Question on hot water and central heating not working correctly.
Standard heating system - gas boiler, timed clock switch, no room
thermostat, mid position valve.
Turned on heating couple of weeks ago after the summer and everything
worked fine. Then heating stopped working. Covered by BGas cover so
engineer called. First he said it was loose connecitons in the
Mid-position valve - fixed it and it ran. Next morning didn't come on.
he came back - couldn't find anything obvious - got it working and
left , promising to call us after 2 days to see what was happening.
Again didn't work that night or following morning. He called today and
is coming again Friday.

Wanted to run these symptoms past the group to see if they made sense
and you could advise , so I can gently point him/BGas in the right
direction - he didn't inspire confidence previously when he didn't try
all options.

After couple of trials I think I've figured these are the symptoms.

1. If hot water is timed to come on before heating then heating
doesn't work.
2. If heating is timed to come on before hot water than heating DOES
work and so does hot water.

Mid-posiiton valve seems to move to all the right positions when taken
off the pipe and tested using the different settings on the times i.e.
CH/HW on/off etc.

I've proved this last night and this morning.

Since I'm not mending it myself I'm not going to get into fine details
but was after guidance more than anything on whether me interpretation
would be feasible.
Cheers....