Well, me being a relatively new homeowner, discovered the past weekend that I have been neglecting to test the pressure relief valve on my hot water heater. Now that I have done so, I am getting a slow drip out of the drain pipe. I tried turning down the temperature on the tank last night (which I wanted to do for electric costs anyways) but it looked like I was still getting some dripping this morning. It isn't much, nothing a daily paper towel couldn't take care of, but it is annoying me.
Any ideas on how to get it to stop?
Oooh, that touched a nerve. Let me weigh in with the experience of 20 years aboard U.S. Navy nuclear submarines: Stop testing your relief valve.
It looks so tempting, sitting there with its little warning label and the handy lever. Its presence is required by the boiler safety code, and every self-respecting plumber would recommend that you check it at least annually. Maybe semi-annually would be safer. Well, I guess quarterly would be even better, but monthly might be best of all. Of course you'll get a better routine going if you check it every day. But wait, what if it stopped working in the last 24 hours? How long have you been (as far as you know) unprotected from a temperature or pressure excursion?
And why stop with the manual check of the pressure spring? Maybe there should be a way to test the temperature actuator, too, right?
You see where this logic leads.
Submariners spend a lot of time doing maintenance at its required intervals, and they're inspected (and held accountable) on their proficiency at doing so. Part of the life is checking that relief valves lift within specification. At least 50% of the time, the relief valve would lift just fine, but it would fail to completely re-seat. (Required leak rate: "zero.") Hours of hilarity would ensue (usually along with weird plant-testing conditions and lots of extra watchstanders waiting until they could stand down) as the mechanics attempted to clean, tweak, and re-seat the valve. You quickly learned to have a spare relief valve ready to install before you ever started testing the installed relief.
When I actually needed a relief valve to lift, it never failed us. In fact a few times it lifted too soon, or too enthusiastically.
My heretical suggestion is that you never touch your relief valve again, or at least don't give in to the temptation until you have a spare one ready to install. It's highly unlikely that your water heater will ever experience a huge pressure excursion that opens the spring-actuated relief. If anything fails, it'd be the thermostat on the heater element (also highly unlikely) trying to turn the water heater into a steam generator. In that event, the thermally-actuated portion of the relief would handle the problem just fine. I also suspect that at least one faucet in the house would start
relieving pressure before the water heater relief stepped in.
Heck, I even hesitate to drain water out of the bottom of our heater to get rid of the sediment. We have a whole-house water conditioner and we regularly check the anode rod, so we hardly ever find any sediment anyway.
Anode rods can be a whole 'nother exercise in frustration, but I recommend checking those every 2-3 years:http://familyhandyman.com/plumbing/water-heater/extend-the-life-of-your-water-heater-by-replacing-the-anode-rod/view-all
Start early in the morning (after everyone's enjoyed a hot shower) and make sure the hardware store is open late... just in case.
Note that the photo shows the guy pulling his rod straight up out of the water heater, because he clearly does not have eight-foot ceilings in his garage. It's worth the extra bucks to buy a segmented anode rod (bendable) so that you don't have a ceiling-clearance problem on the next check.
You'll also need a 1-1/16" socket (which typically requires a 3/8" drive), and probably a three-foot torque-assist pipe. It's also convenient to use Teflon tape when you install the new anode rod so that it's easier to loosen the next time.