The temperature setting on our gas water heater (brand new) is set to medium-high. The water temperature in all the sinks is very hot, as we like it. However, the temp in the shower in the master bath and in the tub in the guest bath is just warm. I see no obvious adjustment on the tub or shower handles to change the temperature. There is no logo on the handles. They are single handles that turn thru 270 degrees to adjust flow and temp. Any help would be appreciated.