The Tank › Not sure if water heater is salvagable.
- April 22, 2017 at 11:35 pm #23675
We have a house we are going to rent out for a few years till the housing market improves here (maybe), so I am doing maintenance to make it as reliable as possible. The house has two builder grade short 50 gal “State” nat gas water heaters installed in series in the attic. They are 10 years old, but I think only have about 7 years of use. My plan was to flushed them out, take a look inside with my borescope, then put in new anodes and clean the burners.
One of the water heaters (the second in line) looks pretty good inside with no rust, shiny enamel inside the tank, and no debris on the burner which still looks silver. The anode looks almost full diameter with lots of white crust, which makes me wonder if it is working. The underside of the tank doesn’t look too rusted with some minor signs of water trickles down the sides.
The other one is a different story. I can see a number of rusty chips in the enamel inside the tank, especially along and at the base of the center column where the hot gas passes through. The aluminium part of the anode appears to have fallen off and is laying in the bottom of the tank, leaving only the central wire where the 24″ long anode was. The wire has about 6 month to a year of white crust on it. The burner also looks well used, with about a tablespoon of fine rust flakes piled on it. I don’t see any rust inside around the bottom outside edge of the tank, just some brown “rusticle” blobs that appear bacterial along the weld seam. The rust chips inside the tank don’t look deep, just chips and flakes with rusty metal underneath. I can see evidence of water on the underside of the tank, although I have seen no evidence of any leaks (condensation or rain down the vent?).
Basic problem is that the house was built around the water heaters so major surgery will be necessary to get the old one out of the attic and replace it. Basically, I was wondering when a tank can no longer be rescued? How much rust / bare metal / chipped enamel inside is considered too much to save the tank? I was thinking of perhaps installing powered anodes to make these water heaters last a few more years. I snapped pictures, if I can just igure out how to download them from my borescope.
Thanks, GeorgeApril 23, 2017 at 11:06 am #23676
Hello, The rust blobs particularly in the second tank are not a good sign. It would be good to see photos of the insides of the combustion chambers, but I think you need to be looking at the possibility of the one tank failing soon. Hopefully they are on drain pans. Also, they should be plumbed with shut-off and bypass valves, so either tank can be removed from service while the other one continues to work. This will buy you the time you need to be able to replace either one. Another approach would be to consider adding a shed outside, at ground level and putting tanks there. They should be simple to replace when the time comes. 😉
Yours, LarryApril 24, 2017 at 12:15 am #23678
Thanks for writing back. I gave it some thought. The “better” tank looks to me like it is a 5 year old tank, but the more beat up one looks like it is 15, even though both have the same install date of 2008. If 2 tanks are in series, does the first one (cold water input) take a lot more abuse than the second one which receives warm water input? The temp on the first (cold water input) tank was always set a few notches lower than the second to try to equalize wear. Of course, the tenant may have reset the first tank to mega hot for some reason and hid it from me, who knows. Anyhow, I suspect the beat up tank will not make it another 4 or 5 years. We will be selling in about 4 or 5 years, so if I replace the beat up, rusting tank now the new tank will catch up with the existing tank at right about the time we sell, and both will be in similar condition, assuming the current trend holds. I’m calling the plumber in the morning for a new water heater, the existing good tank gets a new anode and T&P valve. I can do the house surgery to make an opening, the plumber can carry the %&&@*ing tank into the attic and haul the old one out. The association won’t allow the tanks outside and the garage is too short to put the tanks there, so no choice. Too bad, putting the tanks outside the garage would cut the length of the pipes to the water heaters from about 60′ round trip to 15′ round trip, since the PEX header is in the garage.April 24, 2017 at 5:13 pm #23681
Hello, All considered, I think you have the right plan. Average tank life is 9-11 years, so it’s good to be replacing the bad one now. You did the right thing to have the first tank do part of the heating and the second one top it off. In an ideal world, each tank would have the same run time. Adding to the “too bads”, It’s too bad the architect didn’t give a thought to servicing the heaters or what a time, water and energy savings would have happened by placing them to minimize plumbing runs! 😕
Yours, LarryApril 24, 2017 at 6:55 pm #23682
So, I was contemplating life, fate and the galvanic table this morning and I had a bit of an epiphany. The pipes exiting the tanks are galvanized transitioning to PEX through a brass valve and brass PEX couplings. About a year ago I noticed that the brass valve was dripping and, after removing the insulation, I noticed the galvanized pipe connected to the badly ageing tank was rusted out and leaking. The aluminium anode on this tank might have already failed by then. The galvanized pipe on the other tank was rusty but not nearly as bad. At the time I just replaced the bad parts and put it back like it was originally to fix it quick. My thought is that the brass valve will rust the steel pipe and the tank (just a little), the steel pipe and tank will rust the aluminium anode, and the aluminium anode will rust the zinc coating on the galvanized pipe. The galvanized pipe will become the tanks sacrificial anode, sort of. The epiphany is that the zinc galvanize coating will rust a magnesium anode, so any water heater connected to a galvanized pipe should have a magnesium anode to help keep the galvanized pipe coating from deteriorating and to help prevent brass from deteriorating steel. Does this make sense?
Yeah, I know. Quit using galvanized pipe 😕April 24, 2017 at 8:06 pm #23683
Hi, I like what you were thinking about this morning. Nice mix. 😉 To your question, galvanic corrosion has a LOT to do with the distance between different metals. Also, the protection the anode gives works sort of like a light bulb. Anything lit up, or in direct line of sight is protected, with closer being better. Protection does not go around corners well. That’s why a simple 3″ plastic lined steel nipple works so well in protecting the steel tank from copper plumbing. But, in general, the fewer metals in close proximity, the better. A trick I use is to put a lined nipple between galvanized plumbing and a brass valve. 😎
Yours, LarryApril 24, 2017 at 9:58 pm #23684
So I suppose that short stubby cheapo anode being 2 feet from the bottom of the tank might have somehting to do with the bottom rusting? My thinking was that the galvanized pipe opening is about 5 inches from the top of the anode, so there might be an effect extending some distance into the pipe. Now that you mention it, the metal ring contacting the water where the pipe screws into the tank would terminate any electrical potential generated by the anode and prevent any protective effect from penetrating very far into the pipe. Electricity likes shortest distances. Plastic insulated galvanized nipples with a few wraps of teflon tape extending slightly past the end of the pipe to prevent any water from penetrating into the pipe threads sounds like a good way to deal with a brass valve on iron pipe, or maybe pipe dope applied just right. I would bet that ANY water penetrating into the brass/iron pipe threads, even one turn, would be enough to start some pretty good corrosion. If water is completely excluded from the threads and the barrel of the nipple, the only the very tip of the nipple will corrode. Dang, plumbing kinda makes my brain hurt.April 25, 2017 at 11:31 pm #23687
Hi, I think you’ve just come up with why nearly every plumber has a different opinion about any given plumbing situation! 😀
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