Leaking drain faucet - A.O. Smith BTH-199 BTH-199 100 Gallon 199,000 BTU Cyclone Xi[REG] Commercial Gas Water Heater

Turn Off Power or gas to heater, shut off incoming water supply, open the hot water side of a nearby faucet, attach hose to bottom drain valve, open drain valve, drain tank. Opening faucet should stop it from becoming vapor locked.

I am assuming that you are referring to a calcium or rust build up in the water heater.
If you are having this issue you will need to turn off the water to the heater. You will need a garden hose, access to a outside water soucre, cold water is fine.
Shut off the gas or power to the hot water heater before starting.
Now you will need to place the garden house on the drain fitting on the water heater, placing the end of the hose outside and lower than the drain valve. Open the valve and drain the heater, you will need to open a hot water faucet to help drain the heater. I don't suggest opening the TPR ( Temp Pressures relief )valve due to the fact that they sometimes leak or don't reseal after opening them.
Hopefully the drain valve is not clogged, you should hear and see water exiting the garden hose.
If you are not getting any water from the drain valve you are going to have a challenging task.
If no water is coming out, my recommendation is to get the required tools to remove the hot water line from the top or side or the heater, also a few towels to soak up water A bucket is helpfull also.
remove the hot water line, then you will have to use a small hose to siphon the water from the tank. Once the tank is empty you can then remove the drain valve and replace it.
once you have replaced the drain valve you should ensure that it's closed and use a Gallon of CLR. Poor this into the water heater through the hot water outlet where you removed the pipe from. Now make sure the faucets are closed and replace the hot water line. You can now turn the water back on to the water heater.
After a few minutes open a hot water faucet to let out any air until water flows out, than close the faucet.
Let the water heater set for a few hours, then drain the tank!
when the tank drains, close the drain valve again and refill the water heater. Once again open a a hot water faucet and let the air out till the water heater fills. Again let sit for a hour.
At this point open a hot water faucet at the farthest point from the heater and let the water run for 5 min. , than close it and move to the next closest faucet and repeat until all faucets have been opened and run for 5 minutes.
If you still have a slow flow in a faucet, you may need to repeat the CLR step.
I also suggest that you remove all faucet screens and clean them.
If you still have a clog than you are going to have to remove or replace a piece of water line in the house. The blockage may be hard to find but if you have access to most of the pipe or it's visable you may be able to hear the blockage with the water on. Otherwise this will result in using some water line taps and a pressure guage to find the blockage.

Yes you have a leak on hot pipe or TP overflow tube.
Put ear against pipe to listen for sound of running water.
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html#listen
If TP valve goes into drain line, check if water is running down TP overflow tube.
Check each faucet for leaks.
If pipes are under slab, put ear against each faucet to determine which faucet is closest to broken pipe.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

You have gas water heater with working burner.
But not getting hot water at faucet?

1) Bad faucet cartridge. Test for crossover. Copy following link:
http://waterheatertimer.org/Crossover.html


2) Is there hot water inside the tank? Open drain valve and check for hot water.

3) Drips and leaks: Turn off all taps and put ear against pipe and listen for water leak.
Water leak can run all the hot out of tank.

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Clogged cold water nipple or clogged hot water nipple.
Is water hot at drain valve?
http://waterheatertimer.org/Low-hot-water-pressure.html

If you need further help, I’m available over the phone at https://www.6ya.com/expert/gene_9f0ef4df2f9897e7

Very simple - call a Plumber. He will fix your plumbing problem, and any foreseen potential problems related to your water leak. He may also suggest replacing your 6 year old water heater. Of course ..... for a professional cost.
However, depending on your time, skills, proper tools, patience and luck, it's easy enough to perform yourself:
1. Switch off the water heater Breakers (220v) in your service panel.
2. Turn off the water supply to the water heater.
3. Attach a water hose to the drain faucet. ( a good time to flush sediment -calcium deposits)
4. Open a hot water faucet to vent (above the level of the water heater drain - kitchen sink)
5. Remove the suspected leak components. (a union connection is a good place to start)
6. Install New pipes -3 wrap all male threaded ends with teflon Tap. Tighten securely - using 2 wrenches.
NOTE: Before refilling - you can turn on the water heater supply valve for a few minutes, to flush out any lingering calcium debris.
7. Shut off drain valve - remove hose. Shut off venting hot water faucet.
8. Turn on water supply valve to fill water heater.
9. Open a hot water faucet to relieve air pressure while filling - preferably the bath tub faucet, it doesn't have a screen that might clog.
10. When water flows without air - shut off tub faucet.
11. Look for leaks.
12. Switch the water heater Breakers on.
Note: 50 gallons should take an hour or more to heat up. Turn on a hot water valve momentarily within this heat up time to relieve thermal expansion. ( the PT valve on your water heater will perform this task if pressures/temperature exceed new water heater tolerances - it's just a precaution to introduce these fluctuating pressures on your fragile 6 year old unit)

These are just basic instructions - assuming you fill in the common sense and work safe steps.
Good Luck - The Skill will only come after trying.

You can try to crack it open and get a little piece of crud out of there, I'm sure that is all it is, Just get a tray or something to catch the water, It should stop it, If it gets worse, turn the water off to the heater, then open the valve and hope the bigger piece of crud comes out. It is about all you can do, other than drain the whole thing and take the valve apart and replace the rubber in it. Check it out, Hope this helps.

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.

That is the drain for the reverse osmosis system. You have what is referred to as an AIR GAP faucet. The waste water is pushed up there before it goes to drain just as the drain for a dishwasher does. If water is coming out of the faucet the drain is most likely plugged or the line is kinked causing water to back up and overflow. Check the drain line for kinks and clean out the drain where it attaches to the stand pipe.
RJ

drain valve must have already been leaking, that's why someone put the cap on. It's ok to cap the drain but never the pressure/temp relief. If the water is coming out of the drain (not around it) you could either replace the cap or the drain valve to stop the leak - otherwise it's time for a new water heater.