Energy Saving Gas Tankless Water Heater

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Home Page > Home Improvement > Construction > Energy Saving Gas Tankless Water Heater

Energy Saving Gas Tankless Water Heater

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Posted: Aug 06, 2009 |Comments: 0

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Energy Saving Gas Tankless Water Heater

By: Al Sagafi

About the Author

Al is California licensed General Building Contractor and electrical contractor with many years of field experience. He also hold a Master of Science in electrical engineering. He is very active in renewable energy (http://www.allied-solar.com) and energy saving measures (http://www.justtankless.com) and (http://www.alliedelectricservices.com)

(ArticlesBase SC #1101619)

Article Source: http://www.articlesbase.com/ – Energy Saving Gas Tankless Water Heater

Storage Tank Water Heater History

The Water heater is one of neglected appliances in homes, usually tucked away in some corner of the garage. We don’t pay much attention to it until it breaks. It has been around in its current form for a long time. It was invented in the 1889 by Edwin Ruud and it hasn’t changed much since then. It consists of a 40 or more gallon cylindrical container with a gas burner or sometimes an electric element. It heats the water slowly and keeps it hot all the time. Its burner has a pilot light that is burning gas all the time and the main burner comes periodically into action to heat the water again because the water in the container has cooled off. Well, that goes on day in day out even if the water is never used. That is because the water loses its heat to the surrounding. It is like having a kettle full of water on the cook top all the time. The newer tank water heaters are better insulated than before to reduce the standby heat loss but never the less they lose heat and the water must be constantly reheated. In today’s times where energy has become expensive and will become even more that is a total waste of energy and money. It burdens the environment even unnecessarily and contributes to earth warming and climate change.

The tank water heater is also very inefficient, not only loses its heat, standby heat loss, but it also doesn’t do a good job heating the water through its inherent design. When new, tank water heaters have an efficiency of about 55%. Depending on the hardness of the water it can rapidly fall to 30 or so percent because of water sediments buildup at the bottom of the tank, just like the kettle in which water sediments build up when water in it is heated over and over. The tank water heater has health issues as well. Bacteria and germs love the standing warm water and grow easily and rapidly in that environment. The water is usually not hot enough to kill them. Over time there can also be rust build up in the water tank that reduces the heating efficiency of the water heater in addition of it being delivered to the bathroom faucets and kitchen sink. Sometimes you can see the rust in the tile grout discoloration. Not all of that is unhealthy but a lot of times just undesirable. The tank water heater does push out some of these sediments and some of it remains in the tank and keeps building up. It is not just in the bathrooms we use hot water although the most of it is being used for bathing. We use hot water also to wash dishes sometimes and prepare food. Now if you could see all those microscopic foreign elements, bacteria and sediments you would think again of using it for food or even bathing the kids in tub with that water.

It has happened to all of us that we ran out of hot water taking a shower or a bath. And there is no quick heat up of the water. The water heater is just not designed for that and it takes a lot of energy and time again to heat 40 or more gallons of water. A lot of families have to schedule their showers because in a household with multiple persons you quickly run out of hot water. To make that hot water last a bit longer you can run the water heater at a higher temperature; say 180 degree Fahrenheit so that you mix more cold water with the hot water. Running the water heater at higher temperature wastes even more energy and with it of course money. Typically people take showers in the morning before leaving home for work. The water heater is not intelligent to know that after the shower you all leave the house and won’t be needing hot water until later in the afternoon when everybody gets home again. So it heats up the water again and keeps it hot all day long by heating and heating it again and again. And of course it doesn’t know that you won’t be needing hot water after taking shower and going to sleep, so it heats up the water again and keeps it hot during the night.

Storage tank water heater leaks can be expensive

Well, the other issue with tank water heaters is that they tend to leak water over time. Sometimes this happens for a long time without being noticed. Since most water heaters are placed in the garage they are usually out of sight and nobody pays attention to them. So water damage because of a water leak can go on for a very long time unnoticed and cause considerable damage to the home and surrounding in addition to wasting water and energy. Water damage to subfloors or other structures of homes is not uncommon and the repair of it tends to be costly because it wasn’t detected early.

Earthquake considerations

In earth quake prone areas water heaters pose a different problem as well. If not properly anchored they can tip over and cause water damage, physical damage and of course fire. Water heaters have fallen on cars parked close to them in the garage and considering the weight of a 40 or so gallon water heater full of water is approx. 330 pounds plus approx. 120 pounds for the heater itself, so a total of 450 pounds falling let’s say on a car’s hood. Now that will do significant damage not just to the hood of the car but also to what is underneath it.

And in this case it will also disconnect the gas line and we will have a gas leak as well that can lead to fire and more damage. So it is very important to make sure that the tank water heater is properly anchored to something that can hold the weight just in case. Bolts and steel straps should be strong enough and anchored to main wood studs or masonry walls.

Pressure relief valve on Tank Water Heaters

One other thing to pay attention to is the pressure relief valve. As its name implies it releases the water pressure to the outside by releasing excess water from the tank to avoid an explosion of the tank water heater. You may be surprised to know how often that happens that a small pressure valve fails and the water heater literally explodes. The excess water from the pressure valve of course should be routed to the outside or a drain that won’t cause water damage.

In some older homes the water heater is located inside the house in a place that looks like a pantry from the outside. That of course poses even a greater danger of something catastrophic happening in case of a failure. The idea of a constantly burning fire in an appliance is very unsettling to most people once they are made aware of it. The water heater burner or its pilot is always burning, not just when you use it.

For all the above reasons and more the time of the traditional tank water heater has passed long ago. In other parts of the world mainly Asia and Europe tank water heaters are hard to be found for many decades. There hot water is prepared by something called tankless water heater sometimes referred to as on-demand or instant water heater or point of use water heater.

Tankless Water Heater

The first tankless water heater was invented by an Englishman named Maughan in the 1870s. The idea of tankless water heater is to heat the water only when you need it and almost instantaneously, so no storage of hot water. Like many inventions tankless water heaters went through many designs over the decades. Most of the tankless water heaters were designed to be used at point of use. That is that wherever you needed hot water you would install an electric or gas powered unit and have hot water at the point you needed. This reduced also the plumbing of a house since you didn’t need to run another water pipe for the hot water. Typically you had a small unit in the kitchen; the unit incorporated the kitchen faucet and maybe a very small tank of one gallon or so. Whenever you turned the hot water faucet open you would get hot water automatically after a few seconds. In the bathrooms you had larger units, mostly gas operated that would do the same. No tank and no constantly heating water and with excellent efficiency that would remain largely the same. Efficiencies of 80 plus percents were common plus since there isn’t a tank of water with its associated standby heat loss the overall efficiency would be very much higher. Compared to tank water heater where you heat the water and keep it hot the tankless water heater heats the water only once for immediate use with higher efficiency.

Later years as the technology advanced came along the whole house tankless water heater or on-demand water heater as it is called alternatively. Here the idea is to supply the entire house with hot water on a needed basis only. Large amount of water would be heated as it is needed, be it for a shower or in the kitchen or for the washing machine all at the same time. And the worries or cold running showers were a thing of the past. Now you could fill up the bath tub and not worry to have enough hot water afterward.

That is because tankless water heater provides endless hot water as long as there is water and gas or electricity to heat the water on the go. No storage tank and therefore no ending hot water, and of course with incredible efficiency of 80 plus percent. The newest Noritz 842 tankless water heater has an unbelievable efficiency of almost 94%. Its exhaust venting is made of PVC, almost no energy is wasted and therefore no need to exhaust it. Now that is a contrast to the regular water heater. Since tankless water heater has no storage tank it comes in a small package, roughly 5 times smaller than the tank water heater. It can be mounted on a wall outside of the house and free up valuable space in the garage or in some cases turn that look alike pantry where the tank water heater was into a real pantry inside the house.

The tankless water heater doesn’t use energy when there is no need for hot water and has no standby heat loss. The showers can now be truly endless and no worry for the next person wanting to take a shower. The typical shower uses 2.5 gallons of water per minute and a mid size tankless water heater can supply roughly 6 to 7 gallons of hot water per minute. Now here 2 persons can take shower simultaneously or at the same time and still have enough hot water for the washing machine or the kitchen sink. Today’s Tankless water heaters are very sophisticated computer controlled appliances. They control and keep the water temperature to preset level regardless of water volume and pressure. In other words the water temperature at the shower head is the same regardless of how much water is being used, a second shower is turned on or third user draws hot water. The gas burner or electric heater modulates the energy, gas or electric to the desired level to achieve the set temperature. All this is possible with modern electronics and having a closed loop circuit with high accuracy. The leading manufacturer of tankless water heaters are Noritz, Takagi, Rinnai and Bosch. They have refined their products for extreme reliability and durability. Typical tankless water heater lasts 3 times as long as a tank water heaters with no noticeable degradation in performance or efficiency. Tankless water heater models like Noritz 751 can supply an entire house with continuous hot water and save energy and money.

None of the safety issues of tank water heater applies to tankless water heaters. Their burners come on only when hot water is needed, they don’t have a permanent pilot. The gas burner is electronically ignited and if installed outside it constantly monitors the outside temperature and activates its anti freeze circuitry preventing a pipe freeze when needed. Its electronics also monitors incoming water pressure, flow and regulates outgoing hot water pressure and flow. The highly efficient burner and heat exchanger achieve high efficiency and save energy. Incoming gas volume and pressure is also monitored and in case of a malfunction the unit shuts itself off and provides diagnostic information. Takagi TK 3 is closely related to Noritz 751 and is also able to supply an entire house with hot water. Another saving aspect of tankless hot water heater is that since you never run out of hot water there is no need to mix the hot water with cold water and therefore the water temperature can be set lower. For example the tank water heater is typically set to 160 to 180 degree F even though the water temperature used for shower is roughly 105 degree F. This is done to not use so much of the hot water in the storage tank and make the hot water last longer by mixing it with cold water at point of use. With tankless water heaters there is no need for this, there is endless hot water and therefore the temperature can be set to 110 degree F and there is no need to mix as much cold water. That saves energy too because the water is not heated to the higher temperature. Any time cold water is mixed to the hot water that reduces the efficiency indirectly. Tankless water heaters are green products and help reduce the carbon footprint.

Thanks to government subsidies, tax credits, tax rebates and sometimes additional local utility rebates tankless water heaters can compete favorably with the old fashion tank water heaters. Their initial cost has come down and the payback on energy savings can be very substantial. According to various statistics 30% to 40% of the energy cost of a typical home is consumed by the water heater. Tankless water heaters can reduce that by more than 50%. Tankless water heaters are also popular for commercial and industrial applications. Models like Noritz 751, Noritz 842 and Noritz 931 can be installed in series to provide almost boiling water. Restaurants, Hair Salons, Gyms and many other commercial businesses can benefit from the energy savings of tankless water heaters in addition to the space savings. Smaller units like Noritz 631 are well suited for smaller applications, like apartments or smaller homes. Most units allow you to set the desired temperature via a control panel that can be conveniently installed in the bathroom or any other place. This gives you immediate control of setting the desired water temperature. There may be times that there is a need for higher temperature of 180 degree F for example, this is easy to set through the digital control panel. This is very useful when filling a SPA or filling a large bath tub.

Because tankless water heaters are sophisticated appliances the more critical is their correct installation. They should be installed by licensed, factory certified and experienced professionals. By far the most installed type of tankless water heater is the one powered by natural gas. Electric models are not very economical because of mostly higher electric rates and potentially higher installation cost. Electric units usually have a high power demand and may need supply circuits of 100 or more amperes. This would require an upgrade to the existing electric system of the house that becomes costly. Smaller electric tankless water heaters can be easily used in point of use locations, for example for the kitchen sink. They require much less power.

The most important factor is the location where the tankless water heater is going to be installed. It is crucial to be close to the gas meter and the gas line to be properly sized so it is able to supply the volume of gas needed. Utility gas meters can also be restrictive and not able to supply enough gas. This is usually not a problem, most utility companies can exchange the meter free of charge. Since the tankless water heater modulates its burners it adjusts the gas flow to the burner for desired temperature.

Problems usually occur when the unit needs to supply greater amount of hot water and is not able to receive enough gas volume for the burners. The gas supply and volume is very important to have a trouble free operation. It is not that tankless water heaters use more gas; they use more of it when heating the water instantaneously versus the tank water heater that slowly heats the water. The energy it takes to heat water to a certain temperature is the same. It is important how efficiently that energy is used. A professional installation also tries to minimize the pipe length from the tankless water heater to the next bathroom. This reduces the amount of cold water that is flushed before the hot water reaches the faucet.

There are some pump products on the market that continuously circulate hot water in the pipes so that hot water is immediately available when you open the hot water faucet. These pumps are very wasteful of energy because in most homes the hot water pipes are not insulated and made of copper. Copper is a very good heat conductor so all the hot water in the pipes are constantly radiating heat to the surrounding and cooling quickly. It works sort of like the radiator or the heater in a car. Hot water is pumped through it to cool. These pumps and the associated valves use the cold water pipes for the circulation of water, so the cold water in the pipes become warm as well.

Because of the small size of the tankless water heater it can be installed almost anywhere and not necessarily where the old water heater was. It is also important to make sure the water pipes can carry the volume of water. The tankless water heater of course regulates the flow but having not the capacity means the heater can’t run at full capacity when needed. This means that multiple showers may not have enough hot water at the same time. One thing that tankless water heaters require is a minimum flow of water to start heating the water. That is usually around 0.5 gallons per minute. This is not a problem except when you want hot water at or below that flow rate. A very low flow rate causes the tankless water heater either not to come on at all or to come on and turn off again quickly. This can also happen with newer one handle shower faucets. Here the water mixture for hot and cold water is preset and the volume is increased or decreased. The mixture ratio is set according to the tank water heater temperature which is higher than the tankless water heater.

Here you have potentially a situation that there won’t be enough flow of hot water to keep the unit on and the water coming out of the shower won’t be hot enough. It is easy to fix and adjust the mixture ration of the valve to match the tankless water heater temperature. This situation of course is not directly related to the tankless water heater but it affects the operation of it. A professional experienced with tankless water heaters will know about this and other little things that make the difference.

Storage tank water heater leaks can be expensive

Earthquake considerations

In earth quake prone areas water heaters pose a different problem as well. If not properly anchored they can tip over and cause water damage, physical damage and of course fire. Water heaters have fallen on cars parked close to them in the garage and considering the weight of a 40 or so gallon water heater full of water is approx. 330 pounds plus approx. 120 pounds for the heater itself, so a total of 450 pounds falling lets say on a car’s hood. Now that will do significant damage not just to the hood of the car but also to what is underneath it.

Pressure relief valve on Tank Water Heaters

For all the above reasons and more the time of the traditional tank water heater has passed long ago. In other parts of the world, mainly Asia and Europe tank water heaters are hard to be found for many decades. There hot water is prepared by something called tankless water heater, sometimes referred to as on-demand or instant water heater or point of use water heater.

Tankless Water Heater History

The first tankless water heater was invented by an Englishman named Maughan in the 1870s. The idea of tankless water heater is to heat the water only when you need it and almost instantaneously, so no storage tank of hot water. Like many inventions tankless water heaters went through many designs over the decades. Most of the tankless water heaters were designed to be used at point of use. That is that wherever you needed hot water you would install an electric or gas powered unit and have hot water at the point you needed. This reduced also the plumbing of a house since you didn’t need to run another water pipe for the hot water. Typically you had a small unit in the kitchen; the unit incorporated the kitchen faucet and maybe a very small tank of one gallon or so. Whenever you turned the hot water faucet open you would get hot water automatically after a few seconds. In the bathrooms you had larger units, mostly gas operated that would do the same. No tank and no constantly heating water and with excellent efficiency that would remain largely the same. Efficiencies of 80 plus percents were common. Since there isn’t a storage tank of water with its associated standby heat loss the overall efficiency would be much higher. Compared to storage tank water heater where you heat the water and keep it hot the tankless water heater heats the water only once for immediate use with higher efficiency. This goes for electric tankless water heaters as well as for gas tankless water heaters.

Whole House Tankless Water Heater

The best tankless water heater provides endless hot water as long as there is water and gas or electricity to heat the water on the go. No storage tank and therefore no ending hot water, and of course with incredible efficiency of 80 plus percent. The cutting edge tankless technology leader Noritz introduced the newest Noritz 842 tankless water heater. It has an unbelievable efficiency of almost 94% achieved with tankless technology. Its exhaust venting is made of PVC, almost no energy is wasted and therefore no need to exhaust it. You may ask who makes the best Tankless Water Heater and the answer would have Noritz at the top of the list as the largest tankless water heater manufacture in the world.

Since tankless water heater has no storage tank it comes in a small package, roughly 5 times smaller than the tank water heater. It can be mounted on a wall outside of the house and free up valuable space in the garage or in some cases turn that look alike pantry where the tank water heater was into a real pantry inside the house.

No Energy wasted with Tankless Water Heater

The tankless water heater doesn’t use energy when there is no need for hot water and has no standby heat loss. The showers can now be truly endless and no worry for the next person wanting to take a shower. The typical shower uses 2.5 gallons of water per minute and a mid size tankless water heater can supply roughly 6 to 7 gallons of hot water per minute. Now here 2 persons can take shower simultaneously or at the same time and still have enough hot water for the washing machine or the kitchen sink. Today’s Tankless water heaters with best tankless technology are very sophisticated computer controlled appliances. They control and keep the water temperature to preset level regardless of water volume and pressure. In other words the water temperature at the shower head is the same regardless of how much water is being used, a second shower is turned on or third user draws hot water. The gas burner or electric heater modulates the energy, gas or electric to the desired level to achieve the set temperature. All this is possible with modern electronics and having a closed loop circuit with high accuracy. The leading manufacturer of tankless water heaters are Noritz, Takagi, Rinnai and Bosch. Noritz Tankless Water Heaters are among the best on the market. They all have refined their products for extreme reliability and durability. Typical tankless water heater lasts 3 times as long as a storage tank water heater with no noticeable degradation in performance or efficiency over time. Tankless water heater models like Noritz 751 or Takagi TK-3 can supply an entire house with continuous hot water and save energy and money.

Tankless Water Heaters are Safe

None of the safety issues of tank water heater applies to tankless water heaters. Their burners come on only when hot water is needed, they don’t have a permanent pilot. The gas burner is electronically ignited and if installed outside it constantly monitors the outside temperature and activates its anti freeze circuitry preventing a pipe freeze when needed. Its electronics also monitors incoming water pressure, flow and regulates outgoing hot water pressure and flow. The highly efficient burner and heat exchanger achieve high efficiency and save energy. Incoming gas volume and pressure is also monitored and in case of a malfunction the unit shuts itself off and provides diagnostic information. Takagi TK 3 is closely related to Noritz 751 and is also able to supply an entire house with hot water. Another saving aspect of tankless hot water heater is that since you never run out of hot water there is no need to mix the hot water with cold water and therefore the water temperature can be set lower. For example the tank water heater is typically set to 160 to 180 degree F even though the water temperature used for shower is roughly 105 degree F. This is done to not use so much of the hot water in the storage tank and make the hot water last longer by mixing it with cold water at point of use. With tankless water heater there is no need for this, there is endless hot water and therefore the temperature can be set to 110 degree F and there is no need to mix in as much cold water. That saves energy too because the water is not heated to the higher temperature. Any time cold water is mixed to the hot water that reduces the efficiency indirectly. Tankless water heaters are green products and help reduce the carbon footprint.

Government incentives make Tankless Water Heater more affordable than ever before

Thanks to government subsidies, tax credits, tax rebates and sometimes additional local utility rebates tankless water heaters can compete favorably with the old fashion Storage tank water heaters. Their initial cost has come down and the payback on energy savings can be very substantial. According to various statistics 30% to 40% of the energy cost of a typical home is consumed by the water heater. Tankless water heaters can reduce that by more than 50%. Tankless water heaters are also popular for commercial and industrial applications. Models like Noritz 751, Noritz 842 and Noritz 931 can be installed in series to provide almost boiling water. Restaurants, Hair Salons, Gyms and many other commercial businesses can benefit from the energy savings of tankless water heaters in addition to the space savings. Smaller units like Noritz 631 are well suited for smaller applications, like apartments or smaller homes. Most units allow you to set the desired temperature via a control panel that can be conveniently installed in the bathroom or any other place. This gives you immediate control of setting the desired water temperature. There may be times that there is a need for higher temperature of 180 degree F for example, this is easy to set through the digital control panel. This is very useful when filling a SPA or filling a large bath tub. Tankless water heaters are also well suited for vacation homes. Electric Tankless Water Heaters are also highly efficient and can be easily installed where there is enough electrical power. In most areas electricity tends to be expensive compared to natural gas and a natural gas or liquid propane or LP tankless water heater may be more economical. Today’s units are among the most compact tankless water heaters ever built and carry the energy star classification

Correct Installation makes the difference

Because tankless water heaters are sophisticated appliances the more critical is their correct installation. They should be installed by licensed, factory certified and experienced professionals. By far the most installed type of tankless water heater is the one powered by natural gas. Electric models are not very economical because of mostly higher electric rates and potentially higher installation cost. Electric tankless water heaters usually have a high electric power demand and may need supply circuits of 100 A or more amperes. This would require an upgrade to the existing electric system of the house that can be costly. Smaller electric tankless water heaters can be easily used in point of use locations, for example for the kitchen sink. They require much less power and are very useful.

The most important factor is the location where the tankless water heater is going to be installed. It is crucial to be close to the gas meter and the gas line to be properly sized so it is able to supply the volume of gas needed. Utility gas meters can also be restrictive and not able to supply enough gas. This is usually not a problem, most utility companies can exchange the meter to a larger unit free of charge. Since the tankless water heater modulates its burners it adjusts the gas flow to the burner for desired temperature.

There are some pump products on the market that continuously circulate hot water in the pipes so that hot water is immediately available when you open the hot water faucet. These pumps are very wasteful of energy because in most homes the hot water pipes are not insulated and made of copper. Copper is a very good heat conductor so all the hot water in the pipes are constantly radiating heat to the surrounding and cooling off quickly. It works sort of like the radiator or the heater in a car. Hot water is pumped through it to cool. These pumps and the associated valves use the cold water pipes for the circulation of water, so the cold water in the pipes become warm as well.

This company http://www.chilipepperapp.com/ has come up with an innovative solution. A tankless water heater pump or better a recirculating pump that is electronically controlled and turned on when needed. Tankless pumps like these add additional Convenience and prevent waste of water. The cooled off water in the hot water pipe is returned to the cold water pipes instead of being drained.

Because of its compact size the tankless water heater can be installed almost anywhere and not necessarily where the old water heater was. It is also important to make sure the water pipes can carry the volume of water. The tankless water heater of course regulates the flow but having not the capacity means the heater can’t run at full capacity when needed. This means that multiple showers may not have enough hot water at the same time. One thing that tankless water heaters require is a minimum flow of water to start heating the water. That is usually around 0.5 gallons per minute. This is not a problem except when you want hot water at or below that flow rate. A very low flow rate causes the tankless water heater either not to come on at all or to come on and turn off again quickly. This can also happen with newer one handle shower faucets. Here the water mixture for hot and cold water is preset and the volume is increased or decreased. The mixture ratio of cold and hot water is set according to the storage tank water heater temperature which is higher than the tankless water heater.

Here you have potentially a situation that there won’t be enough flow of hot water to keep the unit on and the water coming out of the shower won’t be hot enough. It is easy to fix and adjust the mixture ratio of the valve to match the tankless water heater temperature. This situation of course is not directly related to the tankless water heater but it affects the operation of it. A professional experienced with tankless water heaters will know about this and other little things that make the difference. For more information please refer to http://www.justtankless.com .

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