Burner Lock out (Still)

13 Feb 2021
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United Kingdom
Had a few problems with my dads central heating just after Christmas.
It was working fine, ie coming on/off on two timed settings each day with no problems.
Just after Christmas i popped in to drop in some shopping and found it had not fired up that morning. I pushed the re set button it cycled but did not fire. After waiting for the lockout to reset i tried again and it fired and run perfectly. This then happened randomly every 3 or 4 days. We decided to get his normal guy out to look at it and after inspecting it, cleaning everything out it was decided to give it a full service and replace a fairly old oil pumpand capacitor at the same time.
All went well. Parts Fitted, Danfos pump, New Nozzle and capacitor. He then went on to set everything up until he was satisfied with his readings on his tester, cleaned up and left.
All worked fine for around a week, then the same fault. It starts Second time, every time and runs perfectly until the next timed setting. The engineer has since been back and changed the magic eye and again, all ok for around a week then wont start on a timer ie 7am...
Push the reset Twice and it fires up second time....
Tank full of oil, new filter at Tank end , good fuel flow at Fire Valve.
Reading up on the set up, the only thing i can think it might be now is the Siemens control box that starts the sequence . Any one heard of similar problems ???
Boiler - heating World
Burner - Ecoflam Minor
Pump Danfos 071N7155
capacitor 4uf
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Is it only on first start that it fails to fire, or does it fail randomly over the day?
Just the first start of the day. I've been there waiting as the timer clicks on. Fan starts, 12 seconds then burner ignites, 10 seconds locks out.
Second try as above but after the burner ignites, (it sounds like) the solenoid clicks and it runs as it should. It will cut on and off with the room stat with no problems until the time period finishes. If I'm not there to push the reset button. The burner stays locked out.
Last edited:
Air in the system it gets dragged in then goes through on the second start. Bob
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Would that be air in the fuel supply line?
And if so, could some sort of non return valve be fitted?
You’ll just have to check the oil line and make sure all the joints are good. Bob
Thanks Bob. I did wonder if there was some sort of "fall back" on the fuel supply as it seems very strange it starts second time every time. The entry point for the copper fuel feed is slightly higher that the oil pump, therefore the fuel travels down to the fire valve then has to climb up towards the fuel inlet port on the top of the pump. I will get all the connections checked out.
Is the tank higher than the burner? If so, once bled you should have no problem with fall back. If however it is lower, then a leaking joint may cause fall back. Check that the filter has been reinstalled correctly.
I would say the tank is slightly lower, very little difference tho. There is very good fuel flow through to the end of the flexi hose at the the pump. I will get the filter and all the joints checked but the problem started before anything had been changed. The heating system had been running fine since last service in September 2020.
Although the tank may be lower, slightly, if the level of oil is higher than the burner, then if you are suffering fall back, it will be through a poor connection.
If the level of oil in the tank is higher than the burner, then if fall back is your problem, then it has to be a poor joint or other leak.
It may throw up a pointer or two if you switch off your boiler and leave it overnight and then check for oil flow. If no immediate flow at the burner connection, then your problem is with supply.
The other option is that the burner is overaired, and you are getting lift off.
Thanks Oilhead. The heating engineer did mention something about the the air when he was here last. I'm sure he said he could not get less air in as it was already set at its minimum setting. He is coming back to check all the joints at some point so I will mention that. Realistically it's the only thing that's been 'adjusted' since the new pump etc was fitted. The fuel line has not really been disturbed apart from the pump entry joint.
Thanks for your input
OK. I had a bit of time today so I've had a look myself at the fuel connection. Checked as you advised, the presence of oil in the feed pipe before starting the burner. Seemed very little unscrewing the inlet gland and only started flowing freely once I'd lowered the end into a container. Oil flow was steady and constant. No evidence of any air. I've the closed the tank stop valve and stripped out all the connections either side of the fire valve, resealed all the joints and opened first the tank then the fire valve. Small amount of air at first then clear, steady oil. Re connected to the inlet, switched on and it fired first time. I've left it all running and set for 7am tomorrow morning, fingers crossed
Nope... Still not working. Went round tonight and it was timed on, pump circulating but burner was locked out and had not started again... Loosing the will to live now

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