effect and reduce hot water delivery time. [5] Navien
Recirculation still needs to be configured correctly.
Running an external pump continuously is not necessarily better. Navien’s own warranty distinguishes between controlled and uncontrolled recirculation. For qualifying residential NPE A2 installations, its published heat exchanger warranty is 15 years under standard or controlled recirculation versus 5 years under uncontrolled recirculation. [6] Navien
That is a good example of why the water heater and the plumbing around it need to be considered as one system.
Can Tankless Be Paired With a Storage Tank?
Yes.
The choice is not always limited to either a traditional storage water heater or one standalone tankless unit.
Tankless equipment can also be incorporated into a system with supplemental hot water storage.
This can be useful in more demanding applications where the plumbing design benefits from having stored hot water available while tankless equipment provides heating and recovery. The exact configuration depends on the home and its demand.
This is not an improvised concept. Navien publishes specific piping diagrams for NPE tankless systems used with one or more storage tanks. [7] Navien
For most homes, this level of design is unnecessary. But it is important because it demonstrates why large or unusual homes should not be reduced to a simple online sizing chart.
Sometimes the best answer is a water heating system, not a single appliance.
Southern Utah Hard Water Matters
Water quality needs to be part of any serious water heater discussion in Washington County.
Washington City’s drinking water information describes Southern Utah water sources as ranging from hard, at 7 to 10 grains per gallon, to very hard, above 10 grains per gallon. The hardness comes primarily from naturally occurring calcium and magnesium. [8] Digital Library of Utah
Water conditions can also vary by location and water source. The Washington County Water Conservancy District reports that more than 80 percent of the drinking water it delivers comes from surface water, with the remainder coming from groundwater. Municipalities may also blend district water with additional sources. [9] WCWCD
That means we do not assume every house in St. George, Washington or elsewhere in the county has identical water chemistry.
Hard water and tank water heaters
Minerals can accumulate as sediment in the bottom of a storage tank.
The steel tank itself is also protected by an anode rod. Bradford White describes the anode as a sacrificial component that gives up its electrons to help protect the carbon steel tank, with water chemistry affecting how quickly that anode is consumed. [10] Bradford White For The Pro®
Eventually, a conventional storage tank remains a vessel that can corrode and leak.
Hard water and tankless water heaters
Tankless removes the large storage vessel, but it does not eliminate mineral maintenance.
Scale can form inside the heat exchanger and reduce heat transfer and performance.
That is why water treatment and appropriate maintenance matter in Southern Utah regardless of which system is selected.
Tankless should not be sold as maintenance free. Its advantage is a different system design with a longer expected service horizon when it is installed and maintained properly.
Why We Generally Favor Gas Tankless for Long Term Ownership
For many homeowners who expect to remain in their home for years, gas tankless has several meaningful advantages.
It eliminates the large storage tank, takes up very little floor space, provides continuous hot water within its rated capacity and avoids the standby losses associated with keeping a tank full of water hot throughout the day.
DOE reports that on demand water heaters can be 24 to 34 percent more energy efficient than conventional storage water heaters in households using 41 gallons or less of hot water per day. For households using around 86 gallons per day, DOE estimates an 8 to 14 percent advantage. [1] The Department of Energy's Energy.gov
Current ENERGY STAR requirements for certified gas tankless water heaters require a UEF of at least 0.95. [11] Navien’s NPE 240A2, for example, is rated at 0.95 UEF and uses condensing technology with dual stainless steel heat exchangers. ENERGY STAR
Tankless also has a longer expected useful life. ENERGY STAR currently cites a life expectancy of about 20 years for gas tankless water heaters, while manufacturer guidance commonly places traditional tanks around 8 to 12 years. [2][12] ENERGY STAR
Those advantages are why we see tankless as the stronger long term direction for many gas equipped Southern Utah homes.
When a Traditional Tank Still Makes Sense
A conventional tank is not automatically the wrong choice.
If a homeowner wants a straightforward replacement, the current tank system works well for the household, hot water demand is predictable and there is little reason to redesign the surrounding plumbing, another tank may be completely appropriate.
Ownership horizon matters too.
Someone planning to remain in a home for fifteen years may place significant value on the longer expected life, space savings and additional capabilities of a tankless system.
Someone expecting to move relatively soon may reasonably prioritize a simpler replacement.
For conventional tank installations, Artisan Plumbing uses Rheem or Bradford White, with the specific equipment selected according to the fuel type, available space, capacity and conditions of the home.
We do not believe one storage tank is the correct answer for every house.
What About Electric Tankless?
For electric tankless applications, Artisan Plumbing primarily installs Rheem.
Electric tankless has some of the same advantages as gas tankless. It is compact, heats water on demand and eliminates the traditional storage tank.
The major consideration is electrical capacity.
Heating several gallons of water per minute instantaneously with electricity can require a substantial electrical load. As one example, Rheem lists a 208 volt configuration of its 36 kW RETEX 36 at 127 amps with four recommended 40 amp breakers. [13] Rheem
That does not make electric tankless impractical. It simply means the electrical service, panel capacity and desired hot water demand need to be evaluated before selecting equipment.
Gas tankless and electric tankless solve the same basic problem in very different ways.
What Artisan Looks at Before Recommending Tank or Tankless
For a Southern Utah home, we want to understand the whole system, including the number of occupants, realistic simultaneous fixture use, shower and tub flow rates, required temperature rise, dynamic water pressure, pipe sizes, plumbing layout, water heater location, existing recirculation, gas or electrical capacity and water quality.
We also want to know what the homeowner is trying to accomplish.
Running out of hot water is one problem. Waiting too long for hot water at a distant bathroom is another. Poor water pressure is another. Hard water scale is another.
Changing the water heater can solve some of those problems, but it cannot automatically solve all of them.
That distinction is what allows the equipment to be selected around the home rather than expecting the home to work around the equipment.
Tank or Tankless: The Bottom Line
For many gas equipped homes in St. George and throughout Southern Utah, particularly when the homeowner plans to stay long term, we believe a properly designed tankless system is the stronger long term choice.
For whole home gas tankless installations, Artisan Plumbing primarily installs Navien. For electric tankless applications, we primarily use Rheem. When a traditional storage water heater makes more sense, we install Rheem or Bradford White based on the needs of the home.
But the brand and model come after the plumbing is evaluated.
Bathroom count alone is not enough.
A good water heater decision accounts for how much hot water the house actually uses, how quickly that water needs to be heated, how it moves through the plumbing, what happens to pressure under demand, whether recirculation is present and how Southern Utah water will affect the equipment over time.
The best water heater is the one designed to work with the house around it.
Frequently Asked Questions
Is a tankless water heater worth it in St. George, Utah?
For many homeowners who plan to stay in their home long term, yes. Tankless can provide continuous hot water within its rated capacity, save space, reduce standby energy loss and offer a longer expected service life. The home’s plumbing, gas or electrical capacity, recirculation and water quality should still be evaluated before converting.
How many bathrooms can one tankless water heater handle?
There is no reliable answer based on bathroom count alone. A tankless heater should be sized according to simultaneous flow demand and temperature rise. A two bathroom home with several high flow shower fixtures can require more capacity than a four bathroom home with modest simultaneous use.
Does tankless give you instant hot water?
Not automatically. Tankless heats water on demand, but hot water still has to travel through the piping between the heater and the fixture. Plumbing layout and recirculation determine how quickly hot water arrives.
Does Southern Utah hard water affect tankless water heaters?
Yes. Mineral scale can accumulate inside a tankless heat exchanger. Traditional tanks are also affected by hard water through sediment accumulation and the interaction between water chemistry, the tank and its sacrificial anode. Proper maintenance and water treatment should be considered with either system.
Can a tankless water heater be used with a storage tank?
Yes. Manufacturers publish system designs that combine tankless heating with supplemental storage for certain applications. This can be useful in homes with unusual demand or more complex water heating requirements. The configuration should be designed specifically for the application. Navien
Sources
1. U.S. Department of Energy, Energy Saver: Tips on Saving Money and Energy in Your Home. DOE reports the efficiency ranges for on demand water heaters compared with conventional storage water heaters. The Department of Energy's Energy.gov
2. Rheem Manufacturing Company, Water Heater Lifespan: When to Repair vs. Replace and Tank vs. Tankless Water Heater Lifespan Comparison. Current manufacturer guidance places traditional tanks around 8 to 12 years and tankless equipment around 15 to 20 years or more with proper care. Rheem
3. U.S. Environmental Protection Agency, WaterSense Showerhead Specification and Technical Guidance. WaterSense labeled showerheads are limited to 2.0 GPM and EPA guidance addresses multiple showering devices. EPA
4. Navien, NPE 240A2 Technical Specifications. Manufacturer flow ratings illustrate the relationship between temperature rise and available GPM. Navien
5. Navien, NPE A2 ComfortFlow System. Navien documents the integrated buffer tank, recirculation pump and controls used in applicable NPE A2 models. Navien
6. Navien, NPE A2 Residential Warranty. Manufacturer warranty terms distinguish controlled recirculation from uncontrolled recirculation. Navien
7. Navien, NPE 2 Piping Applications. Navien publishes application drawings for tankless systems used with one or more storage tanks. Navien
8. Washington City, Utah, Annual Drinking Water Quality Report. The city describes Southern Utah water sources as ranging from hard to very hard because of naturally occurring calcium and magnesium. Digital Library of Utah
9. Washington County Water Conservancy District, Water Quality. WCWCD describes the region’s surface and groundwater sources and notes that retail providers may blend district water with other sources. WCWCD
10. Bradford White, Water Heater Anode Rods. Bradford White explains the sacrificial anode process and the role water chemistry plays in tank protection. Bradford White For The Pro®
11. ENERGY STAR, Residential Water Heater Key Product Criteria. Current criteria require qualifying gas fired instantaneous water heaters to achieve at least 0.95 UEF. ENERGY STAR
12. ENERGY STAR, Save More with ENERGY STAR Gas Tankless Water Heaters. ENERGY STAR cites approximately 20 years of life expectancy for gas tankless equipment. ENERGY STAR
13. Rheem, RETEX 36 Electric Tankless Water Heater Specifications. Manufacturer electrical specifications demonstrate the electrical demand associated with larger whole home electric tankless systems.
