Why does the service tech install a .85 gph spray nozzle when this Crown Boiler has a 1gph rating?

Jack M

Homeowner here. I sometimes get to see my oil delivery company's service guy do the cleaning. I notice that he installs a .85 gph (70 degree/ solid core) nozzle on the Becket burner (not sure of the pressure). But the Crown boiler's tag says 1 gph. From what have read on the forum there are not many advantages to underfiring an oil burner on a steam system and doing so could reduce the efficiency of the system. What am I missing?

icesailor

It depends on the model Crown boiler you have. That is important. Most boilers manufactured are rated at the highest amount that testing can achieve and they can use for sales purposes. Boilers are often bought on price. The cheapest high fired boiler is the winner.

Beckett will test fire the different boilers for the highest efficiencies with whatever type or style of nozzle. Many Crown boilers use 80 degree nozzles, 70 degree and 60 degree nozzles. If the Crown boiler was tested with a 1.00 GPM nozzle, it is not unreasonable to downfire it to .85 GPH. The question is if a 70 degree nozzle is correct. But that may depend on the model boiler, and if the technician who set up the boiler was careful and tested with digital combustion analyzing equipment.

If the rating plate says that 1.00 GPH is the maximum firing rate, It only means that you aren't supposed to fire the boiler at a rate over 1.00. All nozzles are rated at 100# PSI Gauge pressure. You can use a .85 GPH nozzle and run a higher pump pressure. And end up with the equivalent if 1.00 GPH.

You need to know the model number of the Crown Boiler. If it is a crown package boiler with a Beckett Burner on it, there is often a paper sticker on the burner that says what nozzle it is using, and the pump pressure in # PSI.

Jack M

This Crown UPCS4 Boiler is rated at 315 square feet of steam, 75,000 btu hot water, running on a 1gallon per hour Becket RWB burner (like a Beckett AFG). The American Standard 3 column sectional radiators add up to an EDR of 225 (based on online references). I sometimes shut the small radiator off that is in the kitchen's pantry (rest of the house seems to heat faster that way and perishables like onions and potatoes keep longer at a lower temp).
In ten years, no service technician has expressed an interest in looking at the radiators. They clean the burner, replace the nozzle, adjust the electrodes, vac out the boiler, change the filter, check the LWCO, flush the fuel line, and run a combustion test. They are extremely knowledgable, trained, and professional. Most do an excellent job and rarely leave a mess that needs to be cleaned up. I have the cleaning done every April. No-one ever fires the boiler up long enough to make steam or check the pressuretrol. Its on to the next job. I can respect that. There's another customer after me.

Larry_52

Fuel nozzles are rated at 100 psi. So the becket should be at 150psi and he is putting the right nozzle in.

Jack M

Ok, I can see why the .85 gph is used (is this still considered downfiring?) . The service tag from last year provides the following information:
Becket Firing Rate: FB4/ flame retention/ .85 gph/ 70B/ solid
Combustion efficiency: 76.5 %
Smoke (0)
CO2 ( 8.5)
Net stack temp (500)
Overdraft (-01 H2O)
Breech draft (-03 H2O)

I looked over the service tags from the last 6 or seven years and the some of the numbers change but none of them mean anything to me so I'm not sure if the changes from year to year are significant. The highest efficiency ever recorded was 78%.

Larry_52

Jack M said:

Ok, I can see why the downfiring might be used. The service tag from last year provides the following information:
Becket Firing Rate: FB4/ flame retention/ .85 gph/ 70B/ solid
Combustion efficiency: 76.5 %
Smoke (0)
CO2 ( 8.5)
Net stack temp (500)
Overdraft (-01 H2O)
Breech draft (-03 H2O)

I looked over the service tags from the last 6 or seven years and the some of the numbers change but none of them mean anything to me so I'm not sure if the changes from year to year are significant. The highest efficiency ever recorded was 78%.

Bring the guy back, way to much air.

Jack M

Too much air? Where should the numbers be? I can look back over past years. When he was here I asked if the settings on the draft regulator seem right and he said " those never get changed," so I guessing you are refering to the draft settings on the side of the Becket Burner.
I'm scheduled for another service in just a few weeks. If I know the right questions to ask I can try to ask in a knowledgable way (without seeming like I'm trying to tell him how to do his job).

Larry_52

No the nozzle he is using is not under firing if he has the pump pis in the 140 to 150 psi range. If he is in this area then your nozzle is either dead on at 1gph or ever so slightly above it. Down firing would require a .75 to .65gph at the psi of 140 to 150.

As Hatterasguy said you are oversized on your boiler. You might benefit from under firing in this case. The right amount of under firing is based on many variables but a start would be going to .75gph at 145 psi which is .90gph.

Larry_52

Ideally you want CO2 in 12% range. Right now your excess air is 91% which is also why your stack temp is so high. He should be getting CO2 in the 11 to 12 range and that will put excess air near 30% range.

Jack M

If I go way back to 2009 the efficiency was 78% with the following numbers:
Stack temp: 500F
CO2: 9.5%
Overdraft: (-002)
Breech draft: (-006)
(same nozzle specs and firing rate (FD4) on the Becket Model S)

Jack M

Year not marked on many of the slips but this one is probably 2008:
76% efficiency
Net Stack temp: 500 F
CO2: 8.5 %
Overdraft: .-01 H2O (not sure why the decimals are where they are)
Breech draft: .-04 H2O

This one says something extra: V-trans safety chamber. Is that a combustion chamber lining?

Jack M

In 2007: 76% efficiency
500 F stack temp
Smoke: 0
CO2: 8.5%
Over draft: -.02 H2O
Breech draft: -.05 H2O

Jack M

Yes, I remember 2009. That was the year Ken did the service. He was very thorough. This is the guy I wrote to the company president about. I remember how things ran better that year.

If I go all the way back to 2000 (before I owned the place) the
Efficiency: 73.75
CO2: 8%.
Stack temp: 550F
Overdraft -02 H2O
Breech draft: -04 H2O

Note: with the boiler running for 20 minutes the highest reading I can get (with an infra red thermometer) on the flue pipe is 412F (right near the top of the boiler). IS this the same as what is referred to as "stack temp?"

Steamhead

There is no listing in the Beckett OEM Spec manuals I have for the UPCS4 boiler- and mine go back to 1991. So that burner was probably retrofitted.

If we know the pump pressure, we'll be able to determine the true firing rate.

icesailor

They must be using a "Wet Kit" and not a digital analyzer.

Someone must have taught every service person in the company the same wrong information. Anything under 80% efficiency is a joke. And unless the boiler is a big air sucking leaker, the CO2 should be at least 11.5". The stack temperature is way too high. Those results show the limitations of a wet kit. Better than nothing, but no flexibility.

Like Steamhead said, the burner is probably an add on because there is no listing in the Becket Database for a Crown Boiler, UPCS 4. So the replacement burner was probably a AFG. For starters, they work best with a 80 degree nozzle. There may have been reasons to go to a 70 degree nozzle, or it is just something that the tech is trained to do, use the Universal Oil Burner Nozzle,70 degree. Because it is between 60 and 80 degrees.

That crew needs to spend a few days with the Firedragon to brush up on their skills. Things have progressed.

Some old boilers have really bad cleanout sealing and suck vast amounts of excess air. Yours sounds like it does. Furnace cement goes on soft, seals, and dries hard. And leaks.

Then, is the 500 degree stack temperature corrected or not.

Jack M

This is an older boiler (maybe late 70s vintage?). It does not owe me anything. The cleanout does get sealed carefully with furnace cement. What always has baffled me is that on the right side of the boiler the tech needs to smash and chisel the cement loose to access several rectangular steel plates that seal the boiler's heat exchanger. But then, on the front of the boiler there's a flat panel right above the 0-30 pressure gauge that just unscrews. That front panel just has an fiberglass insulated stamped steel cover. There's no cement or anything sealing it shut. With the panel removed you can see the exchanger's passages and sometimes they really look like they need to be brushed down and cleaned.

I know because one year I watched a very young service tech take that panel off and brushed down the heat exchanger passages. He then also removed those right side panels (that are cemented on) That was the first time I've ever seen the front panel removed to clean.
In subsequent years, if the tech seems approachable I try to ask if he would mind pulling that front panel and check the passages. I don't think they like to do it (or don't feel it is necessary?). I can tell they don't want me hanging around but I make excuses and offer a cup of coffee, or turn some lights on. Why is one access cemented shut and why is the other so easy to access (yet rarely used) ?
It is very helpful to understand some of what is going on with the heating system. (I had an earlier thread asking about venting steam lines- learning a lot here)

icesailor

The cemented ones usually leak air. The one that is bolted on, probably needs new gaskets and leaks air. I'd be interested to see what the CO2 was if you closed the air band down until it just started to smoke and backed it off slightly until it stopped smoking, and tested for CO2. If it stayed at 8%, it is seriously leaking air.

Kakashi

A dry base boiler with what looks like a compression union in the supply. I can't really see what burner you have so...

What everyone above said is right under good conditions. Your boiler is old, no offense. If you want to take the jacket off of the unit and high temp caulk or furnace cement all the sections then you have a shot at getting your unit to 11% CO2 and back to above 80% efficient.
Caulk would be my first choice because the cement will break down. I know there are other ways and products to use to make it better but, this was the first to come to mind.
In the long run, the labor may or may not be worth it. DIY and it might be. The choice is yours.

Jack M

Kakashi said:

What everyone above said is right under good conditions. Your boiler is old, no offense. If you want to take the jacket off of the unit and high temp caulk or furnace cement all the sections then you have a shot at getting your unit to 11% CO2 and back to above 80% efficient. s.

Was this dry boiler ever 80%. When I look back at the numbers from 2000 (15 years ago) the service tags still look lower (550 stack/ 8% CO/ 73.75% eff).
Regarding the seal on the sections and leaking air; is this issue similar to a wood stove? How, if the stove is not sealed tight you struggle to control the air to the fire through the air vents? The fire burns too hot and most of the BTUs just go up the chimney.

icesailor

That looks like a Dunkirk Boiler that they sold to anyone and everyone that needed a smaller size boiler. Sears, Texaco, HB Smith and Dunkirk sold them. If that is what it is. I can't see the front, They had a very unusual bottom/front jacket. They were wet base and prone to plug up, and that plate on the side, actually had hanging covers that you had to spooge up with furnace cement. Where they leaked the worst was the connection between the block and the exhaust bonnet.

If it is a Dunkirk, I can't find any information on them. Far better boilers are made now. They had a very short chamber area that was prone to the chamber failing. A Lynn Quickee chamber was a good replacement. Maybe it is a Crown, but Crown has no numbers like that one.

My first house that I built in 1963 was a Grossman's package. That Dunkirk came as part of the package. Mine had a 1725 RPM Delco Burner. A real dog.

If you are handy and scratchy, and want to stick with oil, there are an awful lot of really good oil boilers out there for sale cheap, that would be a nice slide in for that boiler. One not known today as a stellar performer.

Often used in Coastal Areas as a good, heavy mud mooring.

Jack M

icesailor said:

That looks like a Dunkirk Boiler....
Often used in Coastal Areas as a good, heavy mud mooring.

Good to know that it could have a second life.
A web search of "Dunkirk" found a similar (perfect match) boiler. It was referenced as a 1960's boiler. See photo below. I'm not sure that a boiler could last that long.

Regarding "pluggin up" , my boiler did plug up once with soot. Freaked me out.
The poster with the photo wrote "With a good retention head oil burner and good combustion chamber would produce efficiency rates in the low to mid 80%."
Dunkirk:

icesailor

@Larry:

Larry said:

Ideally you want CO2 in 12% range. Right now your excess air is 91% which is also why your stack temp is so high. He should be getting CO2 in the 11 to 12 range and that will put excess air near 30% range.

I don't dispute the 91% excess air. Where or how did you come up with that? I could never get that from my wet kit. My Fyrite Insight gave it to me on every printout.

icesailor

Jack M said:

icesailor said:

That looks like a Dunkirk Boiler....
Often used in Coastal Areas as a good, heavy mud mooring.

Good to know that it could have a second life.
A web search of "Dunkirk" found a similar (perfect match) boiler. It was referenced as a 1960's boiler. See photo below. I'm not sure that a boiler could last that long.

Regarding "pluggin up" , my boiler did plug up once with soot. Freaked me out.
The poster with the photo wrote "With a good retention head oil burner and good combustion chamber would produce efficiency rates in the low to mid 80%."
Dunkirk:

That sure looks like a Dunkirk to me. Notice the funky front covers that come off around the burner The flame viewing door with the soot stains above it. And the third plate (from the bottom) has to come off because there is a cleanout plate in there that if not cleaned out every year, will really insulate the sections. And you have to remove the burner to clean the debris from inside the chamber. It can take up to 4 hours to properly clean one of those dogs.

Peerless JO/JOT's have a similar plate that many soot suckers don't remove and clean out. Some are hard to clean out with a soot saw. Then, you have to clean out the chamber area.

A real Bow-Wow. You'll never clean 8 of them in an 8 hour day by yourself.

Kakashi

You seem to have almost perfect draft on all of your "tests"...

Jack M

Would a wider nozzle spray pattern (80 degrre- as mentioned by Icesailor ) boost efficiency on such a short combustion chamber? Or does Beckett offer a restrictor plate to cut down the air flow in this burner?
How good can the numbers really get (stack temp, efficiency, draft and CO2) on a 50 year old boiler? If Lynn's "mini quickie" combustion chamber fits in this 10.5" long firebox, I have to wonder if it would go another 50 years if I tightened up the box (I had no idea this boiler had been running this long).

Larry_52

icesailor said:

@Larry:

Larry said:

Ideally you want CO2 in 12% range. Right now your excess air is 91% which is also why your stack temp is so high. He should be getting CO2 in the 11 to 12 range and that will put excess air near 30% range.

I don't dispute the 91% excess air. Where or how did you come up with that? I could never get that from my wet kit. My Fyrite Insight gave it to me on every printout.

Theoretical combustion charts. Since the #2 oil is a constant carbon content and known, the supply air is constant and known and he has the CO2 content of his exhaust, then the excess air becomes known. All based on a curve from proper stoichiometric mix.

That is all assumed and when measuring only one value like CO2, but you can not attribute the true combustion gas components from it. You could have a bad mix at the burner and enough air to burn the CO later in the process. As mentioned tramp air leakage can also skew the #'s. His 0 smoke made me confident there was little to no CO. My combustion analysis is always done from O2 and CO alone as it defines the combustion complete. Sometimes meters just use one process variable and use it to spit out the other, instead of using two separate measured processes.

icesailor

@Larry:

My point was that they only showed what can be discerned from a Wet Kit.

Smoke
CO2
Temperature
Computed efficiency.

Not so with a Digital Analyzer. And you get a Print Out with ALL the results.

When I used my old Wet Kit, I closed down the air shutter until it started to smoke. Then, I opened up the air until I got a yellow spot. Somewhere in between was the sweet spot. I closed it back down to the smoke point and adjusted the air open from there.

You can think you are the smartest guy in the room with your wet kit. Until you use a Digital, you never know how stupid you've been. The Stoichiometric is fine for a boiler that doesn't leak like on old abandoned skiff. But if it leaks like the skiff, all bets are off. I worked on quite a few of those Dunkirk Boilers. I'm quite happy that I will never see another one.

ChrisJ

I really don't understand why all modern oil burners, and apparently some older ones, are designed in a way that in order to do regular maintenance you must unscrew self tapping sheetmetal screws out of thin sheetmetal that by the third time will be stripped.

That's what I like about my neighbors 1920s 3 pass boiler that was converted to oil. Swing the doors open and vacuum.

On a gas boiler I understand, but on something you need to pull apart 1-2 times a year!? Seems pretty stupid to me.

I assume the Megasteam is the only modern oil fired boiler that is easy to clean?

icesailor

Some boilers are lucky if they are ever cleaned in their lifetime. Like the guy I knew that bought a brand new Chevy He drove it for 6 years. One day, it quit. He had it towed to the garage. It still had some oil in it. Thick as road tar and just as lubricating.

If you don't use a 24 volt impact drill on the sheet metal screws, they last a lifetime. Modern boilers (2000 on up) are far easier to clean than those 50 year old boat moorings. A lot of so called boiler cleaners only consider it a job well done if the boiler is running as well when they leave as it was when they got there.

Its called brush, suck and sometimes, buff.

Jack M

I'm still not following the calculation for excess air (not questioning it). How can I get my CO2 up to 10 or 12%? If the boiler were tighter would I get those numbers?
A local nonprofit organization for oil heating posted these burner specifications:

icesailor

FWIW: I don't know of any residential oil burner made in the last 25 years that isn't a flame retention burner.

As far as getting the CO2 up, there's more to just getting the CO2 up. As far as I am concerned any oil burner left running with "0 to Trace" will soot up sooner or later. I always went from "A Trace" and backed it off to zero smoke. It stays clean.

With a "Wet Kit", if the CO is too high, it usually means smoke. Which turns into insulting soot. All the adjustments effect each other. You can make the CO2 go up by closing the air shutter, then you get smoke. If the draft is high at the breeching, and the stack temperature is high, it MIGHT be a (air) leaky boiler. But you have to use your knowledge.

Symbiotic Adjustments.

Jack M

Does the stack temp have any relation to the heat ex-changer's capacity to move heat out of the boiler? Or is the stack temp really just combustion efficiency (and the boiler's heat exchange issues are separate issues)?
So a boiler that's mudded up or has some small amount of soot insulating the tubes is not going to directly impact the temperature of exhaust gasses (Even if those factors limit the boiler's capacity to transfer heat out of the boiler).
What are the flue temperatures like in the new triple pass boilers? And is the heat exhanger a factor in flue temps in those designs?

Steamhead

I'd check the input rate on that ES-2- 205°F is low even for that model.

icesailor

""" This becomes painfully obvious when you take a look at oil burners from the '70s's with 550F stack temperatures versus the units built today with numbers down near 350F or less. """

$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$

In the 1970's and before, 400 degree stack temperature was still the gold standard. 11 to 12% efficiencies were easily achieved with any properly set up flame retention burner. Especially with 3450 motors. You could always get 12% and over. You just might soot up the boiler and be called back in the future.

Boilers are tested and approved for their given outputs under laboratory conditions. Conditions rarely duplicated under homeowners conditions on The Island of Long or the Cape with no Cod fish. It wasn't until the introduction of really tightly designed boilers like the Weil-McLain #62 Series that they got a handle on excessive air infiltration. When Carlin developed the 100 CRD burner (Controlled Retention, Double speed) with a 3450 RPM motor, things jumped light years ahead. You need the excess air to burn the fuel. Have the flame come back and re-join the flame as it comes off the retention ring. You have to be careful that you don't give too much air pressure with the air band and push the flame away from the retention ring. There are lots of adjustments. One thing though. Whether it is oil or gas, you're still burning a vapor. A gas vapor, or an oil vapor created by the high pressure atomization of the fuel through the nozzle. The higher the pressure, the better the atomization. But the higher the output. which changes everything.

%%%%%%%%%%%%%%%%%%%%%%%

""" I was recently dumbfounded to find a Burnham ES-2 with a stack of 205F (on gas). It's not a condensing boiler!! Truly amazing. """

$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$

The Return Water Temperature (RWT) has more to do with condensing than on the stack temperature and condensing than anything else. Condensation comes from the formation of water vapor. Fossil Fuels contain hydrogen. Combined with Oxygen in the air, creates water vapor. Ice melts at 32 degrees F. Water freezes at as low as -40 if it is pure water vapor. At 35,000', it might be -35 degrees F. If some jet airliner comes by at 600+ MPH, it is spewing unburned carbon particles out of the exhaust. Which the water vapor connects with to form contrails/Condensing Water Trails. The exhaust has to be first cooled enough to form the ice crystals. Next time it is a day when Contrails are forming. when you hear a jet overhead. look up and locate the contrail. Follow it to the source. There will be a space between the source (The Aircraft) and the start of the contrail. With nothing in between. Just like the 205 degree stack temperature gas boiler with no condensation. In an unlined masonry chimney, it will be condensing in the chimney flue.

Larry_52

Jack M said:

I'm still not following the calculation for excess air (not questioning it). How can I get my CO2 up to 10 or 12%? If the boiler were tighter would I get those numbers?
A local nonprofit organization for oil heating posted these burner specifications:

What are you not following with excess air? Excess air is a percentage of the amount of air found over its known stoichiometric combustion value. So the perfect amount of air for perfect combustion is 0%. Air is known at 21% O2 & 79% N2 approx. So if you burn any fuel with a known stoichiometric value you can determine how much extra air is in your combustion process.

Sometimes excess air is confused with O2 readings. The actual O2 reading is not the excess air %, it is the % of O2 gas in content of exhaust and it starts at 21% and goes down from there. Excess air starts at perfect combustion 0% and moves up from there. You can have over 100% excess air.

Steamhead

Are you taking the reading inside the draft hood, before the dilution air comes in?

If so, you might have an air leak somewhere.

Steamhead

Aha. It's a pretty big factor. Do whatever it takes to get your probe into the draft hood before the dilution air enters. Then get back to us.

Steamhead

Actually, I find that you can often get your probe in there from underneath the hood- angle it in towards the boiler and the tip should be past the point where dilution air comes in.

In extreme cases, I drill a hole in the side of the hood and stick the probe in at an angle thru there.