Call back: high pitched humming coming from water heater. Could not recreate sound however customer showed me video. Started by checking pressure. Checked at hose bib and water heater. Both at 62psi. No issues. Got into crawl space to inspect plumbing and prv install.everything appears to be correct and plumbed properly To rule out possibility of obstruction in ball valve/check on top of dip tube. Removed ball valve, and supply connection to water heater. Checked dip tube check for any obstruction. Installed new ball valve when putting back together. No current noise. Informed customer if problem persists to call.