About a week ago it suddenly dropped water pressure by half, what do you think is causing this problem? We have had the faucet since 2013 with no problems

When water pressure in more than one place is weak, it means that there is some problems in the water pipe/supply. The chance of having problem in faucet/tap is low. I think you need to get a plumber to check the problem. It may be due to water heater problem or cold water supply problem.

The hot side of the faucet is most likely plugged with something that came up thru the water system. The average thankless waterheater requires at least 1/2 to 3/4 gpm flow rate for the unit to sense flow and turn on. If there is not enough flow it will not fire and heat the water. Not sure about this particular unit but a few require at least one full gallon per minute flow. So chances are that if you fix the faucet, you fix the hot water issue at the same time

Feb 2013
1) Copy following links for Intellivent gas control service manual, low hot water pressure, and crossover:
http://waterheatertimer.org/How-to-troubleshoot-gas-water-heater.html#intellivent
http://waterheatertimer.org/Low-hot-water-pressure.html
http://waterheatertimer.org/Crossover.html

2) Unknown if tank has hot water > that is first thing to check.

3) Unknown if air intake screen located under burner is clogged with dust that cause combustion chamber to overheat, tripping FV lockout and breaker TRD glass vial.
Requires removal of combustion parts, replacement of TRD, blow out air intake screen, reset intellivent

4) Unknown if there is error code.

5) Rheem does not post service manuals.
However this unit can probably be repaired.

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

time to flush out the heater. do you have the instructions?
lime and scale build-up will cause this

takes a little time, and requires about 5 gallons of vinegar, and a small pump.

I don't know if this is your problem or not, But I had a new faucet and it did the same thing. I found little tiny pieces of polishing media stuck in side the faucet. Every time you turn on the water it comes out fast , then trickles, drove me nuts, I took it back and got another, no problem, hope this helps.

Have you removed aerator ,screen etc., from end of tap, to see how flow is with it off. If good, or same as other taps when taken off of them, then you've got debris in aerator, and screen.

Take the strainer off the spout and check to see if there is any dirt or rust buildup in the strainer. This happens when repairs have been done. It usually collects at the first place the water comes out of.

THERE TWO CAUSES THAT I KNOW OF: 1. YOUR FAUCETS ARE PRESSURE SEALING MEANING: THEY NEED A MINIMUM PRESSURE TO SEAL MOST LIKELY 25psi, YOUR SPRINKLER SYSTEM IS STARVING THE ENTIRE SYSTEM OF PRESSURE WHICH ALLOWS YOUR FAUCETS TO LOOSE THEIR SEAL. SOLUTION:REPLACE FAUCETS WITH SPRING SEAT SEALING FAUCETS. 2. YOU HAVE A WATER LEAK IN YOUR MAIN WATER LINE AND THE FAUCETS ARE LEAKING AIR BACK INTO THE MAIN LINE WHEN THE SPRINKLERS ARE OFF AND WATER INTO THE SINK WHEN THE SPRINKLERS ARE ON... THIS SCENARIO IS UNLIKELY AND YOU WOULD HAVE OTHER PROBLEMS SUCH AS AIR IN THE LINES AND THE FAUCETS WOULD LEAK WHEN YOU TURNED ON THE SHOWER AS WELL AS THE SPRINKLER SYSTEM.

start by making sure the valve that supplies hot water to the sink and dish washer is fully open. If there is low hot water pressure in any of the other kitchen/bathrooms, then trace the line to see where the pressure drops. If it is only in the kitchen, it should be an old valve, (causes restriction)Good Luck.

it sounds like you need to up the temp on your water heater so that you are mixing more cold with the hot .be careful hot water can cause burns if valve is 4 years old then it has a limit stop do not set above 120 *you will need allen key and thermometer to check temp