The faucet makes a constant noise when it is on, hot or cold.

Sounds as though you need new rubber washers. Remove both hot and cold handles, replace rubber washers, ( bring to HD or hardware store to match up size ) and problem should be solved. Over time washers wear out on all faucets. They are very inexpensive. Hope this helped and good luck.

Check and see if the cold water has been plumbed to the 'c' on the heater, the hot to the 'h', and the relief valve somewhere else, usually on the side. Maybe the plumber cheated somewhere to make installation easy.

10-30-12
Cost calculations for recirculation system vary widely.
These systems cost more, and they cause higher operation cost of water heater.

1) When pump is OFF, then hot water is no longer leaving the tank.
Most recirculation systems have choice of timer for setting specific times of operation, or thermostatic operation that activates pump when sensor detects temperature less than 90 degrees
BUT...

2) Condition of plumbing is suspect here because you are not receiving fully 90 degree hot water from the recirculation system.?.

Bad single-handle faucet cartridge, or bad recirculation check valve, are causes of crossover. Clean recirculation check valve with white vinegar. Replace worn faucet cartridge.
Test for crossover.
http://waterheatertimer.org/Crossover.html

3) There are other suspects, such as water leak.
Drips, broken pipe, bad TP valve.
Turn off all taps and put ear against pipe to listen for running water.
http://waterheatertimer.org/How-to-troubleshoot-electric-problems-with-water-heater.html#listen

4) High costs: Lifting single-handle faucet in middle will immediately cause cold water to enter tank. Even if no hot arrives at tap, because the cartridge is drawing both hot and cold in equal amounts when handle is lifted in middle.
Today it is more efficient to install dual-handle faucets so tank is not receiving constant dose of cold water when single-handle faucet is not used correctly or tediously.
http://waterheatertimer.org/9-ways-to-save-with-water-heater.html

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

Check the faucet washer.

Sounds like your water pressure may be to high for the faucet, an inline regulator might be all you need. You didn't mention if it thumped once or repeatedly, if its the latter, you may need to install an expansion tank. Next time you turn it on, try it to the left (hot), and to the right (cold) to see if it only makes the sound on the hot side, if so an expansion tank may needed. Good Luck

sounds like the diverter inside the valve body is cloged with debris.

only wat to remedy this is to remove the valve and clean out the diverter, or just replace the valve.

Thae stem you got that said hot/cold were designed to fit old style cross handle faucets. So both hot and cold turned the same way. If the cold side you are replacing turns the opposite direction then you will need to get a cold stem. Danco does make them. Ask the retailer where you purchased the H/C stem. I hope this helps..

Sounds like the valve is comming apart internally. This allows the water to get into places it shouldn't and the water pressure forces the valve closed even though the handle is in the open position. Take it apart and check for loose screws and broken pieces. Lowes or Home Depot should have parts. Don't forget to shut off the valve below the faucet (if the plumber installed one) if not one will have ot shut off incomeing water supply.

This needs a new cartridge and may only cost you a couple of bucks at your local plumbing store. If you do this yourself, just make sure you turn off the water to both the cold and the hot and you will probably just need a allen wrench, screw driver and maybe a cresent wrench.

Usually happens when the stops and not ballanced(hot and cold pressures going to the faucet). Try ajusting the stops; open more on the hot or close more on the cold.