All You Need to Know About Tankless Water Heaters

All You Need to Know About Tankless Water Heaters
June 21, 2012 Lorelie

Tankless water heaters, also called on-demand, instantaneous, or instant hot water heaters, are considered to be one of the most popular types of water heaters that are used at home.

When looking for residential tankless water heaters, it is crucial to k now that their tankless system and heating process is entirely different from the tank-type versions.

Basic Facts about Tankless Water Heaters

Unlike the storage-type water heater type, the key advantages of tankless water heaters is its tankless design, continuous flow and endless supply, and less energy consumption (up to 30% to 40% as compared to tank-type water heaters).  This means that you get more savings and you do not have to worry about running out of hot water during your shower sessions.

Tank-type or storage-type water heaters continuously heat water even when you are not using it, whereas the tankless water heaters heat water only when you open the hot tap.

Tankless water heaters can either utilize gas or electricity.  Most homeowners highly prefer the gas-powered tankless water heaters with the electronic ignition.  You can also find tankless water heaters with a continuously burning pilot light; however, keep in mind that both gas and electric-powered models have its own pros and cons.

The size of the tankless water heater that you will need actually depends on the demand, how large your home is, and the members of the family who will be using it.  There are some manufacturers that offer a multi-system set-up that can link several water heaters into a single system, which can satisfy the demand even for the largest of homes.

A majority of these units are whole house tankless hot water heaters, since they have a higher GPM flow rate capacity which enables them to handle demand for more than one application at a particular time.

There are also some manufacturers that offer economic commercial and residential combi boilers or heaters that can be used for water heating and space heating at the same time.

How Tankless Water Heaters Work

There are some models of tankless water heaters wherein the heating element is controlled by the flow-sensing device that is responsible for operating with a constant heat input and maximum flow rate.  The flow rate actually depends on the pressure which can be easily adjusted on the knob.

If there is a demand for maximum flow, the outgoing water toward the hot water tap is cooler as it spends less time passing through the heat exchanger.

Modern tankless water heater models are utilizing the latest technology nowadays wherein the output temperature, the flow, the safety and other parameters are controlled and regulated by the electronic circuit board.

When you open the hot water tap, a flow sensor in the tankless water heater sends the signal to the electronic module.  From there, the signal goes to the gas valve to open the gas flow.

When all the requirements are met, the propane or natural gas flows into the burner that is situated inside the combustion chamber.  The gas is ignited either by the pilot flame or the spark coming from the electrode.

The burning gas heats the heat exchanger wherein the incoming cold water is rapidly heated to the pre-set and desired temperature.  The heat exchanger then transfers the heat from the burner to the water heating instantly.  A vent pipe then vents out the products of combustion by utilizing the direct vent or powered vent system.

By the time the faucet is turned off, the flow stops and the flame goes out.  Simply put, the tankless water heaters heat the water on demand, while providing you with an endless supply of hot water.  They are typically installed on the wall.

Types of Tankless Water Heaters – According to Fuel Source and Demand

There are two main types of tankless water heaters categorized according to their fuel source – electric and gas.

Electric tankless water heaters typically have a compact design, which is great for savings lots of space.  They usually have a long service life since they are less prone to sediments and hard water.  You can either choose point-of-use or whole-house electric tankless water heaters.  Electric tankless water heaters do not actually produce greenhouse gases; therefore, they are environmentally friendly units.  The top-selling brands known in North America are Titan, Bosch PowerStar, Eemax and Stiebel.

Gas tankless water heaters, like their electric counterparts are considered to be environmentally friendly units as well.  Almost all of them use state-of-the-art technology for energy efficiency, and they certainly meet strict emission standards.  They can either utilize natural gas or propane.  Gas tankless water heaters produce higher flow rates as compared to the electric ones.

Tankless water heaters can be further divided into two categories according to demand – by means of the on/off button and the other with modulation.

Tankless water heaters that work with modulation, base the heat output on the flow.  For instance, if the demand for hot water is higher, the modulating gas valve then provides more gas, which finally results to more power.

Tankless Water Heater Manufacturers

Below is a list of the most popular residential tankless water heater brands.  Most of them are Energy Star qualified models, while some brands expensive and the others are affordable.

  • American
  • AO Smith
  • Bosch
  • GE
  • Noritz
  • Rheem
  • Rinnai
  • Paloma
  • Stiebel Eltron
  • Takagi

The Advantages of Having a Tankless Water Heater Unit at Home

  • Reliability rating is 99%.
  • Endless hot water supply.   You will never run out of water.
  • You can save up to 50% of energy and heating costs.
  • Durability – life span is estimated to be 20 years or even more (for some models).
  • High-efficiency heaters are available, and commonly marked as Energy star.
  • All the parts can be replaceable.
  • Flexible installation options – can be installed anywhere, outside or inside the home.
  • Safety – no scalding injuries.
  • Lower greenhouse gas emissions.
  • No tank – therefore no leaking problems.
  • Gives you clean and fresh hot water.
  • Government tax credit, rebate and other incentives.
  • Some models use smart technology with self-diagnostic program (great for repairs) and precise temperature control for comfort and safety.
  • They can use natural gas or propane (LP).

The Disadvantages of Having a Tankless Water Heater Unit at Home

  • Tankless water heaters are reliant on the pressure that is delivered to your house, so you must have a good plumbing system.
  • With the up-front costs, tankless water heaters can usually cost up to 3 times as much as the tank-type water heaters.
  • Upgrades that are needed such as gas line or venting system are costly.
  • Venting gas and propane models require expensive stainless steel tubing.  For some brands, other costly materials are used.
  • The hot water output is split among all your household fixtures, which is the reason why an inconsistent temperature occurs.
  • Gas water heaters normally require the additional expense of an annual servicing.
  • Electric tankless water heaters may need an additional circuit as well as lots of energy.
  • Tankless water heaters require a minimum flow rate in order to activate the heat exchanger.
  • It is impossible to include renewable energy technology in tankless water heating systems.

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