stumped - Cold water is running hot

[Wexford1]

Hi - My cold water tap takes 3 minutes to get cold. In fact, the temperature starts out of the cold water tap at 70 degrees, moves to the 90's and peaks at 102 degrees at 1.5 minutes...and then slowly moves down over the next 1.5 minutes to eventually get to 58 by 3 minutes. Any thoughts why this is happening?

 

[Smooky]

Do you have a recirculating pump on the hot water line?

 

[Sponsor]

 

[Wexford1]

Yes - I do have a recirculating pump on the water line. Though I noticed that this "cold water tap" problem occurred even if I turned down the aquastat on the recirculating pump way down - below 60. On a perhaps related note, I noticed with the recirc quastat was down below 60....the overall hot water was no longer hot....waited over 5-6 minutes. it and it only got to about 90 degrees.. Seems like it is just taking cold water and mixing it with the hot water. Thoughts?

 

[Smooky]

In some recirculating systems the hot water loops back to the hot water heater, in the cold line. It is best to have a separate return line. Proper placement of back-flow preventers is important too to prevent hot water from backing up in the cold water line at or near the heater.

 

[Smooky]

A thermostat in the system can make diagnosis more complicated and it sounds like you have one. To determine what is happening I use my hands to feel the temperature of the pipes. This way you can tell what is going where. There could be a cross-flow somewhere such as at a single handle shower valve.

 

[hj]

There are LOTS of possible causes and we cannot detail every one, or tell you how to test for them. You need a good plumber who can diagnose all the possibilities and find a cure, if there is one.