Ferroli Combi Drawings anyone?

[Doug99]

Hi all,

I recently removed a couple of radiators for decorating and left the CH system dry for about a fortnight. During this period I still used the DHW.

Now I can't get the CH to fire up properly!

CH system is filled, bled and pressurised (2 bar). On setting the thermostat to demand heat, the CH will fire up for approx 1 minute then shuts down the whole boiler (including DHW as the pilot light is extinguished).

The boiler is a Ferroli but has no other markings on the outside to say what type. The plate inside is marked Combi 77 FF.

The only drawings from the Ferroli website which comes close to my system is the Optima 701 with the VFM7 PCB. My model has a slightly different layout to the Optima, manufactured 1991 and fitted with the VFM5 PCB.

Is there anyone who might be able to direct me towards a VFM5 drawing? The LED layout and descriptions are similar but not sufficient to read the sequence for CH operation.

I suspect that leaving the CH dry for so long has had a detrimental effect on the CH sensors and internals.

Can anyone advise what/where the CH sensors are situated and what to expect across each with a multimeter.?

Cheers

DM

 

[ChrisR]

Identify your model - the GC number if not the name.

 

[chrishutt]

Sounds as if there is no circulation through CH circuit. Have you reopened the isolating valves below the boiler (you presumably closed these to continue with hot water whilst CH was drained)? If so, perhaps an air lock or other obstruction?

 

[Doug99]

ChrisR - The model is GC 4726704
Chrishutt - All valves are open and I believe the ferroli has an automatic vent?

Doug

 

[chrishutt]

So how far does the hot water circulate, and how quickly? Presumably the CH stops due to an overheat stat operating, so the circulation must be impaired.

I've got MI for Ferroli 77FF popular - GC no. 4726706 - I think it's same as 700 Optima. This boiler requires external by-pass if TRVs are fitted. PCB is VMF6.1.

 

[ollski]

PCB is VMF6.1.

Depends chris, the replacement board is now the vmf7 (I think), but I did a pcb swap on one of these the other day and the old board was a vmf4.

As to the problem....does the pump run?, if it does does the fan go to high speed?, if it does then check the ch thermistor on the left hand side behind the gas valve. resistance (disconnected) should be 500 - 1500 ohms