You've not mentioned a room thermostat, only a timer. So at the moment the timer controls the boiler and pump. When the timer is 'on' the pump and boiler run so provide heating and hot water.
When you have the Hive installed it operates on the temperature of the room it's located in, so when the room in which it's located is warm enough it will turn off the boiler and pump. So you won't get any hot water when the house is warm.
Yes but I've made sure the required temp on the thermostat is above the current temp.. but if i push the button on the reciever to test it, does it not over ride the thermostat anyway.?
There are no other thermostats installed at present..