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From cooking and bathing to cleaning and heating, water heating accounts for about 18% of a home’s energy use and is typically the second largest energy expense in any home, according to the U.S. Department of Energy. Appliances that require hot water include washing machines, dishwashers, showers, sinks, hydronic heating systems, radiant heaters, and even pools and spas.
The standard options for builders and remodelers are propane- or gas-powered tankless or storage tank water heaters, electric storage tank water heaters, and electric heat pump water heaters. Propane and gas water heaters are available in condensing and non-condensing designs, which can impact efficiency and operating costs.
Benefits of Propane Tankless Water Heating
Propane tankless water heaters offer on-demand, continuous hot water. Because they do not store hot water in a tank, they do not experience standby heat loss, therefore have lower long-term energy costs, as they only heat water when needed. While the upfront costs are typically higher, propane-powered tankless water heaters have a life expectancy of about 20 years, much longer than any conventional storage water heater.
In addition, this equipment does not require a storage tank, offering builders and homeowners significant space savings. The compact size of tankless water heaters allows them to be wall-mounted indoors and out , saving up to 16 square feet of floor space, and they can even be installed in a small space such as a closet, provided there is adequate ventilation.
Propane tankless water heaters provide an endless supply of hot water, averaging over 200 gallons per hour. Conversely, the average 50-gallon electric storage tank water heater has a first-hour delivery rating of just 64 gallons, while a 50-gallon heat pump water heater averages about 67 gallons. These rates are less than one-third of the delivery rate for propane tankless systems.
In cold and mixed climates, propane tankless water heaters have the lowest annual cost of ownership when compared with electric, heat pump, and heating oil-fueled water heaters, with up to 50% cost savings compared with electric options. They can cost up to $100 less annually to operate compared with electric heat pump water heaters (HPWHs), which have less than one-third the hot water flow rate of a tankless system.
Electric HPWHs also have a shorter lifespan than tankless water heaters at 10-15 years versus 15-20 years. These models have makeup air requirements, require a higher vertical clearance, and at least 1,000 cubic feet of space around them. Plus, without external venting, a HPWH will cool the air within that surrounding space, potentially increasing the demand on the space-heating system.
Recirculation system
Although tankless water heaters are sometimes referred to as “instantaneous” water heaters, the delivery of hot water to the fixtures is comparable to traditional models. However, building pros can deliver the instant hot water their customers desire by pairing a hot water recirculation system with a tankless water heater.
When activated, this system circulates hot water through the pipes, ensuring instant access and minimizing the amount of water wasted while waiting for it to heat up, thus saving water and potentially lowering water bills. The recirculation system does add to the cost but it provides long-term benefits and added convenience.
Benefits of Propane Storage Tank Systems
Propane-powered storage tank systems can heat a large volume of water at once and keep it at a comfortable 120 degrees. Like tankless water heaters, they are desirable for large families or those with numerous appliances that require hot water.
Homeowners will also appreciate their many benefits over electric tank-style units:
- A 40-gallon propane unit can deliver as much water as a comparable 50-gallon electric unit. This is because propane storage tank heaters are generally more efficient and heat water faster than electric storage tank units, increasing the availability of hot water.
- Propane-powered water heaters also have a faster recovery rate, which is the time it takes to heat the water back up after it’s been used.
- Larger electric tanks experience greater efficiency losses (thermal losses to the surrounding area) due to their greater surface area.
- Propane units can have lower long-term operating costs compared to heating oil or electric storage tank units, although the upfront costs may be slightly higher.
- What is the size of your household and how frequently do you have guests?
- What is the longest shower someone typically takes in your house?
- How many showers does your household typically take back-to-back? Or at the same time?
- What is the square footage of your home? This may determine whether multiple tankless units are required or the size of the tank-style system you will need.
- What appliances will be served by a propane water heater? Choose all that apply
- Do you anticipate using the hot water for several appliances simultaneously, such as showering, laundry, and home heating?
- Where do you plan on the water heater being installed? How much space do you have to install the water heater?
When compared to propane tankless systems, storage tank systems are typically more affordable than tankless systems upfront, with lower purchase and installation costs. However, they don’t have the lifespan of tankless systems and may cost more in the long run.
Both propane tankless and storage tank water heaters can be integrated into hybrid hot water systems to create an even more efficient and reliable dual-fuel system.
Non-Condensing vs. Condensing Models
Manufacturers offer propane and gas storage tank and tankless water heaters in both non-condensing and condensing models. Non-condensing water heaters use propane to create enough energy to heat the water, with the exhaust vented to the outside. Condensing water heaters absorb additional heat from the exhaust gases while heating water. They require less energy to heat the same amount of water and give homeowners more venting options because the exhaust is cooled down before being vented.
While non-condensing systems can have lower upfront costs, condensing water heaters are more energy efficient and can reduce operating costs, especially for higher-volume uses. “Essentially, condensing water heaters can absorb some of the heat from exhaust gases after the combustion process, which would have been wasted in a non-condensing water heater,” according to Intellihot. Electric water heaters do not have this capability, since they do not combust fuel to release energy.
Which Style Should You Choose?
Applications, frequency of use, and space constraints will determine whether to install a tankless or tank-style water heater.
Learn the appropriate questions you should pose to your clients before deciding which one to purchase:
With the answers in hand, you’ll be able to confidently recommend a water heating option that your client will love to live with.