combi heat request, light on, no heat???

[daffyabc]

Your advice would be most welcome on the following
I have a Main 30he 18 months old with RF towerstat.
I have just turned the boiler from DHW to DHW & CH at the boiler having been off since April.
When the stat requests heat the CH green light pops on,click, and light goes sraight off, a quiet fan kicks in and no CH, (no sound other than fan not even an attempt to heat CH)
DHW is not affected and runs as normal when reqd.

Checks so far :
DHW and HW temp dial to 3/4 max (as normal)
DHW: fine no probs
Not a single warning light on?? : DHW light steady green
Boiler pressure: Ok at 1.5 bar
Bleed rads: All seems ok
TRV's set to full.
No rads isolated
Turn boiler switch to reset: Makes no difference
Turn main power off and on and reset Rf stat: Still no change.
Check RF-TX: Stat RF is getting signal from TX
Stat TX is regularly requesting demand from CH which is normal. the RX apears to be demanding the CH to turn on but no joy from the boiler

Am I missing anything ???? all i did was flick the switch from DHW & CH to DHW in the spring.
what are your thoughts on this one??

 

[kevplumb]

link the stat out on the boiler term block

after you turn off the power

 

[kitch0978]

batteries ok in stat?

 

[rojaca]

On term block you shoiuld have 5 wires. L, N, E, Live out and Live in. Check you have got approx 240v between N and live out on terminal block, when call for heat you should have same between N and live in.
No volts live out- pcb, internal clock on blr? or mains switch fault
If no Voltage on Live in RF stat is not switching
Voltage on both but no htg pcb or loose connection.

 

[daffyabc]

Thanx to all who replied.
I changed the RX for a manual clock as aprocess of ilimination and BINGO.
I take it the RX has had it