Search the web Search this site

Tankless Water Heaters

How Tankless Water Heaters Work

Tankless water heaters perform their task on demand rather than ahead of time. When you turn on your hot water spigot, the tankless heater detects the flow of water and kicks into action. After a number of quick calculations to determine how hot to make the water, the heating element switches on and heats the water as it passes through the device. When you turn off the faucet, the heater goes into shut down mode.

Types of Tankless Water Heaters

There are several types of tankless water heaters. The source energy could be natural gas, electricity, or propane. Some are designed to heat water for every sink and shower in the home. Others are mounted locally near the single faucet or shower head.

Tankless Water Heater Ratings and Capacities

Advantages of Tankless Water Heaters

The main advantage of a tankless heater is that it saves source energy by not being on continuously, only when needed. The other main advantage is that they never run out of hot water. There is no cold water shock if you are the third or fourth person in line to take a shower.

  1. No Heat Losses From Storage Because a tankless water heater only supplies hot water on demand, thermal bridging problems do not occur. Thermal bridging happens when heat travels through the insulating material.
  2. Saves Physical Space Because tankless water heater do not have a large tank to store water, they are very compact. At the size of 2-3 shoe boxes they can be mounted on just about any wall. They should be mounted near the demand points to reduce line heat losses.
  3. Continuous Hot Water Without Limit Endless supply of hot water. The tank never empties. As long as the flow rate of the water is above a certain gallons per minute, hot water continues to flow.
  4. Reduced Carbon Emissions Because they are not continuously keeping a tank of water hot, they can save a bundle in carbon emissions. The savings are even greater when you employ some of the water saving measures we suggest on this site, such as changing your shower heads to low flow.
  5. Reduced Utility Bills Depending on how much you use your tankless water heater, the savings can be from 10 to 50% less.
  6. Tax Credits Tankless water heaters with an Energy Factor (EF) of equal to or greater than .82 qualify for a $300 tax credit according to the extension of The Tax Relief, Unemployment Insurance Reauthorization, and Job Creation Act of 2010 signed by President Obama on December 17, 2010 to 2011.

Disadvantages of Tankless Water Heaters

A few things you should think about before choosing a tankless water heater.

  1. Initial Cost and Installation You can expect a two bed room or larger tankless water heater to cost $1000 to $2000 plus installation. Traditional American storage tank water heaters cost about half that. So you'll need to pencil out the pay back period based on how you use the heater.
  2. Hot Water Delay The tankless water heater senses water flowing through it when the hot water faucet is turned on. It needs to calculate the difference in incoming water temperature from demand temperature. Then it begins the heating sequence. The whole process is controlled by electronic circuitry, so it is very fast. There is a delay in getting hot water to the faucet, however, studies have shown that the delay is about the same as for a conventional storage tank water heater. So the hot water delay problem is more than a myth than reality.
  3. Minimum Flow Tankless water heaters trigger the heating source on when the minimum flow rate reaches a certain level. For most tankless water heaters, the flow rate must be 0.5 gallons per minute (GPM) or higher. The problem with minimum flow rates is that because of impedances in the line may limit the amount of flow. Obstacles such as calcium deposits inside the pipe, small pebbles and stones at the shower head, and low incoming pressure may prevent the burner from turning on.
  4. Return on Investment Payback period depends on how much you use the tankless water heater. Since it cost much more than a conventional storage water heater, in order to offset the initial investment you would need to use it on a full-time basis. If you wanted to use it for your vacation home, which is only used part-time each year, the pay-back period would take much longer, then if you were using it in your primary home.
  5. Reliability and Maintenance Because of calcium build up inside the tankless water heater, if maintenance is not performed once per year, the reliability of the unit will go down dramatically. The cleaning procedure is fairly complex and should be done by a qualified professional. The cleaning solution is typically vinegar, because the water is for drinking. So, no harsh chemicals should be used. The vinegar just adds enough acid to adjust the pH from alkali to neutral.

Where Tankless Water Heaters are Best Used

Although tankless water heaters can replace conventional storage tank water heaters, there are some applications where they can best make use of their advantages. The best application is for medium to large families or living situations. Using a conventional storage tank water heater, the tank runs out of hot water after 2-4 showers. With a tankless water heater, theretically, hot water never runs out because it works on demand. For the same reasons hotels, offices, or any commercial operation that has frequent need for immediate hot water would be good applications.

Another great application is as a back up heater for a solar hot water heater. This may even be necessary if you are in a climate that has mostly overcast days.

Examples of Tankless Water Heater Available Today

There are many models of tankless water heaters on the market today. Once the demand for them picks up, even more models will become available. Models are available in every price range from $200 up. We'll split the field into three categories and give examples in each that are available today.

Entry Level Tankless Water Heaters (Up To $1000)

Features

Models

Company Model Capacities Power Source Street Price

EcoSmart

ECO 8
This 8.0KW Smart Technology electric tankless water heater is configured for climates where incoming water temperatures are in the 65-77F range. The model ECO 8 is well suited for homes in the southern States , Lower Texas and Florida. Digital Temperature Control allows you to set your temperature up to 125 F. Designed for a maximum flow rate of 1.5 gpm Electric $200

Rheem

RTG-53XN
  1. Hot Water Capacity: 5.3 GPM at a 45 degrees F temperature rise (up to 6.8 GPM at 35 degrees F)
  2. Electronic ignition increases efficiency (no standing pilot light)
  3. A remote control thermostat is included with all models with 100 degrees F - 140 degrees F setpoint range (factory set at 120 degrees F)
  4. Built-in electric blower to force exhaust gas to the outside, Must be hardwired to a circuit breaker
  5. Features freeze protection to -30 degrees F
  6. Gas Input BTU/Hr. = 21,600 - 141,000
  7. Energy Factor = 0.82
Gas $440

EZ Tankless

EZDELUXE
  1. Hot Water Capacity: 3.4 GPM (45 °F rise)
  2. Gas Input BTU/Hr. = 87,500 btu (25kW)
Gas $490

Rinnai

R94LSiN
  1. Hot Water Capacity: 0.4 to 9.4 GPM (30° F rise)
  2. Electronic ignition increases efficiency (no standing pilot light)
  3. Compatible with Full Line of Rinnai Digital Controllers
  4. Anti-Frost Protection: 184 Watts
  5. Natural Gas: 9,900 - 199,000 BTU, Propane: 10,300 - 199,000 BTU
  6. Energy Factor = 0.83
Natural Gas or Propane $990

Mid Level Tankless Water Heaters ($1000 to $2000)

Features

Models

Company Model Capacities Power Source Street Price

Bosch AquaStar

2700ES-NG
  1. Hot Water Capacity: 7 GPM (45° F rise)
  2. Electronic ignition increases efficiency (no standing pilot light)
  3. Remote thermostat model TSTAT2 available to digitally control output temperature
  4. Energy Star qualified
  5. Natural Gas: 19,900 - 199,000 BTU
  6. Energy Factor = 0.82
Natural Gas $1100

Rinnai

RC98HPi-LP
  1. Hot Water Capacity: 0.4 to 7.6 GPM (50° F rise) and 0.4 to 9.8 GPM (35° F rise)
  2. Electronic ignition increases efficiency (no standing pilot light)
  3. Compatible with Full Line of Rinnai Digital Controllers
  4. Anti-Frost Protection: 220 Watts
  5. Natural Gas or Propane: 9,500 - 199,000 BTU, Propane: 10,300 - 199,000 BTU
  6. Energy Factor = 0.94
Natural Gas or Propane $1370

Siemans

Fortis 120
  1. Hot Water Capacity: 0.3 to 9 GPM (50° F rise) and 0.4 to 9.8 GPM (35° F rise)
  2. Max Power Load: 120 amps at 240 VAC
  3. Power Requirements: 208 to 240 VAC
  4. First Hour Rating: 230 Gallons
  5. Electric: 28.8 kilowatts, 98266 BTU
  6. Energy Factor = 0.98
Electric $1575

Quietside

DPW-099A Dual Purpose
  1. Hot Water Capacity: 1.2 to 4.5 GPM (50° F rise)
  2. Electronic ignition increases efficiency (no standing pilot light)
  3. PVC Exhaust
  4. Microprocessor controlled
  5. Natural Gas or Propane: 47,800 - 98,000 BTU per Hour
  6. Energy Factor = 0.85
Natural Gas or Propane $1990

High-End Tankless Water Heaters ($2000 and Up)

Features

Models

Company Model Capacities Power Source Street Price

Quietside

DPW-199A
  1. Hot Water Capacity: 1.2 to 7 GPM (70° F rise)
  2. Electronic spark ignition
  3. PVC Exhaust
  4. Natural Gas or Propane: 26,000 - 199,000 BTU per Hour
  5. Energy Factor = 0.90
Natural Gas and Propane $2900

NORITZ

ASME NC380
  1. Hot Water Capacity: 0.7 to 13.2 GPM (45° F rise)
  2. Electronic ignition increases efficiency (no standing pilot light)
  3. Microprocessor controlled
  4. Natural Gas or Propane: 22,500 - 380,000 BTU per Hour
  5. Freeze Prevention: 371W
  6. Energy Factor = 0.85
Natural Gas and Propane $3500

Page Tags

Tags: tankless water heater, solar water heater, hot water heaters, tankless hot water heater, hot water heater, gas water heater, electric tankless water heater, electric water heater, ground water heating.

Fast Electric Bike Book
Build Fast Electric Bike

Water Heaters

Tankless Water Heaters
Tankless Water Heaters

Solar Water Heaters
Solar Water Heaters

Electric Water Heaters
Electric Water Heaters

Hybrid Water Heaters
Hybrid Water Heaters

Geothermal Water Heaters
Geothermal Water Heaters

Home Efficiency Tips