No heating when called for

[jillpad]

During the past week when my Salus RT300RF calls for heat (receiver displays green light), my Mexico HE36 boiler sometime fires up, but mostly won't. I seem to be able to coax a fire-up by lowering the desired temperature setting on the Salus (thus causing receiver green light to go out), waiting half minute or so, then increasing the setting to cause green light illumination. So far this hasn't failed to fire up the boiler. But it's more of a faff than having to switch boiler on manually. I'm wondering if the receiver is faulty - it's about 18 months old and has been reliable up to now, though one occasion this winter of failed boiler fire up may have been for the same reason - whatever that might be.
Is there any way I can check the receiver is faulty? Or might the cause lie somewhere else? Any ideas, please?

 

[mysteryman]

Check the batteries in the remote unit.

 

[jillpad]

Thanks for the reply Mysteryman. The batteries are good.

 

[45yearsagasman]

What other controls on your system and does boiler fire for hot water?
I'm suspecting a faulty ch zone/motorised valve.

 

[jillpad]

I'm grateful for your reply, Gasman. There are Honeywell motorised zone values on the heating and hot water circuits. Obviously the room thermostat problem only affects the heating side. Hot water is unaffected. How would I check that the MZV is the cause of the problem?

 

[mysteryman]

Look at the central heating zone valve - it needs to motor fully open.

 

[littledavid]

I got the same problem with my icos HE15. Hot water is ok and not heating. I just turn off the heating for three monthes then everything does not work.

Sorry no any useful suggestion here.