Danesmoore 20/25 driving me mad

[Rolandb2025]

Hi all.

I hope you guys can shed some light to my issue. We got a Worcester Danesmoore 20/25 oil central heating boiler. It was here 4-5 year ago when we bought our house. From day one we have constant battles with the boiler which was always boiled down to either the photocell or the control box.

The last couple of months every time the timer kick in or we manually switch the boiler on, upon purge it’s goes into a lock out. This happened before but after 2-3 attempt always fired up and run for a number of days without the issue reappearing.

Lately if it’s start it’s run for 10-15min and goes into lock out as soon as the boiler re fire to maintain the heat. This is where it’s gets tricky. The boiler will NOT start until I leave it to completely cool down for a few hours or leave the door open outside in the utility for 30min to an hour.

The control box is new( I have 3 brand new in a box) the photocell is new and before anyone ask I even replaced with a new one as I try to stock some

When I removed the burner to check and to run it outside I noticed that on the second run there is NO spark. It’s seems like that once the boiler run a 10-20min cycle it’s doesn’t allow sparks until it’s cooled down. ( the oil is always tidy and comes out but the ignition won’t start)

I tried every method to resolve it but apart from keep changing parts,control box, photocell, double check working etc I end up against a brick wall

The wiring never been touched and the boiler just got to this stage gradually over the years. Also the boiler been serviced last year but even the plumber is getting fed up at this stage

Also on the after the first run when the control box goes into lockout, after pressing when the pre fire purge starts it’s just clicks rather than fire up and lock out after like 2-3 sec



Any ideas would be helpful as I slowly loose the will to try…

 

[Burnerman]

It’s probably a good idea to wait for someone with a brain cell to come along, but do check out the ignition transformer....occasionally a failure here will take out the control box at the same time.
Look out for any swelling on the transformer which may indicate winding failure.
John

 

[oilhead]

What burner are we talking about, and is it down firing from the top or horizontal from the front?

 

[Rolandb2025]

Hi it’s a b11 burner. It’s horizontal front fire

 

[oilhead]

No spark is indicative of either photocell fault, faulty transformer or control box.
When the spark fails, after checking the electrode connections and leads, disconnect the transformer lead and check for voltage at the plug. If there is no power then you've probably found the fault. To reinforce your diagnosis, isolate the burner, remove the control box and transfer the transformer lead to the live feed to the base. Switch back on and the transformer should spark. If it does not, but there is power, then problem solved. If there is no power, then suspect faulty photocell. When restoring the connections in the base, disconnect the photocell and try start up again. If you get a start and it lights but cuts out after 5-10 secs, then faulty photocell. If still no spark then probably failed control box.