A few days ago my heating started coming on when set to hot water only regardless of the room thermostat setting. There are three pipes coming from the two boxes that go through the floor beneath them. The boiler is in the room below these.

When I switch to heating only the lever moves to the right, on hot water only the lever only moves to the middle and the rads stay hot. If I force it over by hand the rads go off as they should.

Mid Position

My reason for writing this thread is, should the actuator on the right (the one that's very hot to touch) be this hot, when our heating isn't ever in use? Should it be making such a loud noise as though a motor is constantly running inside it? I've noticed that one of the ZA5 actuators is red-hot to the touch, and it's shaking slightly, as though a motor inside is running very clunky. If you require any further information please do ask, any help is appreciated. I'm unsure if we maybe need a new actuator, maybe the motor inside is dodgy? Maybe it should always be hot and something is just loose inside?

The one between A and B is the hot one. We have not used our central heating since 2019 as the house is naturally very insulated, being a new-build. The radiators are always off, but of course our hot water is switched on. One actuator is set to A, and the other is set between A and B (this is probably due to a technician coming out last year to look at our inoperable downstairs thermostat, he said it's cheaper to re-direct the upstairs thermostat to control the entire house, rather than us buying a new thermostat for the downstairs, he did do something inside this cupboard where the actuators are).

Spares