Tankless Water Heaters: There is a Learning Curve

What is the difference between a tankless water heater and a conventional storage water heater?

In order to understand how a tankless water heater works, we must first take a look at how conventional storage water heating systems function. In this type of water heating system, water is collected in a large storage tank, where the heating elements stay in the “on” position keeping the water at the desired temperature. The heating process is continuous, even when the house occupants are away, and use of energy is ongoing, and is dependent on the size of the  water tank and the amount of water that requires heating. By its nature, this process is seen as wasteful of energy, as it has no built-in sensor that instructs it to switch itself off once the demand for hot water is met.

Keep in mind that with a conventional water heating system, it is possible to run out of hot water, if the demand outpaces the size of the storage tank.  The upside is that as long as there is  hot water stored in the tank, it is immediately available by simply opening a water tap, and there is no waiting involved for water to heat up.

In the case of home tankless water heaters, water stays in the pipes until a faucet is opened in a household.  At that time, the cold water starts flowing, and as the water flow turbine senses the flow, it signals the built-in control board to assess the following:

a.  the temperature of the incoming water
b.  the user-selected water temperature
c.  and the difference between the a. and b.

The control board makes a quick calculation and the results causes the gas or electric flow – depending on what type of tankless water heater is involved – to start an electronic ignition sequence that heats the water to the desired temperature by circulating the water through a copper heat exchanger.

The heating process continues for as long as the demand for hot water exists, i.e., until the taps are closed (this is why they are also known as “on demand water heaters”). At that point, the tankless water heater shuts down and goes into standby mode until the next demand cycle. The next time taps are opened, the cycle starts all over again.

In this “resting” mode, there is no usage of gas or electricity. Because of the system design, however, there is a slight lag from the time the water starts flowing to the time it reaches the desired temperature.  Once that temperature is reached, however, the supply of hot water for that particular demand cycle is unlimited, because the heating process is uninterrupted.

If you are considering purchasing a home tankless water heater, here are some of the factors you may want to consider:

Types of Tankless Water Heaters

If you are searching for a home tankless water heater, you will need to decide on the type of energy to use to keep your tankless operational.  Some heaters run on electricity, which at this time is more expensive to use, while others use propane or natural gas. Your choice will depend on the availability and cost of the different types of fuel in your area, the layout of your house, and the amount of hot water you anticipate using.

Time Factors for your Tankless Water Heater Investment

Depending on the cost of the tankless water heater you are considering, the cost of installation, and any possible retrofits required to bring a tankless into your home.  This type of water heater is about 3 times the cost of a conventional water heater, and there may or may not be other costs for retrofitting.  These costs have to be counter-balanced with the potential long-term energy savings (up to 30% in some instances) and the life-span of a tankless unit (approximately 20 years, more than twice that of a conventional water heating system).

Selection Criteria for Tankless Water Heaters

A calculation to estimate the capacity required for your home’s specific needs should be an important part of your research on tankless water heaters.  You can do this by estimating how many different hot water appliances you might use simultaneously at any given point in time, add the total number of  gallons of water required for that point in time, and choose a tankless water heater that can easily provide that volume of hot water.  You will of course factor in the size of your home, the number of people who live there, and their typical activities and schedules.

If you have large house and multiple family members, you may decide to buy several smaller units, rather than plan to rely on a single unit.

You will also want to get someone in to make sure your electrical system can accommodate the use of a tankless water system before you make the purchase.

Ambient Water Temperature in Your Area

The type of tankless water heater you choose will also depend on where you live.  It stands to reason that if you live in a cold climate, you will need a different type of unit than someone who lives in a more temperate climate zone, because the incoming water temperature will be different in each case.  Colder incoming water will require a tankless water heater that can process the water at a higher temperature… faster.

There are Many Brands and Models Available

There are some excellent tankless products on the market.  Some of them are listed below:

Stiebel Eltron Tankless Water Heaters
Rheem Tankless Water Heaters
Sets Tankless Water Heaters
Eemax Tankless Water Heaters
Noritze Tankless Water Heaters
Takagi Tankless Water Heaters
Bosch Tankless Water Heaters
Bradford White Tankless Water Heaters
Paloma Tankless Water Heaters
Chronomite Tankless Water Heaters

Installation Recommendation

Installing Tankless Water Heaters is quite a bit different from installing the conventional kind.  There may be additional venting required, local zoning bylaws, gas lines and electrical capabilities should all be taken into account to make sure they are suitable for the unit you are planning to buy.

Speak to a certified installer, ask for references, and most importantly, ask for  a written estimate outlining all costs, types of materials, and recommendations for everything required to make the installation project work successfully.

Unless you are a professional yourself who has made similar installations in the past, leave the work to a certified installer.  You will sleep much better and will have nice hot showers for many years to come!