How to Buy a Tankless Water Heater

Are you tired of running out of hot water? These ultra-efficient, compact units heat water at the rate you need. This article will help you choose, install, and live with a tankless water heater.

It is amazing how wasteful the way that most homes heat water in this country is. To ensure hot water whenever we need it, we fill huge 40- to 50-gallon storage containers.

It doesn’t always work out this way. It can take a while for the tank to heat up if a teenager is taking a long shower or a spouse is enjoying a soak in the tub. There are also worries about whether it is clogged with energy-draining sediment. Is it likely to leak? Both of these are valid concerns as tanks tend to fail within 8-12 years.

Do Tankless Water Heaters Work?

These are all reasons to invest in a tankless heater. The tankless water heater produces hot water when you need it, and for as long as it takes to heat. This saves 27 to 50% on fuel costs compared with traditional tank-type heaters. A typical tank that is gas-fired wastes 40-50 percent of the fuel it burns.

There is almost zero chance of a catastrophic tank failure because there are no tanks to fail. Tankless heaters were introduced in the United States in 1990. They have evolved to include features such as built-in recirculating pumps for “instant” hot water and wireless connectivity that lets you know via your smartphone when the unit requires maintenance.

Here is our guide on tankless water heaters. We’ll show you how a tankless heater works and tell you everything you need to know about it before you buy it.

What is a tankless water heater?

  1. It all begins when you turn the ignition. Hot-water tap.
  2. Flow sensor The heater detects water entering it and sends a signal for the control panel to turn on hot water.
  3. A gas-fired unit will have the following: Control panel turns on the fan the duct, which draws in the outside air, opens theGas valveThis allows the gas to enter the system and ignites it. Burner.
  4. the heat exchanger heat is captured from the flames and transferred to the water through the exchanger’s tube.
  5. The mixing valve tampers the superheated water that has left the exchanger.
  6. If you are interested in the temperature sensor the panel detects that water is not at the desired level, it will adjust the gas valve and mixing valve. Water valves.
  7. Seal Ventilation A roof or exterior wall can carry exhaust gases. The vents also convey combustion air to the burner.

How to Use Tankless Water Heaters

Tankless water heater cost

Prices for small, gas-fired units start at $170 and go up to $2,000 for high output heaters that can provide two showers simultaneously. The average price is $1,000.

Electric heaters that are tankless cost between $90 to $900. Installation costs are higher than for a simple tank replacement. (See the subsection below entitled “Electric Tankless Water Heater Install.)

How to Install a Tankless Heater

This job is best left to the professionals. It involves making leak-free gas, water, and vent connections in the case of propane or gas units. Or upgrading the wiring and circuit-breaker panels in the case for electric units.

Tankless Water Heater Maintenance

You can sign up for an annual service by a professional, which includes cleaning the burner and changing the water filters. A vinegar flush is recommended for areas that have hard water. This prevents mineral buildup and scale from clogging your heat exchanger. This task takes 20 minutes and can be performed by a professional or a homeowner.

How long do tankless water heaters last?

Tankless gas-burning water heaters are expected to last for at least 20 years, which is two to three times as long as tank heaters. The life expectancy of tankless electric units is 7-10 years.

Where can I buy one?

These heaters are available at big-box and plumbing supply stores as well as online retailers. You can also order one from your plumber.

Pros and cons of tankless water heaters

PRO: They are Compact

Tank-type water heaters are now larger because federal regulations require thicker insulation to reduce heat loss.

They may not fit in spaces that an older heater with the same capacity would be able. Tankless gas heaters can be hung on the wall and are the same size as a suitcase.

PRO: They are safer

They won’t leak water, harbor Legionella bacteria, or tip over in an earthquake, unlike a tank heater. Because the exhaust and air-supply vents are sealed, carbon Monoxide cannot leak into the house from back-drafting.

PRO: They are easy to winterize

Vacation homeowners know how difficult it is to drain a tank of water heater before closing the house for winter. A compressor can quickly drain a tankless heater. Then you simply unplug it.

CON: They are sensitive to slow flow

These units will automatically turn off if there is too much scale buildup, or if the faucet or showerhead aerators become clogged or a turned down faucet reduces water flow to approximately 0.3 GPM.

CON: Payback takes a while

A $1,000 tankless gas heater can save a household about $100 annually, as opposed to a $400 tank-type heater. This is dependent on how efficient it and how much hot water is used.

These tankless gas units are more durable than traditional tanks, so the savings kick in after six years. This is about the time that many tanks are close to their end.

Tankless Water Heater Technology

Tankless technology is continually improving. These are the most recent developments:

Higher efficiency

Condensing gas heaters can extract up to 96 percent of a fuel’s heat. This is a 17 percent improvement on first-generation tankless units. A second heat exchanger captures most of the exhaust heat and sends it out of the vent.

Noncondensing heaters are about 25% more expensive, and they produce an acidic condensate that must be neutralized. Installers will need to purchase a neutralizing cartridge if a heater doesn’t come with one.

Instant Hot Water

It takes about 15 seconds for the water to heat up in a tankless unit. However, hot water will still need to reach your faucet or showerhead just like a tank heater.

If the distance between heaters and fixtures exceeds 50 feet, you should look for units that have a built-in recirculation pump. This will save water and cut down on waiting times. The pump can be activated by a timer or push button, motion sensor, smart speaker, or smartphone. It pushes cold water through the heater.

The pump will shut off after about one minute and hot water is available within seconds of opening the tap.

Wi-Fi compatible

Digital connectivity allows tankless units to be controlled and monitored remotely via your smartphone.

The unit can also identify the root cause of the problem. You can relay this information to your plumber so that he or she will know exactly what to do. This feature eliminates the need to guess when it is time to descale.

Tankless Water Heater Rebates: Great Way to Save

Which size tankless water heater do I need?

Here are the top tips to ensure your heater provides enough hot water.

It takes a huge burst in BTUsA tankless heater can quickly turn cold water into hot water within seconds. If the heater’s Btu output is not sufficient to meet demand, it will reduce flow or deliver lukewarmly.

A plumber will look at the following factors to determine if a heater can meet the household’s heating needs. The temperature of the water when you get into the heater, Peak demand for hot water gallons per hour (GPM), and the heater’s efficiency, as indicated in itsUniform Energy FactorThis information is found in the product specifications.

  1. First, a pro will determine how many BTUs per gallon heater must raise the water temperature to 120 degrees. (See the map on the next slide).
  2. Next Peak demands the sum of all the hot water flow rates for each appliance and fixture. These rates are shown on the next slide. This is because we don’t bathe in 120-degree water. By upgrading to low-flow fixtures or water-saving appliances or by avoiding the use of the shower, you can reduce peak demand.
  3. The total Btu output formula is created by adding the Btus per gallon and peak-demand numbers to the formula. If the output falls between two models you should choose the one with a higher Btu rating. If the output is greater than 198,000 Btus (the maximum residential gas heater output), you will need two smaller units to work together.

Btus Output Calculation

You don’t have to do the math. These figures will help you estimate the heater output that you will need.

1 bathroom, 2 people

140,000 Btus

2 bathrooms, 2-3 persons:

190,000 Btus

3 bathrooms for 3-5 persons:

380,000 Btus

Btus per Gallon by Region

Rates of fixture flow


1.25-2.25 GPM

Kitchen or bath faucet

1.5-2.25 GPM

Filler faucet for tub

4 pm


1-2.5 GPM

Washing machine

1.5-3 GPM

Find the GPM of a fixture by measuring how long it takes to fill a bucket with enough water to make it full to 1 quart. Divide 15 times that number of seconds to get GPM.

Electric Tankless Water Heater

Installing tankless electric units can provide hot water on demand for homes without a propane or gas line. These units heat water with thick copper rods and are much quieter than propane or gas tankless heaters. They don’t require vents so they can be placed almost anywhere.

The downside to electric units is their limited output. It tops out at 36 Kilowatts or 123,000 Btus. In areas with warm groundwater, that may be sufficient to power a house, but they are better suited for point-of-use service in colder climates, where there is not as much demand for hot water. It will require sufficient amperage from the main panel as well as heavy-gauge wires.

Electric heaters are less durable than gas units. They typically last three to five years. It is usually about the same price to replace an entire heater once the heating elements have fried as to change out new elements.

Installation of a tankless water heater

Before you install, your plumber should assess these things:

1. GAS LINETo ensure that a tankless heater’s burner works properly, it must be connected to a gas supply line that provides enough pressure and volume. This means that the pipe must be at least 3/4 inch in diameter. If the pressure drops below a certain point, the gas company must adjust the regulator to the meter.

FYISome tankless units such as the ones made by Rheem You can use a standard 1/2-inch gas line up to 24 feet.

2. 2.Noncondensing tankless heaters are made of stainless-steel vents, which can withstand high exhaust temperatures. Condensing units produce a cooler exhaust and are made with less expensive PVC pipes. Concentric vents have an exhaust pipe within a larger pipe. This makes installation easier as only one hole must be made in the wall.

FYIVent runs are typically limited to 10 feet. However, fans with greater power like those in Rinnai’s Sensei series Vents can now be run up to 150 feet.

3. WATER HARDNESSScale deposits, which can form in heat exchangers or on electric heating elements, slow down heat transfer and restrict water flow. If you have whole-house water softening, the scale won’t be an issue. If your water hardness is greater than 120 mg/liter and it isn’t being treated, you should consider a treatment system.

FYI point-of-use cartridge such as the TAC-ler water conditioner Changes the hardness of the material without using salt or any other chemicals

Outdoor tankless water heater

If your climate and codes allow, consider the benefits of hanging a heater outside.

  • Space-saving: This is one less appliance that you need to store inside.
  • It’s easy to install an exhaust vent that is built into the house so that you don’t have to make a large hole in the side.
  • Service is easy: Any time you are home, a plumber can come to your rescue. Keep in mind…
  • Building regulations place it outside, you may need to get permission from the local building department.
  • Cold weather internal heaters keep the components warm down to -22 degrees F. However, exposed water pipes should be insulated and wrapped with heat tape that automatically turns on in freezing temperatures. South of the Mason-Dixon Line, frozen pipes are less common.