shower temp goes hot cold hot cold

[kawi027]

Okay I currently have a gas water heater with a recirculating hot water pump and copper lines throughout. I have 3 bathrooms (2 down & 1 up). The 2 down showers are the only ones with the problem of the shower temp going from hot, cold, scolding hot, cold throughout a shower, without any other water usage going on (flushing toilet, sinks etc).

I took off both bathrooms shower heads and the problem is still there with the water coming straight out the pipe.
The house never had this problem until recently.

Does the hot water recirculating pump thermostat (which is at 140 degrees) and the water heater thermostat have to be synced (temp wise)? The water heater thermostat does not have degrees just letters (Cold, A, B, C , VERY HOT) I have it on "C".

I thought about installing a anti-scald valve but I dont think I need it since This was never a issue before.

The water heater is about 5 years old and I could not find any visible leaks around the heater.

Sorry for the long essay!

Thanks in advance.

 

[johnjh2o]

Do you have a designated recirculating line? If so the check valve at the heater may be bad. Allowing the cold water at the bottom of the heater to mix with your hot before reaching the faucet.

John

 

[kawi027]

Hey John,

Im not sure if it has its own dedicated line, maybe u can tell me.

There r 2 copper lines that enter my house.
One line comes out of the bottom of the water heater and goes into the recirculating pump then into my house.
The other line comes out of the top of the water heater and goes directly into my house.

 

[johnjh2o]

That is a dedicated line system. There should be a check valve on that line, it would be located were the line enters the bottom of the tank. To check to see if it is bad have someone turn on the hot water while your holding the recirculating line at the tank to see if line goes cold. It won't go completely cold but you will feel a temperature change if the check valve is bad. There are other things that can cause your problem but the check valve is the first thing I would be checking.

John

 

[kawi027]

Hey John,

I appreciate the quick reply.
I just got back in town and am going to check the line this weekend.

Thanks.

 

[kawi027]

I turned on the hot water and both lines coming out of the water heater remained hot.
I finally out of curiosity shut off the power to the recirculating pump and the problem went away! Im guessing i need to replace my pump?

 

[johnjh2o]

Don't replace the pump. Do you have a dedicated return line? I need to have the answer to this to help you.

John

 

[kawi027]

I'm pretty sure I have a dedicated return line. Ive attached a picture of what I think is the check valve you told me to look for. The valve pictured is installed on the line from the hot water recirculating pump and goes into the house. Does this appear to be the check valve?

 

[johnjh2o]

That is the check valve. That may be your problem. If the line cools down on the house side of the check valve when running hot water it is bad. I can't tell from you photo but the large nut on the check valve should be facing up. You could try turning off the water and removing the large nut so you could clean the check and it's seat. Or just replace the check valve.

John