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Small Cabin Forum / Off-Grid Living / RV water heater maintenance
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bobrok
Member
# Posted: 26 Apr 2014 17:33
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Quoting: MtnDon
I would be cautious about a used RV water heater only because many folks ignore the maintenance required. They forget to change the anode rod and the tanks rust out if they are glass lined steel like Suburban. Atwood makes aluminum tanks and those last better.RV water heaters are not all that efficient unfortunately. However they can be a compromise. 6 and 10 gallon models. There are some vendors online with okay pricing. We use a 6 gallon Suburban model. Be aware that the ones with electronic ignition require 12 VDC power.


MtnDon - your post in the other thread was oh so timely because I have a maintenance question I was just getting ready to ask myself.
We also have one of those 6 gallon Suburban heaters on propane. The attached photos show the condition of my anode rod, which I remove each year upon draining the tank. This is original and 5 seasons old.

Initially I was going to ask if this should be replaced or not. Info I have found says that you should replace when it's about 75% gone. Even though this is not at that stage I figure after 5 seasons it's probably a no-brainer to replace it, so I am going to do that.

However, in the process of finding out this information I came across a video showing how to winterize and clean your Suburban tank using a pressure water source and white vinegar and water. Evidently you first thoroughly rinse out your heater using the pressurized water source and then you fill it with the vinegar, let it sit overnight, and then re-flush it with water. This is supposed to remove additional corrosion that builds up on the liner. I've never done this, although I do have to say that when I empty my tank for the winter it is usually not all that bad as far as junk and corrosion. We have hard water that we pump from the lake and filter if this matters at all.

Do you (or anyone else) flush your water tank with vinegar?
Also, how often and at what point of degradation do you replace your anode rod?

Thanks,

Bob
anode rod
anode rod
close-up anode rod
close-up anode rod


MtnDon
Member
# Posted: 26 Apr 2014 18:59
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That rod is still in great shape! They do not deteriorate unless the water tank contains hot water. Sitting in storage with cold / room temperature water there is no or almost no galvanic action. Of course empty there is no problem.

I never flush with anything other than the water in the tank. I never see any crud when I drain it. The tank has a ceramic lining all over the inside surfaces. I suppose the theory behind the vinegar rinse is similar to why we need to clean coffee makers, steamers, etc. Big difference is that steamers and coffee makers heat the water to or near to boiling. That causes minerals to deposit on the hot elements. If the ceramic is in good condition I don't think there is any harm from the vinegar soak, but I do wonder if it is necessary.

Atlincabin
Member
# Posted: 26 Apr 2014 23:26
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A lot of the areas of the country have limestone in their bedrock, so the groundwater becomes saturated with calcium carbonate (dissolved limestone). Calcium carbonate has retrograde solubility, which means that heating the water causes the mineral to deposit (normal solubility, like for table salt, means that hot water can dissolve more salt than cold water - calcium carbonate is the opposite, cold water can dissolve more than hot water). So when you take saturated groundwater and heat it, the calcium carbonate deposits in the tank. This occurs anywhere the water is heated, in your hot water tank, coffee maker, even just cold groundwater coming into your pipes in a warm house will cause some deposition. Adding vinegar (or any acid for that matter) will react with the calcium carbonate and dissolve it, but you do have to leave it for a while (like overnight) for the reaction to do much. That amount of weak acid in your tank is not an issue for the lining of the tank, and can extend the life of your tank and heating rods.

Greg

bobrok
Member
# Posted: 28 Apr 2014 15:45
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MtnDon & Greg:

Thank you for the responses and very useful information. We never run the water heater for more than an hour or so in the evening when we need to clean up and do dishes, so I guess I've been doing myself a favor by not keeping hot water in the tank (as well as saving fuel). Good info. Thanks, again!!

bob

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