So, our hot water works fine on all the other faucets in the house, but they're all 2 handles. When we turn the shower faucet (single handle), it can be all the way to hot, but if it doesn't thump, the water is maybe lukewarm. As soon as we get a thump, it immediately gets hot with the handle in the same position. I had it running for 20 minutes all the way up this morning and my shower was not warm. Once it works though, you have to put it half way back to cold to keep from getting burned. Sometimes it does it right away, sometimes after a couple minutes, and rarely it just doesn't want to at all like this morning. We had someone come out and replace the cartridge last year and the water heater was replaced not long after that. Both seemed to help somewhat (not completely) for a few days or weeks, but that could have been luck. Any ideas?

It sounds like a "balancing spool" is sticking. Some are part of the cartridge and others are a separate piece in the faucet body, it depends on the make and model of faucet.

If the other hot water faucets give hot water then your water heater is fine. As hj said, the problem is with the water control valve in the shower. Modern shower controls have extra parts inside them designed to protect people from getting scalded. This makes the water control valve more complicated than just a simple valve used years ago that rarely failed. Those added parts sometimes go bad with wear and the passage of time.



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How difficult is it to replace that? When the cartridge was replaced, I seem to remember the plumber saying something about a valve and he'd have to put a hole in the wall on the backside to get to it or something?

Also, thanks for the quick responses, this place is awesome



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well, depending on how the plumber has to get access to remove and replace the valve it can be medium sized job involving making a hole in a wall to get to it. Then that wall would need the hole repaired, or an access cover installed for future access. The original valve was probably installed when the house was built so the walls weren't up yet, much easier then.

But before you have the entire shower control replaced I'd look into what hj said, the possibility of another part in there that can be replaced. That would be much simpler and less costly. That plumber that replaced the cartridge has seen the shower control so he should know if there is another part in there to try replacing, I'd check with him. When he replaced the cartridge back then if that didn't fix the problem or if the problem returned shortly afterwards perhaps you should have asked him to come back out, he probably would not have treated the 2nd visit like a separate billing event. If you'd rather have a different plumber come out this time just explain the history of what has been done, he should be able to take it from there.

If you can post a photo of the shower control we might be able to identify it and say if there is another part inside that could be causing the problem.



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I'll see if I can get a pic tonight. Thanks all!!

Unfortunately, the only pic that might help would be one of the part in the wall after the large round ring is removed.

So, there IS an access panel if a pic from behind the wall will help. I won't have a chance to shut the water off and take anything apart tonight to get any pics from the front.

[goo.gl]

I reposted your image in case any of the folks here have trouble viewing it at the other webhost:





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Thanks

I'll try to get another pic up soon.

It is an American Standard valve, so I do not think it has a separate piece in it, but another photo of the other side would verify that.