I promised an update and here it is. To recap, I was hearing this loud whistling sound from a bathroom in my house whenever I would turn on the water anywhere in the house. It seemed to be emanating from the bathtub/shower valve. To test it, I would turn on the water downstairs in the kitchen and the sound would start. After turning on the shower valve in the bathroom, the sound would stop change in pitch and volume. Naturally I assumed it was the shower valve. So I dismantled it, took out the pressure equalizer cartridge to get the part number, put it back together, and the sound went away - for about 8 hours. Then it return louder than ever.
The shower valve was purchased from Restoration Hardware or RH when I had the bathroom gutted and renovated. After shopping around on the internet for a few hours I could not definitively identify the right replacement cartridge by the part number stamped on the old cartridge. So, I called RH customer service. My second mistake. My first was buying anything from RH in the first place. Overpriced and not particularly good stuff. But the wife liked the designs. This is a subject for another thread.
I asked the customer service person for the right part number and she gave me a number that does not match the part number of the cartridge I removed or any part number I could find at any plumbing supply place in the country. I repeatedly asked if she had the OEM part number so I could go find the part somewhere on the internet at the best price. RH wanted $135.00. Of course, she had no idea what I was talking about and continued to give the the same RH part number which is only good at RH. So I wound up purchasing the cartridge from RH to make sure I had the right part. I just wanted the noise to stop. $135.00 for the cartridge. Then she surprised me with a $20 charge because it is a custom order. Then of course there is sales tax and shipping. $165 for a cartridge to rid my home of that brain exploding whistle when anyone uses the water. They told me it would arrive sometime in October. I am an idiot. But the worst was yet to come.
The sound began to occur for apparently no reason. No water was running and there it was again. It would go on and off. Very strange. I went back to the bathroom to listen again. I turned on the sink and it whistled. I turned on the shower and that whistled too. But something drew me to the toilet, and it was not the Mexican food I had the night before. I took the cover off the toilet tank and the sound was much more distinct. I jiggled the valve lever on the toilet float and viola! The sound stopped immediately. I pushed down just slightly on the lever and the sound started again. It was the freaking toilet tank float valve all along! If I had 20 year old hearing maybe it would have been more obvious too me sooner but my ear have been through many years of guitar playing through a 100 watt Marshall and, and my brother's and my sons drum playing. I can still hear a little. Anyway, $15 later with the new toilet float installed the sound has finally stopped completely. I run around the house turning on all the faucets just to enjoy the silence from the upstairs bathroom.
Then I thought, "great!" I can cancel my $165 cartridge order which had not shipped yet. Not so fast. RH claims the shower valve cartridge was a special order, or "custom". Those orders cannot be returned or cancelled. What BS. It is not shipped. Why the hell can't they cancel it? I never would have bought the damn thing from them had they given me the OEM part number in the first place.
The moral of the story is don't buy anything from Restoration Hardware - ever. You pay a lot for merchandise they buy from other manufacturers and resell to you at a ridiculous price. Then they do not stand behind their customers when something goes wrong. When I get the valve cartridge in the mail in October, I will bet it is the same part I can find at most plumbing supply stores, for a lot less money.
To those who offered help, thank you.
