RV Water Heater Flush & Inspection Surprise!

TheRVgeeks Annual Maintenance, Plumbing, Water & Sewer 45 Comments

Even though we’ve been on the road full-time for nearly 15 years, we never stop learning. Since it’s virtually impossible to know everything about every topic, the most valuable tool we keep on board is an open mind.

Last year we added a great new piece of (inexpensive) gear to our DIY utility belt: a borescope. Before that, we’d never been able to see inside our water heater to know what condition it was in, or to see what effect (if any) our annual cleaning regimen was having.

It turns out that a borescope is kind of like a clear sewer elbow for the water heater. We discovered a long time ago that we had no way of knowing what was happening during black tank flushing without a “window” into the sewer hose during the process. As a result, a clear elbow has been an indispensable part of properly managing our RV systems ever since.

Even though we had the epiphany to get a borescope to inspect the inside of the water heater last year, it wasn’t until this year, the second inspection, that we really “get it” when it comes to actually understanding what’s going on in there.

We were all set to do our annual flushing regimen, when the borescope threw us for a loop! Check out the video to see what happened, and what we learned.


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Comments 45

  1. Thanks for your video. We have a 6 gallon Atwood heater. I wanted to use 4 gallons of vinegar to clean, but, the tank was full after about 3 3/4. That would have been ok, but it left vinegar in the line. I by passed the heater and my wife turned on the water and was not so happy with me for the vinegar smell. So next time, I will only use 3 gallons!
    Before I flushed, we were hearing the popping sound from the heater (we have owned the motorhome for 18 months). After draining the vinegar, a great deal of scale came out, and now we have a silent water heater again. Thanks again for the videos.

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  2. Hi guys,

    I plan to flush my 4 gallon propane heated suburban Gyser with a 80 or 90/20 Vinegar mix concentration for the first time. The buildup of scale is bad as seen initially when I flushed it out by running water through. I wanted to ask you about the strength of vinegar choice you guys think is acceptable.

    I contacted a bulk white vinegar supplier in my area (they supply to the hospitality trade) to find out what they can offer me. It turns out there are two options – 5% Vinegar and 10% vinegar concentrations.

    Is it worth buying the stronger concentration? Its about double the price.
    Would a stronger concentration damage anything in my system?

    ————————————————————————————————————————————————————

    The next question I wanted to ask is at what temp should I run my suburban propane heater on overnight? It shows three options, low, medium and hot.

    Another question, do you think it is practical (in the case of my badly scaled heater/Gyser) to cycle the heater on and off a few times over a few days for better results? e.g 8 hours of heat then let it cool then another 8 hours of heat then let it cool etc ?

    ————————————————————————————————————————————————————

    Last question relates to using food grade Citric Acid powder vs Vinegar and mixing that into a large water container and then using the winterizing kit to suck that into the heater gyser. What are your thoughts on Citric Acid vs Vinegar?

    It seems like a cheaper alternative and from what I understand it is the same acid type as vinegar.

    Thanks for taking the time for sharing your knowledge with us!

    Regards,

    Michael

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      Hi Michael!

      First thing… from the sound of it, your water heater is different than what we’re used to here in North America (4 gallon, multiple heat levels, etc), so we’d definitely recommend checking with the manufacturer first to be sure that using the vinegar/citric acid solution won’t cause a problem and/or damage your water heater. If your tank is EXTREMELY coated with scale, we’d recommend a couple of different options: (1) let it “soak” for longer before draining, to give extra time for the reaction to occur, (2) purchase an inexpensive borescope like the one we used in this video to get a look inside the tank after treatment, to see if it needs a repeat, and (3) repeat the procedure if needed. If the scale is extremely bad, the acid in the vinegar will be consumed entirely in the reaction, so it may not completely remove it all. Repeating the procedure will ensure you get it all, without risking exposing the tank metals to too high an acid concentration.

      Second… the white vinegar that we use in our water heater is a 3% solution. So when we fill our tank half full, it ends up being only 1.5%. We’d have some concern about ramping the concentration up too high… because the acid CAN begin to cause problems with the metals in the tank if it gets too strong. Again, not being familiar with your water heater unit in particular, we’d be afraid that there could be some components that would be adversely affected by too high a concentration.

      Third… the chemical reaction between the acid in the vinegar and the lime scale in the tank is accelerated by heating it. So we’re not sure that heating, then cooling, then heating would be any better than just heating it.

      Last… we’ve heard from other viewers that they’ve used citric acid powder in lieu of white vinegar… since the powder is easier to store than gallons upon gallons of liquid. So that approach is certainly viable. It is NOT the same acid as what is in vinegar (acetic acid), but both are relatively mild acids and, at about the same concentration, should achieve the same results.

      Hope this helps!

      1. Thanks for the very in-depth reply!

        My camper is the Nothstar 600ss which I imported from the USA. It uses the Suburban SW4P model as which is identical to the unit in the link below (except mine holds 4 Gallons SW4P with the 4 standing for 4 Gallons):

        Have a quick glance at this link – https://www.airxcel.com/suburban/products/water-heaters/pilot-ignition/gas-water-heater

        Here are details and a clear picture of the Suburban 6 Gallon (SW6P) unit of which mine looks identical –

        https://www.amazon.com/Suburban-5117A-Water-Heaters-Gallon/dp/B002SSEXJG/ref=pd_lpo_sbs_263_t_0?_encoding=UTF8&psc=1&refRID=80924W2YJ21WCYK6JMY4

        You can see the heat settings if in the middle of the picture. It looks like a black plastic half moon shaped dial. That dial has three user adjustable heat settings – Warm setting | middle setting (Medium) | Hot setting.

        My concern is damaging the system if I use the wrong heat setting medium or hot, what do you think?

        With regards to cycling the heat on and off over a period of time, it was just something I read others did when researching across multiple forums, for a better cleaning effect. Figured you may have already tried that. I guess its unnecessary as your method works just fine, why deviate?

        Lastly on the topic of Citric Acid, have you guys ever considered exploring which works better Citric Acid vs Vinegar? Besides the space saving it is also cheaper to purchase, so perhaps its a better product to use?

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          OK… since it’s a “typical” Suburban water heater, just like ours, you should be fine with using this procedure! And since our Suburban doesn’t have ANY temperature settings, we’d assume that it’s set to “High”. We do know that our water heater’s thermostat is set to 130 degrees F, so if you can find any information on what the Warm/Medium/High settings equate to, that might help you decide (although we’d assume that “High” was the same as our 130 degrees, since that’s the max they’d likely want the water to heat).

          As for heating/cooling… unless you were “shock cooling” it to try to get the scale to crack off of where it was bonded to, we don’t see how a repeated heating/cooling cycle would be beneficial. No experience on that, just based on what seems to make sense. Not sure how others are determining that it “works better”… so we’re likely to stick with the simple option of just leaving the heat on.

          We’ve considered exploring the citric acid option, but without two identically-scaled water heaters to test with, any observations we made would lack any empirical validity (we’d just be guessing as to whether or not it worked as well/better/worse than the vinegar did). Since we only treat our water heater once a year, and have ready access to large quantities of reasonably-inexpensive vinegar at Costco here in North America, we haven’t had much impetus to delve into the citric acid powder option. Without concrete testing, our assumption is that as a similarly-weak acid to acetic (vinegar), it will do the job just as well. But maybe it’s time for an Amazon order of some citric acid powder so we can test it out this year! 😉

  3. Hi, Any reason the vinegar can’t be poured into the water tank and then pumped into the hot water tank with the rv pump? I do this to pump RV antifreeze through my water lines when I winterize my RV. I realize I have to do a good job of rinsing the fresh water tank afterward.

    Thanks,

    Dan

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      Hi Dan! As long as you get the vinegar into the water heater, that’s all that really matters. Of course if you have a system that allows you to do it the way we do, without getting all that vinegar into the fresh water tank, it will save you a lot of flushing. In our case, our fresh water tank pickup line is a little above the bottom of the tank, which prevents us from draining all the water out. If yours is like that, the remaining water in the tank would dilute the vinegar enough that it might require more vinegar to maintain a good concentration. Of course if you’ve already used this technique successfully to winterize, and gotten a nice high concentration of anti-freeze through the system, it should be no problem in your case.

      1. I think Dan has a good idea. By “occasionally” using his method, one would also be cleaning the water lines within the RV fresh water system. Thus, doing dual functions. This technique would enable greater concentration of the cleaning, disinfectant qualities of the vinegar. Coupeled with use of a water softner, I would think this is a win-win

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          Thanks Vincent! If you’re staying in hard water areas, like the Desert SW, most of the time, this could be a way to ensure that any scale that could build up is dealt with. We’ve been down there a lot, but haven’t seen an issue (not that it couldn’t be hiding in those pipes)! Either way, be sure to periodically sanitize the fresh water system with bleach (we have a couple of videos about that) to kill off any bacteria.

          1. Thanks. For myself and perhaps many others with the Atwood “15-gal” rated water heater (15-gal rated as it has a hot-cold mixing valve), hard water is a killer, clogging up the valve…loss of hot water. Also, the desert SW is not the only hard water culprit: w have found this throughout travels in the Midwest, Northeast, and especially in the Southeast. As example, here in the Western side of Central Florida, or dual On-The-Go 1600gal/40day system only lasts 25-28 days due to hard water.

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            Interesting, Vincent… hadn’t thought about that issue with the hot-cold mixing valve, but it certainly makes sense. And thanks for the heads up about other areas with hard water. The desert southwest certainly doesn’t have a lock on that! ;) Safe Travels!

  4. Hi I’m so addicted now to watching your videos. My husband watches your videos all the time. I have a question about how many gallons of vinegar to use in our 2008 travel supreme when flushing the water heater. I’m not sure how much to use. Could y’all help us out? Yall are awesome!

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      Hi Leslie! Thanks for the nice note. We generally about a 50-50 mix of vinegar & water, then leave it in overnight with the heater turned on. But as you saw in this video, a lot of that depends on the water conditions where we’ve been camping. Another factor will be the length of time it’s been since you last flushed your heater out. Check out our previous video (here) to get a feel for our standard method. If will give you an idea of about how bad our tank was and how much debris came out of it, and how effective the time & vinegar concentration was.

      We’d suggest that the first thing to do is to buy at least enough vinegar to fill your tank half way (5 gallons for a 10-gallon heater, etc). That way, you’ll have at least that much on hand. If it’s been several years since you flushed it and/or you’ve spent much time in the desert SW, you might consider getting enough vinegar to fill the whole tank. When you first remove the drain plug (on and Atwood), or the anode (on a Suburban), the amount of debris that comes out will give you a good idea how bad the tank is. If you get lots of chunks of white debris that continue to pour out, you probably have a LOT of scale in there. That would mean it’s a good idea to either use a higher concentration of vinegar and/or leave it in longer. If you’re living in it full-time, and it’s a problem to be without hot water for very long, a higher concentration will allow you to leave it soaking for less time and still get the tank clean. If you’re not living on board, and can let it soak for a couple of days, a lower concentration of vinegar should do okay.

      If you really want to know what’s happening in there, pick up an inexpensive borescope (we link to a good one for not much $ right here in the post), and inspect both before and after the vinegar treatment. Hope this helps!

  5. I’ve used my borescope to see behind panels and other hidden areas trying to find wires, lines or what do you suppose is in there, why didn’t I think to look in the water heater? As usual, great video and great idea, I’m chagrined I didn’t think of it myself when I serviced my water heater recently.

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      Hi Dave! We’ve done the same thing… using the borescope to see in all sorts of tight places. But we’ve forgotten we could do it a number of times, too. It’s kind of like when you’re in the store, see something you want to research more about later, and look for a piece of paper in your wallet to write it down… forgetting that you have a high-def camera in your smartphone and you could just snap a picture of it! LOL! A picture IS worth a 1,000 words! ;)

  6. Thanks for sharing the video – I was always wondering why when at the end of the season we never had as much “crud” in our water heater and the anode was always barely used……now I realize it’s because we only camp in Oregon and Washington and it’s the water! Thanks again, love your videos and helpful tips!

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  7. Just a thought for you guys – how much do you pay for 8 gallons of vinegar? Doing that annually, have you compared the cost of just simply planning to replace your water heater element every 2-4 years might be cheaper than using all that vinegar??? If you can buy the water heater element for $15-$20, that might be a much cheaper route.

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      Hi Ken! Good question. But there’s just one thing… doing the vinegar treatment is benefitting the whole water heater, not just the heating element. We agree, if it was just a matter of the heating element failing, it would be cheaper to just let it fail and replace that one part. But the mineral scale in the tank can cause other problems that lead to the failure of the WHOLE water heater (which costs about $500, not including time/labor)… which is a LOT more expensive than a few gallons of vinegar every year! LOL!

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      We use the winterizing kit (the one designed to suck antifreeze into your plumbing to protect it in winter), but the plumbing on your RV may be different. You can see how ours works in the original video here: http://www.thervgeeks.com/plumbing/water-heater-flush-inspect/

      If you (a) don’t have a winterizing kit or (b) your RV is plumbed differently and you can’t use your winterizing kit to get the vinegar into your water heater, you may need to try a different technique. We have heard of some people removing the overpressure/overtemperature valve and using a funnel to get the vinegar into the tank. And we’ve also heard of people piecing together a threaded adapter that screws into the drain port and has about a 3′ length of tubing attached to it that they use with a funnel to get the vinegar into the tank… and then temporarily affix the tubing to the side of the RV so that the end of it is above the level of the liquid in the water heater so it doesn’t all drain out (but be aware that unless you also close off the other end of the tubing, foamy vinegar solution WILL come out the end of the hose during the process, as it builds pressure from the chemical reaction with the mineral scale).

      Hope one of these options helps!

  8. I am so glad I found you guys. Actually I found you guys years ago but I still glad to see your videos and have watched them all many times over. esp, the replacement of the slide out awning, which were a great help to me. After watching this video on water heater maintenance, I can tell you my heater is in the same shape as yours. We do have great water in the great Northwestern USA. Just a big thank you for your videos, I enjoy them and also have learned a thing or two from them

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      Aw, thanks Pius! It means a lot to us that people continue to find our videos helpful… and gives us inspiration to keep on making them! Hope you continue to enjoy them!

  9. Hey guys, great video. I don’t remember; do you use a water softener? We live in North Florida where the well water has a high mineral content and our softner makes a huge different in the amount of scale produced in our home water heater.

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      Hi Dennis! No… we don’t use a water softener. Mostly because we don’t have room to store one when we’re traveling. But also because we only spend a part of the year (winters) in areas where there is hard water. But after seeing the dramatic difference in the interior of our water heater from being in low-mineral-content water areas… we’re revisiting the idea. ;)

      1. We really enjoy your site and information and have done a lot of the things you recommend. I am very surprised to hear that someone as meticulous as you both are do not have a water softener.

        We bought a water softener two years ago and can not believe the difference. It is more than just the water heater. Imagine all that scaling on all your plumbing fixtures. Not to mention, the scale on shower doors and walls. We also have a residential refrigerator with an ice maker and water dispenser, the softener has prevented any stalling in that system. I would highly recommend you consider joining the water softener crowd. We have a sediment whole house filter in front of the water heater and a charcoal filter after the softener. We drink the water, cook with it and wash with it. We use less soap, the dishes dry much nicer and our washing machine is less hard on our clothes. We have the Standard sized On-The-Go water softener http://www.portablewatersoftener.com , and it it plenty for the two of us. It uses regular table salt and is very easy to use and service. It takes up little to no space when we store it on the move. Bought ours on Amazon.

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          Hi Craig! We appreciate your input on the water softener… and we’re aware of all the benefits. But we only spend a portion of our year in areas with hard water, so haven’t had a dire a need for it. We haven’t experienced any problems with scale on our shower doors/walls, plumbing fixtures OR ice maker (and can’t think of any clearer proof of that than the fact that a year’s worth of full-time use of the water heater left virtually NO mineral scale). If our travel habits change, and we start spending more time in worse water areas, we’ll definitely revisit the issue. Glad to hear it’s working well for you (and sounds like you spend significant amounts of time in areas with hard water)! Thanks!

  10. As full-timers we spending a lot of time in the Arizona desert boondocking. That water is super hard. Have you ever use a TDS meter to check the hardness? The Seattle area is about 50 on a scale Arizona is about 990. It’s out of control. Our water heater is an Oasis system. We decided to try something a little bit different and you may be interested in doing this. We decided to run soft water system. I believe it’s called on-the-go softwater. It really does work and it should keep our water heater system pipes corrosion free. This would be a great experiment.
    Maybe these folks will give you a unit to test. We selected the smaller one of three sizes. We really think it’s going to help.
    Great video guys, as usual.
    http://www.portablewatersoftener.com

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      Hi David. We haven’t used a TDS meter before, but based off our experience with the borescope, we’re not surprised by the difference in readings you get between the Pacific NW and the desert SW! And we’ve heard from other people who have added a water softener to their system that it made a huge difference in the maintenance needed on their water heaters, etc. We’ve looked into them in the past, but decided against them because (1) we only spend a couple of months a year in areas with hard water, (2) as full-timers we don’t have the room to add ANOTHER piece of equipment, and (3) doing an annual flush with vinegar has ensured that we weren’t leaving all that mineral scale in the water heater tank. We don’t have plans to spend much time in areas with hard water any time soon… but if our travel plans change, we’ll definitely take a closer look at making room for a water softener! Thanks for letting us know it’s working well for you!

  11. Wow…. Amazing to see the difference of scale from different water qualities. We live in a high mineral area here in Southern California. I have been filling our fresh water tank before each trip with soft water from our house to try and offset the scale buildup. Great video looking inside the tank!

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      Jeff – it’s one of those things that we inherently knew (water quality varies from place to place… some much worse than others), but didn’t expect there to be such a dramatic difference! We know the water in the Pacific NW and BC is good… but assumed there’d still be SOME mineral buildup! So we’d guess that filling your fresh tank with softened water before each trip is really helping. At least as long as you don’t have to fill the tank up with hard water anywhere along the way! ;)

  12. When comparing ‘hard’ mineral rich water to ‘soft’ Pacific Northwest water is is incredible how much excellent rainwater can keep water systems clean.

    This video should be attached to last year’s and sent to every homeowner – fixed or mobile – to encourage regular inspections.

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      Hi Allan… we connect our borescope to our laptop, so we can see what’s happening on a big screen. But the unit we use (and link to) CAN be connected to SOME Android phones, too. Since we’re Apple users, our iPhone won’t work… and we’re not sure what the criteria are for an Android phone to work with the borescope.

  13. I bought the clear elbow to flush the holding tanks but I don’t see how to attach it to the drain hose. The hose attaches directly to the release valve, as does the clear elbow, but there’s no way to attach the blank end of the elbow to the drain hose.

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      Hi Sandra! Sounds like you have one of the higher-end sewer hoses that has built-in tabs/connectors to attach it to the sewer outlet on the RV. The clear elbow we use (and link to) is for a hose that DOESN’T have pre-installed connectors… so the end of the clear elbow slides inside the hose and then you use a large circular clamp to secure it in place. What you need is a clear elbow that has the tabs/nubs on the sewer hose end, so that you can twist your hose’s connectors onto it… like this one from Amazon: Valterra 45° Clearview Adapter. Hope this helps!

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      We were surprised! Gotta love the wonderful BC water! ;) Since we won’t be able to use our vinegar until next year… we could make you a deal on 6 bottles of it! LOL!

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      1. Yes, we switched to a water softener have incidents of calcium buildup causing it mixing valve on our Atwood WH into fail; despite periodic vinegar flushing.

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