When either upstairs shower is used, there is a tapping sound every few seconds (not in the shower itself, but you hear it in other rooms like it's behind a wall. Turn the shower off, you might hear it once or twice then no more. The water heater is in the basement. My first thought was a loose pipe, but there is no expansion tank on the water heater and it is a closed system, so now I'm thinking that's the likely culprit. Though I understand it may be a loose pipe or even a bad shower valve. The water pressure is pretty poor compared to my own home. I'm going to check the pressure with a gauge and add an expansion tank as it should have one anyway.

Have any of you folks ever experienced anything like this? What was the resolution? Thanks!

City water. Pipes are CPVC. I'm not there right now, but heading up next week.

That is exactly what it sounds like, though the slower tap. It never gets real quick. The water pressure at this home is nowhere near as strong as in the video either. I think the pressure has been adjusted down to mask the problem.

Have any of you installed this expansion relief valve instead of a tank? It says it functions in place of a tank and is triggered at 125PSI. I can’t wrap my brain around how it replaces a tank when the tank is accommodating expansion from whatever PSI it is set to incrementally.

https://www.sharkbite.com/us/en/brass-push-to-connect/valves/control-valves/thermal-expansion-relief-valve

Yeah, it has to be hooked up to drain. I don't get how they market it as an expansion tank replacement when it doesn't do anything until pressure hits 125, but the expansion tank is taking that excess pressure above whatever the bladder is inflated to which is typically whatever the water pressure is.

The expansion tank was ~$40. The relief valve is ~$50 at HD. All the lead free brass bits I need to install the expansion tank are at ~$50 and counting though. They aren't cheap. That's why I was considering it.

Long video but pretty thorough demonstration. I guess the idea is that the pressure rises pretty damn quickly to 125 PSI and that's why it is a viable option vs an expansion tank. I'm just going to install an expansion tank barring any major obstacles.

The ticks start very soon after an upstairs shower is started. They continue through the shower period and taper off pretty quickly after the shower ends. Nobody really uses the basement shower. I’ll experiment with it more when I get there if the expansion tank doesn’t fix it.

That sounds like a video I watched. The valve had an anti-scalding mechanism. It would rapidly cycle the water flow causing a hammering effect. I believe they removed a washer from the mechanism and that resolved the issue for them.

For my situation, it's a closed system, so the extra pressure has nowhere to go, which is bad for the water heater and everything else affected. I need to install an expansion tank even if it doesn't resolve the tapping. I'm hoping it does though.

Everyone, thanks for all the suggestions!

The home was purchased like this and it has been making the noise from the get go. My kid has been in it not quite a year. The water heater is newer. No idea why they didn't install an expansion tank, other than it was previously used as a rental and my impression is the owner tended to do things on the cheap.

There is a PRV on the wall behind the water heater, so I know it is a closed system. I've got a gauge to check the water pressure. I know PRVs can go bad too. Hopefully that won't be an issue.

I may be using the wrong abreviation, but I'm referring to the valve that reduces the pressure coming in from the city water supply. I am under the impression that those only flow one way, into the home plumbing, and not back, resulting in a closed system.

Kinda looks like this...

prv (resized).PNG

It’s the drainage pipes. They are PVC. Pressure gauge has yet to pop above ~79. I did the bucket trick and sure enough, no noise. The Pressure Reducing Valve does look like the pic I shared and looking it up online, it has a bypass for thermal expansion. So as you said, no need for the expansion tank.

Thanks for all the suggestions guys!

And now maybe some progress. My daughter showers in the master bath , lot’s of tapping. My wife then showers in the shower I was testing in. I had to replace the shower head in between as I broke the holder for the wand. Replaced cheapie plastic shower wand and removed a screen. New shower head is a Speakman. No tapping at all and my wife takes long showers. Been a long day of driving so gonna look at it fresh again tomorrow.

Back from that trip. The tapping was not drainage. I guess the time it took to fill the bucket half-way wasn't enough to start the tapping. The tapping is definitely supply side and is correlated to the flow rate, but only with the showers. The more the flow, the stronger the tapping. Installing Speakman 2 to 2.5 GPM shower heads greatly reduced the tapping. Sometimes there would be none. Sometimes a little, but it was greatly diminished.

I think there may be a flow issue. Water coming in at the basement measures ~80 PSI with all faucets off. I know you lose some PSI as you go up the floors, but it still should be adequate dropping off from 80. It is nowhere near as strong as at my house when using the same high flow shower head. I watched the pressure gauge at the basement while running the low flow shower head and even with the low flow running, it dropped significantly at the gauge. Something like ~40 PSI.

The big issue was the tapping and they aren't complaining about the flow rate, but I just believe it isn't as good as it should be.

Hot and cold. It's not high pressure though. That was my assumption based on the belief it was a closed system and the home inspection report recommended an expansion tank. I put a pressure gauge on the basement spigot and it never exceeded 80 PSI. So it is apparently not a closed system. The tapping was worse with the shower head that had all flow restrictors removed and the pressure gauge dropped significantly when it was being used, not 5 or 6 PSI, but more like 30 or 40. The shower head couldn't even form a complete stream. It was like 90% there, but there was some trickling like it wasn't getting enough water. I'm going to look at the pressure reducing valve next visit. Other than me adjusting the PSI a bit in testing, I don't think it's ever been touched. I've read they need to be inspected and cleaned every now and then. The home is roughly 20 years old.