Descaling Your Tankless Water Heater

What is Descaling?

Descaling is when you run a solution through the internal components of the tankless water heater to remove mineral buildup, which is especially important if you have hard water.

Why Is Descaling My Tankless Water Heater Important?

If mineral buildup on the internal components of the unit isn't addressed it can lead to reduced water flow/hot water output due to flow inside the components being restricted or clogged. It also leads to reduced energy efficiency, and in the long run a shortened lifespan of your tankless water heater.

Scale buildup can also lead to temperature inconsistencies. The scale works as an insulator, so heat must transfer through the scale before heating the water, which reduces efficiency.

Clogs are possible, which can result in the unit totally failing to produce hot water. The constant need for the tankless water heater to overwork to produce hot water also puts added stress on the valves and internal components which can cause them to wear out & go bad more quickly.

What Are The Benefits of Descaling My Tankless Water Heater?

Descaling your tankless water heater clears mineral buildups which prevents blockages and maintains high energy efficiency. If you already went through the process of doing the research and having a tankless water heater installed, you might as well maximize the energy benefits.

Descaling also helps minimize stress on the valves and internal parts which helps to maximize the lifespan of your tankless water heater.

Lastly, it helps save you money in more ways than one. With a standard tank water heater, the water heater is constantly keeping anywhere from 40-100 gallons of water warm. Tankless water heaters heat the water on demand, thus saving a fairly significant amount of energy. By descaling your tankless unit, you are ensuring maximum cost savings on your enery bill. In addition to energy savings, by reducing the stress on all of its components through maintenance, you'll help to avoid costly material and labor bills to repair or replace your tankless unit.

How To Descale A Tankless Water Heater

Tankless cleanings can be done with a descaling solution or with white vinegar, we've used white vinegar for years and it works great. Descaling should be done for 45-60 minutes.

The only things you really need to descale your tankless unit are 3-4 hoses, a pump, your chosen descaling solution, and a bucket. The best hoses to use are washing machine hoses or garden hoses (preferably shorter ones).

Your first step is to turn off the power and gas to the unit. Next you shut off the hot and cold valves directly below the tankless water heater. Connect one hose to the cold service port above the shut off valve, then connect the other end of that hose to the pump. Next, connect another hose to the pump, with the opposite side of that hose going into a bucket with your descaling solution. Then connect your last hose to the hot side service port, with the other end of the hose going back into the bucket containing the descaling solution.

From there you turn the pump on and let it run for 45-60 minutes. As the descaling progresses you'll notice the solution change color and get darker, this is evidence of all the minerals and buildup being descaled from inside your tankless water heater. If the solution is lighter & more of a browish color, you are probably okay running it for just 45 minutes. If the water is dark & black then 60 minutes is your best bet.

After you finish the descaling process, there are 2 ways you can flush out the vinegar or descaling solution. You can either switch out your solution bucket for a bucket of water and pump it through the unit the same way you did while descaling. Or your second option is to open some hot faucets and run the water for a few minutes.

Once you've flushed the unit, put the caps back on the service ports and shut the service valves, then open the hot & cold water shut offs. Lastly, open the gas valve, turn the power back on and your tankless water heater is back up and ready to go.

Tankless Water Heater Descaling

You Can Descale Your Tankless Water Heater Yourself

Some people may be able to learn how to descale their own water heater by watching some videos, doing some research and reading some plumbing blogs like this one. But the best and easiest way is to have your plumber teach you. Once you have your tankless water heater installed, the following year when your plumber comes to do the descaling you can ask them to teach you. We have had a number of clients watch the process with a notepad and/or while taking videos of which valves to open and close and which ports to connect to. It may seem overwhelming at first, but its really a fairly simple process.

How Often Should I Descale My Tankless Water Heater?

The general rule of thumb for tankless water heater descaling is to do it once a year, however the frequency can vary. In areas with hard water, more frequent descaling will be required. After initial install, annual descaling should be performed for at least 2-3 years. At this point, based on the quality and hardness of your water, you and/or your plumber should be able to analyze the results of the cleanings and determine a maintenance plan for your tankless water heater. It is recommended to consult with a plumber before making this decision. If the water is very dark & dirty over the first few cleanings, or if you know you have hard water, yearly descaling is going to be required. If the solution doesn't darken much, descalings may be able to be pushed back to every 2-3 years. Even under these circumstances, yearly cleanings are always recommended. But if you aren't comfortable doing it yourself and don't want to pay someone to do it every year, there are some instances where descaling can be lessened without jeopardizing the lifespan of the tankless unit.

How To Lessen Tankless Water Heater Descaling Frequency

At the end of the day, descaling is a necessary part of maintaining a tankless water heater. However, there are some things that can improve the water quality going into the tankless water heater that may reduce how frequently descaling is needed. The first answer would be a whole house water softener, especially if you are in an area that is known to have hard water. A whole house water softener will reduce the hardness of your water & improve the quality of the water going into the tankless unit, which in turn reduces the mineral build up inside the unit.

Unfortunately, a whole house water softener isn't feasible or applicable for every home. In this case, a pre-filter being installed prior to the tankless water heater's cold water inlet can also help take impurities out of the water and help to maintain the internal components of the unit. In many instances, a pre-filter is even required by the manufacturer in order for them to honor part warranties.

Tankless Water Heater Installed With Pre-Filter

Tankless Water Heater Installed With Pre-Filter