What nozzle for old Beckett AFG on a new Weil-McLain WGO-3?

seized123 · September 7

This is a question that arose at the end of a thread on another subject (soot in boiler) but it's kind of its own subject. (Thanks to those who helped me on the other thread.)

I put my old Beckett AFG burner with F3 head on a new Series 4 Weil-McLain WGO-3 oil boiler a couple of years ago. The decal on the boiler says flat out that with a Beckett AFG go with a .85 45B nozzle, but the decal on the AFG says .85 70B, confusing the heck out of me back then until I figured out after looking at some literature that was probably because the new Series 4 WGO's, when they ship with a burner, probably ship with the L1 heads, and on the decal they just didn't account for the possibility of someone putting an old burner on a new boiler when they made the decal. (A call to W-M or Beckett, or both, I forget, plus feedback on this website told me this was an okay thing to do.) Regarding the nozzle specifically, I couldn't find much from W-M, but Beckett's OEM Spec Guide, non-pdf version at https://www.beckettcorp.com/support/burner-settings/#residential-oil/ says indeed, for the GO-3 with F3 head, go with the .85 70B (which is in there now), no mention of Series 3 or 4, and the guide was updated after Series 4 came out, so I figured I'm good.

Confusingly, though, it says in the notes for that entry that the 'H' in the nozzle description stands for Hago. It's confusing because I saw no 'H' in the description, probably an omission, but the note is there, and the decal on the old AFG says .85 70B Hago.

Now I stumbled on an Inspectopedia note that said when converting from Hago to Delavan you need to go to the next wider nozzle. (I currently have Delavan; Hago's seem hard to come by but if it makes a difference I can try to get one in that size, or go wider with the Delavan if you think I should.)

The thing is, at last cleaning a couple days ago I had a thin layer of black soot. Testing the boiler "as found," before changing to a clean nozzle, etc. (which I haven't done yet) showed all good except 14.5% CO2, which on the one hand I'm not happy about, but on the other hand I'm happy because at least I have a clear possible cause of soot. (I have zero smoke now, but I realize 14.5% gives me no margin for any changes that could happen through the year.)

Since the air shutters are all maxed open now, when I change to a fresh nozzle I will go to the air bands if testing shows it's necessary (thank you @EBEBRATT-Ed on the other thread).

But my question is, anybody have any experience with this Hago to Delavan conversion, possible going wider? (Had all been good, no soot, I would just have replaced the old .85 70B with a new one and not started this thread.) Or for that matter with an AFG with F3 head on a Series 4 WGO? Since my problem right now is not enough excess air, what effect in general would going wider with a nozzle have? Would going wide increase my need for air (not desirable in my case) or decrease it (desirable, and maybe I wouldn't have to go to the air bands)?

Bottom line: should I try to get a Hago in that size (they seem hard to get), stay with Delavan and go wider, or go with what I have, going to the air bands if necessary? At first I felt fishy about going to the air bands (shouldn't it run okay with just the shutters if you have the right nozzle?) but now I know it's okay, they must be there for a reason.

Steamhead · September 7

First thing I'd do is add some air to bring the CO2 down to ~13%. Then see if the flame is impinging (contacting the firebox refractory) anywhere- in this case it would probably be the rear "target wall". If not, you should be OK. If so, go to the 80° Delavan. Also, did you check the pump pressure?

EBEBRATT-Ed · September 7

@Steamhead I think he mentioned 140psi in the other thread.

@seized123

This is just my opinion and no doubt others will disagree with me.

The best nozzle for your burner in that boiler is the one that combustion tests the best.

IMHO what the MFG tells you IMHO is nothing but a starting point. Sometimes their settings are spot on and sometimes they are not close.

What do you do when you install a burner and you set everything to factory spec and it doesn't work right? Throw up you hand and walk away and say well "I did what the book said"

Having been a rep for burner MFGs in the past I have seen some of the stuff they sell that is supposed to be 100% ok but its not. Yes, I am pessimistic.

I have had many brand-new jobs that didn't work right when set to factory spec. But you have to start there it is a starting point.

As far as nozzles go there used to be many nozzle MFGs. Now that oil isn't as popular as it was some of them have closed or been bought out by other companies. Danfoss took over Hago.

I like Delevan if I have my choice but that's just me.

There is no specific correlation between different brand nozzles. How they measure spray angle, solid spray, hollow spray etc is all different so a direct comparison isn't much more than a guess. still have to test.

HydronicMike · September 7

Searching my database I have a number of customers with GO-3’S, F3 head .85x70B Delavan nozzles that run fine. It’s most likely the original spec.
Over the years, and especially since the introduction of Bio, every burner manufacturer has/is retesting their original specs with higher pump pressures and new burner set ups.
A very light layer of soot isn’t all that uncommon and could’ve been caused by a temporary anomaly. Things like running on a very cold day or a very warm day when combustion was set up at the opposite temperature. Something affecting draft or combustion air temporarily. It could’ve even been caused by the last time you had the nozzle assembly out and nudged the z dimension slightly. There is a little play in it as you tighten the escutcheon nut. 1/4” can be the difference between clean combustion and plugging it with soot in a short time.
I’d stick with what you have. Make sure the heat exchanger is clean, and the very important Z dimension is perfect.
Make sure you are at steady state, and your draft is set first.
Then make sure you are performing the smoke test properly. Pumping it like you’re filling up a bicycle tire is incorrect.
From the instructions:

Insert the filter paper: Open the clamp screw on the tester, insert a clean piece of Bacharach filter paper into the slot, and tighten the screw securely to ensure an airtight seal.
Position the sampling tube: Insert the metal sampling probe directly into the flue gas duct or pipe. Place it in the center of the main flow of combustion products.
Draw the sample: Pull the pump piston through 10 full, steady strokes. Take about 3 to 4 seconds for each stroke. Hold the piston for several seconds at the end of each pull stroke.
Remove the paper: Loosen the clamp screw and remove the filter paper.
Compare with the smoke scale: Hold the official Bacharach Smoke Scale at arm's length from your eyes. Match the shade of the test spot to the numbered reference circles on the scale to determine the smoke density. A reading of zero indicates clean combustion, while higher numbers show excessive soot.
Purge the tool: Periodically purge the pump with clean room air using rapid strokes without any filter paper inserted to clear out soot or moisture.

If you are still insisting on trying different nozzles, you can look up how to perform a nozzle substitution test to try to dial it in even more.
If your shutter is at 10 and your band is fully closed, I’d recommend trying something a little different. The shutter is small steps and the band is big steps. I’d probably open the band to maybe 1, and move the shutter down to about 5.
The goal is to see smoke on the test paper, then continue opening the shutter and re-doing the smoke test until you get to 0 smoke. At that point you’d benefit from a combustion analyzer to show you CO2, excess air and CO. You’d ideally want to open the shutter to drop the CO2 1%.

HVACNUT · September 7

No problem using the 70° B Delavan with the F3 head.

I don't think you should have to take the air band off 0. Most setups with your firing rate show about a 7 or 8 on the shutter, and 0 on the band using a 3-3/8" static plate. Check insertion depth, Z dimension, and make sure there's no low fire baffle installed.

seized123 · 1:01AM

This is all incredible info.

@HVACNUT I meant to answer you on the other thread, but here goes: Yes it’s Series 4. Also I don’t think there’s a low fire baffle in there (though I’ve never knowingly seen a low fire baffle in my life, but I looked it up and I don’t think so). Don’t know if it’s the welded flange thing, but I can look when I open it up. Yes, the AFG burner came off my old WGO-3 (Gold). And @HVACNUT and @HydronicMike I will check the Z dimension, I have the little orange Z-gauge that cost $20 for a little piece of plastic. Not sure how to check insertion depth but I’m sure that’s easy. @HydronicMike I will do what you said exactly and also be very careful with the escutcheon nut. @EBEBRATT-Ed that’s exactly the kind of perspective someone with years of experience can give relatively ignorant diy YouTube-watching manual-readers like me. It’s sort of like how it takes years of experience for a carpenter to know when a 1/32” difference matters a lot, and when a 1/4” difference doesn’t matter at all, which they don’t tell you in the books. (I’m not a carpenter either, but you get my point.)

What nozzle for old Beckett AFG on a new Weil-McLain WGO-3?

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