4 Advice to Choose a Hot Water Boiler System

14, Jul. 2025

 

Selecting a New Water Heater | Department of Energy

It's a good idea to know the different types of water heaters available before you purchase one:

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  • Conventional storage water heaters offer a ready reservoir (storage tank) of hot water which is adequate for everyday use. However, there are some instances, such as when more than one use for hot water is occurring or when there are guests in the home, increasing the requirements for hot water.
  • Tankless or demand-type water heaters heat water directly without the use of a storage tank. This type of water heater is designed to provide an adequate supply of hot water without running out when adequately sized.
  • Heat pump water heaters move heat from one place to another instead of generating heat directly for providing hot water, resulting in high efficiencies and significant cost savings.
  • Solar water heaters use the sun's heat to provide hot water and also save money on energy bills.
  • Tankless coil and indirect water heaters use a home's space heating system to heat water.

Selection Criteria

When selecting a replacement water heater for your home, consider the following:

  • Fuel type, availability and cost. The fuel type or energy source you use for water heating will not only affect the water heater's annual operation costs but also its size and energy efficiency. See below for more on selecting fuel types.
  • Size. To provide your household with adequate hot water and maximize efficiency, you need a properly sized water heater. Visit the pages on different types of water heaters (linked above) for more on sizing.
  • Energy efficiency. To maximize energy and cost savings, check the energy efficiency of a water heater before you purchase it. Visit the pages on different types of water heaters (linked above) for more on estimating energy efficiency.
  • Costs. Before you purchase a water heater, it's also a good idea to estimate the annual operating costs and compare those costs with other less or more energy-efficient models. Visit the pages on different types of water heaters (linked above) for more on estimating costs.

Also be sure to examine ways to reduce your hot water use, such as washing clothes in cold water. You may also want to explore other options such as drain-water heat recovery to save money on your water heating bill.

Fuel Types, Availability and Costs for Water Heating

When selecting a new water heater, it's important to consider what fuel type or energy source you will use, including its availability and cost. The fuel used by a water heating system will not only affect annual operation costs but also the water heater's size and energy efficiency.

Exploring Water Heater Options by Fuel Type

Fuel type and its availability in your area may narrow your water heater choices. The following is a list of water heater options by fuel or energy source:

  • Electricity
    Widely available in the United States for conventional storage, tankless or demand-type, and heat pump water heaters. It also can be used with combination water and space heating systems, which include tankless coil and indirect water heaters.
  • Fuel oil
    Available in some areas of the United States to fuel conventional storage water heaters, and indirect combination water and space heating systems.
  • Geothermal energy
    Available throughout the United States to those who will have or already have a geothermal heat pump system installed in their homes for space heating and cooling. See Heat Pump Water Heaters for more information.
  • Natural gas
    Available in many areas of the United States to fuel conventional storage and demand (tankless or instantaneous) water heaters, as well as combination water and space heating systems, which include tankless coil and indirect water heaters.
  • Propane
    Available in many areas of the United States to fuel conventional storage and demand (tankless or instantaneous) water heaters, as well as indirect combination water and space heating systems.
  • Solar energy
    Available throughout the United States -- most abundantly in the Southwest -- for solar water heaters.

Comparing Fuel Costs and Water Heater Types

If you have more than one fuel type available in your area, it's a good idea to compare fuel costs, especially if you're building a new home. Even if you're replacing a water heater, you may find that you'll save more money in the long run if you use a different fuel or energy source.

However, if you are converting from one fuel type to another, there are other cost considerations, such as adding a breaker or running a gas line to the water heater and venting it outside. Contact your utility for current fuel costs or rates.

The type of water heater you choose will also affect your water heating costs. One type of water heater may use a fuel type more efficiently than another type of water heater. For example, an electric heat pump water heater typically is more energy efficient than an electric conventional storage water heater.

Also, an electric heat pump water heater might have lower energy costs than a gas-fired conventional storage water heater, even though local natural gas costs might be lower than the electricity rates.

Best Water Heater Buying Guide - Consumer Reports

Consumer Reports recently tested several electric and gas whole-house tankless water heaters from brands such as Bosch, Navien, Noritz, Rheem, Rinnai, Tempra, and Trutankless. We compared the results with those of conventional tanked heaters from Rheem, one gas and one electric, as well as with a Rheem electric heat pump water heater, which is a variation on a tanked water heater.

Following a "heavy use" industry standard test, we compared the performance of gas and electric tankless water heaters with the performance of their conventional tank counterparts. The test used a high draw pattern equal to using 84 gallons of water per day. That’s the daily equivalent of taking several showers, running the dishwasher, washing one load of laundry, and turning the faucet on and off multiple times. The test used an inlet temperature of 58° F for gas models and 74° F for electrics (plus or minus 2° F) and a target outlet temperature of 120° F.

Because the tankless water heaters performed so similarly to each other, we averaged the results of each batch, gas and electric, and compared that score with the performance of the conventional gas and electric storage tanks and the electric heat pump model. As a result, we have no model-level ratings like we do with other major appliances.

Using the purchase price, annual energy cost, and an estimated cost of installation, we calculated the payback time for both new and replacement installations. Payback time was longer for a tankless unit that replaced an existing storage tank but more reasonable with new construction. 

Contact us to discuss your requirements of Hot Water Boiler System. Our experienced sales team can help you identify the options that best suit your needs.

Check our gas and electric water heater ratings for more.

Tank water heaters typically hold 40, 50, or 55 gallons or more. The size you buy depends on the number of people living in your home and your peak water usage. A family of four, for instance, might take several showers, run the dishwasher, and wash a load or two of laundry in an average day, totaling 100 gallons of hot water or more. But that doesn’t mean that household needs a 100-gallon storage tank.

For storage tank water heaters, it’s important to consider the first-hour rating, which is the number of gallons a water heater can deliver in an hour starting with a full tank. You’ll find the FHR on the EnergyGuide label. To calculate what FHR will work for your home, use the calculator on the Energy Saver website.

As the result of recently updated efficiency standards, water heaters less than 55 gallons now have a 4 percent boost in efficiency and water heaters 55 gallons or more have efficiency gains of 25 to 50 percent, depending on the technology used—heat pump or condensing. (See water heater types, below.)

And don’t assume that a new water heater will fit where your old one was. Because of increased insulation and other efficiency improvements, some newer models may be wider and/or taller than your old water heater.

Tankless water heaters, of course, don’t hold much water, so the number to look for is the gallons-per-minute rating (GPM). That’s the number that tells you how much hot water the heater can deliver over a set period of time. The higher the GPM, the more hot water the unit can deliver. If you have a big family and multiple bathrooms, you’ll need a tankless water heater with a higher GPM. A typical shower, for example, uses up to 2.5 GPM. Newer washers use from 7 gallons (front-loader) to 19 gallons (agitator top-loader) per wash, but older models can use up to 32 gallons per load, as indicated below. Calculate your needs accordingly.

For more, you can check our water heater ratings.

Warranty: Coverage for water heaters typically runs three to 12 years. Though you’ll usually pay a bit more for longer-warranty models, we’ve found that they tend to have larger elements or burners that can speed up water heating and have thicker insulation for less heat loss. Choose a water heater with the longest warranty available.

Anti-scale devices: Some brands advertise features that are supposed to reduce buildup of mineral scale at the bottom of the tank by swirling the water. Though scale can shorten the life of the heating element, you don’t need to invest in fancy features to get a water heater that lasts. Just look for one with a 12-year warranty, which typically includes a longer or thicker element.

Brass vs. plastic drain valves: These are situated near the base of the water heater for a garden hose that drains the heater. Look for brass drain valves, which are more durable than plastic.

Glass-lined tanks: They’re designed to reduce corrosion.

Digital displays: These help you monitor levels and customize operation. Some electric/heat pump hybrid water heaters let you set a vacation mode that uses just the heat pump for added efficiency when you’re away. Displays on solar water heaters often show tank and collector temperatures, along with pressure readings and other info.

For more information, please visit Commercial Boiler Systems.