Tankless Water Heater, Pros and Cons. For info- ABT Plumbing & Electric 530-272-9120 www.easyasabt.com
I've been installing and servicing tankless water heater for over 12 years. People ask me questions all the time like, is a tankless a good idea for me, do they work for the whole house, etc. It really depends on the application. If you want to save energy, and have endless hot water they're great. If you want to save money, it gets a little more complicated. If you have a large water heater like a 75 gallon or larger, a large family, or family that come to visit often, they will save you money. But if there are only 2 people in the home and you have a 40 gallon water heater, it will take a while to pay for its self in energy savings. The best thing is to have a Licensed plumber who has experience with tankless water heaters come out and give you an idea of cost. Be sure the plumber has experience though, the only time we've seen problems with these is installation issues. Tankless is a good choice, do some research, call an experienced installer, and enjoy the benifits of endless hot water and energy efficiency.
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- ABT Plubing & Electric
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DIY Solar water heater
Here is a DIY solar water I came across while I working
This is an amazing solar water heater. It's been working worry free for over 30 years.
DIY Solar Water Heater, http://www.dr-stinky.com/solar.htm
Get your very own do-it-yourself solar water heater guide here http://www.dr-stinky.com/solar.htm (dont leave off the htm at the end!) Home made solar hot water heater. It has been working for the last 30 years. Simple and cheap to build. On grid or off grid.
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Tankless Buying guide
Q.."Will an instantaneous water heater save me money on my utility bills?"
A..Yes, in most applications you will see a savings. There are some variables that could reduce the amount you save. One example is you will not run out of hot water, so longer showers could cut into your savings. Also, the cost of electricity, propane and natural gas in your area will affect the amount of money saved. The higher the cost for the energy type used to heat your water, the quicker you will recover the higher initial cost of installing a tankless versus tank style water heater.
Positives:
You will never run out of hot water. "You want an hour long shower? No problem!"
Electric units can be installed at the point of use.
You're not paying energy costs to heat water 24 hours a day.
They're easy to install.
Our electric units don't require a T&P valve. (No tank!)
Installing a tankless water heater will indeed be a bonus to the environment. (Why should we choose wastefulness when we're talking about finite natural resources?)
Negatives:
They all need a minimum flow rate & pressure to turn on.
The faster water flows through them, the lower the temperature rise. So,if you expect to take a shower while the clothes washer is running, you will need to select a unit sized to your hot water flow requirements. (Gas units handle this a little better than electric models)
Electric units need heavy gauge wire. Example: the 9.5kw must have 8ga wire and a 50amp breaker.
Gas units need a much larger, special flue pipe and larger gas supply than a conventional water heater.
At times they can produce very hot water. It's easier to get scalded.
Gas units are more complicated than a conventional water heater.
With some brands, parts are hard to find (not a negative if you originally purchase from us, as we like to carry parts for the units that we sell).
Summary:
Tankless water heaters have their place. They're not "the answer" to every hot water need, but if they're used correctly they can be the solution to many of them.
Q.."If these units don't have a tank, how do they know when to turn on?"
A..The tankless water heaters have a flow switch built into them. When you turn on (open) the hot side of a faucet the water then moves (travels). Once the water is traveling at 3/4 of a gallon per minute or faster most tankless water heater switches will then turn on the gas or electricity.
Q.."What's the difference between a conventional flue and a direct vent?"
A..A conventional flue is what most people are familiar with. It typically consists of a double-wall flue pipe going from the top of the heater through the roof, venting outside. The fixture draws its combustion air from the space around it (utility room, garage, hallway, etc.). A direct-vent unit on the other hand, both vents and draws its combustion air through a specially designed pipe from the outside via an adjacent wall.
Q.."Is it possible to drain a tankless water heater to prevent freeze damage when not in use?"
A..Yes. Simply drain both lines 'to' and 'from' the unit. As long as there are no check valves in the way, that should drain the water from the unit. To guarantee that there is no water in the unit, we recommend two drain valves - one before and one after the unit - as well as blowing air through the water line.
Q.."On the electric tankless models; why should I buy the thermostatic model instead of the lower priced flow model?"
A..The thermostatic model has a number of advantages. A non-thermostatically controlled model's outlet temperature is dependent on the flow rate, and it can create a potential problem with anti-scalding valves and the like. When in doubt, please order the thermostatically controlled models. Also, the thermostatic models can have a warm or hot water source, but the non thermostatically controlled models are only designed for a cold-water source/input.
Q.."Can I replace my existing tank type water heater with a tankless water heater?"
A..Yes, but there are specific requirements that will need to be addressed. Gas units will require a larger, special vent pipe and a larger gas supply line that not only will supply the water heater, but all other appliances on that gas pipe run. Electric units will require larger gauge wire and breakers than most tank type water heaters.
Q.."I have a pressure/temperature pressure balancing valve for scalding safety. Can I use all of the above instant heaters without worry?"
A..In that case never install a non-modulating heater such as the small electric tankless water heater model EX95. When ordering make sure to only order a heater that has a modulating valve and also it's a good idea to install an additional scald protection valve before your showerhead.
Q.."I would like to convert my natural gas tankless heater to be able to use LPG (propane) gas instead. Do you offer a conversion kit?"
A..Sorry, but we don't. Even if we could, we probably wouldn't, as in most cases it is not a good idea to convert one type of gas for another. Burners can be different, orifices, etc. Not only is the BTU rating different for these two gases, but also the heat of the flames and a number of other factors. We simply do not wish to sell ("profit from") something that might create a non-safe environment.
Q.."Can I install tankless water heaters in my attic?"
A..AWithout seeing all of your plumbing piping, etc. it is difficult for us to answer with a straight "yes" or "no." One must be sure that a possible water siphoning condition can not be created as tankless water heaters should not have air in the lines. Water siphoning out of any brand of tankless water heater might damage the heater when there is no water (or not enough water) in the lines.
Q.."Your products specify the 'temp. rise' based on the GPM flow; what do you mean by this?"
A..Temperature rise is the amount the heater raises the temperature of the incoming water, based on the flow rate shown of that water.
A..Yes, in most applications you will see a savings. There are some variables that could reduce the amount you save. One example is you will not run out of hot water, so longer showers could cut into your savings. Also, the cost of electricity, propane and natural gas in your area will affect the amount of money saved. The higher the cost for the energy type used to heat your water, the quicker you will recover the higher initial cost of installing a tankless versus tank style water heater.
Positives:
You will never run out of hot water. "You want an hour long shower? No problem!"
Electric units can be installed at the point of use.
You're not paying energy costs to heat water 24 hours a day.
They're easy to install.
Our electric units don't require a T&P valve. (No tank!)
Installing a tankless water heater will indeed be a bonus to the environment. (Why should we choose wastefulness when we're talking about finite natural resources?)
Negatives:
They all need a minimum flow rate & pressure to turn on.
The faster water flows through them, the lower the temperature rise. So,if you expect to take a shower while the clothes washer is running, you will need to select a unit sized to your hot water flow requirements. (Gas units handle this a little better than electric models)
Electric units need heavy gauge wire. Example: the 9.5kw must have 8ga wire and a 50amp breaker.
Gas units need a much larger, special flue pipe and larger gas supply than a conventional water heater.
At times they can produce very hot water. It's easier to get scalded.
Gas units are more complicated than a conventional water heater.
With some brands, parts are hard to find (not a negative if you originally purchase from us, as we like to carry parts for the units that we sell).
Summary:
Tankless water heaters have their place. They're not "the answer" to every hot water need, but if they're used correctly they can be the solution to many of them.
Q.."If these units don't have a tank, how do they know when to turn on?"
A..The tankless water heaters have a flow switch built into them. When you turn on (open) the hot side of a faucet the water then moves (travels). Once the water is traveling at 3/4 of a gallon per minute or faster most tankless water heater switches will then turn on the gas or electricity.
Q.."What's the difference between a conventional flue and a direct vent?"
A..A conventional flue is what most people are familiar with. It typically consists of a double-wall flue pipe going from the top of the heater through the roof, venting outside. The fixture draws its combustion air from the space around it (utility room, garage, hallway, etc.). A direct-vent unit on the other hand, both vents and draws its combustion air through a specially designed pipe from the outside via an adjacent wall.
Q.."Is it possible to drain a tankless water heater to prevent freeze damage when not in use?"
A..Yes. Simply drain both lines 'to' and 'from' the unit. As long as there are no check valves in the way, that should drain the water from the unit. To guarantee that there is no water in the unit, we recommend two drain valves - one before and one after the unit - as well as blowing air through the water line.
Q.."On the electric tankless models; why should I buy the thermostatic model instead of the lower priced flow model?"
A..The thermostatic model has a number of advantages. A non-thermostatically controlled model's outlet temperature is dependent on the flow rate, and it can create a potential problem with anti-scalding valves and the like. When in doubt, please order the thermostatically controlled models. Also, the thermostatic models can have a warm or hot water source, but the non thermostatically controlled models are only designed for a cold-water source/input.
Q.."Can I replace my existing tank type water heater with a tankless water heater?"
A..Yes, but there are specific requirements that will need to be addressed. Gas units will require a larger, special vent pipe and a larger gas supply line that not only will supply the water heater, but all other appliances on that gas pipe run. Electric units will require larger gauge wire and breakers than most tank type water heaters.
Q.."I have a pressure/temperature pressure balancing valve for scalding safety. Can I use all of the above instant heaters without worry?"
A..In that case never install a non-modulating heater such as the small electric tankless water heater model EX95. When ordering make sure to only order a heater that has a modulating valve and also it's a good idea to install an additional scald protection valve before your showerhead.
Q.."I would like to convert my natural gas tankless heater to be able to use LPG (propane) gas instead. Do you offer a conversion kit?"
A..Sorry, but we don't. Even if we could, we probably wouldn't, as in most cases it is not a good idea to convert one type of gas for another. Burners can be different, orifices, etc. Not only is the BTU rating different for these two gases, but also the heat of the flames and a number of other factors. We simply do not wish to sell ("profit from") something that might create a non-safe environment.
Q.."Can I install tankless water heaters in my attic?"
A..AWithout seeing all of your plumbing piping, etc. it is difficult for us to answer with a straight "yes" or "no." One must be sure that a possible water siphoning condition can not be created as tankless water heaters should not have air in the lines. Water siphoning out of any brand of tankless water heater might damage the heater when there is no water (or not enough water) in the lines.
Q.."Your products specify the 'temp. rise' based on the GPM flow; what do you mean by this?"
A..Temperature rise is the amount the heater raises the temperature of the incoming water, based on the flow rate shown of that water.
Great Stuff on Amazon
Bosch GL2.5 Ariston 2-1/2-Gallon Point-of-Use Indoor Electric Mini-Tank Water Heater
Amazon Price: $159.00 (as of 12/23/2009) 
Portable Tankless Water Heater with Shower Head
Amazon Price: $125.15 (as of 12/23/2009)
Bosch GL4 Ariston 4-Gallon Point-of-Use Indoor Electric Mini-Tank Water Heater
Amazon Price: $169.00 (as of 12/23/2009)
More info on tankless water heaters
What is a Tankless Water Heater?
Tankless Water Heaters, also called Instantaneous or Demand Water Heaters, provide hot water only as it is needed. Traditional storage water heaters produce standby energy losses that cost you money. We do not leave our homes heated while vacationing. We only heat our homes when there is a demand for heat. In the same way, a Tankless Water Heater is used only when there is a demand for hot water.
How do Tankless Water Heaters work?
Tankless Water Heaters heat water directly without the use of a storage tank. Therefore, they avoid the standby heat losses associated with storage water heaters. When a hot water tap is turned on, cold water travels through a pipe into the unit. In an electric Tankless Water Heater an electric element heats the water. In a gas-fired Tankless Water Heater a gas burner heats the water. As a result, Tankless Water Heaters deliver a constant supply of hot water. You don't need to wait for a storage tank to fill up with enough hot water. Typically, Tankless Water Heaters provide hot water at a rate of 2 - 5 gallons (7.6 - 15.2 liters) per minute. Typically, gas-fired Tankless Water Heaters will produce higher flow rates than electric Tankless Water Heaters. Some smaller Tankless Water Heaters, however, cannot supply enough hot water for simultaneous, multiple uses in large households. For example, taking a shower and running the dishwasher at the same time can stretch a Tankless Water Heater to its limit. To overcome this problem, you can install a "whole house" type Tankless Water Heater or install two or more Tankless Water Heaters, connected in parallel for simultaneous demands of hot water. You can also install separate Tankless Water Heaters for appliances-such as a clothes washer or dishwater-that use a lot of hot water in your home.
Other applications for Tankless Water Heaters include the following:
Remote BBQ or outdoor sink
Poolhouse or pool shower
Remote bathrooms or hot tubs
To serve as a booster, eliminating long pipe runs, for solar water heating systems, dishwashers and sanitation.
For homes that use 41 gallons or less of hot water daily, Tankless Water Heaters can be 24% - 34% more energy efficient than conventional storage tank water heaters. They can be 8% - 14% more energy efficient for homes that use a lot of hot water, around 86 gallons per day. You can achieve an even greater energy savings of 27% - 50% if you install a Tankless Water Heater at each hot water outlet.
Selecting a Tankless Water Heater
Before buying a Tankless Water Heater, consider the following:
Fuel Type
Location, Size and Demand
Application
1. Fuel Type
The first thing that you'll need to decide when selecting a Tankless Water Heater is the fuel type. You will need to select between an Electric Tankless Water Heater (like Eemax Tankless Water Heaters or Stiebel Eltron Tankless Water Heaters) or a Gas-Fired Tankless Water Heater (like Rheem Tankless Water Heaters).
Requirements for Electric Tankless Water Heaters
Requirements for Gas-Fired Tankless Water Heaters
--------------------------------------------------------------------------------
If you plan to purchase an Electric Tankless Water Heater, consider the Electrical Requirements:
Voltage
Amperage
Circuit Breaker
Voltage
Many retailers sell units that will accommodate 110V, 120V, 208V, 220V, 240V, and 277V.
Amperage
Different Electric Tankless Water Heaters will have various requirements in amp draw. You will want to ensure that you can support the electrical demands of your Electric Tankless Water Heater.
Circuit Breaker
You must ensure that you have a circuit or circuits that will support your Electric Tankless Water Heater. It may be necessary to put your Electric Tankless Water Heater on its own circuit or circuits.
You should consult with a qualified, licensed electrician for more information.
--------------------------------------------------------------------------------
If you plan to purchase a Gas-Fired Tankless Water Heater, consider the Gas-Type and Venting Requirements:
You will first need to identify whether your gas type is Natural Gas or Propane. It is imperitive that you examine your current gas line to ensure that it will meet the requirments of your new Gas-Fired Tankless Water Heater. The requirements of the Tankless Water Heater may exceed that of your existing tank-style water heater.
Next, you will need to consider venting requirements for your specific installation scenario. There are a few important things to keep in mind when purchasing the gas venting accessories for your Gas-Fired Tankless Water Heater.
Be sure that you purchase Category III stainless steel (UL1738 certified) venting for your Gas-Fired Tankless Water Heater. "Type B" venting accessories are not acceptable. Also, be sure to check local building code to ensure that your specific needs will be completely met.
Additionally, many Tankless Water Heater manufacturers offer gas venting "kits". It is recommended that customers evaluate the needs of their specific installation to ensure that they will be getting all of the necessary gas venting accessories. Depending on where you will be installing the Tankless Water Heater, a pre-made kit will probably not meet your needs. Ensure that you measure out the vent route and consider where the discharge will go through the wall or ceiling, consider the necessary clearances, and consider ample access to air for combustion, then buy the appropriate gas venting pieces. *Note: Gas-Fired Tankless Water Heaters may still require a minimal electrical connection. Be sure to review installation requirements for the units you are considering for purchase.
2. Location, Size, and Demand
When deciding which Tankless Water Heater to purchase, you will also need to consider where you will need hot water. Are you looking for a unit that will heat the water at one bathroom sink (single point application), an entire bathroom (multipoint application), or an entire house, apartment, or condo (whole house application)? It is important to recognize the number of fixtures that will require hot water. Each fixture will have its own demands. The chart below illustrates the typical flow rates (demand) for some standard fixtures:
Typical Flow Rates in Gallons per Minute (gpm)
Fixture Type Lavatory Bathtub Shower Kitchen Sink Pastry Sink Laundry Sink Dish-washer
Flow Rates 0.5 2.0 - 4.0 1.5 - 3.0 1.0 - 1.5 1.5 - 2.5 2.5 - 3.0 1.0 - 3.0
The flow rate is especially important, since Tankless Water Heaters will generate a temperature rise based on the flow rate demanded.
For example, a Stiebel Eltron Tempra 12, running on 240 Volt power, will raise the water temperature by 54°F at 1.5 gpm, 36°F at 2.25 gpm, and 27°F at 3.0 gpm, above the ambient incoming water temperature, up to 125°F.
A larger unit, like the Stiebel Eltron Tempra 36, running on 240 Volt power, will raise the water temperature by 92°F at 1.5 gpm, 92°F at 2.25 gpm, and 82°F at 3.0 gpm, above the ambient incoming water temperature, up to 125°F.
Temperature Rise Based on Flow Rate, Up to 125°F
Flow Rate 1.5 gpm 2.25 gpm 3.0 gpm
Tempra 12 54°F 36°F 27°F
Tempra 36 92°F 92°F 82°F
This means that if you are using a 1.5 gpm shower and a 1.5 gpm kitchen sink simultaneously, a total demand of 3.0 gpm, the Stiebel Eltron Tempra 12 will raise the temperature 27°F, whereas the Stiebel Eltron Tempra 36 will raise the temperature 82°F.
Next, you should look at your ambient incoming water temperature. If you live in a cold climate, like New York, your incoming water temperature will likely be much lower than if you live in a warm climate, like Florida. Your best bet is to find out how much temperature rise you will need in order for your hot water to reach the desired heat. If the ambient incoming water temperature for your shower is 65°F, you are using a 2.0 gpm shower, and you want to raise that temperature to 115°F, you will want to look for a Tankless Water Heater that will provide at least a 50°F temperature rise at 2.0 gpm (115°F - 65°F = 50°F). However, if you anticipate additional simultaneous demand, such as the hot water from a sink being used while someone is showering, you will need to add the sink's gpm to the shower's gpm in order to determine your overall gpm demand and then find the temperature rise necessary to meet your overall needs.
60° F
Incoming Water
2 gpm
Shower
110° F
Desired Output Water Temperature
You will need a Tankless Water Heater that produces a 50°F temperature rise at 2 gpm
3. Application
You may have a specific application in mind for your Tankless Water Heater. Here are a few examples of the different models and their functionality for a specific application:
Single Point Application
A single point application is one where only one fixture will require an Electric Tankless Water Heater. Here are some examples of Single Point Electric Tankless Water Heaters:
Eemax Single Point Electric Tankless Water Heaters
Stiebel Eltron Point of Use Electric Tankless Water Heaters
Chronomite Instant-Flow SR Electric Tankless Water Heaters
Eemax Flow Controlled
The "Flow Controlled" range of water heaters from Eemax are ideally suited to serve two points, like two sinks, in close proximity. Here is an example of Flow Controlled Electric Tankless Water Heaters:
Eemax Flow Controlled Electric Tankless Water Heaters
Thermostatic
The Thermostatic Tankless Water Heater serves as a booster for temperature loss from long pipe runs, dishwashers and sanitation. Thermostatic units are good for applications where precise temperature control is essential; such as schools, hospitals and laboratories. Here are some examples of Thermostatic Electric Tankless Water Heaters:
Eemax Thermostatic Electric Tankless Water Heaters
Stiebel E
Tankless Water Heaters, also called Instantaneous or Demand Water Heaters, provide hot water only as it is needed. Traditional storage water heaters produce standby energy losses that cost you money. We do not leave our homes heated while vacationing. We only heat our homes when there is a demand for heat. In the same way, a Tankless Water Heater is used only when there is a demand for hot water.
How do Tankless Water Heaters work?
Tankless Water Heaters heat water directly without the use of a storage tank. Therefore, they avoid the standby heat losses associated with storage water heaters. When a hot water tap is turned on, cold water travels through a pipe into the unit. In an electric Tankless Water Heater an electric element heats the water. In a gas-fired Tankless Water Heater a gas burner heats the water. As a result, Tankless Water Heaters deliver a constant supply of hot water. You don't need to wait for a storage tank to fill up with enough hot water. Typically, Tankless Water Heaters provide hot water at a rate of 2 - 5 gallons (7.6 - 15.2 liters) per minute. Typically, gas-fired Tankless Water Heaters will produce higher flow rates than electric Tankless Water Heaters. Some smaller Tankless Water Heaters, however, cannot supply enough hot water for simultaneous, multiple uses in large households. For example, taking a shower and running the dishwasher at the same time can stretch a Tankless Water Heater to its limit. To overcome this problem, you can install a "whole house" type Tankless Water Heater or install two or more Tankless Water Heaters, connected in parallel for simultaneous demands of hot water. You can also install separate Tankless Water Heaters for appliances-such as a clothes washer or dishwater-that use a lot of hot water in your home.
Other applications for Tankless Water Heaters include the following:
Remote BBQ or outdoor sink
Poolhouse or pool shower
Remote bathrooms or hot tubs
To serve as a booster, eliminating long pipe runs, for solar water heating systems, dishwashers and sanitation.
For homes that use 41 gallons or less of hot water daily, Tankless Water Heaters can be 24% - 34% more energy efficient than conventional storage tank water heaters. They can be 8% - 14% more energy efficient for homes that use a lot of hot water, around 86 gallons per day. You can achieve an even greater energy savings of 27% - 50% if you install a Tankless Water Heater at each hot water outlet.
Selecting a Tankless Water Heater
Before buying a Tankless Water Heater, consider the following:
Fuel Type
Location, Size and Demand
Application
1. Fuel Type
The first thing that you'll need to decide when selecting a Tankless Water Heater is the fuel type. You will need to select between an Electric Tankless Water Heater (like Eemax Tankless Water Heaters or Stiebel Eltron Tankless Water Heaters) or a Gas-Fired Tankless Water Heater (like Rheem Tankless Water Heaters).
Requirements for Electric Tankless Water Heaters
Requirements for Gas-Fired Tankless Water Heaters
--------------------------------------------------------------------------------
If you plan to purchase an Electric Tankless Water Heater, consider the Electrical Requirements:
Voltage
Amperage
Circuit Breaker
Voltage
Many retailers sell units that will accommodate 110V, 120V, 208V, 220V, 240V, and 277V.
Amperage
Different Electric Tankless Water Heaters will have various requirements in amp draw. You will want to ensure that you can support the electrical demands of your Electric Tankless Water Heater.
Circuit Breaker
You must ensure that you have a circuit or circuits that will support your Electric Tankless Water Heater. It may be necessary to put your Electric Tankless Water Heater on its own circuit or circuits.
You should consult with a qualified, licensed electrician for more information.
--------------------------------------------------------------------------------
If you plan to purchase a Gas-Fired Tankless Water Heater, consider the Gas-Type and Venting Requirements:
You will first need to identify whether your gas type is Natural Gas or Propane. It is imperitive that you examine your current gas line to ensure that it will meet the requirments of your new Gas-Fired Tankless Water Heater. The requirements of the Tankless Water Heater may exceed that of your existing tank-style water heater.
Next, you will need to consider venting requirements for your specific installation scenario. There are a few important things to keep in mind when purchasing the gas venting accessories for your Gas-Fired Tankless Water Heater.
Be sure that you purchase Category III stainless steel (UL1738 certified) venting for your Gas-Fired Tankless Water Heater. "Type B" venting accessories are not acceptable. Also, be sure to check local building code to ensure that your specific needs will be completely met.
Additionally, many Tankless Water Heater manufacturers offer gas venting "kits". It is recommended that customers evaluate the needs of their specific installation to ensure that they will be getting all of the necessary gas venting accessories. Depending on where you will be installing the Tankless Water Heater, a pre-made kit will probably not meet your needs. Ensure that you measure out the vent route and consider where the discharge will go through the wall or ceiling, consider the necessary clearances, and consider ample access to air for combustion, then buy the appropriate gas venting pieces. *Note: Gas-Fired Tankless Water Heaters may still require a minimal electrical connection. Be sure to review installation requirements for the units you are considering for purchase.
2. Location, Size, and Demand
When deciding which Tankless Water Heater to purchase, you will also need to consider where you will need hot water. Are you looking for a unit that will heat the water at one bathroom sink (single point application), an entire bathroom (multipoint application), or an entire house, apartment, or condo (whole house application)? It is important to recognize the number of fixtures that will require hot water. Each fixture will have its own demands. The chart below illustrates the typical flow rates (demand) for some standard fixtures:
Typical Flow Rates in Gallons per Minute (gpm)
Fixture Type Lavatory Bathtub Shower Kitchen Sink Pastry Sink Laundry Sink Dish-washer
Flow Rates 0.5 2.0 - 4.0 1.5 - 3.0 1.0 - 1.5 1.5 - 2.5 2.5 - 3.0 1.0 - 3.0
The flow rate is especially important, since Tankless Water Heaters will generate a temperature rise based on the flow rate demanded.
For example, a Stiebel Eltron Tempra 12, running on 240 Volt power, will raise the water temperature by 54°F at 1.5 gpm, 36°F at 2.25 gpm, and 27°F at 3.0 gpm, above the ambient incoming water temperature, up to 125°F.
A larger unit, like the Stiebel Eltron Tempra 36, running on 240 Volt power, will raise the water temperature by 92°F at 1.5 gpm, 92°F at 2.25 gpm, and 82°F at 3.0 gpm, above the ambient incoming water temperature, up to 125°F.
Temperature Rise Based on Flow Rate, Up to 125°F
Flow Rate 1.5 gpm 2.25 gpm 3.0 gpm
Tempra 12 54°F 36°F 27°F
Tempra 36 92°F 92°F 82°F
This means that if you are using a 1.5 gpm shower and a 1.5 gpm kitchen sink simultaneously, a total demand of 3.0 gpm, the Stiebel Eltron Tempra 12 will raise the temperature 27°F, whereas the Stiebel Eltron Tempra 36 will raise the temperature 82°F.
Next, you should look at your ambient incoming water temperature. If you live in a cold climate, like New York, your incoming water temperature will likely be much lower than if you live in a warm climate, like Florida. Your best bet is to find out how much temperature rise you will need in order for your hot water to reach the desired heat. If the ambient incoming water temperature for your shower is 65°F, you are using a 2.0 gpm shower, and you want to raise that temperature to 115°F, you will want to look for a Tankless Water Heater that will provide at least a 50°F temperature rise at 2.0 gpm (115°F - 65°F = 50°F). However, if you anticipate additional simultaneous demand, such as the hot water from a sink being used while someone is showering, you will need to add the sink's gpm to the shower's gpm in order to determine your overall gpm demand and then find the temperature rise necessary to meet your overall needs.
60° F
Incoming Water
2 gpm
Shower
110° F
Desired Output Water Temperature
You will need a Tankless Water Heater that produces a 50°F temperature rise at 2 gpm
3. Application
You may have a specific application in mind for your Tankless Water Heater. Here are a few examples of the different models and their functionality for a specific application:
Single Point Application
A single point application is one where only one fixture will require an Electric Tankless Water Heater. Here are some examples of Single Point Electric Tankless Water Heaters:
Eemax Single Point Electric Tankless Water Heaters
Stiebel Eltron Point of Use Electric Tankless Water Heaters
Chronomite Instant-Flow SR Electric Tankless Water Heaters
Eemax Flow Controlled
The "Flow Controlled" range of water heaters from Eemax are ideally suited to serve two points, like two sinks, in close proximity. Here is an example of Flow Controlled Electric Tankless Water Heaters:
Eemax Flow Controlled Electric Tankless Water Heaters
Thermostatic
The Thermostatic Tankless Water Heater serves as a booster for temperature loss from long pipe runs, dishwashers and sanitation. Thermostatic units are good for applications where precise temperature control is essential; such as schools, hospitals and laboratories. Here are some examples of Thermostatic Electric Tankless Water Heaters:
Eemax Thermostatic Electric Tankless Water Heaters
Stiebel E
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- Andrew_Keith Andrew_Keith Dec 2, 2009 @ 8:45 am
- Water Heating - Information About Water Heating
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- Jun 19, 2008 @ 5:25 am
- Wow!
your lens is very interesting to learn about tankless heater, it is very good informative to the people, thanks for sharing your great ideas.
Checkout my lens that focuses on electricians.
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- Joe Blow Joe Blow Apr 24, 2008 @ 1:12 pm
- Damn, what an awesome article. You learn something new everyday. My wife, being the nag and shower hog she is, is constantly on me to do something 'cause she is ALWAYS running out of water. Screws it up for the rest of us. And poor me, being the ever so faithful loving patient husband I am, am always stuck taking cold showers.
NOT ANY MORE!!!! I can now replace the old bag, err, I mean my water heater with one of the fancy dancy newfangled tankless doohickies. Thanks you so much Andrew!!!
Now please contact me to do the replacement and haul my old hag away!
by AndrewTwidwell
Hello world, my name is Andrew Twidwell, I'm the owner of ABT Plumbing & Electric. We a service companing in the California Gold Country, Nevada Count... (more)
