Ferroli 77 ff - slow to fire up when using heating or DHW

[smokeybradshaw]

My ferroli 77 ff takes about 2 - 5 mins before it will fire up the main burners when using either the central heating or DHW.
The only reasonable way of getting hot water is to switch on the heating, wait a few minutes then run the hot tap.
I called ferroli and they suggested the flow switch but i can't see how this would affect the heating.

Any help would be much appreciated.
Thanks

 

[Agile]

These boilers are really over due for replacement!

There are two possible causes, the system flow switch and the air pressure switch.

The latter needs a competent CORGI prepared to clean 15 years of grime from the airways.

The former needs the pump to be checked for torque and the boiler waterways to be chemically cleaned.

Tony

 

[Slugbabydotcom]

Forget about the heating for now.
If you turn to HW only I am assuming nothing happens Right?
Thats because the flow switch is stuck and the boiler doesnt know that theres a call for HW.

OK so you turn your heating on then run a tap while the boiler is firing for CH. The design is such that you will get some HW but you will have to run the tap slowly as the boiler thinks it is providing CH and only burning half the gas it really needs for HW.

2-5 mins wait could be explained by an anti cycle function of the pcb or there could be something else going on.

Flow switch is a good starting point to check out as these do go wrong fairly regularly

 

[smokeybradshaw]

Thanks for your advice. I've just replaced the flow switch, and still no joy. When the hot tap is opened, the fan starts and the boiler appears to make all the right noises but still the main burners do not light. If you leave the tap running for around 5 mins then the burners will fire up (but this means a lot of wasted water) Not good for my bill!
Any other parts i could clean or replace before i employ a heating engineer.
Thanks again for any help received.

 

[smokeybradshaw]

Forgot to say, replacement isn't a viable (financial) option. I'm 3 stories up, and the flue isn't accessable without a serious amount of scaffolding (and money i haven't got).