warmflow riello rdb3 burner kicking out black smoke

[mojorisin]

One for the oil boys ( or whoever )
Had problems with the loss of pressure for a start, put that down to slight leak on the plate heat exchanger, got that sorted then saw the expassion vessel had water dripping from the bottom. Did a bit of research, thought the diaphram might be knackered, pressed the shreager valve and water ****ed out so changed the EV. Boiler worked for a while then conked out again, no oil getting to the burner so checked and sorted the flow of oil- boiler started, and all looked good until gradually black smoke started coming out, thought maybe some crap had got into the burner nozzel so changed that like for like and still the black smoke! any ideas anyone?
Would altering the gap of the electrodes at the nozzel cause black smoke? any help would be good . Cheers
Ps this is a warmflow 70/90 kabin pak boiler situated outside.

 

[dontknowitall]

It sounds as if the oil pump has failed. Before changing it's worth checking the pressure. When was it last serviced? They should be done about once a year. I'd do a service before I started looking for specific faults as during a routine service you can often find one or two things that aren't quite right.

 

[pmac10]

black smoke would normally mean too much oil and not enough air flow. altering the gap at the electrodes shouldnt cause this, just probably wouldnt fire but have seen a build up on the diffuser cause the electrode to short to the flame tube and cause an explosive ignition with smoke to accompany, just a few thoughts but there are a few more experienced oil guys on here who could better advise.

 

[dontknowitall]

As an extra ... (and it's free!) ...

I was taught the electrodes gap is signficant for the secondary burn. The main part of the flame (primary burn) is caused by the electrodes firing the spray from the nozzle. The electrodes stay activated to burn the part of the spray nearer the nozzle and this is why they and the blast tube need to be set at the correct distances.

If the secondary burn is not efficient then it usually means not all the oil is burning (only the front part of the spray and not the rear). The sympton is you cannot obtain the correct CO2, although you can get within 1% or so of the correct reading.

 

[pmac10]

further to what dontknowitall correctly says, there is no reason to change the electrode gap whatsoever, its set in stone in the burner manual. if changing a nozzle, check the gap first and again after. 4mm allen keys are handy.

 

[mojorisin]

Thanks for that lads... got a proper oil chap coming tomorrow to look at it. A bit technical for a chippy who can just about change a tap washer!

 

[dontknowitall]

You're doing yourself down. Not many people know how to change a nozzle, let alone what one is!!

Hope all's cured before Christmas.

 

[pmac10]

dontknowitall, surely youre not saying the electrodes stay activated after ignition??

 

[dontknowitall]

They don't stop energising as soon as there is a flame. (Admittedly I've just had to look up my notes on this ...!!)

For example, on a Satronic 832.3 control box there are 4 stages in the sequence - Pre Ignition - Ignition - Post Ignition - Burner Running. The electrodes light the flame at Ignition and stop energizing at Burner Running, once the flame is established.

I'm sure you knew that though!!

 

[pmac10]

exactly mate, as soon as the elapsed time for the photocell to establish a stable flame and if a flame is detected but fails, try again etc