Crossover Issue; Mixing valve found in crawlspace?

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Hi everyone,

I have searched/read the Terry Love (RIP) forums many times to resolve issues with the hand-full of homes I have owned. Such great information and knowledge, I have always been able to find what I needed to fix my issue. This is the first time I felt the need to post to get confirmation on my issue and proposed corrective action. Thanks to everyone in the past and in advance.

The short version is I purchased an older home last fall (trunk and branch plumbing) and have noticed an issue with the hot water being lukewarm at the faucets. Cold supply is around 40 degrees, water coming directly out of the water heater is 120+ degrees, but hot water coming out of my faucets is around 95 degrees. As it got colder this winter in Alaska, I noticed the problem go worse and the faucet hot water continued to get colder with one exception. When there is demand on the cold water in another area of the house (i.e. toilet flush), 120+ degree hot water would come form the faucet until the cold water demand in the other area was over.

I suspect plumbing/pipe crossover mainly because when I turn the water heater valves off, I have cold water coming out of all the faucets' when only the hot waver faucet valved is turned on. I have tested the sinks and clothes washer one-by-one using shutoff valves and replaced valve cartridges in the showers.

I spent some time in the crawlspace yesterday looking for possible signs of plumbing crossover and found what appears to be a mixing valve for the toilets based on descriptions from other forum posts.

My questions:
1. Do these pictures appear to be a mixing valve?
2. I believe the best course of action is to remove the mixing valve to eliminate the crossover, correct?

Thanks for everyone's time.


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