Nozzle question

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Old 03-18-14, 08:26 AM
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Nozzle question

The dataplate on my old Weil-McLain P-466 boiler (40+ years old but still going strong), with a Weil-McLain ER burner (burner spec 163-43), says
MBH WATER: 118.6
Oil: 1.30 GPH
but the paperwork says under "Burner Data"
Size 1.25
Nozzle Angle/Type 80 / Hollow.

Over the years, my oil company's techs have installed new nozzles at each Cleaning. A number of years ago, someone wrote on the top of the Service Work Record "100/80A". From other posts, I've learned about the spray angle and about hollow/solid. The tech this year put in a .85 70A, because of some black crude build-up on the flame-lock assembly.

My question is about the oil flow rate:
If the burner's original paperwork says it's to be fired at 1.30 or 1.25 gallons per hour, how come they've downsized it over the years to 1.00, and then, lately, .85?
 
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Old 03-18-14, 08:49 AM
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If the burner's original paperwork says it's to be fired at 1.30 or 1.25 gallons per hour, how come they've downsized it over the years to 1.00, and then, lately, .85?
While it might seem to be a conflict of interest if they also sell you oil, they could be trying to save you some fuel $.

OR, in the olden days it was 'standard' to run the oil pump at 100 PSI . This 100 PSI is the pressure at which the nozzles are spec'd for flow. So, a 1.25 GPH nozzle will flow that amount only at the 100 PSI spec pressure.

The industry has moved in the past decade or so toward running a HIGHER pump pressure in order to achieve better combustion because the higher pressure atomizes the fuel into smaller droplets.

If they are fitting a smaller nozzle, and ALSO INCREASING PUMP PRESSURE to say 140 PSI, they are probably back in the same FIRING RATE. I believe that a 1.00 nozzle at 140 PSI will flow around 1.25 or slightly less...
 
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Old 03-18-14, 11:32 AM
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Thanks, NJ Trooper.

So I should check my fuel pump's operating pressure to see if it's been raised.

But either way, a .85 nozzle is probably too small. It should probably be a 1.00 nozzle, right?
 
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Old 03-18-14, 12:48 PM
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But either way, a .85 nozzle is probably too small. It should probably be a 1.00 nozzle, right?
Maybe, maybe not...

As long as the smaller nozzle can be properly set up to burn clean with all the right combustion 'numbers', there's no real reason to not run with it... but it's often difficult or impossible to down-fire that far without _something_ going out of whack with the combustion. There are LOTS of variables involved!
 
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Old 03-18-14, 01:02 PM
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Ok. Thanks, NJ Trooper! Appreciate the help!
 
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Old 03-18-14, 07:17 PM
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Usually one nozzle size less is the limit if the boiler is not sold with multiple firing rates.
 
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Old 03-22-14, 07:04 PM
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You can retune a smaller nozzle to get good combustion results but the fire has to fill the firebox the way the designer intended in order to get the best heat transfer. You could end up using more oil with a smaller nozzle that appears to give good combustion results.
 
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Old 03-23-14, 08:30 AM
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Bob,
If your running 140psi pump pressure you need a 1.10 gph nozzle to acquire the 1.30 firing rate. I'm not sure how the Weil McLain QB burner allow for different firing rates because they are no longer produced.
If this were a Beckett they have different combustion or retention heads that have a range for different nozzle rates.
For example an F6 head has a firing rate from .85-1.65 gph. A F3 head has a range from .75-1.25.
The difference in the heads which mount on the end of the burner tube is the spacing between the veins for air delivery. The point is if you just start putting in different nozzles without knowing all the facts you may be doing more harm than good.
If you put to small a nozzle for the head installed then you will never attain proper combustion. You can use a smaller nozzle to save oil but all components must match. You must the the nozzle within the range of the head.
The heads can be changed but the burner must be pulled to install a new one.

Beware of a tech who just starts changing nozzles without know all the facts.

Good Luck,
 
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Old 03-23-14, 09:49 AM
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Thanks, guys. This is an OLD Weil McLain ER burner... no idea what head is actually on it (did they mark them in any way back then?).

The guy who came to clean it in January (reputable local oil dealer) found carbon/soot build up on the head, and figured the oil spray was impinging on the head, so he put in a .85-70A nozzle, instead of the .85-80A that was in there. It looked like he set up the air input just by eye.

(I was with him virtually the whole time, and never saw him use any test equipment, like draft gauge or smoke tester, etc, let alone a pump pressure gauge..... even tho he recorded all the test readings on the Service Record.... makes me wonder if he's just thinking, "..this boiler/burner is so old, it doesn't matter..." Now that I've learned (from you all) what "should" be done, I'm not feeling very good about the quality of the "annual cleaning" that we got... even if it is "old"!)
 
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Old 03-23-14, 10:43 AM
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I quietly admit that while I strongly advocate the use of instruments, it probably IS possible for a very EXPERIENCED tech to get VERY close to 'on the money' by eye, but at the absolute minimum, a smoke spot should be done.

However:

even tho he recorded all the test readings on the Service Record....
Intentionally falsifying records because of LAZINESS is bad, bad, bad. Shame on him.
 
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Old 03-23-14, 02:14 PM
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Bob,
There are a couple reasons why oil may have been hitting the head.
One is a worn nozzle. Nozzles have very small holes and are made of brass which is soft. With a minimum of 100psi of oil constantly pushing through the hole it gets out of shape and sprays oil everywhere.
The other reason can be your assembly could be adjusted too far back and the oil spray doesn't clear the head.

I don't know what Weil McLain uses for heads, they are no longer being made.
I have a Weil McLain in my own house and have installed plenty of others and I have never heard of a 70 being used.

I'm sure it came with an 80 and has had one in there all these years and it was working fine. Instead of finding out why he just narrows the spray. This is the same guy whose eyeballs take the place of a 600.00 efficiency tester and then has the audacity to put his results on paper.

I thought Kreskin died when Johnny Carson retired. Apparently he's alive and well and changed professions.
It makes you wonder why people are switching to gas, maybe it's not only the price.
 
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Old 03-23-14, 05:55 PM
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Thanks for your input, guys! I will consider your comments as I move forward.

I, too, have been thinking the last few days about what we may want to consider moving to, since the boiler is about 37 years old and really should be replaced sometime. All options are on the table at this point, but unfortunately, natural gas is not one of them, on our street. But I will be reading up on all the other posts on this site, to learn what I can before we do anything!

Thanks for all your help!
 
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