The humm in the shower could be a faulty washer vibrating.
What are the “Two values in our new house are located in the back” for ?? hose taps, sprinkler solonoids? what ?
All advice is given with-out seeing the job, and hence all advice MUST be taken as advice with limited knowledge on the exact situation. NO responsibility can or will be taken. And yes, I am a licensed Plumber and Drainer with my own business in Brisbane Australia