I just finished descaling my homes tank-less water heater. I think most folks don’t think about this kind of maintenance. The job was actually easy. It involved by-passing the water heater and then pumping three gallons of vinegar through the water heater for 90 minutes. This is really a job that should be done yearly, however, the last time I did it was two years ago. I was really quite surprised at how much sediment came out at the end of the process.

This actually got me thinking about doing the same thing to the Travel Trailers water heater. My RV water heater is not a tank-less water heater but rather a 6 gallon standard water heater. Even though I filter my water at campgrounds and flush my tank each time when we get home, I am positive there is going to be calcium in there.

Keep in mind that when you perform any maintenance on your trailer, you need to exercise caution. If you are not comfortable doing maintenance on your trailer your should let a qualified professional do the work.

The water heater should be turned off completely – no electric or propane switches on. The water should not be hot, it will scald you! The pressure in the tank needs to be relieved. You can relieve the pressure by opening the high pressure release valve or opening the sink faucets.

Once all that has been done you will need to put your water heater into the by-pass mode. This way the vinegar will stay in the water heater and not run into the water lines. If you miss this step not only will you NOT descale your water heater, but you will have really awful tasting water until the lines are cleared.

The parts that are needed to perform this maintenance are all available on-line. More than likely they are available right down the street at your big box store. Keep in mind I do not have an anode rod, so one of my parts is different than yours if you have an anode rod. However, beyond that, the process is the same.

It is worth noting that you can also do this procedure by removing your high pressure relief valve and using a funnel to fill your water heater with vinegar. In my opinion, the following process is probably easier.

Here are the parts you need if you DO NOT have an Anode rod.

A brass 3/4″ GHT Male Fitting to 1/2″ NPT Male Fitting. This will screw into your hose on the 3/4″ side and into your water heater on the 1/2″ side (where you removed your plastic water plug).

A 3/4″ GHT Shut off valve for the other side of the hose.

A short Water Hose. I bought a 3 foot x 5/8″ hose on amazon, and a small funnel for filling the water heater via the hose.

You will also need to purchase 6 gallons of vinegar at 5% acidity. Alternatively, you can buy one gallon of vinegar with 30% acidity and add five gallons of water. Keep in mind that if you are using 30%, you should wear gloves as it is quite caustic.

Now if you have an anode rod, instead of the 3/4″ GHT to 1/2″ NPT fitting, you will need a 3/4″ GHT Male Fitting to 3/4″ NPT Male Fitting.

Again, you could remove your high pressure valve and pour the vinegar into that opening. However, this seems to be the least intrusive way to clean the tank.

I didn’t attach the shut-off valve to the hose until after I poured all the vinegar into the water heater. That’s because the opening in the hose is larger than the opening in the shut-off valve. Once I finished pouring the vinegar I screwed the shut off valve onto the hose; and then closed it so no vinegar could come out.

DO NOT TURN YOUR WATER HEATER ON WITH THE VINEGAR IN THE TANK

Keep in mind you need to keep your funnel elevated higher than the water tank in order to fill it. Additionally you may want to open all your vinegar bottles before you start this task. That way you can complete the task without having to deal with the shut-off valve after pouring each gallon.

Vinegar is acidic and can kill grass. So, I put a bucket under my hose while I filled the tank in order to capture any spillage. After the vinegar had been in the water heater for 8 hours I drained it into the bucket.

Surprisingly, I didn’t see a lot in the bucket which I attribute to the vinegar doing its job by dissolving the calcium. Next I flushed the water heater out with a wand you can buy at any RV supply house or amazon.

It will take a lot of flushing to remove any calcium and the residual vinegar. I probably flushed water into the tank for about fifteen minutes before I could sample the water and not taste any vinegar. I sampled it by just cupping my hand under the drain as water came out. The first time I sampled the water it was surprisingly awful.

In addition, I did get some calcium to come out (see white specks on the cement in the following picture).

Once you have the water heater flushed out you can reinstall your plastic plug. If you have an anode rod in your water heater, you will want to reinstall or replace it with a new one (depending on it’s condition). Next, you can take the water heater off by-pass mode.

So what did I learn after all of this?

  1. It’s an easy job and doesn’t take a very long time to complete.
  2. Even though I have a 6 gallon water heater, I couldn’t get six gallons of vinegar into the tank. This must mean that the tank has standing water in the bottom even though my trailer is level.
  3. You need to flush the tank out really well or else you will have a vinegar flavored water when you take the water heater off by-pass mode. I would hold my hand under the drain on the water tank and sample the water as it ran out. It took quite a while before it was drinkable.
  4. Using 30% acidity vinegar probably would have made the job go quicker since I would have only needed one gallon and then could have used the hose to fill up the balance of the tank to the six gallon capacity.
  5. This is probably best done at the end of the year before storage. It was 110 degrees the day I did it, and the first part of the process was done in the full sun. At the very least, pick a cool day!

In conclusion, this is a job that should be done yearly or if you are a full timer – every six months. It will probably extend the life of your water heater, and allow the water heater to reach temperature faster with less effort.