ferolli 77ff boiler fault
- Thread starter Jimmyjaffa
- Start date
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Hi limit stats with blade connectors usually look like this
or this.
They should be ZERO ohms ( certainly less than 10) when shut and INFINITY (above 10 M ohms) when open. Thins around 1kohms are temperature sensors.
or this.
They should be ZERO ohms ( certainly less than 10) when shut and INFINITY (above 10 M ohms) when open. Thins around 1kohms are temperature sensors.
Hi now ive seen a photo of them ive checked them again,there are 4 of these in total 2 top right of heater exchange,1 to the top left and 1 behind the pcb. 3 out of the for are closed curciut and one to the top left is open curciut an goes to about 32 m ohms on the metre.
skippster76 said:
Top left is the overheat stat....the pilot light is lit isn't it??..the upper thermostat on the right hand side is the frost thermostat, this should be open circuit, if its closed circuit its the problem.
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right thats it ive had enough,the pilot was lit until i removed the wires from the top left stat which caused the pilot to go out.i have replaced all stats now the pilot will now not stay alight every time i let go of the gas nob,think i'll cut me losses and get a new boiler as if it is the pcb i will be better off.
oh and when i switch the boiler power on and the switch is in the middle the fan cuts in constanly.
just a thought you havent mixed the stats up 
Hi no they where all changed one at a time,now the fan is on all the time when i switch power back on and the pilot wont light,time for a new one i think,
The fan should be on slow speed all the time it has a permanent pilot, I think we are missing the fail point here somewhere....I thought you had tried a new board. Where in Brum are you? I think I've got a good vmf5 board somewhere. Anyway where are we now, no pilot?, so we are looking at the ignition unit or ignition microswitch first.....if you want to check stuff I will keep going if you like.
Hi im in hodge hill, the pilot was working fine all yesterday until i removed the wires from the top left stat, the gas valve clicked the nob shot out and the pilot went out, now the fan is on full pelt and i can light the pilot by hand but even if i hold it for 1 minute and let go the pilot goes out. the wires from the top left stat goes to the bottom of the thermo couplin. i replaced the thermo couplin today.the other wire goes to the back of the igniter/gas valve.
I thought as i was replacing the other parts i might as well change the tc while i was at it, when i went and got the stats the bloke at the shop said that three of the stats had the same value 85 dg and the other one with the little white dot on it was 100 dg value, where is the one with the dot supposed to go ikm preety sure its in the right place but if you can tell me i will double check.
Good news i swaped the dotted stat and now the pilot ignites ok,the problem with no feed to the gas valve is now ok,i have 28v. but i have one fault left to sort out, when i switch on the power the main boiler ignites and the orange l e d comes on with the fan at full speed with the main control nob in the middle position, any thoughts ,but aleast we are getting there all thanks to your bursting brain full of knowledge on boilers,jim.
top left overheat cut off 100 deg c ferroli pt. 801240
top right frost stat (not sure what its marked but should be open circuit, unless you've been keeping it in the freezer) 800180
bottom right heating limit stat 88 deg c 800160
middle hotwater limit stat 80 deg c 801000
top right frost stat (not sure what its marked but should be open circuit, unless you've been keeping it in the freezer) 800180
bottom right heating limit stat 88 deg c 800160
middle hotwater limit stat 80 deg c 801000
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