Water Temp Issue - Bathroom Shower

[The Critic]

Master bathroom shower valve was replaced 3 years ago during a partial remodel. Valve used was a Moentrol 3520.

I no longer remember the timeline, but for as long as I can remember, it takes 5-10 mins of runtime for the water to reach the desired temp.

Yesterday, the water did not get warm despite being on for 10-15 mins, so I turned the handle to the “maximum hot” setting. The water immediately became scalding hot. At that point, I turned the handle back to warm…yet the water remained scalding hot. So I turned the handle back to “maximum cold”…water remained scalding hot.

I went ahead and replaced the shower cartridge - no change in behavior. For reference, the cartridge is a Moen 1225 (12801).

Any direction is appreciated. Thanks.

 

[dbias]

When you say no change in behavior is it still only hot water or the first scenario where the hot water takes a long time?

https://solutions.moen.com/FAQ's/FAQ's-Troubleshooting/Bathroom/No_COLD_(just_hot)_or_No_HOT_(just_cold)_water_on_tub_shower_units

 

[Eddie]

When you run scalding hot, you are heating the heat sink in the copper pipe and fittings. When changes to a warm water level it takes time to cool off the copper/brass mass. It takes a small amount of 160 F. water to mix with 70F faucet water to achieve the desired 80 degree desired.

 

[The Critic]

When you say no change in behavior is it still only hot water or the first scenario where the hot water takes a long time?

https://solutions.moen.com/FAQ's/FAQ's-Troubleshooting/Bathroom/No_COLD_(just_hot)_or_No_HOT_(just_cold)_water_on_tub_shower_units

It becomes hot water only.

 

[dbias]

Make sure a piece of the old valve did not break off and is blocking the cold water pipe in the valve body.

 

[paulo57509]

No COLD (just hot) or No HOT (just cold) water on tub shower units

solutions.moen.com

Have you tried this?

For Moentrol models:

Inspect the 1423 balancing spool. This will appear on the front of the valve body, either to the right or above the cartridge. It will look similar to a large flat head screw, and it will be brass in color. A large flat-bladed screwdriver can be used to unscrew the balancing spool from the valve. There will be a spool inside this piece, and it needs to move freely inside of its shell. If the spool does not move freely, then the 1423 balancing spool will need to be replaced.

 

[javacontour]

Anything left in the valve body from the old cart?

Did you get the new one in backwards?

I've used the 1222, but not the 1225. I don't think the 1225 has the anti-scald valve, so I doubt you need to adjust the mix / max temp.

I'd look for rubber from the old valve or built up scale.

I suppose you could also turn off the valve to the hot water heater and see if you get cold water when only cold water is available as a troubleshooting step before you take things apart again.

 

[The Critic]

Make sure a piece of the old valve did not break off and is blocking the cold water pipe in the valve body.

Anything left in the valve body from the old cart?

Passage was clear.

For Moentrol models:

Inspect the 1423 balancing spool. This will appear on the front of the valve body, either to the right or above the cartridge. It will look similar to a large flat head screw, and it will be brass in color. A large flat-bladed screwdriver can be used to unscrew the balancing spool from the valve. There will be a spool inside this piece, and it needs to move freely inside of its shell. If the spool does not move freely, then the 1423 balancing spool will need to be replaced.

Thanks - that is a great find. I just found a picture of the original box and was indeed a Moentrol. I will r/r the balance spool shortly.

 

[tom slick]

I'd bet money on the balancing valve.

 

[gathermewool]

When you run scalding hot, you are heating the heat sink in the copper pipe and fittings. When changes to a warm water level it takes time to cool off the copper/brass mass. It takes a small amount of 160 F. water to mix with 70F faucet water to achieve the desired 80 degree desired.

Time: 0.7 seconds

 

[facility1]

get the proper re-build kit for this model,,,when installing it use dow corning silicone fawcett grease 222 (if rember),put a thin film on body ,also flush out the screen in inlet shut off valve,there should be one ,,,clean shower head also,can create back pressure that can contribute to calcium &maganese build up check PH for hardness,,water softener maybe needed for the long run

 

[The Critic]

Replaced balance spool with a Genuine Moen 1423. Issue is resolved.

A Hand Impact screwdriver was required to get the old one to turn. The mechanism inside of the balance spool was stuck - this explains the symptoms that I was experiencing.

 

[PandaBear]

Wow, that's a lot of cutting to get to the balancing valve. What do you plan to do to cover it back up?

 

[The Critic]

Wow, that's a lot of cutting to get to the balancing valve. What do you plan to do to cover it back up?

That area is covered by the trim plate.