Upstairs radiator heating issue

[BBB145]

I have underfloor heating downstairs, which is working fine and I'm getting hot water, but the upstairs radiators aren't heating at all. I've bled all of the radiators and there isn't trapped air.

The system has a Smart Comfort LK100 controller, a round Wilo circulating pump unit, a Wilo Yonos Pico digital pump unit and two motorized Honeywell zone valves.

The Wilco Yonos Pico unit isn't showing a digital display, so I suspect it's a power supply or electrical component problem with it. However, is this likely to be the issue with the lack of heat to the upstairs radiators? I don't know if this is the unit which controls the flow of water to the upstairs circuits or not....?

 

[stem]

The usual failure for one zone of a heating system is its motorised valve. Your third photo shows two valves marked L & R, hopefully you will know what the letters refer to. Unfortunately it is very difficult to tell what is connected to where on a forum without being physically present. I would also expect that there are at least three motorised valves and two pumps. Something akin to the diagram below.

The programmer/thermostat will tell the motorised valve to open, however if its motor has failed the valve will remain shut, and will not start the boiler or pump. To check, switch the upstairs radiators on (make sure the controls are calling for heat) and slide the valve on the motorised valve responsible for the upstairs radiators from Auto to Manual, it should be loose and floppy. If there is any resistance felt, the valve is not opening.

Another fault may be that the valve is opening, but the internal microswitch inside the valve does not operate and start the boiler. It is less likely to be this because when the other zone, or hot water are on, they would start the boiler and the upstairs radiators would also come on.