Riello 40 problem

zuluman

HI all,

Riello 40 with following problem:

OLD nozzle produces near proper shaped flame, a little dispersement. and some shooting stars.

NEW nozzle (exactly same as old one re size, angle) creates dispersed, irregular flame with shooting stars.

When I fire the burner outside the boiler with new nozzle, the shape is good but has the shooting stars. Also some diesel is not being burned (prob that from the stars) as a small amount of diesel accumulates on the floor after firing for some minutes.

Oil pressure is 12 bar. Combustion head and air intake is set to manufacturers recommendation for nozzle size and was not changed between nozzles.

New nozzle is clean

There is no fuel filter on the oil line. I have not opened the pump to inspect its filter (if it has one?)

Any ideas for (A) the difference in flame between the nozzles (B) curing the shooting stars

Billy Bunting

A little more info on the size/angle of nozzle would be helpful, but just as a start i suggest if you dont have a fuel filter on the oil line do open the pump and inspect the filter there, without a oil filter at the tank you will without doubt have problems there.

DGOBS

1) fit a filter, yes there is one in the pump but a filter less than 70 microns should be fitted to protect the pump
2) firing the burner out of the boiler tells you NOTHING as there is all that secondary air available so the flame picture cannot be set this way
3) if you have a poor flame shape and its not due to impingement, then maybe you have a duff nozzle or you fudged it with a finger (never touch the oriface or filter of the nozzle, handle sides only)
4) you burner should be set using a pressure gauge, smoke pump and flue gas analyser, setting by eye is not recommended as you will never get it spot on (and fuel ain't cheap and CO does not play well with humans)
5) replacing a nozzle without adjustment is not recommended, there is a +/- 5% tolerance on nozzle manufacture so pump and air pressure adjustments may well be required
6) finally firing a burner out of the boiler is dangerous and may result in serious damage to persons or properties

zuluman

Billy Bunting wrote: »

A little more info on the size/angle of nozzle would be helpful, but just as a start i suggest if you dont have a fuel filter on the oil line do open the pump and inspect the filter there, without a oil filter at the tank you will without doubt have problems there.

2.5 USG 60 degrees. It is in a local voluntary organisation heating a large hall. I help out there. I suspected that with the dirt in the pump. The filter of the old nozzle was dirty. Just did not get to take the pump apart yet. I will also clean out the line from the pump to the nozzle head.

Also noticeable is when the burner switches to high flame it opens the air shutter (controlled hydraulically on these models) with a slight jolt. Don't know if this is normal on these models or a result of dirt.

But would the dirt be the problem as the old nozzle has an ok flame shape. Could it be that the old nozzle being possibly worn (larger orifice) still produces an adequate flame even with dirt, whilst the newer one being not worn is maybe having a problem with the dirt? what do you think?

maybe you have a duff nozzle or you fudged it with a finger (never touch the oriface or filter of the nozzle, handle sides only)

In your experience, do you often come across bad new nozzles?
Have you ever had recourse to return it to danfoss for testing?

I was careful and did not mishandle it.

you burner should be set using a pressure gauge

It is at 12 bar. Adjusting it up or down does not have any noticeable affect. I adjusted it up and the needle on the gauge started fluctuating real fast - do not know if that was the gauge or something else.

even noting your claim of the 5% tolerance, I have changed the nozzle in this before without having to change the settings. This nozzle's flame is dispersed (when in the chamber) and displacement is mainly in near the blast tube. It swirls outside the tube and then the flame breaks and swirls again (whilst the main part of the flame is present).

setting by eye is not recommended as you will never get it spot on

True - but the flame should be a lot better than it is even with just eye measurement.

One other thing I am wondering is could the problem with the flame be back pressure?

I have a Co2 wet tester (belonged to my uncle - deceased). Need to read up on how to use it. Anyone know where I can obtain the absorption fluid for these co2 readers? according to the manual it should be changed. wasn't changed in probably many years.
Thanks

DGOBS

wow, wet kits......looong time since I used one, electronic analysers are the flavor of the day.

Yes have had a few (too many) duff new nozzles, but at €5 I never returned them
As for the manufacturing tolerances, I don't make 'claims' I refer to the manufacturers specifications, i.e. it's what danfoss says, not me

As for your flame picture, over aired, impinged, incorrect electrode setting, blast tube or swirl ring position, at 2.5us/g it's a commercial boiler, if there is back pressure you would normally see deterioration of the blast tube leading edge (corrosion)

As this is 2 stage, I assume it's a G10 or larger R40

Really thee is not a huge amount of advise more I could give you here without seeing the issue myself to make a judgement.

With regard to it's location, I hope you carry the correct insurance etc to work on it!
If you are still struggling, go to oftec.org and find you nearest qualified technician to help, this is not a DIY job

zuluman

What part of the country are you getting nozzles at €5?

I have paid 8-12 inc VAT

I assume it's a G10 or larger R40

G20s

As for your flame picture, over aired, impinged, incorrect electrode setting, blast tube or swirl ring position, at 2.5us/g it's a commercial boiler, if there is back pressure you would normally see deterioration of the blast tube leading edge (corrosion)

Do you mean by impinged that the flame is too log or wide for the chamber? If so, it is not this. I have checked the other settings without success and returned them to the manufacturer's settings, which is how they were originally set and functioned fine with the old nozzle, which I also fitted from new about two years ago. I will check the air again but I don't think it is this. Will also look into the dirt issue and maybe fit a 2USG with its correct settings and see if it produces a satisfactory result. If I could get the absorption fluid for my tester, I could obtain an exact reading.

From personal experience, I will be avoiding any oftec so called technicians around here. I am sure there are good oftec technicians and even better ones without any oftec qualification.

DGOBS

Impingement would be too long wide etc, but even the electrodes can impinge into the fuel stream if incorrectly set and distort the flame

Newbie techs can be a handful, but old steady hands aren't!

Get your burner parts at www.hwos.co.uk (roughly 4.30 incl vat for a nozzle)

One other possible issue is fuel quality, draw off a bit into a glass jar and check its turbidity.

Remember, manufacturers settings are only a guide, not fool proof, it's a start point then set to suit site conditions. drop your oil pressure to 10/10.5 bar and drop the air too, slow eveything down a little, then work from there. If ever a nozzle gives a poor flame pic, change it.

You also mention a fluctuating gauge, either a pump issue or not enough fuel, maybe a pump filter or pipe blockage, check the pump vacuum to confirm

DGOBS

Knew I had this somewhere, just had to find it....from Danfoss

Why “shooting stars” in the flame?
It was the Chinese who first discovered that powdered carbon added to firewords produces certain effects and ever since, the sparkle from the little carbon particles when a firework is ignited has delighted everyone. Not so pleasing are the “fireworks” that occur in the combustion chambers of many oil-heating plants. With bad atomizing, the oil mist will contain such large drops that before the drops have a chance to evaporate, they will crack and produce the small carbon particles and the “shooting stars”. Unfortunately, this process produces much mess in the boiler and should be avoided. The large drops will not all be completely burned and gradually the heating surfaces and boiler floor will get covered with a mixture of soot and coke which will ruin the heat transfer, so leading to poor operating economy. Shooting stars in the flame when there is a large volume of excess air will be evident from a soot test, for the soot paper will show yellowish-brown spots from the unburnt oil.
Shooting stars in the flame can come from:
• Too low an oil pressure. • Defective combustion head, or possibly a defective nozzle. • Oil too thick, (too cold?). • Too much excess air.

Hope that helps.......

zuluman

Hi,

thanks for your help so far. I have that booklet from Danfoss and read the section about 'shooting stars'.

I think the dirt either in the fuel or accumulated in the pump or both is an issue. Even if it is not the cause of the problem, there should be a fuel filter.
The boiler is a Robin Hood from 1971. It WAS fitted with a large nu-way or selectos (but I think nu-way) burner. I think this burner had a fuel filter mounted as part of the the burner (from recollection somewhere near the pump or even on one of its ports). Of course, the guys who fitted the Riello didn't bother fitting a filter to the oil line.

the bit with the fluctuating gauge has me bothered too. I reckon there is lots of dirt in the pump. there is enough fuel.

Anyway, I will take things apart and put on the wet kit to see what I can find out.

I used to help my dad service boliers from when i was about aged 8 until 20. I am a little rusty on it now though.

But I won't let it beat me. will report back if I have success.

DoneDL

If the pressure gauge is jumping consider air being sucked in, blockage in the pipe or take the pump off and see if there is a problem with the drive shaft coupling.

zuluman

Today, I took a sample of oil out of the oil line. Whilst the diesel is clear, plenty of muck came out too and settled in the bottom of the jar.

Thanks to no fuel line filter, all this lovely muck is going straight into the pump.:mad:

More to follow ...

DGOBS

Sounds like your tank may need disludging ......have fun...

zuluman

Sounds like your tank may need disludging

Is there any chemical or similar that can aid in desludging?


Dismantled the pump, cleaned it and put it back together. dismantled lines to nozzle head and cleaned. Pieces of dirt at head.

Put all back together. All working but will need further investigation.

Pump filter.

Before:



After

.243

pm sent

Billy Bunting

I hope you've learnt the basic rule of fitting an oil filter on the fuel line and not relying on the pump filter because you will be filling it with ****e after each fill whether or not you clear it now.

zuluman

Billy Bunting wrote: »

I hope you've learnt the basic rule of fitting an oil filter on the fuel line and not relying on the pump filter because you will be filling it with ****e after each fill whether or not you clear it now.

I already knew it.

The lazy so called professional gob*** that changed the old nu-way/selectos (which had a filter on it) for the riello because the nu way presented too much work for them and they didn't want to get their hands dirty, either didn't know or were not bothered to inform the owners.

In and out as quick as they could.

They had no problem presenting the bill though.

Recently, A local church called in an electrician because the heat did not come on. What was wrong? The power had been off. The clock was 3 hours slow. The heat came on 3 hours late - thats all. The priest didn't realise this.

The professional either does not notice the clock is slow or does not want to. He also did not 'notice' that the clock was working (you could even hear it) . No, he installs a new one and presents his bill. All this only came to light afterwards. Chancers that think they are really IT :mad:

Anyway, looked again today and the the pump filter is already collecting a little dirt. Owners will have to fit a filter

The flame produced by the 2.5 USG nozzle is still bad. Irrespective of air adjustment, head adjustment or pressure, the flame is s****. tried a 2.0 USG but it has a 80 degree spray and is sooting the balst tube. The flame isnt great either. The chamber is a bit narrow for the 80 deg me thinks - about 40cm wide (between the bricks) and 1m long.

The stack temp is 650 deg F.

Might try a 2.0 60 S or a Hollow.

The old 2.5 nozzle is the best. For the learning experience, will see about returning the 'new' 2.5 to danfoss for inspection .