Potentiometers-what causes them to need to be adjusted?

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I serviced a feroli optima (lpg)boiler today-first time it had been done for 7 years! DHW worked fine but CH would only get luke warm-gas pressure was minmum setting of aprox 7mb-checked thermistors-both gave the same reading and seemed ok,manual said increase gas pressure by turning up the p1 potentiometer on the pcb-i did this-had to turn it up to maximum to get the required 37mb max/7mb min and boiler now seems to be working fine,im was just wondering what is the cause of the problem??
 
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Other than the rads not getting hot enough when set on 7mbar (they would have eventually)


What problem have you got?

You have now increased the c/h burner pressure to max, hence the output of the boiler (Kw) so the rads will get hotter quicker,
it was probably set up on minimum setting for a reason.
 
Yes I agree, it has been range rated down for a reason, but maybe too far.

The data badge should tell you the power output at the minimum setting, is that suitable output for the poroperty? If it's lpg chances are it's a log cabbin or mobile home which would probably only require minimum setting, which could be as much as 11kw. Imagine putting 11 bars of a fire on in a small log cabin. Rate it according to property.

Sorry I haven't looked up the boiler but it isn't beyond the realms of possibility it has a byflow heatexchanger, so if it can't dump the power into the rads the heat ex will cook the hot water in there, and first time a tap is turned on someone will loose some skin off their hands.

The min max setting for hot water should not be affected by this adjustment, but initial surge of hot water will be rosting hot if heating isn't range rated down appropriately.
 
Property was a 5 bedroomed cottage-the hot water was allready set at 35mb pressure,was just the heating that wasnt up to the job,owner rekoned rads used to get red hot then over time they just got cooler and cooler untill they were hardly giving any heat out at all.
 
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The components on the system will all be ageing. That includes the springs and rubbers in the gas valve, the magnetisation of the solenoid coil, as well as bits on the pcb.

Resistors don't change with time, but capacitors can.
The susceptible capacitor types are "electrolytics", which are higher values, and often used for timing. They hold a charge like a vertical pipe holds water. Height of the water is voltage, diameter is capacitance (capacity, if you like). Over time the capacitance reduces, so it's like the pipe got narrower (furred up!). That means there's less water (charge) in the pipe, so it behaves as though it's smaller than it was. So times get shorter.
If this is one of the gas valve which is modulated by pulses, it's possible that the caps on the board have dried up a bit which would alter those controllng pulses from the pcb.
 
cjb1971 said:
I serviced a feroli optima (lpg)boiler today-first time it had been done for 7 years!

Electronic and mechanical components can all age and alter the operating conditions.

Thats why boilers should be serviced regularly and reset to the original operating conditions.

To those who slate the more economic boilers and say they only last two years, this is an example of an economic boiler which has run for SEVEN years without any servicing!!!

QED ( Except those who make those stupid claims didn't learn Latin ).

Tony
 

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