Pump pressure

MaxMercy

My Slant prepackaged boiler came preset with the pump pressure at 100lbs (which I verified upon installation) on the Beckett AFG with F4 head. Other boiler manufacturers sell Beckett prepackaged boilers set at 140 lbs. Is there an advantage to be gained from downsizing a given nozzle size and raising the pump pressure? Will the pump have a shorter life at 140lbs as opposed to 100lbs? I would think a higher pump pressure would allow better atomization. Thoughts?

EBEBRATT-Ed

Higher pressure does provide better atomization and will not damage the pump.

But, I would set it up with the pressure and the nozzle the MFG recommends.......start from there, that's what they tested the unit at the factory at

MaxMercy

Thanks for the help. According to a Beckett chart:
https://beckettcorp.com/wp-content/uploads/2015/03/832-3-4-1.png ....if I was running a 1.00 (for instance) nozzle at 100lbs pressure, a 0.85 nozzle run at 140lbs would flow the same 1.00gph (give or take), which led to the question if upping the pressure and lowering the nozzle size to get the same flow rate would have any advantage. I noticed Riello burners run close to twice the pressure that a typical Carlin or Beckett does, so I was wondering if an improvement in atomization of fuel using higher pump pressure had some hidden trade-off.

STEVEusaPA

There's really no downside.
It's fine to do that but you have to know how to do a full complete, combustion test, especially smoke. It's possible the spray angle may need to change if there's impingement, which you'll only know with a proper smoke test.
Air will change too.
If you look at older equipment and an older OEM guide, vs. newer guide, they did change many to higher pump pressures.
Test. Test. Test.

Jamie Hall

And to reinforce what @STEVEusaPA implied -- there is no way you can do it at all without the proper combustion test equipment. And as @EBEBRATT-Ed , as soon as you move from what the manufacturer lists, you're on your own.

STEVEusaPA

Jamie Hall said:

And to reinforce what @STEVEusaPA implied -- there is no way you can do it at all without the proper combustion test equipment. And as @EBEBRATT-Ed , as soon as you move from what the manufacturer lists, you're on your own.

I thought i stated it, don't know what I actually implied...lol

But with OEM spec books, even they say (maybe it is imply...hmmm) that these are starting points, and proper combustion testing (and documentation) is the best way to go.

Big Ed_4

Oh yeah .... Higher pressure 140 # and drop it with in 80% along as you are within your Heat loss .

EBEBRATT-Ed

Changing the pressure can alter the spray pattern slightly. It is Usually ok to install a smaller nozzle and up the pressure to get the same flow but the bottom line is you have to test.

Even replacing a nozzle with the exact same nozzle can cause different combustion results

MaxMercy

Jamie Hall said:

And to reinforce what @STEVEusaPA implied -- there is no way you can do it at all without the proper combustion test equipment. And as @EBEBRATT-Ed , as soon as you move from what the manufacturer lists, you're on your own.

Kinda on my own anyway. When the original vert tube steel boiler needed replacement, I stupidly replaced it with the Slant pin boiler at the same BTU rating as the original. Later, supplemental reading shows I'm probably well overfired, so I dropped it to a .85 gph nozzle. It came with a 1.10 gph type W installed, so I put in a 0.85 and set the combustion with that nozzle to reduce short cycling a bit. The 0.85 is the lowest nozzle Slant shows for the boiler I have and the AFG with the F4 head. It's running smooth, quiet, and clean, but I was thinking about going to a 0.75 and up the pressure and retune, if anyone thinks there is an advantage to that. Just bored I guess.

captainco

The atomization of oil nozzles is based on oil heated to 80 degrees and 100# pressure. If your oil is not heated it is always better to increase the pump pressure for better atomization. Also, because the nozzle starts spraying at 20# less than the setting, higher pressure give smoother light-off and shut-down.
Any nozzle can be bad right out of the box, therefore combustion testing is always necessary. My record for bad nozzles in one box is 8.

EBEBRATT-Ed

Trivia question.

Using the same fuel oil at two different temperatures say 50 degrees and 80 degrees at the same pressure (say 100psi)
with the same nozzle

Which sample of oil will go through the nozzle faster? warm oil, cooler oil or makes no difference

captainco

From everything I have read it says more oil flows out the nozzle when the oil is cold but the droplets are bigger.