Oil heating engineer advice ?

[oneshot1979]

Any lads in here heating oil engineers ? 

Could really do with some advice/help with a Worcester Bosch Heatslave problem.

[aga man]

I work with oil boilers, what problems are you having?

Pm me if you prefer

 

[oneshot1979]

Thanks for replying, it's a bit of a tale but here goes.

Started having problems with fuel running back overnight, used to get home of an evening, quickly bleed it it at the pump, hit the reset and away it went, instantly ignited and ran honey sweet. Hot water all night for showers etc.

Decided I'd better sort it out so, had a quick look, braided flexi hose inside cabinet appeared to be loose on the crimps so ordered up a replacement and fitted it, cleaned out the tank and pump filters at the same time. Put it all back together, bled pump, press reset, starts, fires, runs, locks out. 

Fault code on box translates to "stray light"

Had a quick look at the photocell, decided "sod it they're cheap I'll fit a new one, same fault. 

Missus is grumbling by now after 3 days of no hot water, calls on a buddy who does oil, convinces me I need a new nozzle, Ok, new nozzle ordered and fitted, same fault.

Quick phone call, maybe the new photo cell is faulty too, not convinced, but order a 2nd new photocell and fit, same fault. 

"Ahh, Must be your control box"

"But I only changed a hose and cleaned, filters"

"These things happen"

Order and install new box, same fault.

Buddy comes to visit, 2hrs of sucking teeth and drinking tea, "maybe the new nozzle is faulty?" 

"Really ?"

"Gotta try it"

Removes teacup from hand, kindly thanks "buddy" for a great game of parts darts and stomps off to order more new parts.

So, with wallet stinging and ears ringing, I,  strip out burner, clean out pump and check drive, strip out pressure pipe and blow through, remove manual shut off from nozzle holder and clean, clean nozzle holder, install 2nd new nozzle, reassemble burner, confirm correct nozzle and igniter location against manual specifications. Ensure photocell line of site not obstructed.  Wipe down photocell, check fan motor bearings and confirm motor winding resistance within tolerance. Test fuel solenoid coil resistance. Test continuity of loom between photocell and control box. Test all connections and terminations of control box. Check 240v supply to control box.  Check flue intake and exhaust for obstructions, clean main burner baffles and check condenser baffles. Check all temperature manual reset trips for correct circuit operation. Bleed pump into bottle. Confirm good flow, set pump pressure relief valve to 115psi as per manual. Reassemble burner into boiler.

Deep breath, press reset, fan starts, igniter starts, coil opens, oil present, flame ignites, good clean bright yellow flame, igniter cuts out, flame goes out, system locks out. Arrrggghhhhhhh.

Retry with photocell removed and kept dark during purge process, shining torch onto photocell as soon as flame established, still locks out.......

What am I missing ???????????

 

 

 

 

 

[aga man]

Riello rdb burner?

[johnsyboy1974]

Have you got a vacuum gauge? if it goes negative the supply line is the issue. Does the pump pressure (at115psi) alter just before lock out? Does it stay lit long enough to get a combustion sample with an analyser? Make sure your head settings are right too (should give you details in the manual). 
hope that helps 

[oneshot1979]

Burner is a Sterling 40, 

Fuel supply has been double checked, primed right through, filled a litre jug for an oil sample. Pump pressure doesn't fluctuate. Doesn't run long enough to get an accurate reading from analyser. Head settings have been checked and rechecked. Air flap setting untouched since initial install many years ago, but have been checked against manual to confirm.

I have gone so deep into this, what bugs me is it was perfect before I cleaned the filters and put the new fuel line on. I've checked, rechecked, and rechecked my rechecked initial work and cannot see anything wrong.

[Yellow Bear]

Did you check the bore of the replacement hose?

[oneshot1979]

Yup. Removed and tested flow. Also put under vacuum to check against wall collapse.

[aga man]

So that burner would indicate it is not a condensing model.

If it is a single oil pipe system (no tigerloop) then,

To my mind, if you can confirm good flow of oil & no water in oil then the oil pump is at fault, or at least the solenoid stem.

For what they cost I would just replace the pump (which comes with new solenoid)& set pump pressure accordingly.  Flue gas analyser would be good thereafter.

Appreciate you have already thrown money at it but wrongly advised by the sound of it.

[johnsyboy1974]

I agree with the pump solenoid failing. Hope you get it sorted quickly 

[oneshot1979]

Update 

Took advice onboard and removed pump for testing, coil resistance OK, energised coil for 25 seconds and took 2nd resistance reading, OK.

Stripped off filter cover and pump gear cover plate, visible wear between pump shaft, drive plate and gear, but other than that pump itself looked good. Sod it, new pump.

Installed tonight, bled, pressure set, turn on, purge, fuel, fire, count to ten, eleven, twelve, twenty, a full minute, we have hot water, small happy dance in the dark. 

Thank you to all who offered advice.

 

 

 

 

[johnsyboy1974]

Well done, glad you got it sorted

[scolopax]

Always the last thing you try!