I have a leak coming from the "cold" line right at the valve joint. There is signifigant calcuim build up on the pipe from the valve to the connection of the water heater, (maybe 8 inch of pipe) Not sure if plumbers tape will do the trick. Would it be best to call a plumber to come and replace the pipe/fitting.valve shutoff or is there a repair I should attempt

Without seeing how the plumbing to your heater is piped, its hard to say.I would venture to say that the heater is ok, unless its very old, and you just have to repair the leaking pipe. If its plumbed in Copper, and you are not familiar with sweating a joint, then you may need a plumber, however if its Galvanized (iron), CPVC or Poly you could do it yourself. If you could e-mail me a picture or two, I could tell you exactly what to do. If its leaking bad, you need to shut the power off and turn the water off to the heater, should be a valve located in the cold water line near the heater, which will turn water off to heater but leave it on in the rest of the house.
Bud

If I understand correctly you have residential electric water heater, and your shut off valve located above water heater on cold-water line is leaking?

1) Hot water would come out of this valve if it's leaking because water inside tank is hot and under pressure ... also remember, hot water rises so tank is probably heating the water inside the cold line during hours when no hot water is being used.

2) You probably need to replace the valve. But if water is leaking because a pipe is rusted, the valve may be ok, and just the pipe needs to be replaced.
Take a photo of your problem to hardware store or home center.
I used to work in those stores and could help folks get the right parts.

3) Here are some steps for replacing the valve.
Shut off main water source into house. This is usually located underground in same box where meter-reader looks at meter.
Your water heater shut off valve is called a gate valve, and it will be 3/4"
All water heater pipes are 3/4"
You will need two 10-12" pipe wrenches, maybe a new gate valve, maybe a new flex connector, probably short 3/4 pipe pieces, teflon tape for each threaded pipe.
Hardware store or home center can get you the right materials, just take a photo over to hardware store

4) When you get started, turn off water heater circuit breaker for a couple hours so water will cool down. You don't want to get scalded with hot water.
Do NOT drain the tank.
Simply open a bathtub faucet on hot side to release pressure.
When finished, turn on the water, and make sure water is flowing out of tub spout in full stream before turning circuit breaker ON

Add a comment for more free help.
Also take advantage of fixya phone service.
For a price, expert speaks with you over phone while you work on water heater or any do-it-yourself project.
Fixya is always less expensive than a service call.

First shut off power then remove acess cover and carefully move insulation out of the way so you can see around elements.Check to see if leak is coming from around element.If it is determine what type of element you have. Either screw in or bolted in. Both have thick rubber gaskets that can be replaced by draing water heater and removing element then install new gasket and reinstall element.
To drain heater shut off valve on incoming cold water supply line ,make sure electric power is off. Connect drain hose to drain valve and put other end to floor drain or sump basin.You can open faucet on hot side near by to prevent vacumn and drain. If you have screw in type disconnect wires,marking them for reattachment,then use large open end wrench or pipe wrench on hex section of element and turn to left to remove. If you have bolt in element spray bolts with wd-40 or similar and carefully loosen bolts then disconnect wires and remove element.install new gasket and reverse to reinstall. I would recommend that you replace elements at this time if you are sure this was the source of the leak.
If you don't think it's leaking around elements then check fitting on both water lines to water heater to be sure they are not leaking and seeping down thru insulation and leaking out of the bottom of heater. Next check around drain valve for leak and if it's leaking you can try tightening it a little or replace it with 3/4 x2 brass nipple and 3/4 inch female iron pipe boiler drain. Use teflon tape or pipe joint compound on all threaded connections.
After you have eliminated all other sources for leak then it is probably the tank itself. If it is less then six years old the tank should still be covered under warrenty. Most warrenties will give you a new heater but installation will not be covered unless you have extended service coverage.
I hope this helps you some. Thank you

If you have a leaking water heater there is a serious problem.
http://waterheatertimer.org/Water-heater-leaking.html
Page shows how to limp along on a leaking water heater if your water heater needs replacement.

One of three things is causing the water:
1) Loose water connection on top of tank that is dripping down inside tank >> check pipes on top of tank.

2) The vent is clogged or not working correctly causing condensation inside flue pipe.
Condensation water is dripping back down inside tank.
Problem means possible CO poisoning if gas is not venting.
Look at vent pipe to see if joints are corroded.
Use long fireplace match > light match and put into draft hood at top of tank and see if smoke goes up.
Put hand at draft hood opening when water heater turns on to see if vent gas enters home.
Do same test when furnace turns on to see if furnace vent is pushing back into water heater.
Does water heater vent inside same pipe as furnace? You may need to set up separate vent for water heater if furnace gasses are pushing back into home.
Check furnace vent for obstructions.
Look at vent stack top of home to see if hood is in place.
Check if bird nest is built inside warm vent pipe.
Improper flue is top priority for getting fixed so vent gasses properly escape home.
You may have to call a plumber.
Professional plumbing forum:
http://www.thetankatwaterheaterrescue.com/forums/forum3/

3) Your water heater is rusted out.
A rusted tank has to be replaced.
It cannot be repaired.
However, before replacing tank, you do not want a tank failure where tank ruptures and water runs inside home until water is shut off.
This will cause major damage.
Protect yourself first.
Turn off water valve above tank.
Move gas knob to 'pilot' so burner is not heating water.
Open tub spout on hot side to relieve pressure on tank so it will not rupture.

Now you're protected.
Link above shows how to limp along on failed tank until you can replace heater.

You need a new gas water heater from Lowes or Home Depot
Look at label on side of you tank for gallons and btu's of your water heater.
Measure height to flue pipe so you get same height water heater, so pipes don't have to be changed.
You need a pipe wrench and teflon tape which will be wrapped on each pipe thread when pipes are reassembled.

Step1) Drain water heater using valve at bottom of tank.
http://waterheatertimer.org/Water-heater-will-not-drain.html

2) Turn off gas valve going into heater.
When gas valve is perpendicular to gas line, then gas is off.
Dissemble gas line to water heater.

3) Disconnect flue pipe and support flue pipe with wire so it doesn't not fall down. Flue pipe joints should be held together at each joint with 3 screws.

4) Turn off water. Shut off valve is on COLD side.
Disconnect water pipes.

5) Move old water heater out of way.

6) Set new water heater in place. Put water heater in drip pan.

7) Connect water pipes >> cold goes to side marked cold.
Hot to hot.
Buy new flexible water connector pipes at home center for easy installation of water pipes.

8) Connect gas line exactly as it was connected before.
Home center sells flexible gas line connector for easy installation of gas line.
To test for gas leak after installation, mix liquid soap with water and put around gas line joints to see if there are bubbles.
Natural gas has less pressure than water lines, so gas pipes are easy to seal with ordinary wrench.

9) install TP pipe that runs to floor. Use old one off old heater.

10) Fill tank completely with water until water is coming out of tub spout.

11) Turn on gas, and light pilot as shown in manual.
New gas heater sometimes have small water leak when first fired up, so ignore a bit of water.

12) Save water heater manual like it is gold, and read everything in manual.

First thing to do is wrap rag or towel around spraying joint to localize water.
Next, turn off power to water heater.
If gas, rotate knob to pilot so pilot light stays lit but burner does not come on
If electric, turn off circuit breaker.
Close cold-water shut off valve above tank.
Open tub valve to release pressure on water heater.

Wait for water to cool before working on water heater to avoid high pressure scalding water.
When finished, make sure tank is full of water and water comes out of tub valve before turning on power.

Water heater should not have plastic couplings.
I can't see your problem exactly, but water heaters have 3/4" nipples coming out of top.
Easiest solution is use flexible connectors from Lowes or Home depot.



Flexible connectors are 24" or 30" long and have 3/4" nut on each end, so disassemble existing pipes using pipe wrench.
Lowes and Home depot can help you select appropriate pipe >> take several phone-photos of your pipes to home center so they can see your problem precisely.
Attach 3/4" male adapter on end of pipe.
Attach flexible connectors between pipe and water heater nipple.
Cold water line has shut off ... make sure this attached to nipple marked cold.
Make sure hot pipe is attached to nipple marked hot.
Use teflon tape on threads.

Add a comment if you need more help.

You have clog in the water line.
Since all hot water pipes are involved, clog is probably near water heater.

Buy pressure gauge at hardware store that threads onto hose connection.
Brady BTG 100 at Amazon
Picture of gauge

Check outdoor pressure for baseline pressure in your home.
Turn off electricity to hot water heater for an hour or two so there is not scalding water.
Open drain valve on water heater to see if water heater is clogged with sediment.
http://waterheatertimer.org/Water-heater-will-not-drain.html

Put pressure gauge on drain valve and compare with outside pressure.
Open hot water spigot on bathtub and see if tank pressure drops ... if tank pressure drops significantly with bathtub spigot on, then clog is on incoming cold water before tank, and could be on outgoing hot water pipes too.
If tank pressure stays about the same, then clog is on outgoing hot water pipes.

Clog can be sediment caught in cold water shut off valve located above tank. Open and close valve and test pressure again. Take apart incoming cold water pipes above tank and check for sediment. Replace valve. Look at condition of cold water nipple on top of tank.

Sediment caught at hot water elbow near tank.
Sediment can fill up old pipes. Take apart hot water pipes above water heater and see condition.
Look at condition of hot water nipple on top of tank.
You may have to take apart pipes up to first or second elbow.

Pipes can decay at joint where copper pipe connects to galvanized pipe. Check for copper to galvanized connections on cold or hot pipes and replace section of galvanized pipe. Copper pipe will probably be good, the galvanized pipe will deteriorate. Replace copper-to-galvanized joint with 3/4" non-conducting union from hardware store

It sounds like two problems.
Problem 1) Clog inside faucet or clog inside pipes at faucet
Remove supply tubes leading to faucet and see if problem is inside pipes or inside faucet.
My bet is clog inside faucet.

If you have galvanized pipe that meets copper pipe, this can be trouble spot.
Article on clogged water pipes at Inspectapedia:
http://www.inspectapedia.com/water/Water_Pipe_Clog_Repair_Guide.htm

Article on clogged pipes:
http://www.waterheaterrescue.com/pages/WHRpages/English/Troubleshooting/Tanklets/backflushing.html

Problem 2) Water heater leak ... you say tank valve is leaking? Is that cold-water shut-off valve? Or tank drain valve? Or TP valve?

If cold water shut-off is leaking, then replace shut off.

If tank drain valve is leaking, then check if plastic valve is cracked. If drain valve is cracked, then replace with a brass valve from Home Depot. If plastic valve breaks off, then use hammer and screwdriver to gently chip out the broken plastic valve. New valve threads need teflon tape to seal pipe. If valve is just dripping, then put garden-hose cap over end of valve and screw down tight.

If TP valve is leaking, then replace with same temperature and pressure rating. New TP valve threads need teflon tape to seal pipe.

Problem 3) If pressure is low all over house:
Buy pressure gauge at hardware store that screws onto hose connection.

Test pressure on outdoor spigot.
Open faucet and check if pressure drops. This says if problem is inside pipes that enter house.

Test pressure on water heater drain valve.
This says if pressure problem is before -or- after water heater.

If problem is before the water heater, then shut-off valve located on cold water line is suspect.
If problem is after water heater, it could be in hot water outflow pipe on top of water heater, or a nearby elbow.
Remove hot water line leading from water heater and check pressure. This says if problem is where hot water leaves tank.
Read articles above about clogs inside water lines.

From description it Sounds like your bottom hook-up for water line coming in.(cold inlet) Depending on what type of connection you have on water line, it may just need tightening, if not it may require a new fitting installed, or the actual 1/2" NPT nipple going in to tanks is faulty. They use plastic, or galvanized pipe nipples usually, but in some cases you may find a check valve there. Either way, you'll have to determine exactly where it's leaking first. Depending on age of tank, it may even be the piece of aluminum welded to tank where 1/2" pipe nipple is installed. I've has 2 this year that rotted right through that and caused a leak, and had to replace the tanks. Let's hope yours just needs tightening, or a fitting replaced. Make sure you use good pipe dope when changing that nipple if necessary. Many use Teflon tape as well on threads, but I've had better luck with pipe dope.

Hello,
You can buy a replacement relief valve at any hardware or home improvement store. It's real name is a T&P valve or temperature and pressure relief valve. It always has a 3/4" inlet and outlet. It is a very easy procedure to replace. You will need a bucket, teflon pipe thread tape, and a 3/4" x 6" black iron or galvanized pipe nipple. To start the valve replacement, turn off the shuttoff valve on the cold water line. Then open the handle on the relief valve and drain water into the bucket, that is, unless you have a pvc pipe coming off of it into a drain floor, then just drain it without the bucket. Be careful, the water is hot! When the water level gets below the relief valve, it will stop draining. Then remove the pvc pipe, if applicable, and thread in the 6" pipe nipple to use as a leverage tool to remove the valve from the water tank. Turn it counter clockwise to remove. Then put teflon tape on the new valve, going from left to right with the valve threads facing downward. Wrap about 3-4 layers all around the threads. Then twist the new valve into the water tank clockwise and using the pipe nipple tighten by hand until very snug and outlet is facing downward, as before. Remove the pipe nipple and install pvc pipe, if applicable. Leave valve handle open and turn on the cold water until the valve starts spitting, then close the relief valve and let it fill up the tank. If you did it correctly, you are now finished! Good luck!
Douglas

if the line feels cold its the fill line if warm its the hot line either line try to tighten the connection if no good or leak is from solder or connection if u have valves to and out shut them off or turn off main open a faucet relieve pressure at heater either solder the line to repair or if connection Teflon tape joint and retighten connection good luck and thanks for using fixya