All these years, I've save the plastic cylinders that oil furnace
nozzles come in, and I finally looked at what they say.
All start with .75 80^ (degrees) but there is a lot of variety in what
comes next. A,B, W, and the other brand's HA and Hx. (I can't find
it right now.)
I had in my mind that the proper nozzle was listed in the owner's
manual, but now that I'm looking, it seems not. (It says 0.75, but
nothing else) How do these technicians decide what nozzle to use,
just whatever the previous guy used? If so, how come there are so
many different containers left behind?
.75 is gallons per hour firing rate (at 100 psi)
80deg is the spray angle
The letters after indicate the flame pattern eg. solid cone, hollow
cone, more hollow cone, semi-solid cone, etc.
Do a search on "oil burner nozzle cross reference" and you'll find some
charts and pictures that explain the patterns better.
The pattern selection mostly depends on the techs experience and what
nozzles they have on hand. The firing rate is the most important, and
the spray pattern selected will be based on the size and shape of the
Another complicating factor is that some newer burners don't run at 100
psi and instead have high and low firing rates, requiring some
calculation to get the correct firing rate nozzle for the higher
pressure high rate firing.
I did what you said below, and here's what I got
A = hollow (a hollow cone. All of these are cones.)
B = solid
W = might work where A or B is called for, Delevan says.
AH = hollow (not HA as I wrote above)
AS = solid (not Hx as I wrote above. Very different nozzles,
almost opposites, yet techs used both in my furnace, just as they used
Delevan A and B.
All of the nozzles used are the same wrt these two things. The
owner's manual confirms the .75.
This is what I'm concerned about.
So if they don't have the right nozzle, they'll use the wrong nozzle??
That seems to be what you are saying.
As to their experience, shouldn't the manufacturer's experience be
But all 3 patterns have been used in my furnace. It's pretty clear
to me that only one was the right one.
Aha, over the years, the ID plate in the furnace has gotten dirty, and
I'd cleaned off all the boxes that had letters stamped in them, the
model and serial number, but I see I missed one, the nozzle. Here it
says 0.75 80 Solid. Good to know.
Yet at least two of these guys and more I think before I threw away
duplicates used hollow nozzles. I wonder if that's why it has
smelled faintly of oil when the furnace first comes on, before the fan
This is not one of those.
EXT, there is no gas available here.
Extra complaints! (I also noticed after I'd been here a few years,
that the techs were no longer measuring anything. At first they poked
a hole in the flue and measured something, then taped the hole. The
later guy used the same hole. After about 3 years, no one bothered.)
One guy taped the pivoting damper closed. I asked the next guy why it
was taped shut. He didnt' answer me but he took off the tape. None
of these guys were from bargain basement outfits. They all came from
major heating oil vendors in town.
Not really the wrong nozzle, just a less optimum one.
All of them are burning the same amount of fuel in the same basic spray
cone. The density of areas within that spray cone is the difference.
Depending on the combustion chamber shape and airflow some patterns may
be better than others, but the differences won't be dramatic.
Hard to say. The wrong pattern *might* cause delayed ignition and a bit
of oil smell and "whomp" on startup, but other things like igniter
electrodes a bit out of alignment can also.
The hole is supposed to be used for combustion gas sampling, smoke
sampling and draft measurements. These are measures of combustion
efficiency and proper venting.
The barometric damper certainly shouldn't be taped off, it's there to
help manage the draft in the chimney.
It sounds like the quality of the techs has deteriorated in your area :(
If you are interested and have free time, you might check the tech
schools in the area and see if they offer an oil burner service class.
When I took one it was ~$100 for a 12 wk evening class that was
interesting and fun.
snipped for readability. Only 3 of your lines, plus a bunch of mine.
Ah. Delayed ignition. I can be so stupid at times. Last winter and
now the computer is in the basement, and I'm less than 30 feet from
the furnace, and I hear it go on and off. I have to pay more
attention to the time elapsing between the oil pump going on and the
flame starting..... Well it just happened, as I was typiing the
previous sentence, and afaict everything except the main fan started
at once, but maybe I missed a half second when the oil was pumping and
there was no ignition. Furthermore, the smell doesn't happen
every time -- I have to pay attention every time now -- and I don't
smell it in the basement, only in my bedroom when I'm lying down, my
nose about 2 feet from a duct.
Even he didn't use a guage. He may have fiddled with the
counterweight, but no guage was involved.
Maybe so. I really should have learned to pin the company down
before they sent anyone, that he would use the gauges . Instead I
would change companies. (I thought it was too late once he was
wrapping up to ask about gauges. He'd do it reluctanty and not well,
even if he knew better.
That's a great idea. When I googled, Maine and Massechusettes came
up as prior searches! So far only a for-profit technical school with
full semester classes, and a wholesaler, R.E. Michel, with 8 hour per
day classes, $95 for one day or $350 for 3 days hands-on. I have
to talk to them on the phone to see what level they are.
Be sure you have a good working CO detector in the area. While oil smell
in the immediate vicinity of the burner is common, if you smell it
elsewhere from the ductwork it could indicate a cracked heat exchanger
which can let CO into the house.
Unfortunately the public tech schools have been rather gutted by those
who think that somehow such skills are obsolete and are beneath their
darling hell spawn.
Thanks. I have one in my bedroom. I'm the only one here.
Unrelated to this, my previous CO detector woke me up like crazy in
the middle of the night. I turned off the furnace, opened the window
and couldn't decide when the air was fresh enough to go back to sleep.
Plus it was getting colder inside every minute. I guess I took 10 or
15 minutes. The flue was full of soot. Called a furnace guy (who
used no gauges) I check the flue for soot once in a while now.
The part I can see through the barometric damper is very clean.
I thought I found somethin at Univ. of Md Community College, but it's
lost among the tabs right now. My friend took a 3-year course there
on massage therapy.
And thanks, Steve.
Sometimes a boiler is designed to delay fuel ignition for a few seconds.
My 10 year old Empire baseboard hot water oil fired boiler uses a
Beckett burner with a Suntec oil pump that includes a fuel control
solenoid that delays sending fuel to the nozzle for about 4 seconds.
That's not delayed ignition, that's pre-purge. Delayed ignition is when
oil is sprayed, but for whatever reason it does not ignite immediately.
Pre-purge runs just the blower for a few seconds to establish a draft
before it switches on the oil. Pre-purge is usually accompanied by
post-purge which shuts off the oil and keeps the blower on for 10 sec or
so to clear all combustion gasses out the chimney.
The .75 indicates the gallons per hour that get burned. The 80 degrees
indicate the shape of the flame. The furnace manual should show the degrees
required to get the flame in the correct location in the firebox, and the
gallons per hour most likely adjust the BTU output. When I had an oil
furnace, I started out with a 1 gallon per hour nozzle, but over time the
consumption was reduced down to .85 to economize on the fuel burned and to
meet emissions. Then I changed to a high efficiency gas furnace, and cut my
heating expenses considerably.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.