The home made toilet water mixing valve. This
is what it all looks like after I have replaced the old toilet
mixing valve with my new setup
Please note the little arrows on the pipes and the little notes.
I placed the 2 inline spring check valve, just before the 1/2" copper tee that ties the hot and cold water lines together, this way the hot water cannot backup into cold water line, and the cold cannot go back into the hot water line.
Also I put the 1/2" ball valve on the hot water pipe going into my new toilet water mixing valve. The ball valve can be tweaked, to allow just the right amount of hot water, into the mixed water line, the cold water valve can be full open.
The mixed water line, only goes to the toilets, if it is tied to any other faucet, it will cause all kinds of water temperature problems in your home.