Another Rayburn 499k Mx mystery

[ightenhill]

It's been a while since I posted because remarkably the unit has been behaving itself for a while.. But this week it's thrown a tantrum I'm struggling to get my head around.

Boiler side works fine.
Cooker side pump starts.. soft start click.. ignition.. sometimes it lights.. sometimes not. If it does light goes out and tries to reignite.

Blaster tube is replaced, new nozzles, pumps clearly fine.

Could it be a flu baffle issue just on the cooker side that's an issue..

 

[Burnerman]

These horrors do need clean flue ways - there is a fair distance of horizontal spaces before the flue, especially those fitted with Nu Way burners.
However, do check the photocell for cleanliness.
John

 

[ightenhill]

OK all flu ways and baffles totally cleaned out..

I have made some progress (of a sort) so if I describe what now constantly happens it may ring a bell.

So it now fires up as normal for usually between 40 seconds and 1 minute before losing burn. It then tries to reignite but fails. This leads to the ignition clicking off and the control box going to lock out. (have switched control boxes just to check it wasnt as simple as that).. Oddly even when the control box locks out the motor fan is still running. (I did suspect that perhaps the coupling was worn between motor and pump so the oil supply was not getting through consistantly but then why the almost consistent pattern to it failing and why is the boiler side running perfectly).

I do have a quick question re the solenoids. Why 2 between cooker and pump (the boiler has a startup with fan which is different) but I cant get my head around why it uses 2 on the cooker side.

ps photocell is fine - though the cooker side is quite a sooty beast however you can always see a visible flame burning away when it does light

 

[ightenhill]

Ok - Coupling and motor is fine (just relaised it has to be other ise the pump wouldnt be turning and the CH would be off)

All I'm left with is the Solenoids as I have now completely cleaned as best I can the Impeller (I would like to replace this) but how the hell do you remove these - with the grub screw undone I cant shift it a millimetre.

 

[Burnerman]

Does this beast have danfoss oil pumps?
Try swapping the solenoid coil with the boiler side one.
John

 

[Burnerman]

Please allow me to correct myself......does this have only one pump, bottom right and a bank of 5 oil solenoids?
It’s 10 years since I’ve seen one!
I’m sure there is a pressure switch somewhere that compares outside air pressure to that within the boiler.
The photocells must be clean and be able to see the flame.
I believe these things soft start at 100 psi for a while and then switch to 145 psi for normal running.
John

 

[ightenhill]

One pump and then the 5 solenoids - 3 seem to head off to the CH which is working fine.. 2 head directly to the oven burner .. The oven is the problem(it tends to light for 30 secs to 2 mins) ..Have ordered 2 new solenoids for it as it the only thing now I can think of.

Can't see how it's the PC or it wouldn't fire for a minute but I,LL swap them around and give it a go.

 

[Burnerman]

For sure, photocell issues usually show up at around 15 sec after ignition, and that's when the burner locks out.
So, you have swapped the control boxes so that should rule them out.
Have you considered backing the burner out of its housing a small distance and trying that?
I do recall, these things need a good soot clean every 6 months - even when the pressures and CO2 levels are correct.
John

 

[ightenhill]

Replaced both Solenoids on the cooker side today and that seems to have solved it....