Intermittent (small) pooling of water under water heater...

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We have an 11 year old 40-gallon gas-fired storage water heater ("State" brand).
Over the summer, I intermittently noticed a (very) small amount of water pooling in a depression of the floor underneath the water heater - anywhere from damp to maybe 1-2 ounces.
Also, when changing out the thermocouple, I noticed that the metal around the pilot window and the fiberglass insulation were dry but rust-stained.
Now that cooler weather has returned, I haven't noticed *any* pooling or even moisture under the water heater for the past 2-3 months.
Is it possible that the pooled water (and the rust stains on the internal insulation) are just due to condensation from summer humidity (in the summer the basement is about 75% humidity)?
Or is this likely to be an early warning of impending tank failure?
I'm not sure how to explain the intermittent nature of this all...
Jeff
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I guess you could get some condensation where the cold water supply enters but once in the heater, what's to condense?
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Good point... the condensation would have been near the inlet on top but that is dry...
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On 12/6/2013 11:50 AM, blueman wrote:

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Christopher A. Young
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On 12/6/2013 11:18 AM, Stormin Mormon wrote:

I didn't know Toilet Paper had a safety relief valve. o_O
TDD
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On 12/6/2013 12:36 PM, The Daring Dufas wrote:

Made by Standard Toilet Fixtures Union. "If you can't take it any more... S.T.F.U."
Back to the OP, I suspect a leak now and again at the temperature pressure relief valve.
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But everything is dry around the TP valve... and I have never seen any dripping down the side or any moisture near the outlet.. unless it dries up when I am not looking... and then just leaves me with a pooling in the depression...
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blueman wrote:

Does the T&P relief pipe drain to that area? Can you put a bucket under that drain pipe to see if it's coming from there? It's quite common to have pressure spikes intermittently cause the T&P valve to vent if you don't have an expansion tank in the system to absorb the expansion of the water as it is heated.
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I haven't ever noticed any dripping or puddling around or under the T&P...
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Blueman:
I doubt it's the T&P relief valve because you would have noticed water under the downspout of the T&P relief valve, not under the water heater.
If it's directly under the water heater, I would suspect it's simply condensation forming on the inside of your water heater and dripping off.
If you have a gas fired water heater, then your tank is the shape of a very tall donut. Inside the hole of that donut is a piece of steel about 4 feet long and 3 inches wide that's been twisted to form a helix. It's job is to cause the rising flue gas to be directed against the inside of the tank to maximize heat transfer from the flue gas to the water tank. If your tank hasn't fired up in a while, that helical piece of steel cools down. Then, when your tank fires up, there is plenty of water vapour in that flue gas to condense and drip off that piece of steel.
The rust stains I suspect are from the outer sheet metal jacket of the tank rusting on the inside. Here I think DadiOH hit the nail on the head. Your cold water supply pipe comes down onto the water heater from above. I suspect condensation on that cold water pipe during the hot humid days of summer drips down onto the top of the tank and finds it's way between the water tank and the outer sheet metal jacket of the tank.
I wouldn't worry about any of your observations. Your water tank is 11 years old, but residential hot water tanks will last between 10 and 20 years, with 15 being a pretty good average, so it's not due for replacement quite yet.
Hot water tanks don't fail catastrophically so that there is a flood of water in your basement. Generally, they start to leak so that you see a faily big puddle under the water tank, but you don't have a "flood".
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nestork

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These docs appear to dispute the claims made in your last 2 paragraphs.
http://arm-i.com/chla/documents/CH%26LA_Insurance_Services_Risk_Alert_Water_Heaters.pdf
http://www.slideshare.net/LizKroft/water-heater-infographic
They may be very conservative in their estimates of longevity, but the possibility that a WH can fail catastrophically does exist.
You know the Myth busters just had to blow one up...
http://sdinspections.com/tag/water-heater-safety
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DerbyDad03;3161535 Wrote: >

> (http://www.slideshare.net/LizKroft/water-heater-infographic )

Yes, but the young lady that wrote that article is a moron.
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nestork


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On Fri, 6 Dec 2013 22:50:33 +0100, nestork

within a month or so the spots got a bit bigger. Out went the heater - in went a new one, and no more water spots. It was 18 years old and I wasn't taking any chances.
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On Friday, December 6, 2013 4:50:33 PM UTC-5, nestork wrote:

ter. If it's directly under the water heater, I would suspect it's simply c ondensation forming on the inside of your water heater and dripping off.
The only problem with that theory is that there should be condensation under a lot of WH's. I've never seen water under any of mine until they were failing. And where would condensation come from anyway? The tank is hot, even in summer. It might be rain water making it's way down the flue somehow, but that seems doubtful too. The WH is 11 years old, was this there in years one and two?
If you have a gas fired water heater, then your tank is the shape of a very tall donut. Inside the hole of that donut is a piece of steel about 4 feet long and 3 inches wide that's been twisted to form a helix. It's job is to cause the rising flue gas to be directed against the inside of the tank to maximize heat transfer from the flue gas to the water tank. If your tank h asn't fired up in a while, that helical piece of steel cools down. Then, wh en your tank fires up, there is plenty of water vapour in that flue gas to condense and drip off that piece of steel. The rust stains I suspect are fr om the outer sheet metal jacket of the tank rusting on the inside. Here I t hink DadiOH hit the nail on the head. Your cold water supply pipe comes dow n onto the water heater from above. I suspect condensation on that cold wat er pipe during the hot humid days of summer drips down onto the top of the tank and finds it's way between the water tank and the outer sheet metal ja cket of the tank. I wouldn't worry about any of your observations. Your wat er tank is 11 years old, but residential hot water tanks will last between 10 and 20 years, with 15 being a pretty good average, so it's not due for r eplacement quite yet. Hot water tanks don't fail catastrophically so that t here is a flood of water in your basement.
Not usually, but I'll bet it;s not hard to find cases where failure has caused a lot of damage. If the basement is finished, it could leak for long enough to screw the floor. Even in my basement, when mine starting leaking, it did so in the middle of the night. I woke up in the middle of the night and noticed a faint unusual buzzing. Turns out it was the water flowing in the pipes. It was just a very tiny stream, but it was enough that it flowed toward the center of the basement and wetted some stuff I had stored. If you have one of the pans under it, with a place to channel the water if it leaks, that's a plus.
The question here is with an 11 year old WH, how lucky do you feel? That age is in the range of where gas WH begin to fail.
Generally, they start to leak so that you see a faily big puddle under the water tank, but you don't have a "flood". -- nestork
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I only found the moisture because my water sensor alarm went off... and I had only just installed the sensor the month before... even when it went off there was hardly more than an ounce total of water if that...
So perhaps it was always there every summer intermittently but I just had never checked there... I can't say...
I agree that otherwise it would be suspicious to just find it now... but perhaps it was always there but I had just never noticed...
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trace.
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Thanks for the detailed analysis. You explain perfectly the symptoms I experienced.
It also btw would explain why the inside of the floor in the combustion seemed rusty too.
Could some of this also just be "condensate" from gas combustion? I know that my high efficiency gas furnaces all have condensate drains and while perhaps in a conventionally vented gas water heater most of the condensate goes up the flu, perhaps some of it condenses before going up the flu.
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combustion will dry out the stack and get a draft going in VERY short order with a properly functioning stack. It's NOT condensation - bet your life on it.
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On Saturday, December 7, 2013 5:57:12 PM UTC-5, blueman wrote:

It's typical for there to be rust inside the combustion area without the tank leaking.

I doubt it.

The combustion gases are hot. The tank, assuming it's been operating, is also hot. So those gases should not be able to condense in the tank or the vent pipe near the tank. They could condense much further along and if there were a long enough pipe, flue, whatever path where it could condense, then it could run back. But even then, before it got to the bottom of the WH, it would hit hot vent pipe, the burner itself, etc and re-vaporize. I've heard drops and hissing when starting up a WH that has been out of service and had a tank of cold water. Even then, the hissing indicates that it was being vaporized and I never saw any on the floor.
My odds are on the 11 year old tank having a leak.
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I replace my tank early. This avoids failure in zero weather, house guests coming or me leaving on a trip. all of these have occured. the most memorab le failure occured with water spraying out the top of the tank at the flue. luckily i heard water running, it made a mess of stuff for my business
new water heaters are realtively cheap disposable appliances.
take a 500 buck new tank thats 10 years old.
its cost is 50 bucks a year or about a buck a week, around the cost of a ca ndy bar a week....
personally I prefer a larger capacity higher BTU tank.
my current tank is 75 gallon 75,000 BTU. I never run out of hot water
the dripping tank probably is in failure, often leaks start small when the glass lining fails. time to shop for a new heater..
if it were condensation why is it only a issue now after 10 years?
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