Preventing Scale in Tankless Water Heaters

Most tankless water heater manufacturers have a disclaimer in their warranty. One major tankless water heater manufacturer says this:

“Warranty shall be void in the event of an occurrence of any of the following:…. Any damage caused by local adverse conditions including but not limited to hard water deposits, lime or mineral build-up…”

Tankless Water Heater
Tankless Water Heater

Plbg.com has a blog on Basic Tankless 101 written by M. Scott Gregg which is very insightful on this subject.  It’s a very worthy read, but here is the part we are talking about:

” In a tankless water heater, it is only heating water when the water is moving through the heat exchanger coil. As particulate drops out of suspension in the heat exchanger most of it is whisked away unnoticed. Some will bond to the interior wall of the copper tubing, but at a slower rate since it is being flushed as it is being used.

Over time, this scale buildup will result in the overheating of the heat exchanger. This will cause and error code and the tankless water heater will lock out. This means it will not operate until the unit is reset and the problem corrected. Resetting a tankless heater without solving the problem will simply make the unit lock out again. It will protect itself. The error code flashing on the remote or computer board will help the technician figure out what is wrong so it can be fixed.

If you have acidic water (pH below 7.0) it will attack all metal in the plumbing system including your tankless water heater. Acidic water will cause “pinholing” in copper piping (and copper heat exchangers) and can also cause blue or green staining of clothes as metal is eroded from your plumbing system or appliances. How fast acidic water will damage a tankless water heater or other appliance is dependant on the level of Ph in the water. In short, yes, acid water will damage a tankless water heater and anything else metal connected to the water system over time.”

fusion-nltA water softener is a good choice for tankless water heaters and if you decide upon that method make sure that you set it so that the water has ZERO hardness.  Many water softeners are programmed improperly which results in water with appreciable levels of hardness.  That is certainly affect the limiting of scale.  If you are using a water softener, I recommend one that has upflow brining and proportional brining so that the hardness level is always the best it can be, such as the Fusion NLT.

Many people don’t want to go the water softener which uses salt route, so they are duped into purchasing a salt-free water softener which simply does not exist.  I had someone tell me last week that they had a salt free water softener and I told him to bring me a sample of both his treated and “soft” water.  Both, samples tested as 19 gpg (grains per gallon) of hardness.  Yes, someone sold him a  salt free water softener, but that is not what it really does.  AGAIN, THERE IS NO SUCH THING AS A SALT-FREE WATER SOFTENER!  Don’t get me started….

If you don’t want a salt-based water softener and you have a tankless water heater, at US Water Systems, we have the PERFECT solution for you!  The Green Wave Solo Salt-Free Water Conditioner does an amazing job in preventing scale in tankless water heaters.  It can be installed on the entire water supply of your home, but since scale really only forms in water heaters, it is ideal to put it on the cold water supplyGreenWaveSolo to the water heater.  It flows up to 12 gpm and simply seals the pipes and coils so that limescale cannot form and stick.

Limescale is formed when cold water is heated in a water heater. In the process of heating water,  calcium carbonate precipitates and forms limescale. Many people choose to install the Green Wave Solo on just the line to the water heater as the limescale does not form inside cold water pipes. About half the water used in a home is hot water, so the Green Wave Solo cartridge lasts about twice as long as when it is on both the hot and cold supply. Of course, it is completely acceptable to install it on the entire home water supply.  If the Green Wave is installed on just the hot water, the cartridge typically lasts 90 days or more.

red-high-temperature-filter-housings-10-inch-ht10-f46Not only is the initial cost very affordable, but operational cost is extremely low as well.  Most importantly, it prevents scale from forming in your tankless water heater.  Many consumers elect to use a hot water filter after the heater to trap any of the scale formed in the heating process so that it will not damage faucets and appliances.  With the installation of a Green Wave Solo and hot water filter you will not only protect your tankless water heater, but you will also protect your shower valves, faucets, washer, dishwasher and anything else your hot water touches.  Remember, calcium carbonate or limescale does not form in cold water.  This way you can GO GREEN and saltless while protecting expensive appliances ands plumbing.

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This article has 11 Comments

  1. I live in Colorado Springs,co what softener is best with a tankless here in Colorado Springs,co.

  2. We purchased a Rinnai tankless gas water heater 10 yrs. ago & shortly thereafter our washing machine (top loading) went out & we had to purchase a new one. I can’t remember the brand or model # of the new washer, but it would not work correctly with the Rinnai water heater. It’s been so long ago that I can’t remember exactly what the problem was but I think it had something to do with the water heater cutting on & off too frequently. The old one was several years old, but it worked with the Rinnai. It developed a leak from being in storage for 3 yrs. Anyway, we wound up purchasing just a basic top-loading washer with no frills, which works with the Rinnai, but it is very rough on our clothes. There is no delicate cycle except one which agitates just as fast as on Normal except for not as long. I would really like to have a top-loading machine with a few bells & whistles, but don’t know of any that works with my water heater. Any ideas? Thanks!

  3. I would like to have a tankless hot water tank but not sure it would work here. My water well pumps sand and water is dirty looking if filter gets too dirty. I hope to attach a soft water system to this tankless hot water tank but am afraid I’ll have problems if sand gets in either system. Your thoughts ?

  4. Tim, would you mind explaining how a water softener actually works with a tank less system? We recently went tank less, already had a water softener but don’t really understand how it works. We get the process of a regular water heater but if there is no “standing reserve” waiting to be used, don’t get it – Thanks, Happy Thanksgiving. M²

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