Vokera Syntesi 35 central heating only reaching 50deg

Tony,
I never asked for an educational essay, just some advice. I simply asked for any other likely causes as to the source of my problem, which of course there obviously are. The too low max temp?? I reiterate once again, the max temp fluctuates!! It has been sitting at 42 deg for the last 30 min. Yesterday evening it was at 37 deg most of the time but there were long periods when the temp sat at 50 deg. The temp control was at max to begin with before I tested it in different positions. The same issue is present regardless of the temp control knob position AND I have confirmed that the spindle moves the pot. I wonder what you do you not understand about fluctuating.
No doubt, you will insist it is still a faulty control spindle and I am not doing something right. You seem happy to throw your 'expert' advice at everyone and do so in a pompous, lordly manner and then try to waffle your way through with some ropey technical jargon, (is the control also pulse width modulated??). I notice that you have a similar tone in a lot of your other 'helpful' posts.

Kindly now refrain from giving me advice on this matter or any other posts I may place in the future. Whilst, in your opinion, my replies may discourage others from offering me help, no doubt not much can be done to encourage you to be a little more civil to those who use these forums for help. As Alan Sugar would say on The Apprentice - " You're Fired!!"

Gary :D
 
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change the primary thermistor. but for the cost you might aswell change the secondary thermistor at the same time.

a common fault when they reach 4 or 5 years old

Try this first, the cheapest option ;)
 
Tony,

The too low max temp?? I reiterate once again, the max temp fluctuates!!

Gary :D

The CH temperature should be able to be set in a range from about 50°C up to about 85°C. As I said before the actual temperature will vary downwards during normal operation as a result of the modulation time constants and the effect of anticycling.

If the temperature is not reaching the full value then possibly the NTCs have jumbed in value although thats not common or just possibly the track on the CH pot is o/c or damaged or there are other faults on the PCB.. Its easy to change the NTCs.

The temperature is controlled by an analogue supply to the modulation coil of the gas valve, not PWM.

Tony
 
Thank you all for the advice, I can see you have a very good knowledge of boilers and appreciate your help. I have managed to source a couple of sensors online for £8 each which is much better than jumping straight in with a new PCB! Will let you know the outcome.

Regards,
Gary
 
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When repairing boilers its important to deal with the most significant problem first and then when thats sorted out to retest to see if there are any other issues.

Thats why women can be very good at fault finding on boilers because they take a simple view first while the men are running round in circles looking at insignificant issues.

Your current major issue is the maximum CH temperature is way too low.

Tony
 

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