how to choose a tankless water heater?

How to Choose a Tankless Heater – Your Complete Buying Guide

Tankless Water Heater Buying Guide

Nothing is worse than when you’re running late in the morning, and you turn on the shower only to find that you have no hot water. Your water heater is dead. Maybe you’re not running late, but everyone seems to have showered before you, and in the middle of washing yourself, the stream suddenly goes cold. Whatever your scenario, it’s time for a new water heater. Why not consider a tankless water heater so you’ll never run out of hot water?

What is a Tankless Water Heater?

Whether you call it instantaneous, continuous flow, inline, flash, on-demand, or instant-on, a tankless water heater heats water only when you need it. They can provide water for your entire home or at a single point of use for a hot tub, bathroom, clothes washers or other appliances that use hot water. Unlike traditional water heaters, these appliances are small units that work off demand, not capacity. Water heats quickly, so you’ll never run out of what you need. Either a gas (or sometimes propane) burner or via copper heat exchangers or electric coils or copper heat exchangers that heat water as it flows through the unit and into pipes to the point of demand.

Although many tankless units’ capacity has recently increased in size, homeowners can install tankless units throughout their homes at many different points-of-use (POU) to serve hot water needs at will. In addition, the structure of your home may not make it feasible to install a whole-house tankless water heater. In these cases, multiple tankless heaters may be a better choice.

How Does a Tankless Water Heater Work?

When you start an appliance or open a hot water tap, it sends a signal to your tankless heater for hot water, thereby starting the heating process. The temperature of the incoming water determines how much heat the unit needs to deliver water at the desired temperature. When the demand for hot water stops, the unit turns off until it receives another request for heated water.

How does a tankless water heater work?

Tankless heaters come equipped with flow sensors that activate when water begins to flow through the unit. A negative feedback loop brings water to the target temperature that you select. For units operating in acidic environments, durable coatings protect the coils or heat exchangers that heat the water.

How Does a Tankless Water Heater Compare to a Traditional Tank Heater?

For one, tankless water heaters are a fraction of the size of traditional units. Instead of a huge tank, you’ll have one that averages approximately 16 inches wide, 26 inches long, and 6 inches deep. Another big difference is that tankless heater always has fresh water. Traditional tank heaters hold 40, 50 or more gallons, meaning that if you haven’t used water in several hours, it will be stale. With tankless heaters, you always get fresh water. Holding that much water also poses a hazard with traditional heaters. If it springs a leak, you’ll have a mess on your hands.

Is a Tankless Water Heater Worth It?

While tankless water heaters have numerous advantages, they have some notable drawbacks too. The only way to determine if a tankless water heater is worthwhile for your situation is to weigh the advantages against the disadvantages and go from there. Some points will be more important to you than others, which will help you make your decision.

Tankless Water Heater Pros and Cons

What are the Benefits of a Tankless Water Heater?

Obviously, hot water on demand is the biggest benefit as tankless units only take about 15 seconds to heat water that passes through the heat exchangers. However, tankless heaters have several other benefits that make them attractive.

  1. Saves on energy costs – Tankless heaters only generate hot water when you need it, which means they don’t run as much as traditional units. You’ll save between 27% and 50% percent on fuel costs annually. Typical gas heaters waste about 40 to 50% of their fuel to burn to create hot water.
  2. Longer average lifespan – Gas units can operate for 20 years or more, while electric ones last about seven to 10 years.
  3. Easier to winterize – If you have a vacation home, you know how time-consuming it is to drain the water heater tank when preparing to close your home. Tankless heaters drain in a matter of minutes.
  4. Eligible for rebates – The federal Energy Star program has certified most models, making them eligible for utility rebates, which can help offset the extra cost that you’ll pay to buy one.

What are the Downsides of a Tankless Water Heater?

  1. They are more expensive – The cost of a tankless unit can be offputting to some, as well as the cost of installation, particularly for a gas unit, which needs several modifications. The new unit requires different venting and must have the gas supply adjusted as it needs four times the amount of available gas as a regular tank unit to operate properly. Finding this balance can be tricky and requires an experienced professional. Finding and connecting the right size water lines is also a consideration.
  2. No hot water during power outages – Tankless water heaters run off electricity, even those that heat via gas as they run off electric ignition instead of a pilot light. Thus, if you have a power outage, you won’t have hot water for the duration that the electricity isn’t working unless you have a power generator for your home.
  3. One unit may not cover your needs – If you have a very large house, you may need to buy and install multiple units, which can drive up the cost even further.
  4. They are sensitive to slow flow – If you have scale buildup in old pipes, clogged faucet or shower aerators or a faucet with a water flow below 0.3 GPM, tankless heaters automatically shut off.
  5. Payback takes time – Many tankless heaters only save your household about $100 per year. The difference between tankless and traditional prices means you may spend several years before you realize cost savings.

Features to Note When Selecting a Heater

Choosing the right tankless heater for your home is important as you want it to work properly and meet your needs. If the distance between the heater and the fixtures it serves is more than 50 feet, look for a unit with a built-in recirculation pump to save water and reduce waiting time. Here are some other features you should consider.

  • Gas or Electric?
  • Indoor or Outdoor?
  • Smart or Standard?

Gas vs. Electric

Selecting a gas or electric tankless water heaters is a personal decision that you should determine based on your water needs, budget, installation opportunities and personal preferences. Electric units are significantly less expensive, average about $500 to $600, so they are ideal for POU applications. The structures of gas and electric units are entirely different, too, so you should consult a plumbing professional to determine which type of unit is best for your home.

Indoor vs. Outdoor

If your climate and local building code allow for it, consider an outdoor tankless water heater. Outdoor units offer several advantages, the most notable being is that they are easier to install as you don’t have to create an exhaust vent from the interior to the exterior of our home. Having your water heater outside saves on interior space, plus a plumber can easily service it, even when you are not home. The downsides are you may have to get a building permit to have it installed. You may have to get the exposed pipes insulated and wrapped in heat tape in freezing temperatures in colder climates.

Smart vs. Standard

Smart water heaters aren’t necessary, but they are sure nice. Remember that they will add to the price, so they are not a must-have if you are on a budget. Tankless heaters with Wi-Fi compatibility allow homeowners to adjust the temperature and monitor hot water usage on their computer or smartphone. What’s more, smart units can also identify the source of problems when they occur, which means your plumber will know exactly what to do on arrival.

What Size Tankless Water Heater Do You Need?

Determining what size you need is crucial as a heater that is too small won’t meet your hot water needs, while one that is too large is an unnecessary cost. Ask yourself questions like how much incoming water you will need when the dishwasher runs, a load of laundry is in the washer, and someone is taking a shower. Take a look below at the factors you’ll need to consider when calculating the size of your tankless unit.

Sizing Electric and Gas Tankless Water Heaters

Sizing either gas or electric tankless units follow the same considerations. You just look at two factors: flow rate, measured in gallons per minute (GPM) and the temperature rise needed to bring water to the desired temperature. For flow rate, check the manufacturer’s manual for your appliances and fixtures. However, you can also estimate the amount of water need by reviewing this table:

Average GPM Usage Chart
Appliance GPM Average
Bathroom Faucet 2.5 GPM
Dishwasher 0.5 – 1.5 GPM
Kitchen Faucet 2.5 GPM
Shower 2.5 GPM
Toilet 2.2 – 3.0 GPM
Tub 4.0 GPM
Washing Machine 1.0 – 2.5 GPM

Take the number of appliances and fixtures in your home and add up the potential flow rates if all were open at the same time, and you’ll get the capacity you need.

The other important factor, the temperature rise required, depends on the area where you live. Colder areas need a higher temperature rise than warmer areas because water in the pipes is naturally colder in more frigid climates, especially in winter. To determine the needed temperature rise, subtract the input temperature from the output temperature, usually 120 degrees Fahrenheit.

Most on-demand water heaters are rated for inlet temperatures. Suppose you have a dishwasher without an internal heater. In that case, you’ll need a tankless unit with a temperature rise that’s about 20 degrees Fahrenheit higher than for a household that has a dishwasher with an internal heater. Ensure that your heater has a sufficient temperature rise. Otherwise, the water temperature could be reduced at your home’s most distant faucet.

Tankless Water Heater Costs

How Much Will a Tankless Water Heater Cost

Tankless heater prices vary widely, depending on the unit’s capacity and how many features come with it. At the low end, a small point of use tankless heater can cost $90, while high-end units can cost $2,000 and more. The average price is about $1,000. Although low price units seem like a bargain, first-time installation for tankless heaters cost more than simply replacing an old traditional one and must be factored into the upfront costs.

How Much Does a Tankless Water Heater Cost to Run?

Although they are more expensive initially, gas tankless water heaters cost about $200 to operate annually. Electric tankless units cost about $530 to operate annually. Homeowners should note that the difference in the operational prices is due to the cheaper cost of gas and not the structure of the units.

Which are the Best Tankless Water Heater Brands?

You’ll find many different tankless water heater brands on the market. Consider the following manufacturers with an overview of costs by brands:

  • Rinnai gas only $900-$2,0000
  • Rheem gas and electric $170-$2,000
  • EcoSmart gas and electric $425-$1,600
  • Takagi gas only $500-$1,225
  • SioGreen electric only $239-$735
  • Noritz gas only $515-$1,700
  • Bosch electric and gas $140-$2,250
  • Navien gas only $1,075-$1,535

Like any other major purchase for your home, do your homework when deciding what type of tankless water heater is best for your purposes. Establish your budget before deciding whether you would prefer a gas or an electric heater and look at your current water heater situation before determining which type is right for your home.

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