Worcester Danesmoor 26/32 oil boiler lockout problems

[huwnative]

Having lockout problems with a Worcester Danesmoor 26/32 oil boiler.

Past few days, boiler has been locking out. On resetting, fires up for no more than 10 secs, goes back into lock out. Have to reset 2-3 times before boiler fires up, will heat up until boiler switches off. Will have to repeat the process to get the boiler fired up again.

Have tested photocell, seems ok.

Done a resistance test on solenoid, I am getting a reading but unable to confirm whether fully functional until I can confirm the resistance range? Have contacted Danfoss requesting the recommended range, but not received confirmation from Danfoss.

Have changed capacitor, has made no difference.

Any further suggestions would be appreciated.

 

[Exedon]

Have you definitely got oil to burner?
Tried screwdriver inside coil when it should be working to see if there is magnetic resistance?
Don't keep resetting control box great way to make it fail!

 

[huwnative]

Thanks for the reply. Not checked for magnetic resistance, how is that done?

 

[Terrywookfit]

He means checking if the coil is producing a magnetic Field.
A steel screwdriver will hang for a few secs.

Coil resistance is a few K ohm.

 

[huwnative]

Just checked solenoid with the Danfoss magnetic tool, all seems to be in order with the solenoid.

Magnetic Tool

Detect faulty solenoid coils quickly and easily with Magnetic Tool

www.danfoss.com

Any further suggestions would be appreciated.

 

[Terrywookfit]

Check the coil resistance immediately after lockout

 

[huwnative]

Checked resistance immediately after lockout, initial reading was approx 0.023 but then quickly went up to approx 1.956.

 

[Terrywookfit]

Are you using an auto ranging multimeter
1'956or 2k is fine. was initial reading.023 meg 230k

 

[huwnative]

Using auto ranging multimeter

 

[huwnative]

Boiler lockout update. Replaced coil and coil stem, did not resolve the locking out problem. Done a resistance test on photocell, seems ok, checked oil nozzle seems clean, and changed within the last 2 years.

Possible control box issue? Any way of testing this to confirm?

Any further suggestions would be greatly appreciated.

 

[Terrywookfit]

Have you checked that the FZ is not seeing false flame during prepurge.

 

[huwnative]

Terrywookfit, thanks for your reply. I Have checked photocell for resistance, when open reading changes to light conditions and when covered goes straight to OL, so seems ok. Is it worth testing for resistance when photocell is in situ?

Since my post yesterday, have made further live tests on feed going to solenoid: Reading a steady 245v

Checked live feed going to photocell, settles at around 16.5v

Re-checked fuel nozzle, seems to be wet. Fuel not atomizing properly could be a problem?

 

[oilhead]

Does the burner cease firing before or after lockout?
have you checked for frozen or blocked filters?
Follow the logical steps in the fault flow charts

 

[huwnative]

Boiler update. Fitted a new nozzle, cleaned fuel pump filter. Seems to have resolved the problem, boiler not locked out now for a few days.

Thanks for all the suggestions.