Descaling a Tankless Water Heater with Citric Acid Mix

Can you descale a Tankless Water Heater for less than $2.00? You bet, watch this video to see how!

Timeline for this video if you want to skip ahead:
01:30 Dezcal Mix
02:00 Remote Priority Switch
02:30 Utility Sink Faucet Water Flow Test
04:30 Begin Descaling Process
06:13 Comparison to Commercial Descalers
08:43 Flushing the Tankless Heater

See the previous video for how to make the descaling powder:

Used 1 cup (250mL) of the descaling powder in 2-1/2 gallons (10L) of hot water to make the cleaning solution. Starts out around pH of 0.95 and ends up around a pH of 1.2.

Cost Summary, on-line search for the average plumber tankless service call as noted below:
Plumber Service: $200.00
Flow-Aide: $ 50.00
Calci-Free/Haymaker: $ 20.00
White Vinegar: $ 10.00
Dezcal: $ 4.00
DIY Dezcal: $ 1.25

In the end, water heater is descaled, time and effort is the same, why pay more than you have to?

Also, with the gas cost savings on the tankless heater compared to the tank style of about $43/yr., if descaling only costs $1.25 then the ~10 year payback period for the $400 added cost of the tankless heater should still apply.

pH meter:

Right angle adapters for the flush hoses:

Little Giant sump pumps:

Other descaling options mentioned in this video, all fine products no doubt and prices seem to vary widely, so shop around for the best price if you choose to use one of them:

Oatey Hercules-Haymaker:
Water 40% - 60%, Citric Acid 40% - 60% (not sure of the concentration per the SDS)

Rectorseal Calci-Free:
Sulfamic Acid 70% - 99%

Whitlam Flow-Aide:
Hydrogen Chloride, aqueous less than 10%

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Intro:
Louisiana Fairytale by Austin Rogers

[philindeblanc]

One of the BETTER videos on decaling a tankless heater. well done!

[philblum]

Great video, definitely the best I've seen on the topic! I appreciate the advice on using bulk citric acid, and the mixture rate and quantity, vs the vastly more expensive commercial products, which are, as we already suspected, a huge ripoff!

[luvtoskidontyou]

Great video. Thanks for doing this.

P.S. I did notice that the temp was still set to 140° at the end. 😉

[bettyyoung]

Thank you for your valuable information. My friend just bought a condo with a Takagi water heater. Unknown if it has been flushed. I’m going to buy some Dezcal and follow your instructions. I was hesitant to buy the ready made tankless descaling products that you mentioned. I don’t understand why the electricity needs to be unplugged from the outlet? So the tankless water heater isn’t running and the pump is running to circulate the descaling solution? Thank you for your time and effort.

[joepalka]

Very good and informative video. I need to do that too. Maybe mine, Rinnai, is broken, it says I should descale when I get a code... well I never got a code in 7 years and I forgot to kind of do it anyway. I will try this to see if I get any scale in the pail using citric acid. I will start with same dilute. Thanks again

[victordankanych]

Planing to do something similar to mine 50galon hybrid water heater. I have well water

[cheapscotsman]

Used my grainfather brew system to pump citic acid.

[wbailey]

Good job! My only concern is the strength of your descaling solution of 1.2 ph. This is well over 10 times the strength of vinegar which is recommended by tankless water heater manufacturers. Won't this over time damage the hot water heater? If not, why don't manufacturers recommend a stronger descaler?

[rke]

How are you coming up with $12 a year to run it? The unit I have operating cost per year is around $199 annually.

[michaelkuzmin]

Just curious, why do you need sulfamic acid and aluminum sulfate? I am going to use just pure citric acid

[dthatcher]

Interesting, 8 oz citric acid powder plus 2.5 gallons of water is a 2.3% solution... I am planning on doing 16 oz in 2 gal of water to make a 5.7% solution when I clean my tankless next week. Planning to use food grade citric acid (powder).

[philindeblanc]

Why not dilute the muratic acid, (pool supply) which I think is a 60% HL Acid? A gallon of muratic is about 5-6$. your unit looked really clean. I have seen very dirty cleaned water with vinegar after 3-4 hours of it running.

[BigRW]

I put some citric acid in my hot water heater tank and now my water runs blue. I think it's reacting with my copper pipes.