Beginners Guide to Tankless Water Heater

The tankless water heater is also known as on-demand water heater because it provides hot water whenever we turn the tap on. It doesn’t require to keep additional storage tank of 40-50 gallon hot water which has made it energy efficient water heater. If you want to buy the best tankless water heater than must follow these Tankless Water Heater Guide

4 Things to be considered before installing a tankless water heater

Things to be considered before installing a tankless water heater

Timing: Before installing it, you have to shut off the main water supply line in your house. For this reason, you have to forecast the time that may require to install it. Otherwise, you may have to suffer from no water supply for many hours in your house.

Plumbing (Natural Gas): In case of the gas installation process, you must have a gas regulator that can be mounted vertically. Here you have to be ensured that you have a proper ventilation including vent adapter and stainless steel exhaust hose.

Plumbing (Electricity): In case of the electric installation process, you have to meet the amps requirement instructed in the installation manual.

Placement: Last but not the least is the place or location where your water heater will be placed or mounted. You have to install it in a place which is convenient for you to use.

Steps to be followed for installing a tankless water heater

Step 1: Removal of old water heater: If you already have a water heater installed in your house and intended to buy a new one, you have to remove it at first. You also have to disconnect the water supply line and the heat source of the old one before installing the new one.

Step 2: Shut off the water supply line to a house: Before installing the water heater, you have to disconnect the water supply line of your entire house.

Step 3: Install a new gas or electricity supply line: After removing the old supply lines, you have to connect new gas supply line in case of tankless gas water heater or new electricity supply line for it with the machine. It must be vented to the outside and the gas line requires a connection to a 120-volt circuit. Tankless electric water heater doesn’t require to be vented. It does require 240-volt power.

Step 4: Install the new water supply line: After removing the old supply line, you have to connect your water heater to a new one.

Step 5: Mount the new one: Once you have connected your gas or electricity and water supply line with your water heater, now you can mount it on the wall. You can also build a platform which will support your water heater from the bottom in lieu of mounting it directly on the wall.

Step 6: Hook up the water heater to gas or electricity and water supply line and also attach additional parts: After mounting the water heater, you can connect it with supply lines and if necessary also attach additional parts with it.

VIDEO: Installing a tankless water heater


  • You have to assure yourself that you have sufficient amps to run the water heater.
  • If yours is an electric tankless water heater, you have to know the standard of power voltage depending on your location. An electrician can suggest u here unless you are an electrician.


  • Check your local requirements in case of licensed plumber or electrician needed to hire.
  • Check your water pressure whether it is sufficient for a tankless system.

Which tankless water heater is the best?


Takagi T-KJr2-IN-LP Indoor Tankless Water Heater

Takagi T-KJr2-IN-NG Indoor Tankless Water Heater

Takagi T-KJr2-OS-NG Outdoor Tankless Water Heater

Takagi T-H3-DV-N Natural Gas Indoor Tankless Water Heater


Ecosmart ECO 18 Electric Tankless Water Heater

Ecosmart ECO 36 36kw 240V Electric Tankless Water Heater

EcoSmart ECO 27 Electric Tankless Water Heater

Pros of the tankless water heater

  1. Energy Saving power: It provides hot water on instantaneous demand which means you will get hot water only when you need it. It will use energy to produce hot water only when you turn on the faucet. That’s how tankless water heater saves your electricity cost up to 50% compared to storage tank water heaters which used to use your electricity for all the time.
  2. Highly efficient: you don’t have to wait for refill and reheat of a tank. It will work more efficiently which can save your time also. They also shut off the system after producing warm water. Here is no standby heat cost.
  3. Compact size: Usually the size of it is compared to a medium-sized suitcase. So it makes you comfortable to carry out it from one place to another.
  4. Durability: It belongs to a life expectancy of 20 years or even more.
  5. Versatile: It has multipurpose. It can be used for dishwashing, cloth washing and taking shower and so on where you need hot water.
  6. Never Run Out of Hot Water: It continuously provides hot water. That may be slow in speed but constant supply of hot water all the time.
  7. Tax rebate: The majority who uses tankless gas water heater can get $300 governmental tax rebate. 
  8. No worry about flooding out: There is no tension of flooding out whether the tank will break down.
  9. Warranty: It provides a warranty of 6 to 15 years but in real life, it lasts for more years.
  10. No greenhouse effect: Electric models are not responsible for producing greenhouse gases
  11. Increased property values: Seller of the house can demand higher value for their house in time of selling as buyers can enjoy low electricity bill for using it in the house.
  12. Space Savings: you can install it on the wall which saves much space of your house. Small sized water heaters can be placed in a closet or under a cabinet. They can be placed outside your house.

Cons of the tankless water heater

  1. Upgrading cost: You have to call an electrician when it is time to upgrade your water heater which is an additional cost for you.
  2. Initial cost: The installation cost of it is three times higher than traditional water heaters. Since the price of traditional ones is between $800-$1400, the price of tankless ones starts from $1500 and may go beyond $3000.
  3. Unsuitable for large families: Actually it is best suited for a small or medium-sized family.
  4. Output: Traditional water heaters used to supply unlimited hot water for a large family including shower, laundry and dishwasher at the same time but tankless heaters gives the limited amount of hot water. So if you have a large family then you have to install more than one.
  5. Immediate requirement: This type of water heaters need electricity or natural gas instantly. Otherwise, it can’t produce warm water at that time. In case of no supply of electricity or gas, it can’t work.
  6. Using gas powered units: These models produce greenhouse gases, you may need to arrange a large gas line to provide enough fuel, ventilation and propane units need to be stainless steel tubing.
  7. High gas pressure: Traditional water heaters require 30000 to 50000 BTU of natural gas on the contrary tankless heaters may require 199000 BTU of gas.
  8. Inconsistent temperature: It doesn’t always provide the same temperature of hot water to multiple sections.
  9. Retrofitting: Sometimes it is very expensive to retrofit especially when accessories are not available.
  10. The conjunction of water softener: Areas where contains hard water minerals in water, requires connecting a water softener with the machine. Otherwise, it will build a scale inside the heater.

Why install a tankless water heater

There are some unique reasons for which you should install it:

  1. Constant supply: It doesn’t have to wait for your demand for hot water. It doesn’t warm water without your permission. Whenever you command it to warm your water, it will do so. That’s how there is a constant supply of water in your house or office place.
  2. Reliable: It can ensure you that you will never have a shortage of hot water when you need. The supply of hot water is for sure according to It will also inform you about the temperature of your warm water whether it suits you. That’s how it is quite reliable.
  3. Economize In terms of space: It requires less space to install a tankless water heater in comparison with tank-based water heaters. You can install it under a cell or attach it to the wall close to your bathroom or kitchen. You can also use it outside your home for example in your garage also or for doing any other chores outside your home but within your home premise.
  4. Onward thinker: you can be an onward thinker by using this water heater because it is going to be a staple need in coming future, not a rare commodity. It uses less space, less energy and provides instant hot water when needed.
  5. Remote control system: You can use remote to control your water heater and can set it to work according to your preference. You can command your water heater to start its work from one room to another which makes it more convenient to use.
  6. Win-win situation: It is a situation when none of the two parties lose. Here buyers and sellers both can enjoy the benefit of using this technology. Sellers can sell their technology more efficiently and also can work to make improvements on the technology. Buyers can enjoy the unbound supply of warm water in their shower or kitchen.
  7. Focus on niche: After a customer survey, it has been found that this type of water heater is suitable for small families instead of large families. So manufacturers can specifically focus on small families need a niche for them and also can make improvements to make it useful for large families as well.
  8. No cold shower: Water heater is a must for those regions where the temperature is below zero degree Celsius scale. It is essential for old members of a family. This tankless water heater doesn’t provide any cold water while the machine is on.
  9. Cleaner water: it filters the water from inside the heater as there may contain some sort of rust or minerals in the water. So you can ensure to get clean water for shower, dishwashing or cloth washing. It is necessary to have clean water if there are small kids in your house.
  10. Eco-friendly: Electric water heaters don’t use natural gas to produce warm water. Natural gas is harmful to our environment as it is one of the main culprits of global warming.

How to determine the size of a tankless water heater

To determine the size of a tankless water heater you have to follow some criteria mentioned below:

  1. At first, you have to determine the maximum number of fixtures you want to run for example you can run tub, shower, washing machine, dishwasher, kitchen sink etc.
  2. Then you have to estimate the desired flow rate you want from each fixture. Here are some estimations of standard GPM for various fixtures with its average temperature given below:
  • For running a tub, it will need 4 GPM average flow with the average temperature of 102 F.
  • For running a shower, it will need 2.5-3 GPM average flow with an average temperature of 104 F.
  • For running a washing machine, it will need 2 GPM average flow with an average temperature of 120 F.
  • For running a dishwasher, it will need 1.5 GPM average flow with an average temperature of 110 F.
  • For running a kitchen sink, it will need 1.5 GPM average flow with an average temperature of 110 F.

installing a tankless water heater

  1. Now you have to measure your own cold water temperature rise. The standard temperature rise for each fixture is mentioned above.
  2. Electric tankless water heater needs 7-10 inch wide range of space on the contrary gas tankless water heater needs 20-30 inch wide range of space.
  3. After estimating all the criteria mentioned above, you can determine the size of a tankless water heater suitable for you.

The bottom line:

You can also follow this checklist given below for determining the size of tankless water heater before buying it:

  • How much water do you need at one time?
  • Are you willing to run more than one shower at the same time?
  • Are you willing to run a washing machine and a kitchen sink at the same time?
  • How much temperature do you want to rise?
  • Updated a couple of months ago
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