What Is A Tankless Water Heater

Have you ever jumped into the shower only to be met with a stream of icy cold water halfway through? The dreaded cold shower is a common household problem, and often points to an overworked or failing traditional water heater. While those large, cylindrical tanks have been the standard for decades, a more efficient and space-saving alternative is rapidly gaining popularity: the tankless water heater.

Switching to a tankless system offers a multitude of potential benefits, from saving money on your energy bill to enjoying an endless supply of hot water. Understanding how these systems operate, their advantages and disadvantages, and whether they're the right fit for your home is essential for making informed decisions about your household plumbing and energy consumption. Choosing the correct water heating system is not just about comfort but also about saving money and conserving resources.

What are the key things I should know about tankless water heaters?

How does a tankless water heater work compared to a traditional tank heater?

A tankless water heater, unlike a traditional tank heater, heats water on demand rather than storing a reservoir of hot water. When a hot water tap is turned on, a flow sensor activates the tankless unit, which then ignites a high-powered burner (gas) or an electric element to rapidly heat water as it passes through the unit. Once the tap is closed, the unit shuts off, consuming no energy until hot water is needed again.

Compared to traditional tank heaters that constantly heat and reheat a volume of water (usually 40-60 gallons) regardless of whether hot water is being used, tankless systems offer a more energy-efficient approach. Tank heaters are subject to standby heat loss, where heat dissipates from the tank into the surrounding environment, requiring the unit to cycle on periodically to maintain the water temperature. This wasted energy translates to higher utility bills. The on-demand heating of tankless systems eliminates standby heat loss. The water is only heated when it is needed, leading to significant energy savings, especially in households with low to moderate hot water usage. However, it's important to consider that tankless heaters have a limited flow rate, meaning they can only heat a certain amount of water per minute. Depending on the model and incoming water temperature, running multiple hot water appliances simultaneously might exceed the unit's capacity, resulting in a temporary drop in water temperature or pressure. Here's a simple comparison:

What are the main advantages of using a tankless water heater?

The main advantages of using a tankless water heater are on-demand hot water, improved energy efficiency, longer lifespan compared to traditional tank heaters, and space savings due to their compact size.

Tankless water heaters, also known as on-demand water heaters, heat water directly without the use of a storage tank. When a hot water tap is turned on, cold water travels through a heat exchanger, which is activated by a flow sensor. The heat exchanger quickly heats the water to the set temperature. Because they only heat water when it's needed, tankless systems avoid the standby heat losses associated with tank heaters, where water is constantly heated and reheated, even when not in use. This translates to potentially significant energy savings over time, especially in households with low to moderate hot water demand. Another significant advantage is longevity. Tankless water heaters typically last significantly longer than traditional tank heaters, often exceeding 20 years with proper maintenance, compared to the 10-15 year lifespan of a tank heater. While the initial cost of a tankless system can be higher, the extended lifespan can offset this difference over the long term. Finally, their compact size allows for installation in tight spaces where a conventional tank heater might not fit. This can free up valuable floor space in a utility room, basement, or closet.

What size tankless water heater do I need for my home?

Determining the correct size tankless water heater involves calculating your peak hot water demand – the maximum number of hot water appliances you'll use simultaneously – and the temperature rise required to heat the incoming water to your desired output temperature. This will tell you the gallons per minute (GPM) flow rate the tankless unit needs to deliver to meet your household's needs.

To properly size a tankless water heater, start by listing all the appliances you might use at the same time: showers, faucets, dishwashers, washing machines, etc. Each appliance has a specific GPM requirement. For example, a low-flow showerhead might use 1.5 GPM, while a standard showerhead uses 2.5 GPM. A kitchen faucet might use 1-2 GPM. Add up the GPM of all the appliances you anticipate using simultaneously. This is your peak hot water demand. Next, calculate the temperature rise. Subtract your average incoming water temperature from your desired hot water temperature (typically around 120°F). In colder climates, the incoming water can be quite cold, requiring a larger temperature rise. Tankless water heaters are rated by the GPM of hot water they can produce at a specific temperature rise. Finally, consult with a qualified plumbing professional. They can accurately assess your specific needs, factor in local climate and water conditions, and recommend the appropriate tankless water heater size for your home. They can also ensure proper installation, which is crucial for the unit's efficiency and longevity. Oversizing a tankless water heater can lead to inefficiency and higher upfront costs, while undersizing it will result in disappointing performance and cold water sandwiches.

How much does it typically cost to install a tankless water heater?

The typical cost to install a tankless water heater ranges from $2,000 to $5,000, including the unit itself and professional installation. This price can fluctuate depending on several factors, such as the type of unit (electric or gas), the size or flow rate required, the complexity of the installation (existing plumbing and gas line upgrades), and regional labor costs.

Several elements contribute to the overall cost of a tankless water heater installation. The unit itself can range from $500 to $2,500, with gas models typically costing more than electric ones due to their higher BTU output and the need for venting. Installation costs can vary significantly. Electric tankless heaters often require dedicated 240V electrical circuits which can necessitate electrical panel upgrades, adding to the cost. Gas tankless heaters may demand larger gas lines to handle the increased gas flow, as well as new venting systems that meet current safety codes, potentially increasing labor and material expenses. It's crucial to obtain quotes from multiple licensed plumbers or HVAC professionals to get an accurate estimate for your specific needs and home setup. Be sure the quotes include a breakdown of the costs for the unit, materials, labor, permits, and any necessary upgrades to your plumbing, electrical, or gas systems. Consider the long-term energy savings when evaluating the upfront investment, as tankless heaters can significantly reduce energy bills over their lifespan, potentially offsetting the higher initial cost.

What is the lifespan of a tankless water heater?

The typical lifespan of a tankless water heater is significantly longer than that of a traditional tank-style water heater, generally ranging from 20 to 30 years with proper maintenance.

Tankless water heaters achieve this extended lifespan due to their design and operation. Unlike tank heaters that constantly heat and reheat a large volume of water, tankless models only heat water on demand. This reduces wear and tear on the heating elements and other components, minimizing the risk of corrosion and sediment buildup that plague tank-style heaters. Regular maintenance, such as flushing the system annually to remove mineral deposits, is crucial for maximizing the lifespan of a tankless unit. Without this maintenance, hard water minerals can accumulate, reducing efficiency and eventually leading to failure. Factors that can affect the lifespan include the quality of the unit, the hardness of the water, and the frequency of use. Investing in a high-quality unit from a reputable manufacturer and installing a water softener if you have hard water can significantly extend its operational life. Moreover, the intensity of use also plays a role; a unit serving a large household with high hot water demands may experience slightly reduced lifespan compared to one used in a smaller home with lower consumption.

What maintenance is required for a tankless water heater?

The most crucial maintenance task for a tankless water heater is annual descaling or flushing to remove mineral buildup. Regular inspection of air vents and burners for blockages, as well as ensuring proper gas pressure (for gas units), are also important. With these actions, you can maximize efficiency and extend the lifespan of your unit.

The buildup of minerals, particularly calcium and magnesium (scale), is the primary enemy of tankless water heaters. Because water is heated directly as it passes through the unit, minerals precipitate out and accumulate on the heat exchanger. This scale acts as an insulator, reducing heating efficiency, increasing energy consumption, and potentially leading to overheating and premature failure. Descaling involves circulating a descaling solution (typically vinegar or a commercial descaler) through the unit to dissolve these mineral deposits. Depending on water hardness, this should be done annually or bi-annually. Beyond descaling, a visual inspection of the unit is essential. Check the air vents (for gas models) to ensure they are free from dust, lint, and other debris that can obstruct airflow. Blocked vents can lead to incomplete combustion and carbon monoxide production. Similarly, inspect the burner (again, for gas models) for any signs of damage or excessive soot buildup. Finally, verify proper gas pressure to ensure efficient operation. While homeowners can perform basic inspections and descaling (following manufacturer instructions carefully), it’s generally advisable to have a qualified technician perform a more thorough annual inspection and cleaning, especially for gas-fired units.

Can a tankless water heater run out of hot water?

While technically a tankless water heater *can* experience limitations that might feel like running out of hot water, the key difference is that it doesn't deplete a stored supply like a traditional tank heater. Instead, the issue arises when the demand for hot water exceeds the unit's maximum flow rate or the incoming water temperature is too low.

Unlike tank water heaters which store a finite amount of hot water, tankless heaters heat water on demand. When you turn on a hot water tap, cold water travels through a heat exchanger in the unit, which is then rapidly heated by a high-powered burner (gas models) or electric element. The heater will continue to produce hot water as long as the demand doesn't exceed its capacity. If you try to run too many hot water appliances simultaneously (e.g., a shower and a dishwasher) the flow rate might exceed the heater's capabilities, resulting in a noticeable drop in temperature or a complete loss of hot water at one or more outlets. Similarly, if the incoming cold water is exceptionally cold, the heater may struggle to raise the temperature to the desired setting, particularly with high flow rates. Proper sizing is crucial for a tankless water heater. A unit that's too small for a household's typical hot water demands will frequently struggle to keep up, leading to frustrating experiences. A professional plumber can assess your needs, taking into account factors like the number of occupants, the number of hot water fixtures, and the local climate (which affects incoming water temperature), to recommend the appropriate size and model for your home. Choosing the right size tankless heater is essential to ensure a continuous and reliable hot water supply.

So, there you have it – a quick rundown on tankless water heaters! Hopefully, this has helped you understand what they are and how they work. Thanks for taking the time to learn a little more, and we hope you'll come back and visit us again soon for more helpful tips and insights!