Your task, should you choose to accept it, is to help me solve THE HOT WATER MYSTERY!
I moved into my house 1 year ago and since day 1, I noticed the bathtub in the guest bathroom had an issue with the hot water. The water would turn hot and stay hot for 5 seconds and then go cold. I called a plumber out, the plumber changed the cartridge in the valve and the problem was fixed. Hot water steady and consistent.
Cut to a week ago where I changed that same cartridge because I'd developed a slow drip. Guess what happened when I did that ... yep, the hot water started having the same issue as before.
I called the same plumber asking him to come fix it since he did it before. This time he could not. We tried 3 brand new cartridges and nothing worked.
Things to Note:
This is a MOEN T2473EP
The cartridge is 1222
The hot water heater is Tankless Electric AO Smith - 240V / 14 KW 2-CHAMBER TANKLESS ELECTRIC WATER HEATER https://www.aosmithatlowes.com/products/water-heaters/electric-tankless/r2vr-140e/
Hot water heater is only 2+ years old
Today, I had a new plumber come out at $250 an hour who determined the hot water heater is too small. Basically, the GMP in the bathtub is too much and the water heater can't keep up. However the same shower in that tub, can. Weird. if this were true, why was the issue fixed a year ago when I replaced the cartridge?
Lastly ... when I am running the bathtub that is the only faucet running. Nothing else is on including the dishwasher, washing machine or other faucets. Also, the cartridge is set to allow the max hot water.
Thoughts? The hot water is fine everywhere else and in the shower it is purely at the bathtub faucet.
PLEASE HELP ME SOLVE THIS MYSTERY. THANKS!