Iflo digital scr not showing any lights?

Gengar

This unit no longer displays any LEDs. I have changed it out for a re-conditioned one but same result.
I can get hot water from boiler as the boiler activates when I have the wall switch next to the Iflo controller on, so looks like the Iflo is getting power.
Put new batteries in the transmitter thermostat but made no difference to Iflo.
Any suggestions please before I call in a heating engineer?

Rodders53

How electrically competent are you?  Do you have a multimeter and the knowledge to use one?

I'd suspect a lack of (mains) power to the RF receiver box if no lights... The 'override' button should force the boiler to run the central heating if there is mains to it. 

Mains to the receiver box is easily checked with a multimeter at the backplate connections.

Very likely the mains is fed to the thermostat receiver via the boiler with the isolator feeding the boiler mains input. 
So that it works as a combi boiler for the hot water is probably indicative of an issue between boiler and thermostat receiver / cabling.

Gengar

Many thanks for the quick response Rodders53. I have a multimeter so will check the back plate but all the wiring looks good and intact.

Rodders53

Note the 'call for heat' contacts on the backplate Nos 1 (com)  and 3 (n/o)  may not use mains voltage --- depending on the boiler you have.  
Linking the wires (isolate mains first) between  terminals 1 and 3 should make the boiler CH work when you switch the mains back on.

ThisIsWeird

Hi Gengar.

Could you remove the SCR again - leccy off first - and take a photo of the backplate, please?

When you replaced the receiver, did you also replace the backplate, or keep the oldie?

Assuming you know what you are doing, could you - with due care - power up the circuit (the switch near the boiler), and take a voltage reading across L & N? Don't take it at the screw heads, but on the connecting prongs above.

POWER OFF, and examine - using an insulated screwdriver - the prongs. Do they show the same gap? Are they firm?

ThisIsWeird

Exact make and model of boiler? 
I wonder if it has an internal fuse where it supplies the external controls?

Gengar

Getting 250V across L & N.
Using existing backplate but no LED show with existing or replacement Iflo digistat SCR.
Prongs seem firm enough and no loose wires.


 Existing units.


  Replacement units.

Ideal Logic Max Combi2 C24 24
It was only installed in January last year so I will contact Ideal but as it is a control problem they will probably say it is not covered under the warranty.

ThisIsWeird

Any chance of a clearer photo, espec the first one showing the backplate wiring? Also a close-up of the connecting pins on the SCR itself, please.

Did you measure that 240V across the forked connectors?