Flushing an Atwood RV Water Heater

TheRVgeeks Annual Maintenance, Maintenance, Plumbing, Water & Sewer 16 Comments

We demonstrate how to thoroughly flush and clean an RV water heater.

UPDATE – April 3, 2012: Regarding our use of an after-market anode rod. There are questions about which metal to use – magnesium, aluminum or zinc. As we mentioned in the video, we only chose this particular anode due to the extreme difficulty we had removing the original, despite the fact that it is a different material than the original rod. We’ve now inspected it after a year and are not happy that it did not decay as expected this year (did not decay at all), and are concerned it isn’t protecting the tank properly. After hearing from two friends who also have Suburban units, who removed their anodes without much trouble, we’re going back to the OEM rod with no drain, and will be updating the video when we do.

UPDATE — Sept 22, 2013: UPDATE! THE ANODE ROD VERDICT IS IN!
WATCH IT HERE!

Rust, lime scale and other debris can build up in the hot water tank on your motorhome, travel trailer or 5th wheel. Left alone, this can shorten the useful life of your water heater. Simple annual maintenance and care of your RV’s hot water system will save you money by extending the life of the heater.

We recently flushed the Suburban water heater on our Newmar, so rather than do it again, we’ve borrowed our friends’ Atwood water heater to demonstrate how to do it.

Only a few simple items are required, including a wrench to remove the drain plug or anode rod, a tank flush wand, and some white vinegar (1/2 gallon for every gallon of tank capacity). If you have a Suburban brand water heater, be sure to have a new replacement anode rod on hand as well (magnesium, aluminum or zinc/aluminum).

The small amount of time required to do this simple but essential maintenance will pay for itself with years of extra service from your RV’s hot water heater.


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We're handy RVers, not professional technicians. We're happy with the techniques and products we use, but be sure to confirm that all methods and materials you use are compatible with your equipment and abilities. Regardless of what we recommend, consult a professional if you're unsure about working on your RV. Any task you perform or product you purchase based on any information we provide is strictly at your own risk.

We sometimes receive products for evaluation at no cost, and The RVgeeks are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites. But our opinions are our own, you won’t pay an extra penny, and we only link to products we personally use, love and can recommend to friends with complete confidence.


Comments 16

  1. I wanted to let you guys know I love your instructional videos! You guys are my first “Go To” site if I have a question about RV Maintenance and equipment! Thanks for the Atwood video it was very helpful! A question I have is about the Divert setting – since I don’t have something labeled “Divert” is that the same as a winterizing setting? This should pull the fluid into the coach and if I don’t bypass the water heater it should fill it first – correct?

    Do you mind if I ask another question unrelated to the topic above – I noticed you guys lean your engine with a power sprayer. Do you reduce the pressure and should the engine be running or off? I have a Cummins 300 HP Diesel and to my knowledge has never been cleaned – If you guys have a video on how to clean an engine I would love to see that!!!

    Thanks for all you do to help us Newbie’s feel comfortable with our Coach!!!

    Marc
    Garland, TX

    1. Post
      Author

      Thanks, Marc! That’s really nice to hear and we appreciate you saying that! Made our day!

      On the water heater flushing… what we are using to get the vinegar into the system is a “Winterizing Kit” (came installed on our RV, but you can retrofit one if your RV doesn’t have one). It’s designed to allow you to pull antifreeze into your plumbing lines using the water pump. We ALSO have a set of “Water Heater Bypass” valves. These isolate the water heater from the fresh water system… so that when you’re using the “Winterizing Kit” to suck antifreeze into the system, none goes into the water heater (so you don’t have to buy 20 gallons of antifreeze!!)!

      So you don’t need a “Divert” (or “Water Heater Bypass”) valve to flush the water heater… you need a “Winterizing Kit”. And since you don’t have a “Divert” valve… you are correct… using your “Winterizing Kit” will allow the vinegar to fill the empty water heater.

      As for pressure washing our engine, we don’t turn the pressure down, but our pressure washer is only a 1500 PSI unit, so it’s not that powerful. We ARE careful with the spray and keep the nozzle back from hoses/belts/wires and anything else that could be damaged by the water pressure. And because we’ve ALWAYS kept our engine clean, we don’t have much (if any) “gunk” in there that NEEDS heavy power washing to remove it. We’re mostly washing off dust! If your engine is very dirty, you may want to take it in to a shop to have them steam clean it to remove all the heavy oil and buildup first, so that you can just “maintain” it by washing off the light dust, etc.

      One other note – about 5 years ago, our engine developed an oil leak that required a week in the shop for them to address it. As part of the repair, they had to power wash the engine several times so that they could find (and confirm repair of) the leak. We can’t say for certain, but it appeared they were using a MUCH more powerful power washer than we have, and they didn’t seem to have any concerns about harming anything. This was a Cummins engine shop, so we’re sure that if blasting the engine with high pressure water would cause a problem, they would know better than to do it. And nothing they did back there caused any harm. Now maybe they’re aware of certain areas to avoid blasting too closely. So, if we were using very high power water (like at a DIY car wash) we would just be EXTRA careful to avoid aiming too closely (or too long) at any one area of the engine.

      For what it’s worth, we power wash our car’s engine all the time, too… and, since the advent of fuel injection & electronic ignition, there doesn’t seem to be anything to worry about.

      Hope this helps!

  2. One more comment while I await your guidance… The line that I can disconnect from the water pump and replace with my “sucking hose” is the line that comes from the FW tank. So (I think) I’ll be completely bypassing the FW tank and sucking straight into the Hot Water Tank? If that’s true, what setting do the valves need to be set to in order to fill the hot water tank with the 5 gallons of city water? Remember, I’ve already winterized and have blown my lines out. I suppose I could suck 5 more gallons of water in the HWT from my empty vinegar jugs, just filled with water?

    1. Post
      Author

      Hey Steve… our replies must be passing like ships in the night. See our reply back to your comment below. But in answer to your follow-up… yes, it indeed sounds like your winterizing hose attachment for your pump means that it is completely bypassing the fresh water tank. Attaching that hose means the water pump’s “supply” will be coming from whatever container you stick the other end of that hose into. And, yes, that means you could add the remainder of the water needed to fill your tank by just putting fresh water into the vinegar containers.

      BUT… doing this will likely result in vinegar & water ending up in your plumbing lines, undoing your winterizing. In normal conditions, when your plumbing lines are full of water and everything is turned off, the empty water heater is the only place for the vinegar to go to when you use your pump and the winterizing hose attachment. But since you’ve already blown out your lines… that means the vinegar can go everywhere. Sure, some of it will end up in your water heater, but a lot of it will also get pumped throughout the rest of your plumbing. There is no combination of settings on valves that can create a direct path from your water pump to JUST your water heater when the rest of the plumbing is empty, too.

      That’s why we’re suggesting that you may want to hold off on the vinegar flush of your water heater until the spring when you’ve de-winterized the plumbing. With all of the rest of the pipes full of water, the water heater is (effectively) the only place the vinegar can go.

      Hope this helps/makes sense.

  3. Good afternoon guys. Love your videos. I have a 2011 Tiffin with a Suburban water heater. I don’t have a “divert” valve. I also JUST winterized and blew out all my water lines, and would prefer to just import water and vinegar into the Hot Water Tank.

    Is your “divert” valve the same as my “Hot Water Bypass” valve?
    I do have an optional hose that I can connect to the water pump for importing antifreeze.
    What exactly would my steps be after rinsing out the tank and replacing the plug?

    I have 2 valves in my wet bay:
    – City Water/Tank Fill
    – Hot Water Bypass/Normal Flow

    As I understand it, If it’s set to City Water… the water goes straight into the Hot Water Tank… Is that correct?
    Further, If I have the other valve set to Hot Water Bypass, the city water goes straight into the Fresh Water Tank? Is that correct?

    So… when importing the Vinegar, would I have the valves set for:
    – City Water
    – Normal Flow

    Thanks,
    Steve

    1. Post
      Author

      Hi Steve. Keeping in mind that we have no 1st-hand experience with Tiffins and their plumbing set-up, if we have it right, our “divert” valve isn’t the same as your “Hot Water Bypass” but rather the same as your optional hose for importing anti-freeze. We’d suggest that your best bet might be to wait until spring to flush your water heater, because we don’t think you can do the job without getting water into your plumbing lines. When you do go ahead and flush, and the tank is empty and it’s time to add vinegar, the water heater bypass should be in “normal” mode and and the city water/tank fill valve should be in “city water” mode. Then you attach the optional winterizing hose to your pump (turning any valves necessary to activate/use it). Put the other end of that hose into the vinegar bottle(s), and turn on the pump. Since the water heater is empty, and the valves are in the “normal” position, the vinegar will be pumped into the water heater, since it’s empty, and therefore the first available void for liquid to go into. Hope this is clear, and accurate for your system.

    1. Post
      Author

      Hi Shawn! First, we have to be clear that we have zero experience with this type of water heater. Our concern would be how well they work when not hooked up to water and sewer, where we’d think the extremely low water flow typical with dry camping would be insufficient to get any hot water up without running more than needed otherwise, which would use up valuable fresh water and fill the gray tank faster. If your plan is to stay fully hooked up, the reviews do seem positive on this Amazon listing. We’d suggest getting a wider range of experienced opinions by posting your question in the user forums on iRV2. It’s free to sign up and post (there might already be threads on this topic) at http://irv2.com/forums We’re sure there are RVers out there who can shed some details from experience, both on the grid, and dry camping, about how well these work in various situations.

  4. Pingback: RV Suburban Water Heater Anode Rod FAIL - TheRVgeeks

  5. Hello, Like Garry above, I just purchased my first RV (2007 Fleetwood Bounder) and am also unsure as to the maintenance practices of the previous owner. So, I’m getting some VERY GOOD advice from you RV Geeks. :-) My question regarding the flushing of the water heater is this… my RV doesn’t have a winterizing system in it so how can I go about filling the water heater tank with 5 gallons of vinegar? (I have a 10 gallon Atwood water heater)

    thanks for all of the excellent and informative videos.

    1. Post
      Author

      Hi Tony. Thanks for the nice note. There are two ways we know of to get the vinegar in without a winterizing kit. One way is to remove the over-pressure relief valve and use a flexible funnel to add vinegar there (after replacing the drain plug, since it would all run out otherwise). The downside is that the relief valve may require quite a bit of force to remove, since they can sometimes be rusted in place. Second, we’ve heard about people buying a fitting from the plumbing section of a home improvement or hardware store that fits in place of the drain plug / anode, but allows a clear hose (also from Home Depot/Lowes) to be attached after screwing it in. Then hold the hose up above the water heater and pour the vinegar in using a funnel. To keep it from running out, tie the hose up above the heater while heating the tank. Just be prepared for vinegar to back up out of the hose during heating. Hope this helps!

  6. hello.

    Our rv is connected to city water on private property . How does the hot water heater fill with water? I believe the water heater is both propane and electric and I want to use it with just electric. It is not heating the water. I looked in the kitchen and on the front of the tank i see valves, what am I missing?

    1. Post
      Author

      Hi Susana. The odds are very good that you have a bi-fuel water heater (electric/propane) since that is the most common type. If so, you can run it off electricity, propane, or both, depending on your situation. It’s just a matter of turning on the “electric” or “propane” switch, as desired. Being hooked up to electric, you can of course run it off electric only, as you’re planning to do.

      If you’ve turned on the electric switch and you don’t get hot water, there are several possibilities as to what may be happening. First thing, check the 110-volt circuit breakers on both the power source (in the house) and the one for the heater itself (on the RV). Second, the valves that you’re seeing are likely the water heater bypass valves. They must be in the “run” or “normal” position. If they are in the “bypass” position, the water heater is bypassed, and cold water just flows through the line, and you will get water out of the hot water faucet, but it will of course be cold. If your RV was winterized, the tank being set to “bypass” is quite possible, or even likely.

      If still no electric hot water, you might have a failed electric heating element. That can be caused by turning on the heater with no water in the tank, which would almost certainly burn out the element. Water runs into the tank automatically when the bypass valves are set to normal. The empty space in the tank fills up when you connect to city water or turn on the water pump. If the tank was winterized and left in the bypass position, the tank may still be empty. Turning on the electric element in that case could burn it out.

      Let us know if any of this helps you sleuth out the problem, and please let us know how you make out.

      Good luck!
      Peter & John

  7. We have just purchased our first motorhome, (a used Winnebago Adventure) and have watched most of your videos.
    I certainly appreciate your efforts, as they are very well done. (I have learned a TON)

    Not knowing when or if the Hot Water tank has been descaled, I took on this task. However I was concerned about dumping the heated vinegar on the driveway to run off into the grass, (grass does not like vinegar) so I used a piece of
    1/2″ pvc pipe 18″ long fitted with a 1/2″ male fitting on one end and a ball cock on the other. After draining the tank and flushing, I inserted the pvc into the drain hole, refilled with vinegar and water, then turned on the heat.

    Now I can drain the vinegar into a bucket and dispose of it without risk to the grass.

    Thanks, and keep up the good work, looking forward to the next video.

    1. Post
      Author

      Hi Garry. First of all, congratulations on your first RV purchase! We’re excited for you. Second, thank you so much for your kind words. Third, thank you SO MUCH for adding this tip here on a thread about hot water tank flushing. We always appreciate when someone adds to our knowledge base, and it’s great that we can still pick up new ideas after 12+ years, especially from someone just starting out RVing. You really can teach old dogs new tricks. :)

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