Worcester Danesmoor 20/25 Intermittent lock out

So I return..... the boiler has worked fine snce last episode in June http://www.diynot.com/forums/plumbing/worcester-danesmore-rs-20-25-lock-out.405591/
Now after replacing Satronic control unit, ignition pack, pump and motor(yes I know cheaper to replace burner etc etc...). The boiler is quieter and fires most times. However sometimes it locks out, on reset the fan starts, ignition sparks then a comparatively long wait time before the oil solenoid clicks almost at end of timer cycle before lock out. On reset fires immediately. Is there a way of shortening the oil solenoid opening time ?

 

No, it is fixed by the satronic box. Have you checked for fuel blockage? Is the mixture too weak?
When running, what CO2 figure are you getting?

 

Seeing as you have already replaced the control box the first thing I would try is the photocell. Inexpensive part that does sometimes give a longer than normal purge phase.

 

I'll put me head on the block here and would prefer the experts to come in, but I use the TF 832.3 box instead of the 830.3......it has a shorter purge time.
Neither explain why the thing is locking out though!
John

 

Thanks fo rthe replies.
The boiler was working fine before the motor and oil pump replaced, its not a "burning issue" nor CO, its a delayed oil solenoid opening time, I will replace the photocell and report back......having said that, the photocell wont see the flame because the burner is not lighting so......it locks out. It appears to be a delay in the oil solenoid opening right near the "time out" limits for non lighting sequence and the boiler doesn't light. Other occasions its fine so its not lighting in 2 or 3 times a week.

 

I agree with comments on Satronic box purge times (or for that matter any othe make of control box) although box specs' vary, the boiler and control box must remain 'strict-to-spec' matching per burner manufacturer. Photcell detect period is strict to the box and does not affect any timings other than flame detection time while a weak cell can cause run-time lock out. Some larger control boxes do have crossover adjustment but that is way beyond a domestic d.i.y scope.

Within flame detection time, the valve opening is crucial to almost simultaneous ignition detection - we are talking milliseconds here at times and flame establish time has to be with the few seconds flame establish time allowed per the control box spec' before lockout occurs.

I suggest therefore to exchange the fuel solenoid valve, check if there is an upgrade spec' or improved valve.

A sluggish or 'lazy' valve will give the symptoms being described, they can be assumed to be working o.k when in fact they are millisecond(s) (albeit intermittently) slow.

Good luck

 

Using a volt stick or similar, does the click come as soon as current is detected or is it delayed? If you hear the click a soon as current is detected, then the solenoid valve is not faulty.

 

Mr Therm the pump is brand new complete with oil solenoid so I dont suspect sticking or faulty valve. It is the length of time after fan and ignition have started, it comes right at the end of the sequence just before lock out time. The previous solenoid /pump fired in a shorter time frame.

 

I think you are going down the wrong path here. Are you sure that the delay is not related to an ignition problem. Recheck the position of your electrodes. Make sure the distances are per the MI.

Also check that there is no shorting (electrodes too close to diffuser plate for example).

Ensure that the HT leads and connections are in good order.

Lastly make sure the transformer is doing what it should be doing.nDifficult too prove as there probably won't be any evidence that the transformer is faulty (usually trial and error proves this

Let us know how you get on

 

How long after the solenoid valve feed is energised does lockout occur? On a TF box, this should be 5 sec.
Take the burner from the boiler, disconnect the solenoid valve lead, and try starting the burner. You can then watch the spark and make sure it isin the right place. Have you removed the burner immediately after lockout? Is there any oil wetness round the blast tube? Is the photocell open circuit when no light? If not, this will inhibit the solenoid valve opening. Maybe you need to have it sorted out by a professional.

 

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