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How to install, clean and maintain a small hot water heater



A point-of-use water heater can reduce wasted heat and enable you to access comfortable and warm water easily throughout your home. 

These heaters work a little differently from other, more traditional types of water heaters, meaning homeowners considering this type of appliance will want to understand how these water-heating appliances work. We will also explore how to install this type of water heater and the cleaning and maintenance required. 

Let’s explain what you need to know about these small water heaters and how they respond when users need on-demand hot water. 


What is a point-of-use water heater?

A point-of-use (POU) water heater heats the water close to where it is needed. For example, a water heater for a sink affixes near the pipes for the faucet. The water flows over the heating elements inside the heater when a user requires hot water, and the unit delivers nearly instant hot water. 

This process is different than traditional tank water heaters. These larger units will generally have a central heating unit that warms water throughout the whole house and stores it in a tank. When the hot water is needed, the unit sends hot water to pipes that carry it throughout the home to any faucets that demand the warmer water. As the water travels, you will experience standby heat loss; this can happen in large cape-style homes, split-level ranch homes, or even mobile homes. Depending upon your tank’s capacity, some people find that this type of electric or natural-gas tank water heater can run out of hot water too early.

Since the POU heater warms the water right next to where it is needed, less heat is lost as the water moves through pipes. When homeowners add these heaters near their showers and baths, it can also reduce the need to increase the water temperature on a storage-tank water heater. This can help to improve energy efficiency and ensure that your home only heats the water needed. Increased efficiency can sometimes qualify you for rebates from utility companies.

These energy-saving water heaters help create more eco-smart and high-efficiency houses and comfortable environments, making them a great addition to many homes. If you have decided to install a point-of-use water heater, we will walk you through what you need to know about how these water heaters work and how to properly install them.


How to install a small point-of-use water heater in 4 steps

A point-of-use water heater requires some basic home improvement skills to install it successfully. You first need to understand how to work with plumbing. If you have the necessary skills, this can be a DIY project. If not, it may be a good idea to hire a plumber to get the job done. If you know how to work with plumbing and this sounds like an easy installation, we will walk you through each part of installing your water heater. Here are the steps you will need to follow.

Step 1. Prep for the install

Before installing the mini tankless water heater, make sure you have done the necessary preparations and gathered any tools you might need. Important things to have on hand include:

  • Cutoff valves, if they are not already in position
  • Torch or a similar tool for soldering the pipes
  • Wrench
  • Access to cut off the water supply where you will install the water heater
  • Access to your main circuit board

To prep your work area, begin by turning off the water supply to the line where it connects to the water heater. Drain the water out of the line so you can freely work with the pipe. You may need to solder a cutoff valve on the pipe stub from the floor or wall where you will install the unit. Next, cut the line to leave enough room to install the water heater and solder a second valve onto what’s left of the line. Avoid soldering directly onto the water heater. 

Step 2. Position the small water heater

Now get your water heater into position. If you live in an area with regular earthquake concerns, take extra precautions when setting up your unit to ensure that it sits on or against something like wood, plastic or carpet. Securing the unit like this will help avoid pipe or electrical damage in an earthquake. 

As you position your unit, do not use extension cords. Make sure the unit can connect directly to its power source. It generally works best to position the unit with a drip pan. 

Step 3. Hook up hot and cold water lines

Once you have positioned your unit, hook up your hot and cold water lines. Begin by connecting the water-supply line to the cold in-feed fitting with a soldered copper pipe. You can also use high-pressure flex connections. Wrap Teflon tape around the threads before you make the connection. Tighten the connection by hand, then use your wrench to make sure it is secure.

After connecting the cold water-supply lines, follow the same process for the hot water lines. 

Step 4. Wire and power on

Once you connect the water lines, prepare to wire the system. Pay attention to whether you are working with a 240-volt or 120-volt unit.

With the 240-volt unit, attach the white wire to one of the hot terminals and the black wire to the other. These will generally be labeled L1 and L2. Then attach the grounding wire to the grounding screw. 

If you have a 120-volt unit, twist the white supply wire to the white wire in the unit. Similarly, twist the black wire to the black wire in the unit. Cover both wires with wire caps. 

Finally, turn the water back on to this particular water line and let the unit fill with water. Once the unit is full, you can turn on the power to the unit. Turning on the power before the unit is full can damage your heater. 


How to clean and maintain your small water heater

Now that you have successfully installed your mini tankless water heater or mini tank water heater, make sure you properly care for the unit so it continues to provide you with warm water. 

Caring for the unit will help your water heater last as long as possible. It minimizes corrosion (which can happen even with stainless steel) and helps the unit operate efficiently. Taking the time to flush out the water heater will help remove any sediment that might have built up inside, which can cause damage or make it harder for your unit to operate. The process you use to flush your heater will depend on the flow rate of your electric mini tank water heater.

How frequently you will want to flush your tankless electric water heater, natural-gas tankless water heater or mini tank water heater will vary depending upon how hard your water is. With typical water, flush your water heater about once per year. However, if you have hard water, you may need to flush it two or three times.

To complete the flushing process, follow these steps:

  1. Gather a submersible pump, a big bucket, food-grade white vinegar and hoses. You can even get a flush kit, which provides you with all these handy tools.
  2. Turn off the power to the heater and use a voltage tester to make sure you turned it off successfully.
  3. If you have a gas unit, close the gas isolation valve. If you have an electric tankless water heater, you don’t need to worry about this.
  4. Turn off the water by closing the hot and cold water values.
  5. Open the hot-water pressure relief valve to release the pressure.
  6. Connect your hoses to the cold-water service port and the hot-water service port.
  7. Connect the cold-water hose to the pump and place it in the bucket, along with the open end of the hot-water hose.
  8. Pour 4 gallons of white vinegar into the bucket.
  9. Open the hot and cold service ports and turn on the pump. This allows the vinegar to circulate. Keep it going for at least an hour to break down the sediment. If your unit runs less than 4 gallons per minute (gpm), you will need to leave the pump on longer.
  10. Switch off the pump, close the cold-water service port, and take off the hose.
  11. Get rid of the vinegar.
  12. Open the cold-water shut-off valve so that some water can come through and flush out any remaining vinegar. Let it run for about 10 minutes, then close the shut-off valve again. Let any remaining water drain, remove the other hose, and close the hot-water service port.
  13. Take the filters out of the heater and clean them at the sink to get rid of any additional sediment. Replace the filters.
  14. Open the hot- and cold-water shut-off valves, open the gas shut-off valve, and reconnect the power.


Protect your water heater from costly repairs with Cinch

Once your water heater is in place, you want to make sure it will serve you and your family for years to come. Fortunately, a Cinch Home Services Built-in Systems plan can help protect your water heater with a valuable warranty. 

If you encounter covered problems with your water heater or other major appliances, all you need to do is place a quick call to Cinch. We will connect you with a vetted technician who can diagnose the problem and get it fixed as quickly as possible. See what a Cinch warranty can do for your peace of mind today with an instant quote.


Here’s what you need to know about installing and taking care of a small hot water heater in your home.