Hot Water Guys | Tankless WaterHeater FAQ’s
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Tankless Water
Heater FAQ’s

WHAT IS A TANKLESS WATER HEATER?

A tankless water heater is a water heater that heats water without the use of a tank. The water is instead heated on demand as it flows through a heat exchanger. Most newer homes are being built with tankless water heaters for their efficiency and ability to heat non-stop water. Tankless water heaters offer a few large advantages vs a standard tank water heater. Tankless water heaters use much less space, as they have no tank for water storage (the majority of the space used by a standard water heater is used as water storage). The water flows back and forth through a copper heat exchanger, absorbing heat from the forced air as it pass through the fins of the heat exchanger. Digital smart tankless units, will measure the inlet water temperature and flow rate to self adjust the gas regulation. This technology allows for efficiencies of up to 97% with condensing tankless water heaters. Most storage tanks suffer from heat loss when not in use, this STAND-BY Heat Loss is the major reason for tank types efficiencies of around 75%.

TANKLESS WATER HEATERS

Tankless water heaters offer a few large advantages vs a standard tank water heater. Tankless water heaters use much less space, as they have no tank for water storage (the majority of the space used by a standard water heater is used as water storage). The water flows back and forth through a copper heat exchanger, absorbing heat from the forced air as it pass through the fins of the heat exchanger. Digital smart tankless units, will measure the inlet water temperature and flow rate to self adjust the gas regulation. This technology allows for efficiencies of up to 97% with condensing tankless water heaters. Most storage tanks suffer from heat loss when not in use, this STAND-BY Heat Loss is the major reason for tank types efficiencies of around 75%.

TANKLESS = NEVER RUNNING OUT OF HOT WATER

Because a tankless water heater heats the water as it flows, you can have a never ending supply of hot water. This is especially great for large families, apartment buildings, living communities or anywhere else that has a great demand for continuous hot water. We’ve actually found that the portable tankless water heater units, like the EZ 101 Propane Tankless are great for RVers as they replace their 6 Gallon water heaters that were only good for a single shower. Now while on the road, the entire family will have a chance to take a hot shower.

 

What is GPM (Gallons Per Minute). 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 is 45 degrees, and the temperature rise is 45 degrees at 3.2 GPM. What this means is that the output temperature of the water coming from the heater will be 90 degrees at a maximum flow of 3.2 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 3.2 GPM tankless water heater to a forty gallon tank type heater is possible. For example, if a tankless unit produces hot water at 3.2 gallons per minute, this rate of flow will run a 40 gallon tank type heater out of water in only ten minutes.

 

Tankless heaters do not store water. Therefore, you will not be using hot water that has been stored in a tank full of rust and sediment. Over the years, a tank heater accumulates rust and sediment which builds-up inside as a scale deposit that coats the sides and fills the bottom of the tank. Just think, this is the place where your hot water is being stored for your use.

 

Tankless heaters can be placed almost anywhere on an exterior wall. They are also much smaller than a tank heater. We have models that can be mounted indoors or outdoors.

 

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.

 

Tank type gas water heaters typically use a natural updraft exhaust. This method relies upon the suction (draft) of rising hot air to draw out the gasses though a flue exhaust pipe. The natural draft method is not an exact science. Wind and weather conditions, condition of and method of connections as well as internal household drafts and air movement can allow exhaust gasses to escape into the interior of the home. Malfunctioning water heater and furnace exhaust is a common cause of exposure to carbon monoxide gasses. Water heater exhaust by-products include carbon monoxide, nitrogen dioxide, sulfur dioxide, nitric oxide, microscopic particulates and additional harmful combustion bi-products. These particles can cause irritation to the eyes, nose, and throat, as well as causing nausea, fatigue, and dizziness. An indoor tankless heater with a sealed forced air exhaust eliminates these potentially harmful gasses as they are evacuated via the sealed stainless exhaust pipe.

GAS OR ELECTRIC?

Typically, electric models are used only for a single sink or a half bath installation, or for use in a workshop or small cabin. Electric units require 60 to 150 amps of 220V electricity on a stand-alone circuit breaker. In comparison, A Toyota Prius Hybrid car uses 201 Volts and 80 amps to propel itself at highway speed. Many older small town rural homes still operate on a 60 amp capacity service. Large whole house electric models may consume more electricity than the combined demands of the whole dwelling. Gas models are preferred for multiple bath installations as they are almost always more economical to operate.

What’s the biggest benefit of a tankless over a tank type heater?

The time it takes for hot water to arrive at the tap is the same on both types. The best thing about the hot water that comes from a tankless model is that you will receive an endless supply of hot water for as long as you open a faucet. With traditional tank type water heaters, you have hot water until the hot water tank’s supply is depleted. Then you must wait for the storage tank of cold water to re-heat before you again have hot water.

So…
If you are running out of hot water with your current tank type heater, and are thinking of purchasing a tankless model, you may wish to conduct a simple test by keeping track of the amount of time from when you turn on the hot water to the moment the hot water runs out. Take the total capacity of your tank-type heater. (This information can usually be found on the information stickers on the side of the tank.) Divide the capacity of the tank type heater (in gallons) by the number of minutes that it takes to run out of hot water. This is your peak usage of hot water and this calculation should be the minimum GPM that you need when selecting a tankless heater.

To perform this test, the home owner must decide which hot water devices to run for this test as the more valves open the higher the total GPM will be. So, if you have two showers and sometimes they are in use when the hot water runs out, then this would be the ones to use for the test.

For example:

If your test results in your 40 gallon heater running out of hot water in 12.5 minutes. Use the equation, G ÷ M = GPM, where G is equal to the total Number of Gallons of your tanked water heater and M is equal to the total time the water was running before it went cold. To be accurate in your calculation it is recommended that you wait an hour before running your hot water, only to make sure that your hot water heater is full of hot water.

40 gallon water capacity divided by 12.5 minutes = a flow rate of 3.2 gallons per minute.

If a tankless water heater doesn’t have a tank, how does it make hot water?

The tankless water heater heats water as it flows through the tubing in the heat exchanger inside the heater. When you open a faucet or turn on the shower, a sensor detects water flow and turns on the burner which heats the water. You can learn more from this site, it is very informative on how a tankless water heater works: http://homerepair.about.com/od/plumbingrepair/ss/tankless_hwh_2.htm