Water Heaters - Drain Plug is leaking

My hot water heater has a constant drip from the drain plug. What should I do?

If you're speaking about the spigot at the bottom for draining the tank, check the hardware store for a screw-on cap. If it's the t&p valve you can try actuating the valve manually to try to flush out debris that might be making it leak, or replace the valve. If it's t&p don't even THINK about capping that (Mythbusters did one of their best shows on the subject). If it's a simple threaded plug, you will need to turn off power, drain tank, and then remove the plug. Wrap threads with teflon tape and reinstall. Turn on water and open a hot tap to expell air. Only turn power back on when tank is full.

If it is coming from the T&P relief valve, the cause could also be from a lack of or defective thermal expansion tank.

First we need to understand exactly what fitting you are talking about so we can properly help you. If you are unsure, try to take a picture of the problem and upload it to a site like photobucket.com and then post the link to it here on this site.

Since you mentioned the expansion tank, Mark, let me ask a question: Is there any hard and fast rules about having one? Our current house has one and I installed a new one when the heater crapped a few years ago, but the house we owned and lived in in NC back in the 80's-90's didn't have one. Well water here, city water there. Just curious. :confused:

TG...I'll save PG some typing.....He posted this on another thread.

"All homes need thermal expansion tanks, or protection as the code states. If you have a well and no Pressure Reducing Valve after the water tank, you will not need a TET because the water tank will do the job. If you have city water and have no PRV or check valves between you water heater and the water main, you should not need one either. All other instances will most likely require a TET. In my city it is a requirement for all water heaters."

Just because one was not installed does not mean there should or should not be one.

The code states you must provide some kind of approved thermal expansion protection for hot water storage tanks. (not quoted, but will look up the exact code if wanted)

A well system has an expansion tank for the home water main which will serve as a thermal expansion tank also, provided there is no backflow or check valve between the water tank and the hot water heater.

City water usually has a water meter and more recently, some kind of check valve or backflow preventer stopping the water heater from expanding back into the city water mains, which is why an approved means of thermal expansion is needed. ie: thermal expansion tank, watts pressure relief ballcock, etc.
If your city water has no backflow device, you may not need an expansion tank.
You may have a backflow device on your water main and you water heater does not blow off. That is because the factors included are incoming water pressure, Size of water heating device, and btuh used to heat the water.

I live in a big city in NH and we are required to install a thermal expansion tank with all water heater installations along with mixing valves.

Thermal expansion tanks for boilers vs. water heaters are NOT the same and you need to state the purpose of the tank when purchasing.

Got it. Thanks for the education. :thumbup: