oil boys- burnerman

[Murf520970]

Basic question on nozzles . If you only have a nozzle that's either smaller or larger than the exact one yoy require what's the correct procedure regarding adjusting the pump pressure to accommodate the different nozzle, as in do you do any calculations to work out the kg through the nozzle to arrive at the correct psi . Thanks

 

[Burnerman]

I'm sure I'm not the best one qualified to answer that one - I hope the real pros are in there somewhere but happy to give it a go.
Most oil boilers are capable of delivering a heat output within parameters specified by the manufacturer, and there own specifications are generally available.
Here's an example of a Worcester Heatslave 20/25 which is a medium to largeish domestic combi.
Depending on how its set up, the output will be between 20 and 25 kW, obviously.
For 20kW output, Nozzle is .60/80 deg EH, pump pressure 130 psi
For 22.5kW output, Nozzle is .75/80 deg EH, pump pressure 105 psi
For 25kW output, Nozzle is .75/80 deg EH, pump pressure 130 psi.
(Notice in the last two, the nozzle is the same but the pressure differs).
One of the most important things is that the CO2% is between 11 and 12% which is reasonably standard, but as a rule on smaller outputs the CO2 will be a little less, say 10.5%.
The spray angle shouldn't be tampered with. EH means an 'extra hollow' nozzle (spray pattern).
Generalising, excess pump pressure causes overfiring and burning of the baffles, maybe with local boiling in the heat exchanger, too little pressure causes soot formation and excess CO2.
Let the others jump in now, but which boiler do you have and for interest, what are you trying to achieve?
John

 

[Agile]

He had originally asked in the CC and I sent him the link to the Danfoss nozzle pages.

But I recommended that he asks here and specifically mentioned you as someone who knows a lot about oil boilers ( even if you think that you are not the best qualified ).

John is also very knowledgeable about car mechanics too!

Tony

 

[Murf520970]

Cheers agile , I've spoken to burnerman on here before about oil matters, I also read the link you kindly provided . just wanted a opinion from them that do it day in day out . I do oil agile but wanted to cut out the calcs & other crap & play it more by ear etc

 

[Agile]

Of course John has not actually answered your specific question!

You wanted to know if there was a simple relationship between the nozzle size and power output against pump pressures.

I suspect they are somewhat non linear and probably rather try it and see.

But John has given you an example and you may have to just accept that as a typical case and make guesses based on that.

Perhaps John may be able to say more along the lines of what I know you really want !

There may somewhere be a graph of power output against pump pressure for specific nozzles.

Tony

 

[Burnerman]

At this point I have to remind folks that I'm not a heating engineer, and have never pretended to be one..... I am a Mech.e though, for what that's worth.
I've been involved with oil systems since a boy though, with family systems and so on.....my two properties are oil fired.
With that and a huge thirst for knowledge, I have reasonable experience but nothing compared with some of the genuine professionals on here!
I don't google either, and prefer to comment on things on which I have personal experience.......and really like helping people if I can.
John

 

[Burnerman]

Back to the original question.....there must be some sort of relationship between nozzles and pressures but I've never come across it - whether it's linear or logarithmic or neither I just don't know.
For the reasons of over firing I wouldn't tamper with manufacturers settings in a domestic boiler though.......what are you up to, Mr. M?
John

 

[Murf520970]

There are calcs based on the kg output noted on the side of the nozzle . Each nozzle size passes a certain amount of kg of oil per hr . So if I don't have the correct size nozzle for the burner rated at 30 kW I can fit a smaller one & wind up the pressure to make up for smaller kg per hr rating . I always have a large selection of nozzles though so don't get to play . Just wondered if there's an easier way to do it .

 

[Boilerman2]

I urge you to get hold of the Danfoss book "Facts worth knowing about oil nozzles" - an excellent publication which includes a quick reference giving Kw input with different nozzles sizes/oil pressure no maths required!!

 

[Murf520970]

That will do nicely sir .

 

[U6]

http://heating.danfoss.com/PCMPDF/DKBGPG060A802.pdf

Even similar, Eogb launched an app (oil nozzle size) does it all for you.

 

[Tipper]

If necessary I used the Danfoss nozzle/pressure table to adjust the nozzle pressure accordingly. If you do do this because of either changing boiler output or because a certain nozzle is temporarily unavailable, then you must check and adjust the combustion using a flue gas analyser.[/u]

 

[Murf520970]

If necessary I used the Danfoss nozzle/pressure table to adjust the nozzle pressure accordingly. If you do do this because of either changing boiler output or because a certain nozzle is temporarily unavailable, then you must check and adjust the combustion using a flue gas analyser.[/u]

I know mate do it all the time