Nozzle angle & flame impingement

Jud_Aley · July 8

I have a hot water boiler with an old Carlin 101 CRD. The manual for the burner calls for a Hago 60 degree SS nozzle.
The oil company techs have been installing 60 degree All Purpose nozzles for years and the flame has been impinging on the back wall of the refractory firebox and its starting to crack.

I installed a 70 degree SS nozzle and the flame did not impinge on the back wall.

Then I installed a 60 degree SS as per the manual and there is a very slight flame impingement.

My question is should I stick with the 60 degree or go back to the 70?

Thanks.

HVACNUT · July 8

Well, the answer to your question is, you should not make any changes to the burner unless you have the instruments to ensure proper combustion. You could do more harm than good. What you need, if what you described is correct, is a new oil company or have a supervisor come out. Do the Techs use a digital combustion analyzer and smoke tester? Do you have a printout of the results? Is draft set correctly?
1.75 GPH is the minimum firing rate on the 101 CRD. Max is 2.75. There are chamber size requirements for each nozzle size, or BTU input. What model boiler? What GPH nozzle is being used?
And hands off!

Steamhead · July 8

Another thing- is the oil company using Delavan nozzles rather than Hago? If so, the 70° nozzle might be necessary- Hagos tend to have wider actual sprays for a given angle designation than Delavans.

But, as @HVACNUT says, choosing and installing the proper nozzle is a job for a knowledgeable pro- and you haven't had one work on yours yet.

Where are you located?

Jud_Aley · July 8

Actually, it’s a 100 CRD. I have the manual for it.
The nozzle I put in is an actual Hago 1.0 GPH 60 degree. The oil company had been downsizing the nozzle every year from a 1.25 to 1.10 to 1.00 and finally a .85 Delavan All Purpose, someone told me they probably did this instead of cleaning out the heat exchanger and smoke pipe “A down fire Cleaning” he called it.

The boiler was sold by Sears, but when the Abatement company removed the asbestos from the boiler they cut the sheet metal jacket off and any model number that was on the jacket is long gone.

Thru one of the properties I manage I finally found an oil company that actually does a full combustion test, small company with only three techs. They will come sometime in the next month (They are currently tied up with AC work).

In the mean time I set the Air band and Air Shutter as per the manual, I have a Bacharach smoke tester and its reading at #1 on the card right now, but I know that is only one of many measurements to test for and will have the new oil company do a full combustion test. Also being July the boiler is not running on a regular basis so I'm not concerned about sooting it up or doing any damage.

We specialize in Remodeling and maintaining antique homes and I see lots of really old equipment out there that is still in use, every year I see coal to oil conversion, old iron fireman still in the basements, every now and then a house with coal bin still full of coal.
From reading all the posts on The Wall I have learned what needs to be done to maintain oil burners so with this post I'm just looking to increase my knowledge by asking this question.

I will get the combustion chamber measurements later on and post those.

Thanks - Jud

Steamhead · July 8

Also some pictures.

On a Carlin, the air band and shutter are not the only adjustments. Hopefully the techs you have coming will know this.

So where are you seeing all these old boilers? What part of the country?

STEVEusaPA · July 8

If you are running #1 smoke, assuming you did the test correctly (most techs go too fast), you'll be sooted up sooner than you think.
If you didn't set the proper draft first, your smoke test is useless.

Generally with a Carlin, if you have the right head adjustment, and right air band adjustment, with the right nozzle, it will just need fine tuning for perfect true zero smoke combustion.
If you really want to know which nozzle is best you would need to do a full nozzle substitution test.

Jud_Aley · July 8

I'm in southwest CT, we work along i-95 between Rye NY and New Haven. This link should get you to a file of photos of old boilers, furnaces, a "Gas Machine" I assume was to make gas for the cook stove or for gas lighting?........... https://1drv.ms/f/s!At4yVY1gyiiyqJdWRiIQbV0X6oQ-vg

Jud_Aley · July 8

I set the head adjustment as per the manual for a 1 GPH nozzle, I believe the range is 1/16 to 3/16".........None of the 5 different techs that came last year ever set the burner head or mentioned it, one did clean it.........once I got the manual from Carlin I read about it, found it on the burner, both the knurled wheel at the oil line and the set screw were loose and I could slide the head back and forth in the burner tube 1/2". Right now its set at 3/16"

HVACNUT · July 9

Since you dont know the make and model boiler, the chamber dimensions are important. That's also in the manual so you can see if 1.00 GPH is acceptable. The Carlin 100 can also use a Delavan A (hollow cone) nozzle at 1.00 GPH. A 60° A is what I typically use with that burner but combustion and smoke tests must be done with any adjustments made.

Steamhead · July 9

Also, the pump pressure needs to be checked. The old standard was 100 PSI, but we're now running burners with higher pressures and smaller nozzles to achieve the same firing rate and improve atomization. This helps lower-quality fuel burn better. Both Beckett and Carlin publish charts to determine firing rates at different pressures.

Jud_Aley · July 9

Its a refractory chamber....12"L x 14"W x 12"H. The center of the burner head is about 5-6" from the bottom. I attached the 100CRD page with with chamber dimensions and recommended nozzles, seems the chamber on this unit is very wide at 14"

HVACNUT · July 10

Please stop and wait for the oil company. Within a month right? Let them do what they know how to do. The settings in the manual are guidelines only. That's where the smoke test and analyzer comes in.

Jud_Aley · July 13

I am waiting for the oil company tech and have no intention of trying to make the final settings on the burner. The burner is currently turned off.

My original question in this post was about Flame Impingement on the back wall of a refractory chamber.

Should the flame be fully hitting the back wall and rolling up and above? That’s how it was set by one tech, he told me he always sets it that way…. “No need for combustion testing, I’ve been doing this for years”.

Or should the flame be stopping just shy of the back wall?

Or does it not matter as long as the combustion test numbers are correct?

Its helpful for me to have a basic understanding of things given that we oversee several properties with oil fired units, all told, 6 oil boilers & 1 oil furnace.

Thanks.

EBEBRATT-Ed · July 13

There is no problem with the flame hitting the chamber. If the chamber was to small, you would get flame impingment which is oil spray hitting the chamber before it has a chance to burn...this would leave soot or carbon. If you don't see soot or carbon you are fine. It is normal for the flame to hit the back wall.

Keep in mind the manufacturers chamber dimensions are MINIMUM dimensions in most cases. A slightly larger chamber seldom causes any issues.

It best to work with the MFG dimensions rule of thumb is 100 square inches of floor area for each gallon burned.

so a 1.25 gph burned would be 125 sq inches of floor area=10x 12.5 sq "

HVACNUT · July 13

The 99 and 100 Carlins do seem to throw a longer flame than Beckett, Riello, and even their own EZ1 with a flat disc turbulator.
As far as impingement or unburned fuel being a concern, again, proper combustion and smoke tests will tell. It's not exactly a yes or no question.

Steamhead · July 13

I wouldn't want to have the flame hitting the target wall, or anywhere else for that matter. It can, under certain circumstances, chill the flame enough that CO and/or sooting will increase. The combustion test will verify this.

Every year, I seem to work on at least one oil-fired boiler where someone installed a solid-cone nozzle when they should have used a hollow. The resulting elongated flame pattern produces a dark spot on the target wall, and there's usually a lot of soot. I install the hollow-cone nozzle, clean and tune it, and the next year there's hardly any cleaning to do.

rick in Alaska · July 14

Also, if the tube insertion depth is off, that can cause the flame to be longer than it should. Not sure, but if they downsized the nozzle, the 3/16th dimension you have is probably too far in. That is something that can only be checked by instruments.
The fact you are running a #1 smoke tells me you are surely off on something. It should be a 0 smoke only.
Rick

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