APT Imm24 replacement

PeWu79

My current setup consists of 3 motorized zone control valves, 3 thermostats (1 downstairs heating, 1 upstairs and 1 for HW cylinder) and APT Imm24.
I'm not happy with the fact that I have to switch both the thermostat and the APT (either manually or auto) to have the heating on.
My ideal option is a thermostat being able to trigger the boiler.
Is this achievable by replacing the APT to a 3 channel digital programmer?

My current wiring as per the photo attached.
Note the 2 loose wires - any chance these are the thermostats ones?

machiavellianme

Who knows what they are. No offence but a picture of some wires with no idea where they came from isn't very helpful. It may be worth getting an electrician in and doing the job properly/safely.
It looks like you only have 2 channels there.

PeWu79

Thanks machiabellianme.
My friends on the estate have the same or very similar setups - they surely were done by electricians, so I thought that it could have been some sort of 'common practice' and therefore an electrician could advice on this...
That's why I'm asking....

PeWu79

Even if get it connected to a new 2/3 channel programmer will the thermostat trigger the boiler or will it still be a manual job?

Irish Steve

The APTImm24 is a time clock for an immersion heater, it is not a multi zone heating control clock, so if that's been used to "control" the heating and hot water, it's a cheapskate cobble that should not have been allowed to pass inspection, and means that your only control over the activity of the zones is to mess with the thermostats to turn them on or off, which is not the way they are supposed to operate. One time clock to turn 3 zones on and off is not the way that the system is supposed to be set up, the concept is to have a multi zone clock that can have different operation times for each zone that is being controlled.

You need a decent multi zone time switch to allow independent control of the 3 zones, regardless of what the thermostat is actually calling for, and if the system is set up correctly, the thermostats won't be touched very often, unless you want to significantly change the temperature in a specific zone or of the hot water.

Having said that, unless things have changed, the time clock provides power to the heat valves, via the thermostats, and there is then a switch on the valve that provides power to the boiler, which means that if the valve opens, the boiler can fire. It matters not which valve actuates, the only requirement is that there is a live supply to the switch in the valve, after that, the boiler is happy.

Depending on the location of the various devices, retrofitting the proper clock may not be the simplest task, as you will probably need an additional 2 live feeds from the clock location to the valve/boiler location, which may mean chasing walls to be able to put them in.

PeWu79

So I replaced the APT timer with ESI 2 channel programmer.
I wired it similarly to the APT but I split the  HW and CH cables into separate zones.
I set the programmer to gravity as I only can get CH together with HW.
Everything seems to be working... but when the stats heating requests have been satisfied, the boiler does not switch off automatically... 
It goes into kind of a "standby mode" - the green light flashes every second and it switches off only when the heating period set on the timer is over....
It is Vokera 24m and according to the manual it should switch off.

Any thoughts?