Riello RDB burning dirty

[BenTens]

I am having a bit of trouble trying to set up a second hand Riello RDB burner on a Rhino combi boiler. There was no instructions, so I phoned Rhino who instructed me on what Nozzle and pump pressure the burner should be set at for 26kw. I fitted a 0.75 80 ES nozzle and set the pressure at 9 bar as they instructed. The trouble is it does not matter how much air I give the burner it keeps burning sooty and I know I should not use my analyser but I needed to see what was going on with the CO2 and it stays at 13.6% regardless what I set the air intake at.

By the way I have serviced the boiler and cleaned everything out before doing any tests. I have also checked the air intake and the flapper is moving in and out, so it seems to be working. Any ideas what to try would be a great help? Thank you very much.

 

[leakydave]

Is the rubber seal on the air box intake intact? I have seen a boiler with the seal missing pulling in extra air and throwing combustion readings out.

 

[Agile]

But this one seems as if it has inadequate air!

Is that 9 bar pressure really correct?

 

[muggles]

But this one seems as if it has inadequate air!

Is that 9 bar pressure really correct?

@Agile Or possibly too much air 9 bar isn't unusual, why would you think it might be wrong?

OP - do you have the correct blast tube for your nozzle?

Did you thoroughly flush out all the oil pipework on the burner prior to using it? If it's second hand you don't know where it's been or its history and there could be muck in the lines which has now got into your new nozzle

What nozzle was in there originally? If the blast tube is wrong that can cause it to smoke. Is the new nozzle working correctly? Always worth trying a second one just in case the first was faulty - does happen.

 

[oilhead]

My guess would be blast tube. Does yours have the rear brake plate behind the diffuser plate (Mickey Mouse Ears)? A .75 nozzle at 9 bar needs the trumpet shaped blast tube with only the single diffuser, but I would not discount a problem with the boiler. Is it clean, and is the flue clear and unobstructed.

 

[Agile]

Did you ever see it working before you bought it?

If not was there evidence of sooting in it?

Do you really know how it came to be replaced?

I an always suspicious of second hand items!

Unless they are pretty new and all the parts are available.

We see a lot of posts about used things which turn out to have some obscure fault which cannot be fixed.

 

[Terrywookfit]

Did you ever see it working before you bought it?

If not was there evidence of sooting in it?

Do you really know how it came to be replaced?

I an always suspicious of second hand items!

Unless they are pretty new and all the parts are available.

We see a lot of posts about used things which turn out to have some obscure fault which cannot be fixed.

All parts of a RDB burner are readily available. As previously stated It will be a wrongly configured set up!!

 

[oilboffin]

First set the oil to 105 psi air to 41/2then try it make sure the fan is clean and free to spin
You should only buy a used burner if you know what you're doing.Bob

 

[oilboffin]

Don't talk to rhino phone up riello they'll set you right.

 

[BenTens]

Just thought I would update you all. By the way it is a second hand Rhino boiler, not a second hand burner. I took all your suggestions in to consideration. As I said before the burner is supposed to run at 26kw at 130psi with a .75 80 ES nozzle. I tried the maximum air and dropping the pressure down to 105psi which helped, but only slightly the CO2 dropped from 13.6 to 13. I tried removing the restricter plates and even changing the complete air box, which also made no difference. What eventually worked was when I dropped the nozzle size down to a 0.55 80 ES, set the pressure at 125psi and air intake at setting 5, and I get 11 CO2 now with no smoke.

I tried phoning Rhino too about setting it up for 0.75 nozzle, and if the blast tube is right one for the burner, and they just hung up on me, because they had no idea. I phoned Riello and it was a call back service.

Anyway thanks for your help. If any of this gives you a better idea of why it would not work with a 0.75 nozzle please let me know. I would love to learn what it could be for the next time I run in to this problem.

 

[Agile]

Yes, that Rhino, hard of hearing and likely to charge!

 

[Burnerman]

Ben, a burner is a burner and can be configured in every way......are you convinced that the blast tube is the right one for this boiler like the others have suggested?
They come in various lengths and profiles.
John

 

[Burnerman]

Duplicate - sorry

 

[oilhead]

You have reduced the burner output, so that the fuel input is matched to the air it is getting . As stated before by several of us, the combustion air is restricted by the blast tube, or flue restriction.
Is the flue a conventional chimney, open flue horizontal, or a balanced flue? Where have you removed the restrictor plates from?

 

[Agile]

Or in general terms, combustion is designed around the size and shape of the air inlet, blast tube and flue.

If any of the parameters or components are varied then the combustion characteristics may no longer be correct.

The maker will list the possible variables that they allow which will operate correctly.