Water Temp Fluctuates in Shower but OK in Tub

[SAS]

I have another post where I was looking to add a pressure balancing valve to my 2 handle shower. Actually, it's a 3 handle shower and I think the problem is related to the diverter. My daughter pointed out to me that when she bathes the baby in the tub the water temp stays constant. In the shower, however, it goes from hot to cold and back again every 15 or 20 seconds. We don't have this problem in any other shower or sink.

It's a Delta shower set, and I recently replaced the diverter cartridge with a Danco replacement I picked up at Home Depot. The old one was leaking through the stem and handle. I've removed the new cartridge and everything looks fine. What I find particularly puzzling is that the problem only occurs with the shower. I took off the shower head to make sure that it wasn't the cause, but the problem persists. Unless someone has another idea, I guess I'll buy a Delta part if I can find one. Any other suggestions?

 

[Cacher_Chick]

You did not mention how your water is being heated. The symptom reminds me of a tankless water heater that is cycling due to the limited flow of the shower head.

 

[Sponsor]

 

[SAS]

You did not mention how your water is being heated. The symptom reminds me of a tankless water heater that is cycling due to the limited flow of the shower head.

It can't be related to the way in which the water is heated, because when you turn the diverter to send the water to the tub the temperature no longer fluctuates. Also, the other showers and sinks in the house do not have this problem.

 

[Reach4]

It can't be related to the way in which the water is heated, because when you turn the diverter to send the water to the tub the temperature no longer fluctuates. Also, the other showers and sinks in the house do not have this problem.

Are you implying a tankless?

Suppose the problem shower was a lower flow showerhead?

 

[SAS]

Are you implying a tankless?

Suppose the problem shower was a lower flow showerhead?

No, I'm not suggesting anything about a tankless heater. It's just a traditional electric water heater. I removed the shower head to eliminate it as a possible cause, and I still had the same problem. I'm pretty sure it's related to the diverter cartridge, but I'm not sure how. I'm going to call Delta to make sure that I have installed the correct cartridge, and maybe I'll try to see if I can find someone who sells the original Delta part.

 

[Reach4]

No, I'm not suggesting anything about a tankless heater.

That was cacher_chick, and it made sense to consider that as a cause.

It's just a traditional electric water heater.

That possibility is now eliminated.

 

[Jadnashua]

Is the temperature variation cyclic, random, and at what rate? Is there any change in sound while this is occurring?

 

[SAS]

Is the temperature variation cyclic, random, and at what rate? Is there any change in sound while this is occurring?

It's not quite cyclical or random. It can occasionally stay reasonably constant for as long as a minute, but generally it switches every 15 or 20 seconds, and the changes are quite significant. I've ordered a new, genuine Delta diverter cartridge and will install it once it arrives. While it seems likely to be the cause, especially since I didn't have this problem before I replaced the old one, I can't understand the mechanics of how it could cause this effect.

In hindsight, I should have kept the old diverter cartridge. It was leaking through the handle, but probably only needed a new O ring.

 

[TanyaP]

I'm having this EXACT issue....since I'm a woman and have no experience in this, can someone lead me in the right direction as to how the hell to correct this? I'm tired of running in the shower! It's good for cardio but I've got waist length hair and I have no time for all this! I also have 2 children who use this shower. I can't deal with the screams anymore when they shower!

 

[Terry]

Tanya,
A good fix is to replace the valve with something pressure balanced. It's been code for decades now, but old plumbing still can have the shock factor.
Here is a link showing parts that and installation that does that.

https://terrylove.com/forums/index.php?threads/delta-600-shower-valve-replacement.70932/

The new trim allows you to work from the tub and shower side, and cover the three holes in the tile or solid surface.

 

[Dplumber]

Hey SAS. My apologies since this is an old discussion, but I’m curious to know if you ever found a resolution to your water temp variation problem.

Having the same issue. Wondering if you have any advice. Thanks