Help setting up old oil boiler

[Mjt1980]

Hi

Iv been called out to an oil boiler breakdown found the fault (fuel pump) Iv fitted a new fuel pump and got the boiler running again I checked the existing nozzle and found it was a 35sec nozzle I fitted another nozzle today but can't get anywhere near with the co2 reading the boiler is a 1980s heatmaster boiler the company is now bust with a selectos d42/a burner any help on correct nozzle size would be great Iv fitted a 0.50/60r with the pressure set at 140psi as this is the only information I can find.

Martin

 

[Mjt1980]

No one?

 

[SimonG]

Lower oil pressure and adjust air until co2 is good. Its an old boiler.

 

[Mjt1980]

Ok that's great I will try it on Monday

 

[Dotty]

Why do people still insist on working in psi?

Set it to 8 bar as LP inferred.

 

[SimonG]

Cant beat psi

 

[Best]

I still have some detailed info on the D42 Selectos burners, but not specific to that boiler.
If that burner has the adjustable blast tube diffuser, then that will add to the complexity of setting it up.
If it has the fixed one piece blast tube/diffuser, then should be straight forward using an analyser.
Dont worry if CO2 isn't much above 10%

 

[Mjt1980]

It is the adjustment head version it's my ppm that through the the roof

 

[TVP&H Ltd]

What is the output of the boiler?
What size nozzle did you remove?
Is it running on class C2 or class D oil?
Have you cleaned and made sure all the baffles are in good condition and in the right sequence?

There are still a huge amount still running class D (35sec) fuel.

 

[Mjt1980]

Hi it was fitted with a 35sec class d nozzle but is running on class c. Iv cleaned all the baffles and they back in right sequence. Not sure on the output as there is no information on the boiler.

 

[TVP&H Ltd]

What size was the nozzle removed?

 

[Mjt1980]

0.55/80 r

 

[TVP&H Ltd]

One issue could be you have changed the flame angle from 80* to a 60*. The burner was used for boilers in excess of 20kw. Swap the nozzle for a 0.8/80s set the pump to 140psi. Set the air intake at approx 1/3rd open then test.

None of the old manuals I have got list a nozzle smaller then that for this burner.

 

[Unregistered]

Ok that's great thanks for that I will give it a go tomorrow and let you all know

 

[Best]

I have an original Selectos burner instructions for a D42, which is 40 plus years old. But there are newer models also with adjustable flame ring.
The flame ring (diffuser, as I call it) distance away from front of blast tube is - Flush for up to .75 nozzles, then 1/16" out for .85 up to 1.0 nozzles.
The pump pressure for Kerosine on Thorn ODY boilers was 100psi for .65, 80 degree AR nozzle with a CO2 of 10%.
You probably need a S nozzle of 80 degrees.

 

[Mjt1980]

Right guys and update i have fitted another nozzle today 0.65\80 s turned the pressure down to 100psi the ppm reading have dropped but there still high around 600ppm the co2 was around 7.8% i have cleaned the boiler baffle ect but still can't get the ppm down to where i would like. Do yo think its worth running the boiler for a couple of hours and retaking a sample?

Martin

 

[WHPES]

Have you checked the flue for obstructions?

Has any oil dribbled into the combustion chamber, or has any soot got into it?

 

[Mjt1980]

Yes the flue is fine no problems there

 

[WHPES]

Is it a balanced flue model? If so, the seals between the air inlet and discharge may have broken down allowing combustion gasses into the air intake.

If not, try changing the position of the flame spreader in relation to the nozzle.

Your problem will probably be something to do with air

Also check fuel is not leaking from behind the nozzle. Sometimes the nozzle holder can be worn with repeated taking nozzles in and out, A couple of turns of PTFE round the nozzle thread will fix this.

 

[Mjt1980]

it's a conventional flue system I will try to move the flame spreader and see if that makes a difference.

 

[WHPES]

PS, high CO readings are either:

1) inadequate air supply (incomplete combustion due to insufficient oxygen)
2) Too much air supply (effectively "blowing out" the flame)
3) feedback of combustion gases into the air supply (Trianco Eurostar balanced flue boilers are prone to this as the seals in the flue can break down over time and need resealing)
4) Combustible material in the combustion chamber (such as soot either from a problem or after a flue has been swept) or oil which has dribbled into the chamber due to a fault on burner shut off, or a leak from behind the nozzle. This is why you should wait for several hours before final set-up of a boiler where the flue has just been swept, or a brand new boiler which may have oil from the manufacturing process still inside it, else you get spurious results.
5) fuel contaminated with heavier fuels or mineral oils
6) poor flame pattern from incorrect positions of flame spreader, blast tube and nozzle holder (or in the case of unmaintained boiler, build up of soot on the flame spreader, or worn out nozzle)

 

[WHPES]

Try the following:

Nozzle tip to flame spreader - 5mm

Flame spreader to edge of blast tube - 25mm

Just a hunch but worth a go

You want to be aiming at about 5 to 40ppm CO with 11 to 12 % CO2.

Another good idea is to keep hold of burners from boilers you have decommissioned. If you really can't find the problem, just whack another suitable burner on.

 

[Mjt1980]

Ok that's great that's a good tip I will start to keep back a few good burners.

 

[WHPES]

I have several used burners of different types, all in running order, so if I get a callout on a Sunday evening etc I can often just swap for another one the same which I know is in working order. I can tinker around with the bad one in the workshop at my own convenience later on.

 

[WHPES]

You're probably just going to have to play around with the spreader position until you get it right. A small amount of adjustment can have a massive effect.