plumbing misadventurs
February 21, 2011 12:36 AM   Subscribe

I caught my hot water heater dripping almost as soon as it started... so why is the ceiling below dripping water now?

My hot water heater started leaking. I caught it almost immediately. In the time it took me to verify what was happening and figure out how to turn everything off, water collected in the drip pan underneath the heater (1-2 gallons? It was about half full). No problem, I think, the drip pan drains to outside. I turn the cold water supply and gas off, drain the water heater via the bathtubs, leave the water in the drip pan, and go to bed, with plans of visiting Home Depot in the morning.

20 minutes later I hear dripping. In my office, directly below the water heater closet, there is water streaming from a heat vent. There are wet spots on the ceiling. There is a ~3ft long, 1/2in groove in the ceiling drywall that is clearly collecting water. I set up buckets and poke holes in the drywall to drain the water where it is collecting. I head upstairs and mop up what's left in the drip pan. 20 minutes later, ceiling drips have stopped.

Any idea what might have happened? Did the drip pan/drain fail somehow? What should I make sure the plumber does when I call him in the morning?
posted by deadweightloss to Home & Garden (11 answers total)
I caught my hot water heater dripping almost as soon as it started...
Perhaps you didn't. Perhaps it leaked periodically, depending on temperature/pressure.
posted by Namlit at 12:41 AM on February 21, 2011

I caught my hot water heater dripping almost as soon as it started...
Perhaps you didn't. Perhaps it leaked periodically, depending on temperature/pressure.

Definitely a possibility, but there was no sign of a major leak prior to the one I noticed (i.e. the floor outside of the drip pan was not wet), and since the downstairs leak happened so soon after the leak I noticed, I suspect it's more likely that one directly caused the other.
posted by deadweightloss at 12:48 AM on February 21, 2011

Well, water (as my plumber says) has an uncanny ability to run sideways (along pipes and so on, without even actually dripping, I think he means). So perhaps some little quantity per time unit has been able to escape all night and collect in some place in that ceiling. Plumber will know. Otherwise change plumber too.
posted by Namlit at 12:56 AM on February 21, 2011

I am not a plumber. I'm probably wrong, but here's a bit of a brainstorm anyhow.

Could it be that closing the supply valve caused pressure to build up in the line and spring a leak?
posted by Sys Rq at 1:14 AM on February 21, 2011

the drip pan drains to outside

What does this mean, exactly?

Sys Rq: Could it be that closing the supply valve caused pressure to build up in the line and spring a leak?

posted by jon1270 at 3:42 AM on February 21, 2011

I am wondering what you mean when you say you drained the heater via the bathtubs? Did you drain into a bucket and then pour into the tubs? Did you use a hose? Are the tubs lower than the heater? Did you let in some air while draining? (the pressure relief valve?).
posted by InkaLomax at 3:52 AM on February 21, 2011

The drip pan, by code, can't just run outside. (It would allow cold air in, in the winter.) It likely runs down to the drain of a fixture below it. If it's not well sealed, it can leak. Use some towels, soak up the drip pan water.
posted by notsnot at 4:06 AM on February 21, 2011

The most obvious possibility is that the drip pan, well, drips. It either isn't actually connected to a drain, or the drain line has a leak in it.
posted by Forktine at 5:17 AM on February 21, 2011

Agree with forktine and namlit. Water heater leaks can be weird. I had one that just "misted" for about a week before anyone noticed.

A one time water leak like that is no big deal. Let it dry out for a couple weeks and patch the drywall.

(Hell, my whole house was wet once. There was a fire in the top floor, and the fire department hoses put a good soaking on the place. It rained in the basement for about a day, and it was pretty much back to its usual dry-as-desert self after a week. No mold, smell, what have you.)

A tiny, consistent drip over time is going to cause a lot more damage than a couple gallons in a one time spill.

But fix the drip pan.
posted by gjc at 5:59 AM on February 21, 2011

Note that the water heater is full of water. Shutting it off will isolate it from the pressurized system, but it is still full of water, and will happily continue leaking for awhile.

Check the other piping in the area above the leak, if you can. While I am thinking the same as others here - that it's the drip pan itself - now is a good a time as any to verify that it's not something else.

Just tell the plumber what you told us. Don't be surprised if you have to replace the water heater. Note that in some places (like California), water heater replacements are code issues, require a permit and post installation inspection by the city. Water heaters are expected to last about ten years, and a new one should have an anode rod. The anode rod has a higher current potential than the rest of the water heater, and will get eaten away before the water heater tank does. Most people don't replace the anode rod ever - until they buy a new water heater. Anode rods run from $20 to $60. I don't know how often they should be replaced, but you could check it once a year.

Also, don't connect copper directly to the steel fittings on the water heater. Use a dielectric coupling.
posted by Xoebe at 2:49 PM on February 21, 2011

In the end, the plumber was quite convinced the old drip pan was never properly installed; the rubber gasket connecting the pan to the drain is supposed to be installed on the inside of the pan, but was on the outside, so most of the water in the pan went into the floor/walls instead of the drain. Got a new pan and heater put in, properly this time. Still have drywall damage downstairs to deal with, but as frustrating as it is that the pan failed, this could have been so much worse, so I'll take it...

Thanks for all the answers.
posted by deadweightloss at 7:37 PM on February 21, 2011

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