Yes I will agree, I did not understand how storage radiators were ever classed as central heating. There were systems with a central heat store and fans to direct heat to rooms as and when required, but most had no central control at all.
It does seem that as soon as central heating started to be fitted into homes, we tried to decentralise the control.
Size matters, a two up two down, would have just lower room control, and enough heat came through the floor for bedrooms, but as the size grows, we find bedrooms used as offices, studies, rooms to do homework in, and I never really got my head around living room and best room.
However, my own home, 14 heated areas, if I heated all 14 24/7 it would cost a fortune, so rooms are heated as and when required, but having one boiler means only one room needs a flue, OK we also have an open fire, but is does make the building on the house cheaper and simpler if only one boiler serves the whole house.
But control wise, we can group rooms, with some being heated 24/7 like the bathroom, some overnight like the bedrooms, and some day and evening like living room, and some just when required, like an office, craft room, etc.
Once the house has rooms only used on some days, or some hours in the day, we still want a central heat generator, but the control needs to be spread around the house.
How we control will vary, as a couple, as a family with small children, changing as the children grow up, returning to two again in latter years, so the central heating has to be designed so it can also vary as the family grows.
So in the main, the old motorised valve is out, as it is too inflexible, the new motorised valve or TRV as we now call them, can have heads swapped and reprogrammed to suit our changing needs. There will be the exception, where the granny flat is all either heated or not heated, but in the main, we look for a system which can change with our needs, and the TRV with interchangeable heads, seems to best allow for changing needs.
So we may have three bedrooms and only one has a linked TRV head, there is often no need for every room TRV head to be linked, and where radiators are against a cold wall, it may be better to have a wall mounted sensor, and it may be an advantage if that sensor has local controls (i.e. a wall thermostat) and it may work out better if so many controls are grouped together as zones.
But the idea of every room having its own hub linked temperature control or the opposite where every room just has a proportion of a control rooms requirements, does not really work, we have to select some happy balance between the two.
This balance may well be just using the TRV to stop rooms overheating, but even though I know the theory, when my mothers room got too hot, I blamed the wall thermostat, which of course is nonsense, as both the wall thermostat and the TRV both need to be faulty for a room to overheat.
I quickly realised my error, and went to set the TRV, so want the room at around 21ºC to 22ºC and I look at the TRV head, and it says *123456, who in their right mind, labels a thermostat *123456?
Well it seems the TRV at setting 2.5 will be fully open at 17ºC and fully closed at 21ºC so 5ºC between fully open and fully closed, so to have a room at 20ºC it will depend on outside temperature, radiator size, room size and the setting of the lock shield valve, as to what number it needs setting at.
Even with an electronic TRV head, it may mean fully open and fully closed only has a 0.5ºC variation, but to exercise the valve, which happens every Saturday at noon, we hear the motor running for 5 minutes, that how slow the valve is, so with no lock shield valve, the radiator would be stinking hot before the valve can close, so we need to set the lock shield valve.
Mother house, found every lock shield valve wide open, should have be set by installers, but they didn't. And I could not find my differential thermometer to set them with. But once electronic heads were fitted, I had a display
so clearly the current should not exceed target, so if it did, the lock shield needs closing a little. Once set it worked spot on, but it took some time to gradually trim in each room. More than 4 rooms, but once the lock shield set, the old mechanical TRV heads worked fine.
So confident I now knew how to set up the lock shield, moved to new house, but this had an on/off boiler, not a modulating boiler, and it did not quite work out the same. So yes the method does not work with all. There seems to be an exception to every rule.
I now realise why to become an engineer, we are looking at degree standard, and heating and ventilation engineers do earn their pay.
But in the main we are not looking for temperature control to within 0.5ºC of what is set, we work with near enough engineering, the easy method is something like Drayton Wiser TRV heads on every radiator and let them call for heat when required, but the heating engineer can reduce that, and only fit linked TRV heads to some radiators.
But as the homeowner we have to decide how much we are willing to pay, I have just 4 linked thermostats, even with 14 radiators, and I find that near enough. I will not claim perfect, it's not, but it is near enough.
My memory is shot these days.
