Calling All Pedants
 

Have a faucet drip about 50 drips/minute in unused bathtub (faucet 2 years old and used maybe 24 times). I won't attempt plumbing repairs.

Thoughts on plumbing service call for just this issue please (not who to call).

I know you specifically asked for just advice on who to call, but I want to tell you I had this exact same issue, although on 16 year old tub faucet.
I have very little handiness, and no plumbing expertise, but after watching a couple of YouTube videos, I ordered the washer kit, and honestly, in less than 30 minutes , and about $6 spent at Amazon,I had it fixed.

Just curious, what brand and model is the faucet? Is it a Delta?

Mike Scott Plumbing

I would buy a new faucet in case yours cannot be fixed. You can always return it. The Delta faucets that the builder installs are less than $100.

It is a Delta.

While it may seem odd, you should check your expansion tank at the hot water heater. Ours lost all air pressure and the result was one fixture that constantly leaked. The excess pressure had to go somewhere and that fixture was the place.

A few quick taps can either rule this out or save you time fixing the wrong problem.

I would also suggest buying a pressure gauge from Amazon for 10 dollars. You screw it onto an outside hose bibb and immediately measure your house water pressure.

Your later post indicates it is a Delta faucet, ours (also Delta) have a lifetime warranty. A call to Delta will get you a free repair kit. I have not used ours yet as I have found moving the handle slightly off the full off position stops the drips. The repair looks straight forward, except you need to turn off all the water to the house.
As for the previous comment regarding the expansion tank, these do fail, about 5 to 7 years if (big IF) they were properly precharged to around 60-70 PSI. It is my understanding if this was not done the initial charge of 40 PSI will cause early failure.

this is the YouTube video I watched (a few times) before attempting to repair.

https://www.youtube.com/watch?v=PrzEz4_SJL8

I contacted Delta for the replacement kit, which may or may not have been free(since I was not the original owner), but was definitely going to involve some back and forth, so I just found the kit on Amazon.
https://www.amazon.com/dp/B001DU1ZGY...roduct_details

My faucet was identical to the faucet in the video. Don't know if yours is or not, but my understanding is that the guts haven't changed much, if at all, and that's why so many builders use Delta.
Out of the kit I got, the two single "O" rings were not used, just the springs, caps, and the double "o" (figure 8) ring.

Turning off water is just a matter of turning the valve in the garage and running water out of the kitchen sink and shower until it stops.

Honestly, this was nothing difficult. I took photos with my phone as I disassembled the parts just to be sure I had everything properly positioned when I put it back. I did the whole job while my wife ran an errand to the grocery store. Was done before she got back.

BTW, the chrome parts I dumped into a bucket of 50-50 water and white vinegar while I was playing with the seals, and they came out of it with all that water pitting soap scum removed.

OP, I may have misread your post. Is this a bathtub faucet or a sink faucet? If it is a bathtub faucet, you may have a mixing valve issue. I commend Laker14 for fixing this as a DIY. But, personally, I would not attempt it. First, when you turn off the water to your house, if something goes wrong, you may not be able to turn the water back on without a serious leak. And, second, if you need to replace the entire mixing valve cartridge, and you don't properly seat the o-rings, you can create a slow leak behind the wall which you won't see until you have a major problem. I would hire an experienced plumber.

I bet there’s No PRV and your water pressure is 65psi +

I had the same thing happen to me. You can get a new cartridge from the hardware store for about $70 or you can call Delta and they will send you a new one for free.

If it is a Delta faucet, they carry a lifetime guarantee. My bride has replaced several faucet parts with great results. I'd do it, but she has a higher level of patience.

Not sure why you need to turn off water to the whole home. There should be shut off valves for the faucet. Just turn both off, then do the repair.

While we're on the subject, the shut off valves used by The Villages are extremely cheap, and there have been numerous issues where one has failed and caused a huge issue. Many times, the first time you use them they don't actually shut off the entire way. I went through my new home and replaced all the shut off valves with higher quality ones. After a number of mishaps in my neighborhood, my neighbors followed suit.

Note that replacing a cartridge on a sink faucet and a shower mixing valve are 2 different things. You can turn off the water under the sink, replace the cartridge, and immediately see if you have a leak. But, for the shower mixing valve, you need to turn off the water for the entire house, replace the cartridge, and hope that you properly seated the o-rings inside the wall. If you didn't, water will leak inside the wall every time you turn on the shower. In my house in Virginia, I watched a master plumber damage 3 o-rings because of a defect in the cylinder inside the wall before he got one properly seated. I have installed several sink faucets, but I would not attempt to replace a shower mixing valve. Usually, when you need to turn off the water to the house, I will defer to a plumber.

There is no shut off valve for the bathtub faucet. You need to turn off the water for the entire house.