Whilst your property manager sounds like an idiot and deserves a good kick up the bum... If i was a tenant and not advised of the unusual/non-conventional system (before I moved in) I'd be trying to get it "corrected". Having to set the thermostat every time you wanted to use hot water would drive me bananas!
I have to agree with this. If you look at it from the tenants perspective, they are paying money to rent the property and probably expect a conventional system. It's something that definitely needs to be explained to tenants before they sign a lease. Also it would depend on the rent, if it is a very reasonable price I would put up with the inconvenience.

The house we are renting now is about 30 years old and we pay slightly less than the median for our suburb. There is mould on the wall in the corner next to the shower because of leaky taps. It drives me nuts, but we are renting because we can't afford to buy yet and never would if we kept on paying ridiculous rent prices