I'm sorry Ric I think you may have misread that - The Actual Temperature in the Bathroom was 19 with the Set Temperature at 15 not the reverse. I just wanted it a little warmer.A bathroom 4°C below setpoint not calling for heat sounds frankly crazy.
There are a number of factors that have made me follow this route. I'm 73 years old and will probably only be in this house for another few years, certainly not long enough for there to be any payback on a boiler replacement and probably not even by installing new and better sized and distributed radiators. The rooms in this bungalow are very large as are the windows. The Lounge , main bedroom and hallway all have SSW facing windows. The Lounge is about 25 sq metres with a single radiator and even the hallway where the wall thermostat is located is close on 14 sq metres with a half glazed door with side panels about 2.5 metres wide, so quite susceptible to temperature change from the late afternoon/early evening sun or from opening the external doors at either end. It certainly isn't the best place to have a thermostat to control the overall house temperature but that is where it is. I have tried a Honeywell Sundial thermostat but it wasn't hugely successful.
With weather as it is at the moment, dull one moment and blazing sunshine the next I'm already seeing the benefits in terms of comfort. To be able to tweak the set temperature on the radiator whilst sitting in my chair is already worth the relatively small amount I have spent. Also when I come to leave the property, an hours work in fitting the old valveheads back and 5 minutes disconnecting and reconfiguring the remote boiler switch and, the system will be back to a operable "standard" dumb state.
If I find that what I have done does not work effectively I merely have to re-program the hall thermostat, turn the boiler programmer back to Auto and disable the piece of software that switches the boiler on or off right now but at the same time I can still keep the individual room programmes in the valves but know that the hall thermostat will control the maximum temperature at any moment in time.
I did find this website when I was researching Short Cycling - Boiler Short Cycling - http://www.home-heating-systems-and-solutions.com/boiler-short-cycling.html and was interested to read this
solution. Which is effectively what I'm doing except I have 10 Thermostats