What is a zone? When I moved into this house it had two pumps, and no zone valves and DHW was thermo syphon. The plumber pointed out TRV's form zones, but the two pump system did not really work, if we ran the pump for the flat, the house radiators had a low reverse flow, and vice versa.
As already pointed out TRV's have a range, so set at 2¼ may normally heat the room to 20°C, but it would still allow the radiator to heat up if room at 21°C and would not be fully open until 18°C. This is with the liquid sensor, with the electronic sensor the range is smaller, but with a motorised valve
off is off and also it has a built in micro switch, unfortunately only one with external connections, so I need a relay to have that micro switch work both pump and boiler, but with that micro switch I can turn off the pump and boiler, I can't do that with a TRV. It would have been a lot easier if the plumber had used one pump, but for some reason beyond my ken he left the two pumps in.
I am not sure what name I should use, as clearly a TRV does control a zone, and with electronic heads they are motorised, hence the picture to show the motorised valve, but I don't want cavitation, so when the motorised valve closes I want the pump to stop.
There is no by-pass valve, I would told it will not work with pump on the return? I am an electrician not a plumber, my dad could wipe lead pipes, I have never tried, and don't really want to work with lead, I have no wish to be a plumber, when pipes need altering I employ one, although my pipes are copper, so suppose need a cupricer not plumber? Well no connected together with solder which did contain lead.
But what I am saying the hardware is installed, and as the house holder in the main we work with what we have, and try to alter without causing massive disruption. And every house will be used differently throughout its life. We use two bedrooms and the other two upper rooms are used as an office and a craft room. Visitors use the flat under main house.
And we have now used motorised valves to be able to turn off the flat. But in the main house we use TRV heads to turn off rooms not in used, or select the times when rooms are heated. This allows us without hardware changes to change room use, so what is now our garden room, was first a dinning room, then a bedroom, and all we had to do was change the program for the TRV.
The house before this was open plan, so we could not really change where was heated, the TRV's in that house stopped the bedrooms over heating, we did not have any down stairs. Mothers house again when we returned to look after mother before her death, one down stairs room was her bedroom, and one of the upstairs rooms became our living room. Our first house was hot air central heating so no option all rooms heated, vents in all internal doors to allow return air.
I know I tend to think every house has internal doors, and they are closed, cau'r drws I would get from mother, put wood in hole from father, told we were not living in a barn. We are lazy today, we have got use to central heating, and there is a tendency not to close doors, raising butt hinges are not so common today.
But I still program each room independently for main house, and the electronic TRV head does that well, plus it insures the TRV does not stick by exercising it once a week, so reduces maintenance.
