New electric water heater giving 100 degree water

[jamco70]

1. Started getting warm water instead of hot water from 7 year old Rheem electric water heater set to 120 degrees.

2. After research, I replaced both elements.

3. When I turned the power back on, the water heater immediately threw a "Lower thermistor failure" code.

4. Rheem no longer makes this particular thermistor and I did not want to wait 2 weeks to get it from Home Depot by mail.

5. Replaced water heater with brand new Rheem water heater. Set one thermostat to 120 and the other to 125, according to manual.

6. Experiencing same problem....have to turn temperature control all the way on Hot to get warm water in shower, kitchen faucet, and master bath faucet. Haven't put a thermometer on the "hot" water but there's no way it's coming out at 120 degrees. It's like 100 degrees.

7. Talked to plumber, suggested it is a bad mixing valve in the kitchen sink faucet????

I have never heard of such a thing. Before I spent hundreds of dollars more on a plumber or time to throw parts at the kitchen faucet mixing valve, can anyone weigh in on this? Is this a real thing, could it be this or something else? Have been dealing with this for going on 2 weeks now.

Side note: we are remodeling the master bath and replaced the cartridge in the Moen shower body but the shower tile isn't done yet so we haven't been using that shower. Could a wrong or improperly installed cartridge be the culprit?

 

[Twowaxhack]

Get some water out of the water heaters relief valve and take it’s temperature.

 

[Terrill]

Make sure the shower faucet has the cartridge installed. If it's just capped the hot and cold will cross over. If the plumber didn't remove the plug, that would be your crossover problem.
You do mention that you have a new shower cartridge, so if that is the case, no crossover there.

 

[Geofd]

I have heard that you can install Moen cartridges backwards I believe it's when there is a back to back shower valve installation but someone here more familiar with Moen can confirm

 

[jamco70]

Make sure the shower faucet has the cartridge installed. If it's just capped the hot and cold will cross over. If the plumber didn't remove the plug, that would be your crossover problem.
You do mention that you have a new shower cartridge, so if that is the case, no crossover there.

View attachment 38362

Could he have installed the wrong cartridge and that is causing this problem?

 

[Terrill]

Could he have installed the wrong cartridge and that is causing this problem?

Can you post a picture of what you have?

 

[jamco70]

Can you post a picture of what you have?

 

[Twowaxhack]

Have you checked the water temp from the relief valve yet ? What was the temp ?

If you turn the cold water inlet to the water heater off and go to a lavatory faucet and turn it on to the hot water side, does the flow eventually completely stop ?

 

[Terrill]

Moen Posi-Temp. Looks good there. Starts off cold, rotates to the left to hot.

 

[jamco70]

Have you checked the water temp from the relief valve yet ? What was the temp ?

If you turn the cold water inlet to the water heater off and go to a lavatory faucet and turn it on to the hot water side, does the flow eventually completely stop ?

Water came out of the relief valve at 118 degrees. Turned off cold water inlet and turned on hot in a bathroom, it ran warm with lower pressure and then turned to ice cold water with higher (normal) pressure.

 

[jamco70]

Moen Posi-Temp. Looks good there. Starts off cold, rotates to the left to hot.

Could it be a wrong cartridge? House was built in 1995, was that pre- Positemp? Or does it not matter?

 

[Twowaxhack]

Water came out of the relief valve at 118 degrees. Turned off cold water inlet and turned on hot in a bathroom, it ran warm with lower pressure and then turned to ice cold water with higher (normal) pressure.

You have a cross connection between hot and cold.

 

[jamco70]

You have a cross connection between hot and cold.

I just checked the cartridge in the shower fixture that was replaced. He left the cartridge with the notch in the Up position. Could that have been causing this crossover problem all along?

 

[Rickyman]

I just checked the cartridge in the shower fixture that was replaced. He left the cartridge with the notch in the Up position. Could that have been causing this crossover problem all along?

Are the tub spout and shower arm capped for tiling.

 

[jamco70]

Are the tub spout and shower arm capped for tiling.

Yes.

 

[Rickyman]

Yes.

I think you found your cross connection. Turn the inlet water off to the water heater and turn on a hot faucet. Rotate the Positemp stem until water stops coming out from the faucet. Restore water to the water heater and enjoy a hot shower

 

[jamco70]

Make sure the shower faucet has the cartridge installed. If it's just capped the hot and cold will cross over. If the plumber didn't remove the plug, that would be your crossover problem.
You do mention that you have a new shower cartridge, so if that is the case, no crossover there.

View attachment 38362

I think you found your cross connection. Turn the inlet water off to the water heater and turn on a hot faucet. Rotate the Positemp stem until water stops coming out from the faucet. Restore water to the water heater and enjoy a hot shower

I think you found your cross connection. Turn the inlet water off to the water heater and turn on a hot faucet. Rotate the Positemp stem until water stops coming out from the faucet. Restore water to the water heater and enjoy a hot shower

Tried that just now, the cold water never stopped coming out no matter what position the stem was in. Bad cartridge?

 

[Rickyman]

Tried that just now, the cold water never stopped coming out no matter what position the stem was in. Bad cartridge?

Did you wait a minute when you had the notch on the stem facing down?

 

[jamco70]

I did let it run a couple minutes. Hot water knob on kept giving cold water. Should I leave it on for longer, until it runs out, or should that have been long enough?

Could it be a bad water inlet valve at the water heater contuining to let cold water in?

I don't know where my contractor got this cartridge or if it was even new. Bad cartridge?

 

[Twowaxhack]

Make sure the tub/shower that’s capped off remains in the off position. Remove the spout cap to make sure.

Then go to the water heater and turn the cold water valve off at the top.

Now go to a lavatory faucet and turn on the hot water side. It should flow water and then eventually trickle to nothing.

Try that and report back.