Ryan Stewart


We take water heaters for granted until something goes wrong. Your water heater needs maintenance regularly. If you’re looking for the answer to how often do you need to flush and service the heating unit? Then, we got you!

To keep it protected from mineral deposits, you need to service the water heating unit at least once a year. If your residential unit has a hard water supply, then you should consider flushing at least every six months.

 If the water softener is installed within the tankless heater, you can skip the unit’s service for two years. But maintaining the valve pressure and flushing annually is highly recommended.

This article will provide you with complete information on when, why, and how to flush your water heater. 

Have a look at Quick Chart before scrolling any deeper.

Unit TypeFlushing Time Period
Tankless Heater (Runs on Hard Water)Minimum 6 Months – Maximum 09 Months
Tankless Heater (Heat’s Soft Water)Minimum 6 Months – Maximum 12 Months
Electric Tankless Hot Water HeaterOnce a Year
Gas Water HeaterMinimum 8 Months – Maximum 12 Months

How often does a water heater need to be flushed?

It is strongly advised to service a water heater at least once a year. Due to heat, minerals in water can build up and rot the walls of the heating unit. 

To negate this problem, a tankless water heater requires periodic flushing.

How Often Should You Flush a Tankless Water Heater Depending on Water Type?


Descaling annually is excellent for the overall health of water heating units. 

  • If your area is supplied with hard water, flush out your hot water tankless heater every six months.
  • If your residential bloc has a soft water supply, then sediment flushing will serve the purpose once a year.

Do you need to descale a water heater if you have a water softener?

If you have a water softener installed within the unit, you can skip the descaling for 18 months. But, It is always advised by manufacturers to flush a heater every year.

How to Flush Sediment Out of a Tankless Water Heater?

Due to heat and steam, calcium and other minerals in water can build up and destroy the heating unit. 

Service your tankless water heater once a year following these steps:

  1. Turn off the cold water supply.
  2. Cut the power supply.
  3. In the case of a gas water heater, cut the supply by turning off the valve.
  4. If you have an electric hot tankless water unit, shut off the breaker.
  5. Allow the unit to cool down for 90 minutes.
  6. Turn on the hot water tab nearby. This will help to prevent any vacuum.
  7. Connect the garden hose to the drainage spigot.
  8. Turn on the spigot and let the water run for several minutes.
  9. Reopen the cold water supply and let the tank fill again.
  10. Drain again and repeat this step until you get rid of all the sediment.
  11. Close the drain valve and reopen the supply valve.
  12. Power up the water heater and run a test trial.

It is always advised to be careful while dealing with electric appliances.

Is it essential to flush the tankless water heater annually?

Yes, it is necessary to drain the water heater once a year for better performance. It is recommended to rinse it every six months if your heating unit has a hard water supply.

Why is it essential to service your water heater once a year?

Annual service has a significant impact on heating units. It enhances their work. Apart from that;
It reduces the repairs
Ensure the units better performance
Minimize the scaling effect
Improves the heat speed
No noise
No clogs

How can you make your water heater last longer?

The long life of a water heating unit can be ensured by;
Flushing and draining it at least once annually
Pressure relief valve testing after every six months
Annual maintenance can add up five years to a gas tankless water heater.

What will happen if you stop flushing the water heater unit?

The longer it goes without any annual service, the more minerals it will stick to the bottom of the tank. It will cause problems like;
Less efficiency
Corrosion and clog
Blockage of valve
More energy consumption
It is also advised to service the tankless water heater, even if it’s not being used.

How annual flushing helps the health of your water heater?

Regular service adds up at least five years more to its life. 

Life of a Water Heater: 8 to 12 years
Life of a Tankless Water Heater: 12 to 15 years
Tankless Gas Heater with annual flushing: up to 20 years.

Due to mineral collection in the tank, the heating unit may rot. Such sediments wash out during heater service, which is great for the unit’s overall health.


Flushing the tankless water heater is very crucial. It enhances productivity and longevity. Residential areas with hard water supply need to service their heating unit every six months. If the water quality is “Soft” or “water Softener” is pre-installed, then an annual sediment flushing will add five years to the life of a tankless water heater.

If you have bought a water heater expansion tank and are looking for how to install it? Then, we got you! In this article, we will provide you with a complete guide on the installation process of the expansion tank and tell you where it is best to install it.

The advised water pressure is 60 PSI for residential buildings. But the average pressure in U.S households is 80 PSI. A water heater expansion tank is essential to negate the threat of leakage due to high pressure.

A Complete Guide on Water Heater Expansion Tank Installation Process.

After doing complete research on water heater expansion units, we completed this task in 7 quick and easy steps. 

But first, have a look at the tools we use. The plumbing unit will depend on the types of expansion pipes and orientation of the water heater. 

Required Plumbing Equipment For Installation.

  • An Expansion Tank
  • Pipe Wrench
  • Dielectric Water Heater Union (For Copper Pipes) or Pipe Joints
  • Hacksaw
  • Drill Machine (You may need it later)
  • Pipe Sealing or Teflon Tape
  • Tee Fittings
  • Hand Pipe Thread
  • Screw

The Installation Process of Expansion Tank to Water Heater in 7 Easy Steps.

Once you gathered the required plumbing items. Follows these instructions;

  1. Disconnect the power and water supply.
  2. Bring out the expansion vessel with all accessories nearby the heater.
  3. Check the cold line.
  4. Install the water heater expansion tank by placing it on the hard water supply line.
  5. Attach the heater tank.
  6. Restore the power and water supply.
  7. Test Trial.

Step 1. Power and Water Disconnection.

Stop the water supply to the heater by switching off the valve attached to the supply line. Once you’re done, cut the power supply of the heater too.

  • For Water Heater on gas: Turn Off the Supply
  • For Electric Unit: Switch off the Breaker

Step 2. Gather the Accessories.

Measure the size of an expansion water tank by using measuring tape or thread. Remember to get some joint fixture tape. Place all the plumbing gear nearby for batter reach.

Step 3. Confirm Cold Water Supply Line.

Find the cold water supply line. Mostly it is horizontal to the water heater. You’ll need this to attach the expansion unit.

Where to Put an Expansion Tank onto a Water Heater for Best Results?

It is always recommended to install it above the water heater directly.


Place its position on the “Cold Water Supply Line” for best results.

Step 4. Install the Expansion Tank.

Install it by following these easy steps;

  1. Put the unit on a supply line
  2. Make a hole in the wall by using a drill. It is an essential step for mounting
  3. Screw-in the tank
  4. Attach the cold water supply line to it
  5. Cover the joints with plumbing tape to avoid any leakage.

How Do a Water Heater Thermal Expansion Tanks Work?

Standard water heaters use the simple rule of the steam engine. When the water heats up, it forms extra steam. The extracted moisture can cause vessels to explode due to extreme pressure. 

Expansion tanks are highly recommended if a house has a closed plumbing system. They equalize the pressure. A thermal expansion vessel creates more space for hot water to run as it is filled with cold air, preventing the system from exploding.

Does the Orientation or Mounting Position of an Expansion Tank Matter?

No, it can be installed in any direction. The mounting position doesn’t matter for a properly fixed expansion tank. You can install them upright, horizontally, and even upside down.

Step 5. Attach the Heater Tank.

Once you are done attaching the heater tank. Attach back the pipes of the water heater. Warp the spot with plumber tape. 

Secure the connection with a wrench. Don’t make it too tight.

What is the Best Pressure for Water Heater Expansion Tanks?

Between 50 PSI to 60 PSI is the advised pressure.


The air pressure can be easily checked by using a tire gauge.

Step 6. Restore the Supplies.

Switch on the water supply and let it run. Restore the power source. It is always advised to follow safety protection while handling electricity.

Step 7. Test Trial.

Have a quick test once you’re done attaching the expansion tank to the water heater. Turn on the tap and place your hand under the running water to sense the temperature of the water.

How to Know That Your Expansion Tank is Working?

The tank should sound hollow. It should be filled with air. If boiler expansion makes a dull thud, it needs repair as it may be full of water.

Quick Guideline for Sizing an Expansion Tank.

To save you from complex physics lessons or scientific formulas like ΔL = αLΔT, we have set a chart to help you buy a good size tank.

Water Heater Capacity (In Gallons)Supply PressureTank Size
50 – 6040-50 PSI2-Gallon
6060 – 80 PSI3.2 – 3.5 Gallon
8040 PSI2 Gallon
80-8550- 60 PSI3.5 Gallon
8080 PSI4.4 Gallon

Why Choosing the Right Size Expansion Tank Matter?

Water expands dramatically when it heats up. If the water pressure is too high and the attached expansion tank’s small size, there will be a blast threat due to extreme built-up pressure.


A water heater expansion vessel is very crucial. Section 608.3 of the California Plumbing Code requires a thermal expansion tank if you have a water heater. It is always advised to install it on the cold water supply line.

There is no “one size fits all” when buying water heaters. You may come across dozens of articles claiming that “they got the right size.” Still, the exact size of tankless water heater you need to buy depends on your needs, number of bathrooms, taps, and desired water temperature.

In general, a family of 2 needs a 6-8 GPM gas tankless water heating unit. The perfect tankless water heater size depends on several factors, including the size of the home, Water Flow rate, and temperature of underground water in your area.

This article will provide detailed information on tankless water heater sizes. So, you can buy a suitable heating unit according to your needs.

Tankless Water Heater Sizing – A Science Lesson Overview.

Two factors determine the “size .”Normally, every water heating unit follows 

ΔL = αLΔT equation. 

We have broken it down to save you from a complex physics equation. 

  1. Flow Rate (Gallon Per Minute / GPM) – Required Quantity of Hot Water
  2. Temperature Rise (ΔT) – Difference of Temperature From Desired & Supplied Water.

The typical faucets temperature is around 110°F to 120°F. 

The average underground water temperature in the U.S is 57°F. 

It can rise to 70°F in southern parts while freezing in the northern regions.

Determining The Tankless Water Heater Size – Finding Out What You Need.

There is no hard rule. All you need to do is figure out the amount of hot water you’re going to consume. 

Here, have a look at how much water daily home appliances use.

  • Faucets – 0.75GPM to 2.5GPM
  • Low Flow Shower Heads – 2.2GPM
  • Standard Shower Heads – 3GPM to 3.5GPM
  • Washing Machine – 2 GMP
  • Dishwasher – 1GPM to 1.5GPM

The determining formula is simple and basic. Let’s suppose that, On a moment, you need to run a faucet, running washing machine, and crockery is being washed in the dishwasher. 

Then you need;


The quick math can be done in different situations and numbers of fixtures. 

Have a quick brainstorming on the following tip:

Consider buying the tankless water heating unit assuming that you need to run all the taps at once if you have a family of 5. For a family of 4, 8GPM to 10GPM is the ideal size.

What size of s tankless water heater do you need to replace a 50-gallon traditional water heating unit?

The short answer to this specific question is, “It depends on your demographics.” 

If you live in the southern part of the U.S.A, then a 7 GPM gas tankless water heater or 18kW electric tankless water heater will work just fine.

On the contrary, you’ll need to buy a 10 GPM tankless gas heating unit or 27 kW electric water heater for the replacement if you’re living in the northern part.

Our Assumed Size – Depending On Your Family Members.


For your convenience, we have done a lot of research and found out the “ideal size of gas and electric water heaters” depending on the size of your family.

The Number Of MembersGas Tankless Water Heater (GPM) Electric Tankless Water heater Size (kW)
What size tankless water heater do you need to purchase for a couple?6-8 GPM10-18 kW
What is the ideal size of Tankless water heating unit I need to buy for a family of 3?7-9 GPM15-23 kW
What would be the perfect tankless water heater size for a family of 4?8-10 GPM20-28 kW
What is a suitable size water heating unit for a family of 5+?9-11 GPM25-34 kW

Caution: The perfect size may vary depending on the underground water temperature and quantity + required temperature.

The Silent Factor – Underground Water Temperature.


This image has been taken from Renni Tankless Water Heater underground water map.

Underground Water Temperature.

The temperature of underground water also determines the size of the heating unit. 

If you live in the northmost part of the U.S, the water will be colder, and it might be impossible for a 5 GPM gas water heater to instant supply the hot water.

On the contrary, In Florida, the temperature of underground water is relatively high. There will be an instant supply of hot water and less energy consumption.

How to pick the perfect size tankless water heater for your home?

While looking for a gas tankless water heater, it is advised to consider that such heating units consume more energy. The primary difference between electric and gas heating units is the former has less life span while the latter consumes more power.

Tankless Water Heater Buying Guide – Know Your Needs

Here is a list of a few things you should consider before buying a tankless water heater.

1. Daily Usage.

The size will depend on the usage. If you need to run more taps simultaneously, you need to buy a large heating unit.

2. Location / Demography.

The north v/s south debates look absolute right here. The southern states have more hot underground water, while the northern part of the U.S has cooler water.

3. Size of Home.

If you live in a big home, you may need to invest in an ample water tankless heater for a constant supply. 

On the other hand, if you are called a cozy place home, a small size water heater will work wonders for you.


A water heating unit is an essential household item. Regardless of all the scientific equations, there is no one-size-fits-all. Just right size depends on several aspects, including your needs, supply line, and area of living. 

While in the meantime, a 6 GPM gas tankless water heater is an ideal assumption for a couple. We would recommend a 10GPM gas heating unit for the family of 4.

Tankless water heaters are known for their better performance and long life expectancy. The foremost thing that arose into our mind while purchasing them is the “period of the lifespan.” 

A tankless water heater’s average life span is somewhere from 18 to 20 years. The life expectancy actually depends on various factors, including the water quality, i.e., hard or soft.

A gas-burning tankless water heater can last for 20 years with good maintenance. The life expectancy of a hot water electric tankless heater is between 8 to 11 years.

This article will provide a complete guide on their water heater lifespan, a rundown on what’s cutting the duration, and tips on making it last longer.

Expected Life of a Tankless Water Heater.

Many manufacturers don’t give a guarantee over 10 years. But, the average expected life is 18 to 20 years. It can be increased by flushing them regularly.

Type of Tankless Water HeaterAverage Life Expectancy with Good Maintenance
Runs on Gas20 Years
Electric Consumption11-12 Years
Heats up the Hard Water Quality15 Years
Heats up the Soft Water20 Years

How Long Does an Electric Tankless Heater Last?

They have a shorter life expectancy as compared to gas water heaters. It works properly for eight years. An annual maintenance check can increase the lifespan up to 11 years. 

What is the Life Expectancy of a Gas Tankless Water Heater?

A tankless water heater that operates on gas typically lasts for 20 years. Such a long life can only be expected with proper flushing of the system. 

What is the Expected Life of a Tankless Water Heater with Hard Water?

Overall, 85% of the U.S has hard water. Such water quality can cut the timespan of appliances. A tankless water heater lasts only 12-15 years with hard water. 

How to Increase the Lifespan of Tankless Hot Water Heaters?

Over time due to heat, minerals in water can build up and rot the walls of the heating unit.


These can cause uneven heating and disturb the system. The Longevity of Tankless Water Heaters can be extended in two ways;

1. Annual flushing

The overall performance and health of the heating unit must be flush annually. Flushing over a year costs around $150.

Why is it Important to Flush the Tankless Water Heater Once a Year?

There are several benefits of it. It impacts the performance and enhances the working quality.

  1. Reduce the repairs.
  2. Ensure the unit’s longevity.
  3. Minimize the effect of scaling
  4. It helps to improve the heat speed
  5. Noise reduction
  6. No obstructed pipes and clogs

2. Regular Descaling 

How to Descale a Tankless Hot Water Heater?


3. Required Equipment and Products.

  • Four gallons of white or regular vinegar.
  • Two drain hoses.
  • Large bucket (preferably 5 gallons)
  • Descaling Pump.

4. Steps for Descaling.

Descaling is a critical yet time-taking task. We have jumbled down the whole process into seven easy steps.

  1. Cut the power carefully.
  2. Shut off the water valves.
  3. Attach the hoses to input and output valves. In Bucket, put the other end of the hose.
  4. Fill the bucket with vinegar or other descaling solution. Then, place the pump into the bucket.
  5. Open the hot water valve and turn on the pump with care. Let the pump run for 45 minutes.
  6. Resin the water heater thoroughly.
  7. Disconnect the hoses and turn the water heater on by attaching the regular fixtures.

Tips and Cautions on Tankless Water Heater.

As a daily use item. We may overuse them often. It is essential to know and operate them as per the user manual.

How to Know that Your Tankless Water Heater is Going Bad?

Here are the six common signs.

  1. It has passed the warranty years.
  2. You notice some water heater leaks.
  3. Dirty or discolored water.
  4. It is making noises.
  5. Slow or not enough hot water.
  6. Required constant repairs.

If you noticed 3 out of these signs, you might need professional help. Or, it’s time to replace the tankless water heater.


With proper maintenance and annual system flushing, a tankless water heater can last 20 years. Electric water heaters may be less costly, but they have less lifespan than gas-consuming water heaters.

Tankless water heaters are known for their instant hot water supply and long life. Sometimes, there will be interruptions in continuous supply. Here’s how you can quickly reset them in such a scenario.

Find the reset button on the tankless water heater. It is often RED and located behind the metal panel, which is removable. In some units, it may be located near the thermostat. Press the reset button and then release it after hearing the click sound.

This article will provide you with complete step-by-step information on “How to troubleshoot a tankless water heater?” We will also cover;

  • Where is the reset button located on the tankless water heating unit?
  • How long do you need to press the troubleshooting button?
  • When to reset it?
  • Common Error Codes 
  • Why does your heating unit trip?

How to Reset a Tankless Water Heater?

To reboot your tankless water heater, all you need to do is follow “Three Simple Steps.”

  1. Find the red button on your heating unit.
  2. Push it for almost 5 seconds.
  3. Release it.

There is no hard rule for resetting a tankless heating unit.

How Can I Reset My Electric Tankless Water Heater?

Troubleshoot your electric unit by following these six easy steps. It is always advised to cut the power supply before touching any electric appliance.

  1. Turn the breaker off.
  2. Locate the “raised panels.” Commonly, there are two panels on the electric unit. 
  3. Once you open the “upper panel,” you’ll find covered insulation to keep the moisture away.
  4. Under the insulation sheet, there is a reboot button. Usually, the color of the switch is red. Sometimes the button color is black.
  5. Push the button and screw back the raised panel to its actual shape.
  6. Turn the breaker on.

Why my electric tankless water heater is often tripping? 

 You need to restart or reset your water heater due to;

  • Power Surge.
  • Moisture in Panel.
  • Broken or Worn Out Heating Element.
  • Breaker Issue.
  • Overloading or Overusing.

If you notice tripping often, consider getting some professional help then.

How Can I Reset Your Rinnai Tankless Water Heater Anual Descaling?

After descaling, here’s your quick guide to factory reset the Rinnai tankless water heating unit.

  1. Find the “Connect” button on the module.
  2. Press and hold it.
  3. Wait for the LED blink red and white.
  4. Once you notice the clour changing, release it.
  5. Quickly tap three times.

This will restore the setting to its original factory settings.

Finding the Button.

To reboot the tankless water heater, you need to “press the button”! Sounds easy. But if you are searching for “Where is the red button located,” we got you!

Where is the reset button located on the tankless water heater unit?

The red button is located behind the “upraised panel in the tankless water heating units.” To find the factory reboot button, you may need to remove the panel.

How Long Do You Need to Press the Red Reset Button on Tankless Water Heater?

To troubleshoot your heating unit back to factory settings, press the button for 3 to 5 seconds. It is not recommended to hold the button for too long.

Troubleshooting The Tankless Water Heater – Find Your Unit Brand

1. Takagi Tankless Water Heater.

Some of the common errors in these specific branded heating units are;

  • Error Code 661: Issue with bypass valve
  • Error Code 761: Water temperature is over 104°F

How can you reset your Takagi tankless water heater?

Troubleshoot your unit easily and quickly by following these steps.

  1. Cut the power. (This step is advised as a safety precaution)
  2. Remove the front cover.
  3. Hold and press the dip button 1 & 2 for 3 seconds.
  4. Turn on your unit and enjoy a non-stop supply of hot water.

2. Rinnai Tankless Water Heater.

Rinnai is a trusted brand by millions when it comes to home appliances. Its unit’s display errors start from 02 to 79, including no error code per user manual.

How can I reset my Rinnai tankless water heater without any professional help?

Here’s how you can quickly reboot your Rinnai unit at home.

1. Look for the connect button.
2. Hold it for 5 seconds.
3. Once you notice that the LED light blinks to white, release it.

Doing this will shift the module back to the factory settings.

3. Rheem Tankless Water Heater.

Rheem has a manual that displays every error code with a complete description. If you need to reboot it, follow these steps.

  1. Disconnect the circuit by turning it off.
  2. Take off the panel cover and find the reset button.
  3. Press the button inwardly.
  4. Release it once you hear the “click” sound.
  5. Put back the panel safety cover and turn on the circuit.

4. Noritz Tankless Water Heater.

Noritz is second to none when it comes to compatibility. They are capable of beige controlled by remote. There is always a “two-digit” error code displaying the problem. To reboot your Noritz unit, all you need to do is “press the reset button.”

5. Marey Tankless Water Heater.

Marey is a trusted brand because its heating unit often doesn’t cause any problems. Most of the issues people face are either the system won’t start, or there is no click sound when they reboot it.

Marey’s user manual has a complete guide with solutions to its error codes. If you are looking for the answer to “How to reset tankless heater by Marey?” then all you need to do is hit the reset button.


After years in the water heaters and plumbing industry, I can conclude that most tankless hesitating unit trips because the thermostat is not working correctly. To reset your heating unit, you need to hit the “Red Reboot Button” located inside the panel.