I had a mixing value problem last year and had to replaced it.
Three things I've done different this year in an effort to prevent a reoccurrence:
1. Bought a plastic flush wand like this one (
https://www.amazon.com/Camco-Rinser-...s%2C149&sr=8-1) and thoroughly flushed the hot water tank.
2. Filled the hot water tank slowly to prevent any remaining debris from circulating in the water.
3. Wait for a few minuted before turning on hot water faucet again to let any remaining particles settle to the bottom of the tank.
Step 1 was done when winterizing and steps 2 and 3 were done when I de-winterized. Not sure that step 2 and 3 are necessary but I did remove a lot of debris using step 1.
FWIW!