On Monday, November 11, 2019 at 5:10:29 AM UTC-5, ~BD~ wrote:
Hi

Since my son recently picked up and 'fiddled' with my remote Honeywell
sensor for my central heating system, I been experiencing erratic
behaviour of my heating system.

The receiver unit in my airing cupboard had a red light instead of
green. I've changed the batteries in the sender unit and have myself
'fiddled' with the controls until everything appears to work properly.

This morning, though, there was once again a red light on the receiver
unit and the bathroom radiator was cold. Although the pipes around the
tank were hot, there was was once again a red light on the receiver
unit. I've pressed the reset button and the central heating pump is
running again and the bathroom radiator is getting hot.

Has anyone any suggestion about possible cause and how to rectify?

--
David B.
Devon, UK

It's possible it has nothing to do with your son playing with the remote.
If you take the batteries out of it, push the buttons a few times, then
leave it without batteries for an hour or so, that should reset it.
Have you looked online or in any manuals you have for what the red light
means? Also on such a sophisticated system, if it shuts down I would
expect there would be an error msg, flashing lights, at the unit itself
to indicate the problem.