Delta shower valve mystery

BowWow

BowWow

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We have a Delta shower valve in the master bath that gradually loses hot water with age, but it's getting more frequent.

2012 or so, replaced because it was leaking.
2020 replaced because lack of hot water, problem instantly fixed.
2023 summer, replaced because of lack of hot water. Instantly fixed problem.
NOW....hot water not hot again........in 6 months or so.
In the meantime.......the guest bathroom shower is still on the same delta cartridge from 20 years ago.....scalding hot water.

I'm stumped.....
 
I was just going to suggest a similar thing. It might be something in the line that's clogging the valve, especially if there's a significant distance between the two valves (maybe separate lines from the water heater).
 
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Haven't looked at the inner workings of a shower valve in a long time, but they used to come with some contraption as an anti-scald device.

Wouldn't let you get full hot water out of it. I would just take it out to get whatever temperature the water heater was set at.
 
Are you on city water or on a well? If on a well do you have filtration system to catch black sand and such that gets sucked up through system? When you replace are you having whole valve body changed out or just the cartridge inside the valve body? Sounds like you getting to much cold mixing with the hot like a valve is sticking or an oring failure. If it's a constant issue which it sounds like it is I would replace the entire fixture valve body an all with a different model or make.
 
City water.

This shower is closest to the host water heater, so it's possible it has it's own line. No other how water issues is the rest of the house.

No filtration system.

I saved the old one from this summer, I will see if I can take it apart tomorrow.

I have been replacing the entire cartridge at almost $60 the last two times. I'm.guessimg some sediment is settling at this location for whatever reason.

When I replace the cartridge, scalding hot water, to to the point that I have to turn the hot water back a bit. The last two weeks or so, full hot water setting is warm to somewhat hot.
 
I would say your getting to much mixing with cold after awhile of use. Like o ring or something isn't letting the cold shutoff more as you turn toward the hot side. The more hot you get the less cold you get and vise versa but that's obvious. I think after having to change cartridge so many times already I would just replace entire fixture with new valve body and all. Something about that particular model doesn't seem to want to stay working. Most times when I new bath fixture is installed it shouldn't have to be messed with for many many years.
 
My son had the same issue with a new valve. I opened the valve and found the anti-scald valve sticking due to grit. I broke it loose, touched up the slider with 800 grit paper and put it back in service.
 
I break the anti scald stop off then set the water heater to 120 degrees.

I've noticed that Delta mix valves use a lot of plastic. The one on my kitchen faucet needs replacing again, just did it 6 months ago. Mushy plastic
 
1075tech said:
Haven't looked at the inner workings of a shower valve in a long time, but they used to come with some contraption as an anti-scald device.

Wouldn't let you get full hot water out of it. I would just take it out to get whatever temperature the water heater was set at.
Click to expand...

I was going to say same thing. Its a stop for the handle to hit up against. Its located under the handle best i can remember. It just slides on splined teeth and it may have moved.
 
Are the Master and Guest bathrooms on the same water heater?
 
The anti scale device my son’s shower valve has was a sliding cylinder that matches the output pressure by it sliding left or right to compensate for a hot/cold water pressure variation. It’s very simple. I was able to access it by turning the water off to the house, removing the handle, cover, then pulling the valve out, clean and reassemble.
 
My opinion here...not a plumber, but I've done a bit of plumbing work here and there over my life.

Any time you replace something when plumbing your waterworks, flush the piping BEFORE putting your final plumbing fixture in place.

ANY TIME.

ESPECIALLY in an older house.

You'd be amazed at what gets flushed out, sometimes.

As an example, I needed to replace our kitchen faucet and decided that was the time to rework the hot water piping under the house. (The slack-jawed, booger-eating moron who originally plumbed the house ran the hot water from the heater in the utility room right next to the kitchen all the way to the back of the house to the master bath, then the hall bath, then back to the front of the house to the kitchen sink, which is LITERALLY 6 feet from the heater.)

After a bit of cutting and sweating copper pipe under the house, I replaced the faucet in the kitchen and then flushed several gallons of water from the piping into a bucket under the sink before I reconnected.

Good thing, too, because the first thing that went through my mind when I looked in the bucket was "Where the $#&% did all this gravel come from?"

😆

Not only was there some fine grit and a bit of sand, there were actually small bits of gravel as large as about 1/8". I didn't measure it, but I'd say about a tablespoon or so. If I'd not flushed, but only would the aerator have clogged, but the sink sprayer would have gotten gunked up inside the faucet, where the valve shifts over when you use the spray hose.

I dumped and flushed a couple more times to be sure it was clear. Then afterwards, before anybody had a chance to use the showers, I did the same in the bathrooms just to be thorough.
 
I took the old cartridge apart.....spotless. This cartridge was used for about 3 years before the water began to get colder. Not a single iota of dirt, grit, etc. The metal cylinder with holes inside of of it was a little stiff to move but I broke it loose and it moves from side to side and spins now. I don't know if it was like this when I removed it, or it was from being in the garage for 6 months or so. I may have gotten carries away with the plumbers grease and it may have caused something to stop moving. It's really thick and tacky like a wax. I'm going to replace the cartridge again........ But I'm going to lubricate the metal cylinder with some type of silicone lube. We'll see.

IMG_20231226_113327973.jpg
 
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BigWaylon said:
There’s your problem. Why are you heating hot water? 😝🤓
Click to expand...
I was waiting on someone to come along and say it. I didn't want to be the guy. You'll hear it called water heater which is what it is. But you also hear it called a hot water heater alot. I've messed with customers when I was still in the construction game when they would call needing there hot water heater fixed. I'd tell them that hot water heaters haven't been made in decades but I would be happy to replace it with a new water heater.
 
Well the cartridge is replaced and just like that.... back to scalding hot water. I can't find anything wrong with the three-month-old cartridge either........The metal cylinder moved freely.

Delta uses a spring loaded plastic disc for the anti scald device. However.... it was still set on the maximum hot water setting. It's a pretty simple device that allows the knob to be turned only so far on the hot water side. If this happens again, I will remove it or grind off the tab that limits how far the knob can be turned, like mentioned above. We will see..... And the factory Delta cartridge is now $65.... ouch.
 
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