If you’ve finally decided to end the hot water wars by bringing home a tankless water heater, congratulations! However, before taking the plunge, there’s one more CRITICAL DECISION to make—choosing the type that best suits your needs.
Today, there’s a wide range of tankless water heating systems available, each tailored to meet different requirements. Whether you’re building your dream home or renovating your current space, selecting the right on-demand water heater can be a true game-changer.
In this article, we’ll explore the various types of tankless water heating units, along with their BENEFITS and DRAWBACKS, to help you make an informed choice. Let’s dive in!
1. Electric Tankless Water Heaters
Tankless water heaters are designed to heat water on demand, eliminating the need for a storage tank. They are particularly suited for regions with warmer climates and smaller households where hot water demands are lower and not simultaneous. This makes them an energy-efficient and space-saving option for modern homes.
Electric tankless water geysers work by instantly heating water with thick copper wire rods, without storing the hot water in tanks. Installing these units is relatively simple and more cost-effective compared to other types of water heaters. Here’s the technology behind it.
However, the hot water flow from electric tankless units tends to be weaker, making them less suitable for larger households or situations where multiple hot water devices are used at the same time. In my experience, having used them at home for over five years, it has been a FANTASTIC addition to our household of four. It operates flawlessly, quietly, and has consistently met our needs.
If you can manage with slightly slower water flow, electric tankless heaters are an excellent choice. They are silent, compact, and more eco-friendly, as they rely on electricity rather than gas. Furthermore, their energy efficiency often qualifies them for substantial government rebates, making them an even more appealing option.
Advantages
I recorded significant savings on monthly utility bills, by almost 34%, once I started using an electric tankless water heater at home.
The machine is about the size of a small suitcase – space-saving and looks great because of its sleek, modern design.
I get an endless supply of hot water that does not run out, unlike tank water heaters.
I do not have to wait for hot water – the supply is instantaneous, even without a storage tank.
Disadvantages
The flow of water might not be sufficient to meet the daily high hot water demands of a large household or commercial establishments such as restaurants.
The initial installation cost can seem high but is ultimately balanced out by slashed energy bills in the long run.
2. Gas Tankless Water Heaters
Gas tankless water heaters, unlike electric models, use a HEAT EXCHANGER with a gas burner to instantly warm up water, powered by either natural gas or liquid propane. You can estimate its consumption and cost involvement easily with this calculator and plan your fuel accordingly.
For reliable operation, they require a separate exhaust or venting system and a consistent gas supply infrastructure. These systems are well-suited for handling high hot water demands, making them a popular choice for large residential homes and commercial establishments.
Gas tankless water heaters come in two types: condensing and non-condensing, both of which provide unlimited hot water on demand. Let’s take a closer look at these two subtypes.
A. Condensing Tankless Heaters
Condensing gas tankless water heaters are ideal for meeting HIGH hot water demands, offering a stronger water flow compared to electric models. They are also highly efficient in colder climates with chilled groundwater.
These units CAPTURE and RECYCLE thermal energy from exhaust gases by passing water through an additional heat exchanger before venting the gases outside. This process preheats the incoming water before it reaches the main burner chamber, allowing the unit to operate at a lower BTU while achieving over 90% fuel efficiency. Besides, they maintain the same gallons-per-minute output as similarly sized units. (Calculate BTU for your water heater HERE)
Within the heat exchanger, the exhaust gases are CAPTURED, CONDENSED, and COLLECTED for further use. This not only produces more hot water but also reduces energy waste, making condensing units a sustainable and more cost-effective option.
Advantages
A condensing tankless system is ultra-energy-efficient, achieving a Uniform Energy Factor (UEF) of more than 0.90, helping us save more on our energy bills and optimize operational expenses.
Employing condensation technology results in the formation and supply of more hot water than non-condensing units.
Preheating the incoming cold water reduces the overall time required to supply hot water, which is especially convenient during winter.
Since the vapor from a condensing gas tankless water heater is cooler we can go for budget-friendly venting with conventional PVC pipes, reducing setup costs.
Ideal for the environmentally conscious folks – condensing tankless units are more eco-friendly due to their enhanced efficiency and reduced energy consumption, resulting in a smaller carbon footprint.
Disadvantages
Condensing tankless systems typically involve higher initial setup costs, though it is paid back in the long run.
It needs frequent cleaning and maintenance routines to prevent mineral buildup within the system.
We have to set up a separate drain installation to drain off acidic residues from exhaust gases condensing inside the unit.
B. Non-condensing Tankless Water Heaters
Non-condensing tankless water heaters are a cost-effective and reliable option for homes with moderate hot water demands. They are well-suited for use in mild climates and can easily integrate with existing plumbing systems.
Like condensing models, non-condensing units increase the temperature of water by combusting gas. However, they use only a single heat exchanger and DO NOT capture or recycle residual heat from exhaust gases. Instead, the exhaust gases are expelled directly through the vent, and the water is heated to the desired temperature using the thermal power generated during combustion.
Due to the high temperature of the exhaust gases—often around 150°C—non-condensing units require durable metal venting systems that are both heat- and corrosion-resistant to ensure safety and long-lasting performance.
Advantages
Non-condensing heaters are more popular because of their lower initial cost of setup and minimal maintenance.
These are also highly energy-efficient, achieving UEF greater than 0.80, which is great for our pockets.
We find it easier to install non-condensing tankless heaters than the condensing types. This is because they do not need separate drainage since the exhaust gases do not condense within the system.
These are ideal for compact areas since they occupy very little space and require minimal maintenance.
Disadvantages
This type of gas tankless heaters offers less flexibility in venting materials, being compatible with heat and corrosion-proof metals only, like stainless steel.
The non-condensing variety is less energy-efficient than the condensing models, which leads to relatively higher operational costs.
These are generally less energy-efficient than condensing units, which might make them less environmentally friendly.
Also Read: Condensing Vs Non-Condensing Water Heater Comparison
3. Point-Of-Use Water Heaters
Point-of-use (POU) tankless water heaters are perfect for single applications with lower hot water demands, such as sinks in commercial spaces like restaurants, offices, and airports.
POU units use electrical resistance coils to warm up water to the desired temperature and do not require venting, making them convenient and easy to install.
These compact, on-demand devices heat water only when needed and are typically fitted close to the sink, basin, or appliance they serve. By placing them under a sink or beside a shower, they provide an instant supply of hot water with minimal heat loss during delivery.
At my Donahue’s Welding Shop, I’ve installed a POU tankless heater in the restroom, and it efficiently handles our sudden hot water needs. The heating process is truly instantaneous—there’s no waiting for hot water to flow from the faucet. On top of that, these units are highly energy-efficient, which is a significant advantage.
Advantages
We really enjoy the swiftness with which the POU tankless heater fulfills our frequent hot water demands at the workshop.
The installation part is straightforward – no separate venting is needed; I can install it right at the point of use of hot water (hence the name POU) by mounting it on the wall – consequently, the costs are also low.
These are perfect as decentralized heating fixtures if you want to install a hot tub at home without renovating the entire bathroom.
POU tankless heaters are highly energy-efficient, using electricity only while raising water temperature and minimizing standby heat loss, unlike traditional geysers.
There are no chances of leaks or overheating, which makes them impressively long-lasting – our POU is older than 5 years and still up and running smoothly.
Disadvantages
This type of heater might be inefficient if your daily hot water demands exceed 20 gallons, which makes it unsuitable for large homes.
It might require frequent maintenance and descaling if your locality has hard water.
4. Whole-House Tankless Water Heaters
A whole-house tankless water heater is best suited for large homes to serve multiple bathrooms, laundry, and kitchens or households with very high water usage.
These units are essentially another type of compact, on-demand tankless heating machines that provide hot water for my entire home. Unlike POU heaters that serve individual applications, a whole-house model can EFFICIENTLY supply hot water to multiple faucets, appliances, showers, or even the entire house at the same time.
These models are either electrically operated or gas-powered and typically ensure more stable water temperatures even while serving various applications across the whole house. Given their advantages, I am planning to install a whole-house tankless heating system for my home, in addition to the smaller electrically-powered one I mentioned earlier.
Advantages
If you choose the correct unit size, whole-house tankless water heaters can provide an unlimited supply of hot water throughout the day whenever you need it.
I can be sure that I consistently get hot water that is “hot” and not lukewarm or warm or anything cooler.
Units equipped with scale reduction technology involve minimum hassles for maintenance.
These have a longer lifespan than any conventional water heating system with a tank.
Disadvantages
The initial cost of purchase and installation is higher than traditional tank heaters, including additional expenses for upgrading existing electrical circuits or gas lines at home.
Whole-house tankless heaters typically consume more power to fulfill the higher demand for hot water. So, they might not be as energy-efficient as POU variants.
5. Outdoor Tankless Water Heaters
Outdoor tankless water heaters are specifically designed for installation outside the home, making them an excellent choice for space-constrained residences in mild to moderate climates.
For homes with limited indoor space, an outdoor tankless unit provides a continuous supply of hot water without compromising valuable interior room. Built to endure various weather conditions, these geysers ELIMINATE the need for a separate venting system, further optimizing indoor space.
Outdoor tankless water heaters are available in gas and electric models. However, it’s essential to install them in a well-ventilated area to ensure safe exhaust gas release.
Advantages
The space-saving design of outdoor tankless heaters allows us to cherish hot water in cold winters without letting us bother about the limited availability of indoor space.
Since these units heat water only on demand, they typically consume less energy, helping us save more on our monthly utility bills and lowering our carbon footprint.
This type of tankless water heater is highly durable and can function reliably in different weather conditions like rain, snow, and high temperature.
We do not need to install separate venting systems since they directly drain outside, eliminating any chances of flooding, unlike tank-style heaters.
Disadvantages
We must consider the climate of our area and ensure proper insulation or weatherproofing of the outdoor tankless unit since harsh weather conditions can dampen their efficiency, requiring more maintenance.
6. Recirculating Tankless Water Heaters
Tankless water heaters with recirculating pumps are ideal for large homes and multi-storied buildings, particularly in cold climates, as they ensure hot water is instantly available at consistently high temperatures throughout the home.
Installing a recirculating tankless system is a significant upgrade. It provides an endless supply of hot water on demand while minimizing water wastage. These systems work by CIRCULATING hot water to maintain a constant supply near outlets, preventing the water in the pipes from cooling down. This ensures hot water is readily available at every faucet or outlet, virtually eliminating wait times.
I personally prefer a recirculating tankless heating model because it not only delivers on-demand hot water without delay but also helps reduce water wastage and optimize energy consumption—making it a practical and more eco-friendly choice.
Advantages
Recirculating tankless water heaters eliminate our frustration of waiting for hot water to arrive by ensuring continuous availability at every fixture of our entire household, regardless of how big our home is.
We can significantly lessen the wastage of water because there is no need to wait for the cold water to run until hot water comes out of the faucet.
Constantly recirculating the hot water ensures less energy is consumed to warm up the water, and standby heat loss is also minimized, which translates to savings in our power bills.
Since it prevents wastage and helps conserve water, this can be a wonderful option for eco-conscious homes.
It helps us complete our daily chores conveniently and efficiently, especially in winter, with its continuous supply of hot water.
Disadvantages
Tankless heaters with built-in recirculating pumps are typically more expensive than the other types, which can be a potential drawback for many.
The recirculation pump can use more energy since it continually operates to ensure ready hot water, but newer models have significantly improved energy efficiency.
In conclusion, selecting the right tankless water heater depends on your specific needs (read pros and cons). With a wide range of options available, you can choose a model that prioritizes energy efficiency, instant hot water, or space-saving convenience.
By understanding the various types of tankless water heaters and their unique advantages and drawbacks, you can make an informed decision that ensures your home remains comfortable while keeping utility costs in check.
Quick Recap
Tankless water heaters offer a space-saving and energy-efficient alternative to traditional water heating systems, catering to various household and commercial needs.
Electric Tankless Water Heaters are compact and eco-friendly, ideal for smaller households with lower hot water demands, though they may struggle with simultaneous high usage.
Gas Tankless Water Heaters, including condensing and non-condensing types, efficiently handle larger water demands, making them suitable for big homes and colder climates.
Point-of-Use (POU) Water Heaters are excellent for single applications, providing instant hot water with minimal heat loss and easy installation.
Whole-House Tankless Water Geysers serve multiple faucets and appliances simultaneously, perfect for large families, though they involve higher upfront costs.
Outdoor Tankless Water Heaters free up indoor space and perform well in mild climates, requiring weatherproofing in harsher conditions.
Each type of tankless water heater has its advantages and limitations, requiring careful consideration of your household size, water usage, and budget to select the right one.
