i'm glad they didn't waste alot of money to wash down someone who was contaminatedThose are real cheap heaters. The mixers are ASSE stamped.They only put out a couple of gallons a minute, but that's all they need. They will only run the sink or the shower, not both at one time. If more than one person gets crapped up at a time, tough.
If I was a guessing man they only use one at a time. redundancy is crucial in a piece of equipment that important.I'm not trying to pick your stuff apart but, why didn't you just go with a single temperature modulating heater and just turn the thing down?
It just seems so over complicated for no reason.