WB Oil Boiler Lockout but not with covers off??

2 Apr 2018
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United Kingdom

I have a Worcester Bosch Danesmoor Front Service (FS) 18/25 oil boiler.

It has started to lockout after it has been on a while but the lockout reset buttons (on the front panel and the button of the control box) do not reset the boiler..

The only way to get it going is by switching off the mains supply to the boiler.

However I have noticed that if I leave the front and top covers off the boiler it does not lockout.

Does anyone have any idea what this might be? the WB Support line were no help whatsoever.

I have seen this referred to on another posting but not the reason.

Many thanks
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there is a autore-set high limit thermostat. its in the manual.
check circulation? covers off may be helping as there's little insulation on these buckets.
to big for load?whats it heating
I don't think it's the auto reset as the demand indicator stays on (the manual says it will go out).

I'm not sure what you mean by check the circulation. The system has recently been cleaned out (due to having a pipe leak).

The boiler is just being used to heat a house, fairy large system, equivalent of 17 rads (counting doubles as 2).
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Do you have to press the control box reset? If not, then the high limit stat is favourite, but until you test the circuits, you cannot give us any useful information
Pressing the control box reset did not restart the boiler. I had to switch off the power to the boiler to reset it.

I have not had a fault that required this before (and I have had a few!).

I am still getting this problem

It has started to lockout after it has been on a while but the lockout reset button under the front panel does not reset the boiler.

I have to press the red button on top of the control box (to reset the control box?)

Then switch off the boiler via the timer controls.

And then it will start up

However I have noticed that if I leave the front and top covers off the boiler it seems to help and reduce the lockouts but they still occur.

Does anyone have any idea what this might be? the WB Support line were no help whatsoever.

Is something over heating?

Many thanks
Sounds like you are not actually getting lockout at the boiler if you have to turn the power off to reset . Turning the power off does not reset this boiler, it always requires a button to be pressed. Most likely cause is a partially seized port valve or lazy syncron motor
Hello all and thanks for your comments.

I have a bit more information on this fault.

The pump in the system was on it's lowest setting of 3 (No.1) and so I've put it on No. 2.

It also drives a coil in the hot water tank and a plumber I had a year ago restricted the flow by closing up the tap feed and so I thought this might be causing the boiler to overheat if the flow was slowed. I have fully opened the tap.

The system seems generate a lot of gas as I hear burbling in the morning and a radiator almost above the boiler needs frequent (weekly) venting as the very top of the rad is cooler.

Could the boiler be boiling the water into gas?

But I still have the problem. It locks out more if I put the top and front covers on with the top cover having the most effect and if that is on the lock outs occur more frequently.

I have been reading about the Control box (Bentone Satronic DKO 970) and the codes it flashes when a lock out occurs.

When the lock occurs it flashes: On continuous- Long flash- Long flash-Long flash-Long flash-Short flash- Short flash-Long flash-Long flash-Long flash-Long flash-On continuous and repeats.

The only way to restart the boiler is to press the lock out button on the inside front panel or red button on top of the control box (both are in parallel I think) and then switch off the power to the boiler and then switch power back on.

The information about the control I have found does not seem to say what this flashing code means.

Does anyone know what this flash code means?

I am considering calling out Worcester Bosch and paying their high fee for a callout!!

Many thanks.
just call a local engineer to come and look at it. but the code you have given is not correct as this control box doesn't produce that code.
this box only produces 3 codes.
Sequence: illuminated phase dark phase Flash-Code dark phase ❘ ❚ ❚ ❚ ❚ for 10 sec for 0.6 sec for 1.2 sec Error diagnosis Error message Flash-Code Possible fault lockout ❘ ❚ ❚ ❚ ❚ within lock out safety time no flame establishment stray light ❘ ❘ ❚ ❚ ❚ stray light during monitored phase, detector may be faulty Flash-Code for manual lock out manual/external lockout ❘ ❘ ❚ ❚ ❚ ❚ ❚ ❚ ❚ ❚ .

Most likely fault you have is a boiler that is need of a good service. leaving the case off should have absolutely no effect on this boiler as the set up is normally balanced flue.
The most common component to fail on these is the pump solenoid followed by the motor coil becoming weak
Well, my local guy who services the boiler every year says that unless it fails while he is there he cannot fix it and I need to wait until it fails completely.

The boiler has a chimney and not balanced flue and putting the covers back on definitely makes it worse.

I am 99% sure I have the flash code correct. Is it sending two flash codes one after another?

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