leakage from the top of my hot water heater

[weaver7]

I just noticed that my hot water heater is leaking steadily from the top of the unit. the water seems to be coming from the larger tube fitting in the direct center of the unit. Now I don't mean to sound ignorant, but I never knew that I was to release the pressure from the hot water heater at least once yearly, but I have only owned a home since 2003. I followed all directions with the user guide that explained how to drain the tank, by doing do I located where the leakage is coming from, is this going to mean that I have to purchase a completely new hot water heater or is this a quick fix and if so, how? HELP PLEASE!!

[LazyPup]

In your post you did not mention if this is an electric or gas water heater, however you did say the pipe is located in the center of the water heater top and you manually released the pressure. From that I am able to conclude that this is an electric water heater and the problem is a leaking T & P Valve (Temperature/Pressure Relief Valve). This is a very common problem and one that is quick, easy and rather cheap to fix.

The best method is to get the new valve before you begin the change out. This way you will have an absolute minimum disruption of your hot water service. (Typically about 10 to 15 minutes) Nearly all T&P valves used in residential service are the same, but just to be sure, directly under the manual lift release handle you will see a metal data plate tag attached to your valve. The tag will say that the valve is rated for 210degF and it will have a BTU rating. Note the BTU rating and make sure the new valve you get it rated for the same BTU rating or higher. (The 210degF temperature is standard to all T&P valves)

When you get the new T&P valve you should also get a roll of PTFE (Teflon) pipe thread tape. Teflon pipe thread tape is now made in different densities for different purposes. Both the mount and the discharge port of the T&P valve are 3/4" pipe threads and for sealing 1/2" or greater pipe threads or fitting you should use the "RED Triple Density" tape. (The tape will be in a red plastic dispenser and the tape itself will appear a light pink color.)

If your tank is mounted in a basement or utility room the discharge pipe from the T&P valve may only make a 90deg turn downward and end near the floor. If the tank is mounted on the ground floor, an upper floor or in an attic space the line should run outdoors.

If the discharge line is a copper pipe soldered in place you may need a mini-tubing cutter to remove the discharge line. If you have to cut the line to get it off you should also get a "5/8" compression union" so you will be able to easily reconnect the line.

If your discharge line is a PVC line you can cut it with a hacksaw or ordinary wood saw. You will then need a 3/4" PVC coupling and some PVC cleaner and glue to reconnect the line.

You will need a medium sized pipe wrench (14" to 18") to remove the discharge line and the old T&P valve and install the new valve and replace the line.

When you have your parts and tools assembled you can begin the change out:

1. Turn the water heater "Cold water" supply valve off.
2. Pull the electrical service disconnect or switch the electrical circuit breaker to the "OFF" position.
3. Drain the water heater. The water heater does not need to be drained all the way, but you must be sure it is drained enough that the standing water in the vertical lines above the heater will not spill out when you pull the valve.
4. Unscrew and remove the T&P discharge line.
5. Unscrew and remove the old T&P valve.
6. Wrap 3 full turns of the Red Teflon tape on the mount threads of the new valve making sure you keep a good tension on the tape as you wrap it.
7. Insert the probe of the new T&P valve into the mount and screw the new T&P valve in place.
8. Use the pipe wrench to tighten the new valve in place but be very careful on the last turn to insure you stop when the discharge port it lined up with the discharge line location. (Absolutely do not unscew a pipe thread even a fraction of a turn to line it up or you can be assured it will leak).
9. Make aure the water heater drain valve is closed.
10. Open a hot water faucett at the highest point in your hot water system (usually the bathroom lavatory hot water faucett) to bleed off the excess air as you refill the water heater.
11. Turn the water heater "Cold Water Supply" valve on and make sure it is fully open.
12. watch the hot water faucett where you are bleeding the air out. Expect a lot of air followed by water spitting and sputtering a bit, then a full flow of water. When you have a full flow of water turn it off.
13. You should then go to each hot water faucett in the house and bleed off any excess air in the line.
14. Reset the electrical disconnect or the circuit breaker.
15. Check the water heater to make sure the new valve is not leaking at the mount. If it is leaking you will need to turn the valve one more full turn to tighten it.
16. After you are sure the new valve mount is not leaking you can reconnect the discharge line. If you had to cut the line you can use either the compression union or the coupling to reconnect where you cut it.

[PeruvianHighlander]

Thank you for a very informative description. I have the exact same situation as weaver7, except my hot water tank is gas, not electric. Are there significant differences I should be aware of, when replacing the T&P valve? Thank you!

[LazyPup]

T&P valves are required to be in the upper 6" of a water heater vessel, however, Because the heat from the flue pipe could cause a false temp increase in the T&P valve body, T&P valves are installed on the side of a gas water heater.

Aside from the physical location of the T&P valves the method of installing remain the same.

In some rare circumstances when a Gas water heater is installed in a basement or crawlspace below grade where you cannot achieve a gravity flow drain for the T&P valve outlet, they opt to use a WATTS 210 GAS Shutoff valve and a Pressure relief valve.

A Watts 210 Gas shutoff Valve will look like a brass Tee connected to the upper side of the water heater and the gas feed line goes through the TEE then on to the Burner Gas Control. In this situation if the temperature of the water exceeds 210degF the Watts 210 valve shuts off the gas supply to the burner. A pressure relief valve is then installed at any convenient location above grade where a gravity flow drain line can be achieved.

[PeruvianHighlander]

quote:Originally posted by LazyPup

T&P valves are required to be in the upper 6" of a water heater vessel, however, Because the heat from the flue pipe could cause a false temp increase in the T&P valve body, T&P valves are installed on the side of a gas water heater.

Thank you, again, for this information. Last night I replaced the T&P valve and I could not have done it without your help! I do have a concern, however. I had to read the line a few times before understanding what you meant. The flue pipe is basically the exhaust pipe for the heater, which is in the middle od the top of the tank, correct? The problem is that my hot water heater uses gas, but has the T&P valve mounted on the top. There are two different locations on the top for mounting, but no other mounting points. The old one was horribly corroded and it took three hours to replace everything because of the corrosion and saudering and desaudering copper pipes. Is there anything I can/should do because of the location of the T&P valve, to prevent false temperature readings?

[LazyPup]

The manufacturers engineer their tanks very well. If your tank happens to have the T&P on the top of the tank you can rest assured they carefully considered the location so I would not be concerned.

You stated that your tank has two possible locations on the top of the tank. More than likely the second location you are loking at presently has what looks like a shiny plug with a six sided Hex Nut shaped head. If so, that is the Sacrificial Anode for your tank.

One of the major causes of failure in a water heater vessel is electrolosys corrosion. Electrolosis is an electro-chemical reaction that occurs when dissimilar metals are in a wet location. Fundamentally the water acts like a battery electrolyte and a small current of energy is generated between the two metals. In the process some of the metal from the less noble metal is transferred one molecule at a time to the more noble metal in the same fashion as electroplating. Over a long period of time it will eat away at the less noble metal until a leak occurs. In order to prolong the life of the tank they purposely install a rod of less noble metal, which is called the "Sacrifial Anode". In reality it is just what the name would imply, a long rod of excess metal that we are willing to sacrifice to preserve the tank. Over a long period of time the zinc or aluminum rod is erroded away and deposited on the inner liner of the heater vessel. In order to prolong the life of the tank we then replace the sacrificial anode about once every 3 to 5 years, depending upon the tank manufacturers recommendations.