Originally Posted by Pleesehelpme
Along the side of our hot water heater is a pipe that recently started dripping and seems to be getting worse as days go by. Can someone tell me what this pipe is for and what needs to be done to stop this drip?
As others mentioned, it sounds like the Temperature and Pressure Relief valve (T&P valve). Typically, the valve will start leaking water at 150 psi or 210 degrees when it's working correctly. Here's a link for further clarification and procedures for replacing it:
Did the city do some work on your incoming water line recently? If so, they could have installed a backflow preventer valve. That would prevent excess pressure from your plumbing system from being dissipated into the city's system. (Excess pressure is created when water is heated.) In that case, you would need a thermal expansion tank in your system to prevent over pressure conditions. You can call your city's water dept and ask if a backflow preventer is installed on your home's water line.
You can check the pressure in your home's plumbing by buying a water pressure gauge and connecting it to a hose bib. Here's a link to a Watts gauge that has a red max pressure hand. The red hand will remember the highest water pressure like at night when you're sleeping.
Ideally, your home's water pressure should be about 60 psi after you open a faucet to release pressure and then close it for the reading. If the pressure is higher, adjust your water pressure reducing valve (aka water pressure regulator) if you have one. --- Then, leaving the water pressure gauge on a hose bib, the red hand should not exceed about 100 psi.
The T&P valve should be manually operated at least once a year to insure that deposit build up will not hinder release of water. The water heater should be partially drained at least once a year to flush out sediment so that's a good time to manually open the valve to flush it out and then to allow air into the heater's tank for draining.
You could try manually operating your T&P valve to clear any sediment that may be trapped on the valve's seat. If you do this, turn off the cold water input valve to the heater and put a container under the bottom of the discharge pipe. Flip the lever on the T&P valve and BE CAREFUL since the water will be HOT! Residual pressure in the system will discharge water out from the T&P valve. You could then slowly open the cold water valve to allow more water to flow out from the T&P valve to flush it out. The water will still be HOT! --- Then turn off the cold water input valve, close the T&P valve and then re-open the cold water input valve to return to normal.