Alpha Oil Boiler lockout intermittently

4 Sep 2012
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United Kingdom
Hi I have an Old (1992/3) ALPHA range / boiler - its has two ecoflam minor 1 Boilers - I had fuel oil delivered the other day and the next day it locked out. I reset it and after about 1-2 hours it locked out again.

The boiler goes through its cycle and heats the water and every so often when it tries to fire up it will not start - There is a low humming noise then it locks out -

So far I have done the following:

cleaned the filter near the tank - it was very crudded Up probably never been cleaned in years
changed the pump filter - again this was blackened
bled the fuel pump - some air bubbles came out but all good now.
taken the photocell out and cleaned it

None of this has stopped the intermittent lockout.

I have tested the starter capacitor - it was supposed to be a 3.5uf capacitor but there was a 4uf capacitor in there - The reading was 3.25uf so I have ordered a new one just in case.

The solenoid was changed about 18 months ago and I can here it click etc so don't think its that.

I think I have pretty much exhausted everything I can garner from the internet etc

does anybody have any other ideas that I can try or is the next step an engineer.

thanks in advance
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New capacitor fitted but still intermittently locking out - done everything I can do so will call an engineer out
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How intermittent and does it start everytime before going out to lockout? If the latter, have you bled the oil line thoroughly by running off 2 -3 litres ?
Does the cooker burner still run unimpeded?
Hi - I have not bled the oil line so I'll have a look at doing that.

The boiler runs sometimes for several hours stopping and starting whenever there is a call to heat. However on occasion it fails to start - You can hear a low humming sound as if the blower (?) is trying to get going but it doesn't and it locks out - pressing the reset button its starts 98% of the time. I used the cooker yesterday for several hours and no lockout on that - ( I did think initially that maybe the oil was waxy or something due to the very cold weather) its a different burner though. I called an engineer yesterday but waiting for them to reply.

The only other thing that I can change is the solenoid stem valve in the Danfoss pump - would a sticky solenoid valve cause these sorts of issues? It's frustrating as it works fine for hours and cleaning out the filter by the tank and replacing the pump filter I thought that would solve it. The capacitor was weak so that was replaced but still issues. Doing anything more is outside my comfort zone.
If the motor hums it sounds like it’s trying to spin but can’ you’ve replaced the capacitor I think it's time to check the motor on the bench.
At the same time you can see if the oil pump has any tight spots. These aren’t high torque motors and one of my tests is to have it fixed to a bench and then switch it on whilst holding the shaft, trying to stop it spinning.
The valve you mention in the pump is worked by a solenoid but it only switches the oil on ready for ignition. This is typically up to 8 sec after the motor and fan have started - its called the purge cycle.
John :)
Thanks - I think pulling the burner out from bottom of the range is probably a step too far for me. I'll mention it to the engineer when we get one
Final update - new pump fitted and no more lockouts - the motor seemed fine and smooth, the pump had a little resistance so went with that- They are both original 18-19 years old - so to be expected I guess. Never had Oil boiler before always gas but I learned a hell of of little about them in trying to get to the bottom of it.
Thanks to everyone who helped - burnerman , oilhead
You had oil delivered so prob stired up crap and into pump if it’s fine enough it’ll go and goose the pump also change the nozzle. Bob
yeah nozzle was changed at the time - although it looked quite clean better safe than sorry

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