Oil Boiler Locking out

24 Mar 2015
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United Kingdom
I have a Trianco TRO boiler of indeterminate age that runs the heating and the hot water.
By and large it operates fine other that it keeps locking out.
The symptoms are : it will fire up and run off and on for perhaps an hour from cold. Then at some point the lock out light will come on. If I press the reset switch it may fire up again immediately but more likely I will need to press it half a dozen times before the pump will come on and then the boiler ignite. The boiler will always ignite after the pump comes on.
When I press the reset button and I hear and feel a slight buzzing I know the pump will not operate so I continue to press the blooming thing until it does. If the boiler is still warm from its last firing it is more than likely to require 6 or more presses of the reset switch. The boiler may then run for 20 minutes before locking out. If the boiler is cold one press of the switch does the trick and it will rum for an hour. I have never heard the boiler try to fire up unsuccessfully causing lockout (unlike a previous Worcester unit).
Any thoughts?
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If pressing the lockout lamp/switch doesn't cause the burner to start running immediately (taking into account it's reset time) it's possible that the motor can't spin the pump.
This could be due to a stiff pump, motor capacitor or the motor itself.
At first I thought it was going to be the age old solenoid coil problem which frequently fails when it gets hot, but not too sure with yours.
John :)
Thanks John,
My first thought it may be a solenoid problem - I had never considered the pump itself. But the fact that I hear and even feel a slight buzz when I press the reset and the pump doesn't come on suggests you may be right. I don't get the same buzzing when I press the reset and the pump does operate.
Aye it does seem that the motor is having a hard time Ian.
Is there any sign of swelling on the motor capacitor, or is it out of sight?
John :)
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At the moment I am not able to get to the boiler as it sits in the corner between a unit and the cooker - I will get the cooker out of the way and have a look - assuming I know what I'm looking at!

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