Modern Gas Fired Tankless Water Heaters
So maybe you have a flex-fuel or Gasoline-Electric hybrid vehicle in your driveway, maybe a compost pile in your back yard? You’ve insulated the house, installed the thermal-pane windows, and may even have a newer energy efficient furnace. Now that you are warm and cozy and “feeling the green” are you still heating a big tank of hot water 24/7/365? If it is a gas tank type heater, did you know that not only are you wasting gas by heating hot water constantly, but you are drawing heat from your home via the draft type exhaust pipe. Maybe you need a tankless hot water heater to complete your green home?
“A gas-fired tankless water heater, what is that? Please tell me more?”
In Europe and Asia tankless water heaters are the norm. In the United States, homeowners are more familiar with tank storage type water heaters. Today more and more families are making an effort to conserve energy and preserve our natural resources by switching to tankless technology.
Primarily, tankless models differ from the typical large cylindrical heaters because they have no storage tank. On demand type, instantaneous tankless water heaters are better as no energy is wasted by pre-heating and holding a large quantity of water in reserve for future use. Tankless heaters produce almost instantaneous hot water in a continuous supply on demand.
“How does a tankless heater work?”
Sensors inside the heater detect that a hot water tap (faucet or shower) has been turned-on and the heater begins to run, making hot water that exits the heater into the hot water pipes leading to the faucet, sink, or shower. When the faucet or shower is turned off, the heater shuts down and the flow of hot water stops. Modern gas-fired tankless heaters don’t even have a pilot light! They have automatic electronic ignition to save even more energy.
“So they save energy. Are they better than a tank-type water heater in other ways?”
Tankless heaters can supply a larger total volume of hot water than a tank water heater. The reason is that a tank type heater has only a certain total capacity available. Tank type heaters are sized by their reserve hot water capacity in gallons. Typically only 30, 40 or 50 gallons of water is stored and if you exceed this capacity you must wait for another full tank to heat which can take several hours on some models. With a tankless heater, you have an endless supply of hot water for your needs. The way in which a tankless heater is sized is by its capacity to provide hot water at a specific GPM. In the USA, the volume of water flow is measured in GPM (Gallons per Minute)
When a large volume of hot water is needed, more than one tankless heater can be joined together in a group and work in unison. For a tankless heater, the important thing to remember is how to properly size the tankless heater unit to the needs of the household or business in question by calculating your maximum peak GPM needs.
“Please tell me more about GPM and how to properly size a tankless heater?”
As previously mentioned, tankless water heater manufacturers size their heaters via GPM specifications. Often this is also included with fine print about the temperature rise. If your groundwater temperature is 45 degrees, and the manufacturer advertises that the heater can supply a temperature rise of 60 degrees at 4.0 GPM. What this means is that the output temperature of the water coming from the heater will be 105 degrees at a maximum flow of 4.0 Gallons Per minute. Tank type heaters are sold as total gallons held in reserve in the tank. For example, a typical tank type heater may hold forty gallons of water. Comparing a 4.0 GPM tankless water heater to a forty gallon tank type heater is possible. For example, if a tankless unit produces hot water at 4.0 gallons per minute, this rate of flow will run a 40 gallon tank type heater out of water in only ten minutes.
“Please tell me about the latest evolution of tankless water heaters. Because several years ago, I was told they were not very good.”
It is a fact that the early models of tankless heaters sold in the USA years ago were small and could not meet the needs of a typical household. (Especially the electric ones.) They were primitive and often broke down. Sometimes the homeowner had to wait for a visit by a qualified technician and then parts were needed and had to be ordered. Because of these experiences of years past, tankless heaters had developed a reputation for malfunctions and an inadequate supply of hot water. Today’s models are designed to last fifteen to twenty-five years, and are much more reliable. If the unit being installed is properly sized to meet the needs of the home or business, and properly maintained, it will supply reliable continuous hot water for many years to come.
“Is there a down-side to a tankless water heater?”
The biggest enemy of any water heating device is hard or sediment filled incoming water. (For example, as you may have experienced, this is the leading cause of failure in coffee makers) As with any type of water heater, the tankless varieties also work best when used with a water softener or at the very least a filter installed on the incoming water supply. Just like a tank type heater, manufacturers of tankless models recommend diligence in performing periodic flushing and internal cleaning as recommended. The interval period for this maintenance depends on the hardness of the water and the type of filtering and/or treatment being done to the incoming water. Learn more about properly maintaining a tankless water heater.
In addition, households with well water will need to address the need for a more constant water pressure. Well pumps cause fluctuations in pressure that can confuse the internal control devices of a modern tankless heater. Find out more about using a tankless water heater with well water.
“I have been told that the exhaust for a tankless water heater is special. Is this true?”
The exhaust on a tankless heater is much different. Most of today's models use forced-air ventilation or are direct vent. (Direct vent is also known as "balanced" or "dual chamber" exhaust-intake) Because of much higher exhaust temperatures, stainless steel pipe designed for this purpose is always used. This is an important part of any indoor installation and is a requirement of industrial, local and national safety codes. This type of pipe has special sealed joints. This pipe is not the same as normal water heater or furnace exhaust pipe and the components do not interchange. With this type of exhaust the gasses are forced outside under pressure, not by a natural updraft as in a tank type heater.
American homeowners are now accepting tankless water heaters as the wave of the future. The average American homeowner is just now finding out about this technology when in fact, people in other countries around the world know of no other way to heat water.
“If I buy one now, will it be obsolete in only a few years?”
More than ninety percent of the manufacturers of tankless water heaters are based in Asia. These heaters are built in modern new factories operated by companies that have been building millions of tankless heaters for decades.
At this time, it is our understanding that there are no gas-fired tankless heaters produced in North America
This is not new technology, it seems new to the typical USA homeowner because we are just now becoming aware of how much energy they save. These days, as a society we are beginning to change our wasteful ways and try to save energy. But as a homeowner, we are not only trying to save energy, but to also reduce our energy expenses as well. These new modern direct vent tankless water heaters have evolved to the point where the USA federal government has declared this technology "mature". What this means is that little future change is expected in these devices. They have reached a level of development where they are about as energy efficient as they can be and the design seems to have peaked as well. In fact, generally speaking most direct-vent heaters from all manufacturers are basically the same design.
And in fact, some of the big-box home improvement chain stores are selling tankless water heaters under several different brand names that are in fact identical and produced in the same Asian factories. For some popular models, only the labels, brand names, and retail outlets differ.