Tankless or Demand-Type Water Heaters
Known as demand-type water heaters or instantaneous water heaters, tankless water heaters supply hot water only when it is required. They do not generate the standby energy losses typical with storage water heaters, which can result in significant savings in energy costs. You’ll learn the fundamentals of how they function, if a tankless water heater is a good choice for your house, and what factors to consider when choosing the best model for your needs. Take a look at theEnergy Saver 101: Water Heating infographic to determine whether a tankless water heater is the best option for you, and our AskEnergySaver conversation on water heating for additional information on energy-efficient water heating.
How They Work
Tankless water heaters provide fast heating of water without the need for a storage tank. When a hot water faucet is switched on, cold water is sent through a heat exchanger in the unit, where it is heated by either a natural gas burner or an electric element, depending on the device. Consequently, tankless water heaters are able to provide a continuous supply of hot water. The need to wait for a storage tank to fill up with adequate hot water is no longer an issue. The output of a tankless water heater, on the other hand, is limited in terms of flow rate.
Tankless water heaters that run on natural gas have higher flow rates than those that run on electricity.
For example, having a shower while also running the dishwasher at the same time might cause a tankless water heater to reach its maximum capacity quickly.
You may also install separate tankless water heaters for equipment in your house that need a lot of hot water, such as a clothes washer or dishwater.
Demand water heaters are also used in the following other situations:
- Bathrooms or hot tubs in a remote location
- Increases the efficiency of household appliances such as dishwashers and laundry washers. Thermoelectric booster for a solar water heating system
Advantages and Disadvantages
Demand water heaters can be 24–34 percent more energy efficient than typical storage tank water heaters in residences that utilize 41 gallons or less of hot water per day on average. For houses that utilize a lot of hot water – around 86 gallons per day – they can be 8 percent to 14 percent more energy efficient than standard models. If you install a demand water heater at each hot water outlet, you may be able to achieve even larger energy savings in some circumstances. A tankless water heater will cost more up front than a normal storage water heater, but they will often live longer and have lower operating and energy expenses, which may more than compensate for their higher purchase price in the long run.
- They also feature readily changeable parts, which might potentially increase their lifespan by many years.
- With tankless water heaters, you won’t have to worry about the standby heat losses that come with traditional storage water heaters.
- When compared to a storage water heater, the removal of standby energy losses might sometimes outweigh the savings from using a tankless water heater.
- A tankless water heater’s pilot light has a cost associated with it that differs from one type to the next.
Instead of a standing pilot light, look for versions that contain an intermittent ignition device (IID). This mechanism is similar to the spark ignition system used on certain natural gas furnaces, as well as kitchen ranges and ovens, among other things.
Selecting a Demand Water Heater
Before purchasing a demand water heater, you should take the following factors into consideration:
- Consider the following factors as well when purchasing a demand water heater:
Installation and Maintenance
It is possible to maximize the energy efficiency of your demand water heater with proper installation and maintenance. A variety of elements influence the success of an installation. These considerations include the type of fuel used, the environment, the needs of local construction codes, and safety concerns, particularly with regard to the combustion of gas-fired water heaters. As a result, it is recommended that you use a licensed plumbing and heating professional to install your demand water heater.
- Request written cost estimates, as well as contact information for references. Check with your local Better Business Bureau to see whether the firm is legitimate. Check to see if the firm will seek a local permit if one is required and if they are familiar with local building rules.
If you’re determined to install your water heater yourself, first speak with the manufacturer about the best way to proceed. The relevant installation and instruction manuals are normally available from the manufacturer. Contact your municipality for information on acquiring a permit (if one is required) and on water heater installation codes in your area. Periodic water heater maintenance may considerably increase the life of your water heater while also reducing the amount of energy it consumes.
Improving Energy Efficiency
If you’re determined to install your water heater yourself, first speak with the manufacturer about the best method to use. Installer and instruction manuals are often available from the manufacturer. Contact your municipality for information on acquiring a permit (if one is required) and on water heater installation codes in your particular area. The use of periodic water heater maintenance may considerably increase the life and efficiency of your water heater while also lowering energy costs.
Solved! How Does A Tankless Water Heater Work?
Image courtesy of istockphoto.com
Q: I recently moved to a home with a tankless water heater, and I want to make sure I’m correctly maintaining it. How does a tankless water heater work, and what issues should I look out for?
A:Tankless water heaters are becoming increasingly popular in new construction. In contrast to storage tank heaters, which store large volumes of hot water in an insulated water tank that can be utilized at any time, tankless water heaters may provide hot water on demand as necessary. As long as cold water enters the tankless unit and departs practically quickly, it will be heated to the desired degree. In either case, depending on whether the water heater is fueled by natural gas or by electricity, it heats the water through the use of a gas burner or electrical resistance heating coils.
This is due to the fact that they are more efficient over a longer period of time.
Are you interested in having a tankless water heater installed in your home? A highly regarded professional can assist you. Get free, no-obligation project quotes from local specialists in your area.+
Tankless water heaters heat water directly without using a storage tank.
Image courtesy of istockphoto.com Heaters with a water tank, such as the traditional kind, can store hot water over time and be utilized at a moment’s notice. Tankless water heaters eliminate the need to store water in order to distribute it throughout the house. When a hot water faucet in the home is turned on, cold water is sent through the tankless heater. It is heated by a gas burner or an electric heating coil as it passes through the device on its journey. It is then supplied to each individual tap in the house.
Because there is no need for a tank to hold water, a tankless heater may be attached on a wall with relative ease.
Maintain the peak performance of your tankless water heater.
Get free, no-obligation project quotes from local specialists in your area.+
Tankless water heaters deliver a constant flow of hot water: about 2 to 5 gallons per minute.
Water heaters that have a storage tank may produce hot water until the tank is completely depleted of water. A tankless water heater provides a constant supply of hot water at a rate of 2 to 5 gallons per minute, allowing a residence to have a constant flow of hot water. Some gas-powered tankless heaters are capable of producing even larger water flows than electric tankless heaters. A storage tank heater, on the other hand, is more likely to run out of hot water than a tankless heater, especially when numerous sources are consuming the water at the same time.
The water may not be as hot or it may be discharged with less pressure if someone is having a shower and running the dishwasher at the same time.
Also possible is the installation of separate heaters for different equipment.
The panel adjusts the gas valve, the mixing valve, and the water flow to achieve the desired temperature setting.
The majority of tankless water heaters are equipped with a front-facing control panel that allows the user to adjust the heater’s settings. This panel allows homeowners to fine-tune the gas value to precisely match the amount of gas they want to consume. Panels can also be used to regulate the quantity of power used by electric tankless heaters. Water, electricity, and natural gas bills may be more easily managed as a result of this. The tankless water heater panel also allows for the customization of many parameters, such as the mixing value and the volume of water that is circulated.
If a homeowner does not have a specific purpose for making a significant change to their settings, they should avoid making radical changes.
Is it difficult to figure out what’s wrong with your tankless water heater? A highly regarded professional can assist you. Get free, no-obligation project quotes from local specialists in your area.+
Some common issues with tankless water heaters include system overload, blockages, and ignition failure.
In spite of the fact that tankless water heaters are acclaimed for their overall efficiency and require less maintenance on average than storage tank water heaters, they are not without their drawbacks. As previously stated, if homeowners use too many hot water applications at the same time, the unit may get overloaded. After that, the system will have difficulty supplying hot water and may even fail completely. This problem, on the other hand, may usually be prevented by the use of thoughtful or preventive behaviors.
When this occurs, the heater is experiencing difficulties venting, which can potentially result in an overflow of the system.
Another typical issue is when the tankless heater fails to ignite for a variety of reasons.
Gas and water valves should be checked to ensure they are not completely open, as this is frequently the root source of the problem.
Regular maintenance keeps water flowing and removes mineral buildup.
Tankless water heaters are not without their drawbacks, despite the fact that they are commended for their overall efficiency and need less maintenance than storage tank water heaters. Using too many hot water applications at the same time, as previously stated, might cause an overload in the system. If the system cannot provide enough hot water, it will struggle to keep up and may even fail completely. In most cases, however, this may be avoided by engaging in thoughtful or preventive behaviors.
When this occurs, the heater is experiencing venting difficulties, which might result in an overload.
The failure of the tankless heater to ignite is another prevalent concern.
Gas and water valves should be checked to ensure they are not completely open, as this is typically the major cause of failure.
If you’re experiencing persistent issues with a tankless water heater, call a professional.
Tankless water heaters are generally simple to operate and need little maintenance during their lifetime. It is possible, however, that they will develop problems or complications outside of their usual maintenance. Any homeowner who notices that any of the concerns listed above are occurring on a frequent basis should contact a professional plumber who can quickly examine the situation and discuss the best remedy with the homeowner. Find dependable local contractors for any home improvement project+
How a Tankless Water Heater Works
Tankless water heaters operate in a completely different way than tanked water heaters, and as a result, have entirely distinct components. As opposed to maintaining a significant supply of hot water in storage, the water heater only comes on when there is a need for hot water, such as when a shower or a faucet is switched on. Consequently, instead of heating the water continuously throughout the day and night, the tankless water heater is turned off until it is required. When the tankless system detects that it is in need of hot water, a burner is activated inside the system.
It is necessary to turn off the hot water in order for the system to operate in standby mode.
Here are some animated animations that demonstrate the differences between a tanked water heater and a tankless water heater. As a guideline, the following steps will help you better understand how a tankless water heater operates:
STEP 1 – Hot water tap is turned on
Making sure hot water is flowing through your pipes is essential, and this entails turning on the hot water. The reality is that this isn’t always the case these days, either. If your faucet just has a single knob, make sure you turn it in the direction of the hot water. It’s considerably easier if you have two knobs instead of one. Find the hot water knob and turn it to the on position to allow hot water to flow through.
STEP 2 – Water enters the heater
Making sure hot water is flowing through your pipes is essential, and this entails turning on the water heater. That is not always the case, of course, in the modern day. Turn the knob in the direction of the hot water if you only have one. You can make things much simpler if you have two knobs. Locate the hot water knob and turn it to the on position to allow hot water to flow through the faucet.
STEP 3 – Water flow sensor detects the water flow
Now that the internal computer has been activated, it quickly calculates how hot the burners must be in order to get the water up to the proper temperature for drinking. This can be accomplished through the use of a gas burner or an electrical element. In any case, it ensures a steady supply of hot water, eliminating the need to wait for a tank to refill with hot water.
STEP 4 – Computer automatically ignites the burner
As soon as the internal computer has been activated, it quickly calculates how hot the burners need to be set in order to get the water up to the proper boiling point. This can be accomplished through the use of a gas burner or an electrical component. No matter whether method is used, it ensures a steady supply of hot water without the need to wait for a tank to refuel.
STEP 5 – Water circulates through the heat exchanger
With a tankless water heater, you’ll have a limitless supply of hot water to use whenever you need it. When there is no longer a need for hot water, the tankless water heater automatically shuts down and ceases to use energy. As a result, you will benefit from energy savings as well as consistent and fresh hot water. In order to make an informed choice about whether or not to switch to a tankless water heater, it’s vital to understand how they operate. Not only do you want to understand how it works, but you also want to know what the advantages of using a tankless water heater would be.
In addition to the money benefits, many consumers choose tankless water heaters since they consume less energy than traditional tank water heaters when in operation.
Tankless Water Heaters: 7 Pros and 6 Cons You Should Know
Compared to typical tank-style water heaters, tankless water heaters, also known as on-demand or instant water heaters, provide a number of advantages and can be a good long-term investment. However, like with every product, they have their drawbacks, and they are not the best answer for every household situation. Tankless water heaters, in contrast to classic tank-style water heaters, which continually consume electricity to provide a hot water supply, only consume energy when you switch on a hot water faucet or when you use appliances.
In addition to the energy and cost savings, there are a number of other advantages to using a tankless water heater rather than a typical tank-style heater.
The most important drawback of tankless water heaters is that their upfront cost (both for the device and for installation) is substantially greater than that of tank-style water heaters (see chart below).
On average, tankless water heaters are three times more expensive than traditional tank-style water heaters, including installation. Tankless water heaters offer a number of drawbacks as compared to traditional tank-style water heaters, in addition to their high initial costs:
- They take longer to supply hot water
- The temperature of the water is variable when numerous outlets are turned on at the same time
- And they are unable to deliver hot water during a power outage
Making the decision to purchase a tankless water heater is a challenging one, so it’s critical that you grasp all of the facts before making a final decision. The purpose of this essay is to give you with a complete summary of the advantages and disadvantages of tankless water heaters so that you can make an informed decision based on your specific scenario. Let’s get this party started. To jump to a certain part, simply click on one of the links below. The Benefits of Tankless Water Heaters include the following:
- Energy and cost savings over the long run are a plus. Pros: an unlimited supply of hot water
- A smaller footprint
- A lower risk of leaks and water damage
- And a lower cost. Advantage: There is no danger of the tank exploding. Benefits include a reduced risk of burns and exposure to toxic metals. Pro: A life expectancy of more than 20 years is expected.
The disadvantages of tankless water heaters are as follows:
- The unit and installation are expensive up front, which is a disadvantage. Cons: It takes longer for hot water to be delivered. Cons: Sandwich made with cold water
- If more than one outlet is used, the water temperature does not remain constant. The disadvantage is that it is difficult to get a lukewarm temperature. During a power outage, there is no access to hot water
- Disadvantage The bottom line: Is a tankless water heater a good investment?
Pro: Long-term Energy and Cost Savings
The most significant advantage of tankless water heaters is that they are energy efficient and so save you money over the long term of ownership. When a tank-style water heater is in use, it expends energy continuously to maintain the temperature of a 40 to 50-gallon water supply in order to ensure that hot water is available when it is required. In contrast to traditional water heaters, tankless water heaters heat water on demand rather than maintaining a constant supply of water. The lack of standby heat loss caused by tankless water heaters eliminates the need for regular warming of the water.
- It takes only seconds for the water to be heated and then circulated throughout your home through the pipes, where it is used to flush toilets and wash dishes.
- Water use and the efficiency of your prior tank-style system determine the amount of energy you will save.
- An electric tankless water heater is 24 percent – 34% more efficient than an equivalent gas tank-style heater when you consume less than 41 gallons of hot water per day.
- This is because they are running more often.
- You can save anywhere between 27 percent and 50 percent.
Pro: Unlimited Supply of Hot Water
Consider the following scenario: you return home from a day at the beach with your family and everyone in the house has to shower. The hot water has ran out after the sixth shower in a row, leaving you with no choice but to take a cold shower. That scenario will never occur if you have a tankless water heater installed. Allow me to explain. For each tankless water heater, there is a maximum flow rate; in other words, each tankless water heater can only heat a particular volume of water at any given moment.
For the time being, tankless water heaters provide an unending supply of hot water, provided that your water use is less than the maximum permissible flow rate at any one moment.
Taking a shower for 10 hours (or more) with a tankless water heater will result in water that is as hot as taking a 10-minute shower. This is because tankless water heaters function by heating water from an external source on demand.
Pro: Take Up Less Space
Tankless water heaters are quite advantageous if you have a limited amount of available space in your house. When compared to tank-style water heaters, they are often attached to the wall and take up substantially less physical area than they do. To give you an idea of how tankless and tank-style water heaters compare in terms of size, the average 40 to 50-gallon tank-style heater is 54 to 60 inches tall with a 20-inch diameter and is shaped like a cylinder. Tankless water heaters, on the other hand, are smaller in size and are typically smaller in capacity.
Tank-style (on the left) versus Tankless (on the right) (right) Unlike tank-style heaters, which take up valuable floor space and are typically found in the basement, tankless heaters are fixed to the wall like a circuit breaker and may be stored in most closets.
Pro: Lower Risk of Leaks and Water Damage
One of the most serious concerns associated with tank-style heaters is that minerals from hard water accumulate within the tank over time, causing corrosion and, eventually, leaks. The absence of a tank means that there is no possibility of leaks or floods with a tankless water heater. This does not rule out the possibility of problems with tankless water heaters. There is a potential that they will encounter issues that will result in leakage, but the likelihood of experiencing a huge leak that floods your whole basement and causes severe damage is remote.
Pro: Zero Risk of Tank Exploding
The current plumbing code mandates that all tank-style water heaters be equipped with a temperature and pressure relief valve, which opens to relieve pressure and prevent the tank from bursting. Temperature and pressure relief valves are two types of relief valves. Minerals and silt from the water might block the valve and prevent it from performing its job effectively over time. When this occurs, a potentially hazardous amount of pressure might build up, putting you in danger. If you have a tank-style water heater, experts recommend that you test the valve at least once a year; find out how to do so in the video below.
Tankless heaters, on the other hand, do not have a tank, thus there is absolutely no possibility of an explosion ever occurring.
Pro: Lower Risk of Burns and Exposure to Toxic Metals
The use of tankless water heaters, according to many experts, is safer than the use of traditional tank water heaters. Beyond the fact that they do not have a tank that may explode, they also offer more accurate temperature control, which means you are less likely to get burnt by hot water when using them. Additionally, as previously stated, tank-style heaters fail over time owing to hard water, which causes the inside lining of the tank to rust and corrode, leading the heater to fail. That mineral buildup and particle accumulation ultimately finds its way into your water pipes, exposing you and your family to potentially dangerous pollutants.
In addition, because tankless water heaters do not store water in a corrosion-prone tank, the water they distribute throughout your house is purer and safer for your skin to drink.
Pro: Life Expectancy of Over 20 Years
I recently released an essay on the issue of how long water heaters last and how to extend the life of your water heater. I hope you will find it informative. Tank-style water heaters have an average lifespan of 8 to 12 years; tankless water heaters, on the other hand, have an average lifespan of more than 20 years. If you’ve already found your “forever home” or want to remain in your current location for an extended period of time, investing in a tankless water heater will prevent you from having to replace your water heater for an extended period of time.
Con: High Upfront Cost of the Unit and Installation
The most significant disadvantage of tankless water heaters is the large initial investment required for the device and its installation. According to HomeAdvisor, the typical cost of a tank-style water heater with a capacity of 40 to 50 gallons, including installation, is $889. Installation of a tankless water heater costs around $3,000 on average. Tankless water heaters are more expensive than traditional water heaters, mostly because of greater installation expenses. Often, more wiring must be added in order to manage the higher load, and/or a new vent pipe must be erected to accommodate the increased load.
Tankless water heaters can also be harmed by hard water (water that contains high quantities of minerals), which makes them work harder and finally fail.
The cost of installing this additional component is added to the total cost of the project.
Please keep in mind that the prices shown above do not include installation.
- Rheem Performance Platinum 9.5 GPM Natural Gas High-Efficiency Tankless Water Heater
- Rheem Performance Plus 8.4 GPM Natural Gas Indoor Tankless Water Heater
- Rheem Performance Platinum 9.5 GPM Natural Gas High-Efficiency Tankless Water Heater Rinnai High-Efficiency Plus is a high-efficiency water heater. Natural gas tankless water heater with a flow rate of 11 GPM
Water Heaters in the Form of Tanks (links open listings on HomeDepot.com)
- Rheem Performance 40-gallon tall natural gas tank water heater with a 6-year warranty and 36,000 BTUs of output
- Rheem Performance 30 gal. short 6 year natural gas tank water heater with 30,000 BTUs
- Sure Comfort 40 gal. tall natural gas tank water heater with a 3-year warranty and 34,000 BTUs of output
Con: Take Longer to Deliver Hot Water
Another disadvantage of tankless water heaters is that they create and supply hot water at a slower rate than traditional tank-style water heaters, which increases energy costs. Keep in mind that tankless water heaters do not maintain a constant supply of hot water that is ready to be used whenever you want it. When you turn on a hot water faucet, the water in the pipes is either cold or, at best, room temperature since it is not being used. Once the chilly water has been drained out, hot water will begin to flow through the faucet; however, it may take anywhere from a few seconds to a minute depending on the distance between the heater and the faucet.
The hot water produced by tank-style heaters is not instantaneous, but because they have a supply ready to go and do not require activation, it reaches the outlet more rapidly.
Con: Cold Water Sandwich
As part of your investigation into tankless water heaters, you’ve almost certainly come across the phrase “cold water sandwich.” Cold water sandwiches occur when you use hot water intermittently, causing you to feel an initial surge of hot water, followed by a cold water rush before the hot water surge returns, soon becoming cold again. It’s important to remember that when you switch the hot water on and off fast, like you would when hand-washing dishes, the pipes still contain hot water in them from just a few seconds earlier.
The experience of eating a cold water sandwich is not a huge problem, but it might be disorienting if you are not used to it.
Con: Inconsistent Water Temperature When Multiple Taps/Showers/Appliances Are in Use
When I first started writing on this topic, I described a scenario in which your family returns home from a day at the beach and everyone has to shower. Using tankless water heaters in this situation allows your entire family to shower side by side without having to worry about running out of hot water at any point. The disadvantage is that tankless water heaters are unable to keep up with the demands of numerous showers operating at the same time. Having a shower and running the dishwasher at the same time is not only a problem with showers; depending on the size of your water heater, you might run into problems if you do both.
The amount of water that a tankless unit can heat in a given length of time is referred to as the flow rate.
The flow rates for each type of outlet are depicted in the chart below to give you a sense of the average flow rates.
|Outlet||Average Flow Rates (GPM)|
|Bathroom Faucet||.5 – 1.5|
|Dish Washer||1 – 1.5|
|Washing Machine (Clothes)||1.5 – 3|
|Shower||2.5 – 3|
The bottom line is that tankless water heaters are available in a variety of sizes, ranging from large units designed to manage large families with a lot of water to tiny ones designed to handle households with little water use. It is critical to assess how much heat you will require for your family and to purchase the suitable size heater. Just keep in mind that if you turn on too many faucets, showers, or appliances at the same time and exceed the flow rate capability of your water heater, the water will not be hot enough.
Con: Difficult to Achieve a Lukewarm Temperature
Overall, tankless water heaters are available in a variety of sizes, ranging from large units designed to accommodate large homes to tiny units designed to conserve water. In order to choose the correct size heater for your home, it is critical that you first identify what you require. Just keep in mind that if you turn on too many faucets, showers, or appliances at the same time and exceed the flow rate capability of your water heater, the water will not be hot enough for your needs.
Listed below is a brief guide to assist you in determining the size of tankless water heater that you require.
Con: No Access to Hot Water During a Power Outage
When a storm comes through and takes out the power in your home, the hot water in your home is also gone. The energy source for tankless water heaters can be either natural gas or electricity, however even gas-powered tankless water heaters rely on an electric control panel to run the unit. As a result, regardless of the sort of tankless water heater you have, you will be without hot water if your electricity goes out. Compared to tankless water heaters, tank-style water heaters have a major advantage in this category.
Bottom Line: Is a Tankless Water Heater Worth It?
The use of tankless water heaters has a number of advantages over the use of conventional tank-style water heaters. They conserve energy (and so save you money), they give infinite hot water, they are tiny and compact, they never leak, and they do not contribute to the presence of hazardous metals in your drinking water. The best part is that they last twice as long as traditional tank-style water heaters. Alternatively, you’ll have to pay around $3,000 up front, and they deliver variable water temperature in various conditions, as well as leaving you without hot water in the event of a power outage, among other things.
Some basic questions to ask yourself include the following:
- What if you only have $3,000 to invest in an appliance that won’t pay off for several years and you don’t want to risk losing your money? Is your home a new build or do you intend to live there for an extended period of time (10 years or more)? Do you frequently run out of hot water as a result of taking multiple showers in succession? Was it possible for you to profit from additional room in your basement (and who couldn’t? )
If you responded “yes” to any of the questions above, a tankless water heater may be the best option for you. It’s generally best to hold off and stay with a tank-style heater if you responded “no” to one or more of these questions, particularly question1. Tankless water heaters may be found on Amazon and HomeDepot.com, where you can read more about them and see the latest models. On HomeAdvisor.com, you can receive free, no-obligation estimates from specialists in your region to get a general idea of what installation prices will be in your area.
If you found this post to be useful, you may like to read the following articles from the past:
- What is the approximate weight of a water heater? (With a total of 37 illustrations)
- 6 Simple Solutions for Dealing with Standing Water in the Bottom of Your Dishwasher
- What Is the Water Consumption of a Washing Machine? (With the help of 28 real-life examples)
- What is the average lifespan of a hot water heater? 5 Ways to Make Their Lives Longer
- How to Fix a Dryer That Isn’t Drying (10 Do It Yourself Solutions)
- HomeAdvisor vs. Angie’s List: What’s the difference? What’s the similarity? What’s the advantage? When it comes to window coverings, blinds or shades are the better choice. average cast iron bathtub weight (with 15 examples)
- Average washing machine and dryer weight (with 40 examples)
- Average cast iron bathtub weight (with 15 examples)
- A Quick Guide to Choosing the Best Type of Roller for Painting Cabinets What Is the Water Consumption of a Dishwasher? (There are 25 real-life examples)
How It Works — Whole-Home Gas Tankless Water Heaters
Whole-home gas tankless water heaters heat water using the same concept as normal gas water heaters, but they do not require a storage tank to be installed. They conserve energy by heating water only when it is required, so avoiding energy losses that occur during standby mode operation. Cold water is sucked into the water heater when a hot water tap is switched on in a house or other building. The gas burner is activated by a flow sensor, which heats the heat exchanger as a result. The incoming cold water circulates through the heat exchanger, leaving the heater at the temperature selected by the user.
Tankless water heaters are more energy efficient than traditional tank-type water heaters because they heat water only when it is needed, rather than keeping a tank full of hot water at all times.
In addition to extracting more heat from the combustion gas, the secondary heat exchanger also cools it to the point where condensation occurs – so the term “gas condensing” is used to describe these types of heaters.
This type of tankless water heater, like gas condensing furnace, must be vented through a vertical PVC pipe and a condensate drain to avoid overheating the water supply.
Read This Before You Buy a Tankless Water Heater
Consider the following: The method used by the majority of houses in this nation to heat water is ridiculously inefficient. Every year, we fill up large storage tanks of 40- to 50-gallon capacity with water and then continuously pump energy into them to ensure that we have hot water available anytime we want it. But, unfortunately, this is not always the case. The wait for the tank to reheat might be lengthy if a teenager is taking a long shower or the spouse is enjoying a long soak in the tub.
Is there a chance of a leak?
Tankless Water Heater Installation: Is It Worth It?
Investing in a tankless water heater has a number of benefits, as detailed above. It creates hot water just when you use it and for as long as you require it, resulting in a reduction of 27 to 50% in fuel expenses when compared to tank-type heaters. (A typical gas-fired tank wastes 40 to 50% of the fuel it burns, according to the manufacturer.) As a result, there is virtually no chance of a catastrophic leak occurring because there is no tank to fail. Furthermore, since their introduction in the United States in the 1990s, tankless heaters have become increasingly sophisticated, with features such as built-in recirculating pumps (which provide “instant” hot water) and wireless connectivity, which alerts you via smartphone when a unit requires servicing.
Our tankless water heater guide will explain how they function, what you should know before purchasing one (and before the installation comes), and the idiosyncrasies of how they operate so that you won’t be caught off guard if you decide to go tankless.
How Does a Tankless Water Heater Work?
Doug Adams created the illustration.
- It all starts with the first turn of the hot-water faucet (1). A flow sensor (2) detects the presence of water entering the heater and sends a signal to the control panel, causing the heater to begin generating hot water. During operation of a natural-gas-fueled unit, thecontrol panel (3) activates thefan (4), which pulls in outside air, opens the gas valve (5), which allows the gas to flow into the unit, and ignites the burner (6). In order to transmit heat from the flames to water passing through the exchanger’s tubing, a heat exchanger (number 7) is used. The mixing valve (8) regulates the temperature of the superheated water that exits the exchanger. Whenever the temperature sensor (9) detects water temperatures that are too high or too low for the intended setting, the panel will modify the gas valve, the mixing valve, and the flow-regulating water valve (10) in accordance with the results. Ventilation is provided by a sealedvent (11) (or a couple of vents) via a roof or exterior wall, which removes exhaust gases and supplies combustion air to the burner.
Several people were thanked for their contributions: Phillip Maxwell, Residential Product Manager, Rheem; Eric Manzano, Product Training Supervisor, Noritz; Joe Holliday, Senior Vice President, Product and Business Development, Rinnai; and Fred Molina, Water Heater Products Manager, Bosch Thermotechnology
What to Know About Tankless Water Heaters
Several people were thanked for their contributions: Phillip Maxwell, Residential Product Manager at Rheem; Eric Manzano, Product Training Supervisor at Noritz; Joe Holliday, Senior Director of Product and Business Development at Rinnai; and Fred Molina, Water Heater Products Manager at Bosch Thermotechnology.
How Much Does a Tankless Water Heater Cost?
Prices range from approximately $170 for modest gas-fired units to more than $2,000 for high-output heaters that can serve two showers at the same time; $1,000 is a reasonable starting point for most buyers. Electric heaters without a tank range in price from $90 to $900. The expenses of a first-time installation are higher than the price of a simple tank replacement. Electric tankless water heater installation (see item below headed “Installing an Electric Tankless Water Heater”).
How to Install a Tankless Water Heater
This is a work that should be left to the professionals, since it entails creating leak-free water, vent, and gas connections in the case of gas or propane units, or upgrading the wiring and circuit-breaker panel in the case of electric units, and it is best left to the professionals.
Tankless Water Heater Maintenance
Sign up to have a professional do an annual service that includes cleaning or replacing water and air filters, as well as inspecting the burner’s operation. The use of a vinegar flush every 500 hours in places with hard water prevents mineral accumulation, known as scale, from blocking the heat exchanger. That 20-minute task may be completed by a professional or by a homeowner.
How Long Do Tankless Water Heaters Last?
It is expected that gas-burning tankless water heaters would last 20 years or longer, which is two to three times longer than tank-type heaters. Tankless electric units have shorter life lifetimes, ranging from 7 to 10 years, compared to conventional units.
Where Can I Buy One?
They may be found at plumbing supply stores, big-box stores, and internet sellers, among other places. Alternatively, you may order one via your plumber.
Pros and Cons of Tankless Water Heaters
Thanks to Noritz for the use of his photo.
PRO: They’re Compact
As a result of new federal requirements requiring stronger insulation to decrease standby heat loss, the size of newer tank-type water heaters has increased. Consequently, they may not be able to fit into locations where an older heater with the same capacity might. Tankless gas heaters are approximately the size of a suitcase and are mounted on the wall.
PRO: They’re Safer
A tank-type heater, on the other hand, may leak and spill gallons of water if it springs a leak, but it will not house Legionella germs or topple over in an earthquake. The air supply and exhaust vents are also closed to prevent backdrafting, which would otherwise allow carbon monoxide to enter the house.
PRO: They’re Easy to Winterize
It is important to note that, unlike tank-type heaters, they will not leak large amounts of water, house Legionella germs, or topple over during an earthquake. The air supply and exhaust vents are also closed to prevent backdrafting, which would otherwise allow carbon monoxide to enter the home.
CON: They’re Sensitive to Slow Flow
A tank-type heater, on the other hand, may leak thousands of gallons of water if it springs a leak, but it will not house Legionella germs or topple over in an earthquake. The air supply and exhaust valves are also closed to prevent backdrafting from introducing carbon monoxide into the home.
CON: The Payback Takes Awhile
An annual savings of only around $100 for a household using a $1,000 tankless gas heater vs a $400 tank-type heater is possible, depending on how efficient the heater is and how much hot water is utilized. The savings, however, begin to accrue after six years, when many tanks are reaching the end of their useful lives due to the extended lifespan of tankless gas systems.
New Tankless Water Heater Technology
An annual savings of just around $100 for a household using a $1,000 tankless gas heater vs a $400 tank-type heater is possible, depending on how efficient the heater is and how much hot water it produces. The savings, however, begin to accrue after six years, when many tanks are reaching the end of their useful lives due to the extended life of tankless gas systems.
Condensing gas heaters can extract up to 96 percent of the heat from a fuel, which is a 17 percent improvement over first-generation tankless devices. This is possible because of a second heat exchanger, which collects a large portion of the exhaust heat before it exits the vent.
In addition to being around 25% more expensive than noncondensing heaters, condensing heaters produce acidic condensate that must be neutralized. If a heater doesn’t come with a built-in neutralizing cartridge, the installation will have to install one after the fact.
Instant Hot Water
Despite the fact that tankless water heaters heat water in around 15 seconds, you must still wait for the hot water to reach your shower head or faucet, just as you would with a tank-type heater. The recirculation pump should be used when the distance between the heater and the fixture is greater than 50 feet. This will conserve water and minimize the amount of time spent waiting. It is this pump that pushes the cold water in the pipes back through the heater. The pump can be activated by a timer, a push button, a motion sensor, a smart speaker, or a smartphone (see illustration above).
Tankless systems with digital connectivity let you to control the temperature as well as monitor gas and hot-water use from your mobile device. Furthermore, the device is capable of identifying the cause of a problem. Please communicate this information to your plumber so that he or she may arrive on the job site knowing exactly what has to be done. This function also eliminates the need for any guessing when it comes to determining when it is time to descale.
Tankless Water Heater Rebates: A Great Way to Save
Carl Tremblay captured this image.
What Size Tankless Water Heater Do I Need?
Here’s how the specialists ensure that your water heater produces adequate hot water: 1. A large burst of BTUs is required for a tankless heater to convert cold water into hot water in a matter of seconds. However, if a heater’s Btu output is insufficient to meet demand, it will reduce the flow rate or, in the worst scenario, offer tepid water. A plumber considers three aspects when determining whether or not a heater will be able to satisfy the demands of a household:
- The temperature of the water that enters the heater
- The maximum demand for hot water expressed in gallons per minute (gpm)
- The efficiency of the heater, as shown by its Uniform Energy Factor, which may be found in the product specifications
- The first step is as follows: A professional determines how many Btus per gallon of water heater is required to increase the incoming water temperature to 120 degrees (see the map on the next slide)
- Flow rates for all of the appliances and fixtures that may be consuming hot water at the same time are added together to form peak demand, which is calculated as follows: (These rates are detailed in the next slide.) As a result of not bathing or washing in 120-degree water, we save around 20% on our overall use. Water-saving fixtures and appliances, as well as delaying laundry while the shower is in use, can help you minimize peak consumption. In the calculation, the total Btu production is computed by inserting the Btus-per-gallon and peak-demand amounts in at different points along the way. If the difference in output is between two models, go with the one with the greater Btu rating to save money. You’ll also need two smaller units that function in tandem if your output is greater than 198,000 Btus, which is the limit for domestic gas heaters.
Btus Output Estimate
Not interested in completing the calculations? Make a rough estimate of how much heater output you’ll want using these statistics.
- The following figures are for one bathroom for one to two people: 140,000 Btus
- Two bathrooms for two to three people: 190,000 Btus
- Three bathrooms for three to five people: 380,000 Btus
Btus Per Gallon by Region
- Kitchen or bath faucets should flow at 1.5–2.2 gpm
- Tub filler faucets should flow at 4 gpm
- Dishwasher: 1–2.5 gpm
- Washing machine: 1.5–3 gpm
- Showerhead should flow at 1.25–2.5 gpm
How to Determine gpm?
To get the real gpm of a fixture, time how many seconds it takes to fill a bucket to the 1-quart mark and multiply that time by the number of gpm. gpm is calculated by dividing 15 by the number of seconds in a minute.
Electric Tankless Water Heater Facts
Thanks to Stiebel and Eltron for their assistance. In addition to gas lines and propane tanks, tankless water heaters operated by electricity can provide the benefits of on-demand hot water to homes that do not have them. Compared to gas or propane tankless heaters, these systems, which heat water using thick copper rods, are significantly quieter and roughly a third smaller in size. And because they do not require vents, they can be fitted practically anyplace, even beneath sinks and in small closets, without compromising performance.
In locations with warm groundwater, that amount of hot water may be sufficient to feed a whole house; but, in colder climates, they are better suited to point-of-use service, where the demand for hot water does not become excessive.
Furthermore, electric heaters have a lifespan that is approximately half that of gas heaters: Warranty periods typically range from three to five years.
As soon as the heating elements fail, it is frequently more expensive to replace the complete heater than it is to simply replace the heating elements.
Tankless Water Heater Installation
Doug Adams created the illustration. What you and your plumber should look for before the installation day is as follows:
If you want your tankless heater to work effectively, you must connect it to a gas supply line that supplies enough volume at a high enough pressure to run the burner. In many circumstances, this will need increasing the diameter of the supply pipe to 3-4 inches in diameter. Furthermore, if the pressure is insufficient, the gas provider will be required to change the regulator on the meter. For your information, some tankless systems, like as ones manufactured by Rheem, are capable of working with a regular 12-inch gas line as long as it is not more than 24 feet in length.
Tankless gas heaters that do not condense employ stainless-steel vents that can resist high exhaust temperatures. Condensing systems feature a cooler exhaust and use PVC pipes, which are less costly than other types of exhaust. Installing a concentric vent, which has an exhaust pipe inside a larger air-intake pipe, is easier than installing a traditional vent since only one hole in the wall needs to be made. As a point of reference, vent runs have traditionally been limited to a maximum of 10 feet.
Heat transmission is slowed and water flow is restricted when scale deposits accumulate in a heat exchanger (or on electric heating components) over time. If you currently have whole-house water softening, scale will not be an issue for you. However, if your water is not being softened and its hardness surpasses 120 milligrams per liter, it is worthwhile to invest in a treatment system to remove the hardness. For your information, a specific, point-of-use cartridge, such as the TAC-ler water conditioner (Stiebel Eltron), can be used to change the hardness of water without the use of salt or other chemicals.
Outdoor Tankless Water Heater
Matt Risinger captured this image. If your environment and local rules allow it, think about the advantages of hanging a heater outside in the winter.
- Matt Risinger took the photo. If your environment and local rules allow it, consider the advantages of hanging a heater outside.
Tankless Water Heater Venting
Carl Tremblay captured this image. Are you in need of assistance with repairs around your home? A house warranty may be of assistance. The This Old House Reviews team has put up some in-depth guidelines that you can read here:
- Carl Tremblay took this photograph. Are you in need of assistance with house repairs? Perhaps a house warranty will be beneficial. The This Old House Reviews Team has put up some in-depth instructions that you can read here:
How Electric Tankless Water Heaters Work
Water heating systems that do not require a tank are quite straightforward in concept: instead of heating water and keeping it in a tank where energy is wasted throughout the day, tankless systems heat water on demand, just as hot water is really required and utilized. This notion developed in Europe and Asia, where tankless heaters have been in use for many years and have become commonplace. Because of rising energy prices in North America, as well as a growing interest in “green” technologies among customers, tankless water heating technology began to spread across the continent in the early 1990s, particularly in the United States and Canada.
Nonetheless, they offered consumers on-demand water heating and the opportunity to reduce their water heating costs as well as the associated environmental footprint.
In spite of the wide range of technological options available, there is one fundamental notion that underpins each unit: When you switch on a hot water faucet, a flow sensor detects it and automatically turns on the tankless water heater.
Because the heater only works for a few minutes each day, rather than cycling on and off all day like a standard tank-type water heater, a significant decrease in energy expenses may be accomplished – often between 30 and 50 percent.
In addition to reducing the formation of hard water scale, this results in extra energy savings.
As a result, they are guaranteed by far longer warranties than traditional water heaters, and they do, in fact, last significantly longer.
Despite the fact that all tankless water heaters are based on the same fundamental concept of heating water on demand only as it is required, there is a wide range of technologies available, ranging from simple on/off models to heaters that provide automatic thermostatic control regardless of flow rates or the temperature of the incoming water.
It gives us great pleasure to offer the Stiebel Eltron range of tankless water heaters, which includes the well-known Tempra Series, which has the most advanced sort of thermostatic temperature control technology now available in the industry.