Cleaning the coil

Hi everyone. Im taking my hot water coil out today to clean it. Heavy soot has caused it to not work properly and blowing fire out the bottom periodically . Any advice ? I looked around for old threads, but only found one from jordi that made sense,but was more about the fire and damage it did.

Hey buddy

I have to do the same thing. Wish i had more to share, lol. I will in about a week…

Thank you. I read you post from awhile back. Scary stuff. Made me stand to attention real quick yesterday when it did it to me.

Dirty filthy job, don’t try to save the wrap, replace it & while the coil is out descale it with a 12v pump. I have cleaned all of mine many times & it blows. Use minimal degreaser & a lot of hot water & don’t clean it on concrete or you will be cleaning it as well. Good luck

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  1. When do you know it is time to clean? Just not working like it should?
  2. Any links to videos on how to do it? I am guess the coil itself is a bit heavy. Mine has a large eyebolt on the top that I assume some kind of device was used to aid in placement (maybe engine stand or something similar?)

It is recommended to clean once a year minimum, depending on usage. If you have a local PW service store, it may be beneficial to just let them do it.

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I clean when you get black smoke & temp rise is starts dropping off you can pop the ignitor cover & look to see degree of soot buildup. Also I replace & adjust electrodes & replace thermostat. I use a forklift to lift out & as Jordie said if your first time take it to a shop & watch them pull & clean. I know that pulling & cleaning coils is their last priority & its not cheap. Good luck


Yep. Me, my helper, clothes,tools,lawn,trailer,bath tub and fork lift ,which is me and my helper, and dog are all covered in diesel soot. But it was a good day. Learned a ton and saved $85 an hour on there mechanics hrly rate. Thanks for ya’lls help and advice. Going to Hotsy tomorrow to get new electrodes, fuel nozzle new insulation wrap and thermostat and more odds n ends.


Everybody says the same thing about cleaning coils, ITS DIRTY! Quick question, would you mind explaining how you cleaned yours? I’m confused because some people online show themselves running muratic acid through the inside of coil to clean it. But it looks like you cleaned the outside. Did you clean both the outside and inside? Looking to do this to my coil soon and it’s fairly difficult to find insight on how to do it! Hope you had some mechanics soap near by lol

I would to understand the cleaning process more myself since I am on my first hot water unit

My coil was clean inside… But my outside was so packed in soot due to a fuel pump malfunction that it couldn’t breath out the top,forcing air and fire to go underneath. I 2 stepped it with acid then soap to neutralize the acid. Over kill. Maybe. Then let it soak about 20 minutes in degreaser. Cleaning the inside is easier . Get yourself a circulating pump that you don’t care about, buy coil cleaner, unhook you’re 2 lines from the coil. #1.Bucket with coil cleaner mix in it.#2 garden hose out of bucket to suction side of circulation pump.#3 hose out of circulation pump to coil.#4 out of coil with hose back to bucket to complete the circulation process. Hotsy says to run circulation pump for around an hour. I get hotsy coil cleaner, only because it’s still got a warranty on the coil and unit. I want them to see my receipts when it blows up. You tube has a video on this ,I’ll try to find it. I’ve heard you can use muratic,PH or Hf acid. I’ve also heard you can eat to much out of your coil thus weakening the metal over time if not mixed properly . So IMO only ? I’d go with a good coil cleaner. It’s cheap. You’re sch 80 coil is not. Another tip. Before you shut down you’re machine always run all the hot water out. Helps alot with scale build up. I’m so thankful for all the advice I’ve received here on this forum from top notch guys , I’m more than happy to pay it forward on what little this old truck washer knows. Hope this helps fellas


Yes sir that helps big time!! I was fortunate enough to learn right when I got my unit to always let water cool down. I always run it for quite a bit after I shut the burner off, I hope that has helped me lol. Again I appreciate the advice!

I just cleaned mine, be prepeared to get dirty… Degreaser works best, a fine wire brush helps…

Replace the insulation, Clean out your nozzle (it has a filter in it) check electrodes replace if worn and install to correct specification using the electrode guage, check with the burner manufacture for proper setting on your specific machine.

Run a descaler thru the coil remove mineral deposits.

After the service, Run Red Devil Soot Remover in your diesel ocassionaly, it helps keep soot down to a minimum and helps from it building back up so quickly.

If you rely on your burner alot, Try to make it a habit to clean it once per year, keeps things happy and safe.


  1. Acid isn’t going to touch soot.
  2. Purple degreaser (everyone’s got one) that is caustic and butyl based was your best bet.
  3. For the interior do NOT buy a true descaler…those muriatic will cause more damage than good, you want an ice machine cleaner/descaler based on phosphoric or citric acid so as to remove the mineral deposits in a non aggressive way.

Acid will cause flash rust on coils. I have used minimal degreaser & hot water to clean for 20 + years with excellent results, heavy caustic degreaser will flash coils if your not careful. Did you use hot water to clean ?

I did use hot water

That’s odd. Because when I applied HF acid to my coil. The lawn turned black and my coil was very clean.

That the degrease I used guys.