Air Intake

John_34

Is there any advantage to installing optional air intake piping for an oil burner so that all air for combustion comes from outdoors?

Ken_8

In the famous words of the host here...

That depends.

The use of "conditioned" inside air with ~70° air laden with existing energy and shooting it through a boiler - only to be wasted in the chimney exhaust is wasteful. Especially when compared to the option of taking cold air - with no heat-wasted combustion air from inside - and using all outside air, with no "wasted" energy at all.

However, the efficiency of o-buners is predicated on the notion that the hotter the flame - the more "complete" the combsution process. More complete combustion generally translates into higher efficiency.

And therein lies the conundrum.

If this is so, would not zero degree air (say from outdoors)crashing into "atomized" oil, have a negative impact on just how complete the combsution (really just the cracking of oil-molecules) process might be? As opposed to say, 70° "heated" air taken from within the heated space - helping the combsution process ever so slightly instead?

I'm sure this is exactly what happens. The problem is, I don't know which has more impact - and therefore what scenario is superior! (Other than an educated guess that the only answer still - is...)

That still depends!

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dconnors

1 advantage for sure

The combustion process can cause a negative pressure within the structure which will cause unwanted air infiltration. i like dedicated combustion air but that does have a negative impact on burn quality. Make sure you are using a burner operating on a pump pressure of 140psi or higher.

Ken_8

Say what?

In moderately tight construction, infiltration is not unwanted - but the exact opposite!

Further, pump pressure should not be 140# - unless the manufacturer states that is THE correct pump pressure for the burner configuration, model and boiler it is mounted to.

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dconnors

infiltration

Infiltration will occur in any building. It just gets worse when we put mechanical venting in place. The best results happen when we control what happens to a building. As far as pump pressure, I have fooled with pump pressure far longer than the current vogue. Some of us years ago had to deal with cold fuel and derating a nozzle while increasing pump pressure was the only answer we had.

Weezbo

depends ... Where on planet Earth you are located...

and at what time of year. severe cold outside air i would temper ,mix,pre-heat...take your choise. in milder climates..dedicated air for the boiler is a very sane idea without any outside human intervention in the supply side air intake.fire likes oxygen so it gets it where it can..dedicated air pretty much ensures it wont be the oxygen You and Your Lungs Heart and Brain seem to have a veritable proclivity, too:) cool?

dconnors

Energy Conservation Professionals

Randy at ECP will be more than happy to discuss and inform on building envelops

Ken_8

Doc,

You speak in negative terms about infiltration. I suggest we'd all be dead if it were not for its existence. Unless of course you have a fresh air HX. Some infiltration is essential and desirable in most homes. In winter, when all windows are typically closed and storms up, we need it most. The negative pressure you suggest as a "bad" thing - that occurs when the burner fires, is not bad at all - and probably saves many lives each winter in so-called "modern" construction methods of the past 20 years.

I have run across guys like you who twiddle with pump pressure - and then fail to make note of that change from OEM spec. and destroyed more than their share of target walls and boilers.

The $20,000 law suit that resulted from an "expert" like your self who failed to note he cranked the pump up to 300# on a 'D' tube C/B boiler at the local YMCA comes to mind. His co-worker put the nozzle in called for by the OEM burner/boiler maker and within a day, blew out the back wall and half the tubes (and much of the basement partition when that part of the 'D' tubes blew out from the water flashing to steam) and ruptured the back wall of the boiler.

Of course the guy who jacked up the pressure to 300# to "improve" light-off said the other tech. was at fault because he should have tested pump pressure before putting the larger nozzle(s) in that the OEM data suggested were correct.

The oil company fired the guy who reset the pump pressure and "ate" the twenty grand. Fortunately, the damage to the building was minimal and no one got hurt.

You may have been in this biz more than most, but you sure as heck didn't learn very much along the way.


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dconnors

labels labels labels

thats why we use labels to indicate what we do. seems ideas dont go far here

Rob_16

I think the company fired the wrong tech there is no way the second tech tested the combustion after he changed the nozzle

dconnors

i agree

but the tech that made the change should have labeled the burner as to the changes. there was a time that all of this was experimental. as we did the experiments we recorded our changes and results......enough said. i still maintain that all air whether combustion or not should be regulated by more than chance.

Rob_16

The other advantage to controlling infiltration is you can heat the air you bring in so the cold air does not leak in and make the home feel drafty

dconnors

again i agree

we do it all the time in commercial applications. it can also be done in residential applications.

Ken_8

Time out.

If a manufacturer puts a label that says the burner operates at 5.00 GPH at 100# and the boiler and burner are matched, all the OEM labels are based on pure engineering and matched "approved and sanctioned" testing and approvals - which you seem ever so non-chalant about throwing into a cocked hat!

You jump in and decide to increase pressure and reduce nozzle size to counteract the pump increase, you are now legally responsible for performance and liability issues. We have all done "things" attempting to overcome poor combustion characteristics that are slightly "off" factory specs. But the notion of increasing pump pressure and reducing nozzle size to accomodate that nuance should only be done out of desperation - and no documention we can afix will ever be permanent enough to be understood by the typical service tech who "knows" all nozzles are rated for 100# and expects the pump to be set that way - who may follow your steps next time around.

Guys who do "commercial" work will be at a higher level of competetnce and training. I have seen too many "Magic Marker" scribbles on the side of 'J' pumps saying 150# only to find them actually at 100 or 200 than I care to recount.

Suggesting the second guy should have done combustion efficiency test after what should have been a simple nozzle replacement is intersting, but will actually happen about one time in 50. Is that right? Hell no. But is the reality of the conditions we work in.

Let's agree to dis-agree on this one.

Lastly, can you tell me with any certitude what the end spray angle will actually be when you take a 100# 5.00 x 60° semi-solid nozzle and replace it with a 3.50 x 60° @ 200# ?

Be honest. You wouldn't have a clue!

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Rob_16

There have been a number of times when we could not get a unit to fire well, after a call to the tech support or a visit from their rep. we would be told to raise the pump presure and dowd size the nozzle almost all the time it worked. We tried an experment, took a boiler and fired it with 3 nozzles of the same make and rating all 3 fired differantly this industry has to teach our techs that you have to test. We have to make sure the unit is running properly when we leave the job

Ken_8

This industry has to learn that

the manufacturer makes the standards and has the equipment certified and insurable after extensive beta, field trial and likeminded field fed back. Once they set the standard and instruct us as to how to setup their boiler/burner we assume full respomnsibility for altering that "standard" by screwing around with the factory spec. regarding nozzle pressure, the acceptable range the burner and boiler are designed to handle and the written instructions included with all packaged units.

I have never seen a written directive that suggests altering pump pressure and using a conversion "chart to find the modified firing rate to determine the new nozzle size equivelant to be in print. Is is done? Rarely. Do phone jockeys at Carlin, Beckett, and Riello suggest you try it? Absolutely.

Will they authorize it in writing and company stationery?

NO! You assume all liability at that point.

Nuf said.

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Ken_8

Answer my question

What would the resulting spray angle be?

No clue, right?

I rest my case. Unles you have a half million dollar test chamber in the back of your truck you cannot measure the resulting free carbon byproducts, the resulting spray angle, the ozone production, the flame center temps, the cracking molecular thermodynamic, the radiation impact on the reflected flame impact, the combustion pattern changes and impact on certain stress relationships, etc.

All we have is simple test instruments. Why do you suppose its so hard to get a boiler approved for production? The lawyers have to look harder than the engineers!

And you want to assume THAT liability in the field with an analyzer and a screwdriver?

Unless you have graduate studies in metalurgy, physical flame spectometry and a P.E. or M.E. after your name - you're playing literally with fire.

Why do you think the "acceptable" nozzle and burner configurations data is included with the burner/boiler? Because they need to waste paper?

Come on. Get real. I'd like to keep my business for the next geneation - not lose it to some slick lawyer by violating manufacturer's setup parameters.



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Rob_16

I am not going out there and setting units to my own settings just to say they are my own. If I install ZYX boiler and put in just what he factory says and leave and that unit is making high levels of CO and someone gets hurt they are coming after me. I'm not saying I am smarter then the engineers God knows I'm not but I am the guy in the field under field condition making the test. If I can make some adjustments in the field to make a unit fire to specs I will make that adjustment and sleep better at night. No I don't know what angle the nozzle is but if i test the unit properly and meet test specs and CO levels these units run fine

Weezbo

Ken....

doc heat didnt say crank the pump pressure up he said check to see that the pump pressure was 140....the reason he is saying that is the boilers and burners that run at or lower than.. do tend to put up a lot of resistance to perfect operation...to downsize a nozzel or change the angle or increase the pump pressure isnt unheard of...i didnt take what our man has said to mean jack up the pump pressure and overfire it. not that i dissagree at the thrust of your logic it is though maybe a little like not quite catching what he had said in the first place.ihave seen cold oil hit the back of a fire box and luckily it was lined...on more than one occasion...something that might interest you is an experiment Alan was doing with a herrman modulating oil burner. he can explain alot of the paticulars..he disscusses the effect of oil pressures on flame etc.i realize it is a bit off subject however you might find some insights worth your efforting.The pump pressure is capeable of 700 psi.now dont think i suggest to crank up a burner to 700 psi and down size the nozzel to get a clean burn in severly cold weather.for one thing you would have a heck of a time finding such a pump.and the math would take a bit of figuring. i am curious as to the bumping up of oil pressures is it attributed to effects noticed by technicians or engineers maybe Alan MEcurio knows ....and what would further clarify the answer would be a date as to when this reasoning came in vouge...i am young in a sence only in my 50's and honestly i have only been aware of bumping up the pump pressure for about 30 years or so.an old indian taught me that the rational behind a ten percent increase in pump pressure was to ensure better atomization.about 7 or 8 years later i worked on my first riello.i hope i am not jumping to conclusions buh the only burner that i had heard of that stroked along at a signifigantly higher pressure in a residential setting was a riello.

Weezbo

Oil tech talk Burnham 180

i dig what you are saying.i like breathable air. i also think it wise to stay within the parameters spelled out by the boiler and burner manufacturers...do check this short few words on pump pressures out. if you are into service work you would need to know some of these modern variations that are pulled out of the blue as it were.some times i hear things and go oh oops when did they do that>?now i get to run back and get a different nozzel:)for the boiler i bought this morning:) go figer.havent even gotten the burner out of the box...

Darin Cook_3

My 2 cents

docheat's statement about increased air infiltration is not far off base. Any fan that runs in the home and can move air to the outside will increase the " Stack Effect " on said home. Do we need X amount air exchanges per hour you betcha. Where is that fresh air coming from? As in alot of cases it may be moving through the walls and ceilings dragging fiberglass and other assorted goodies ( mold particles) with it. Unless you do a blower door test you do not know what the leakage is on the home to begin with. We have done alot of energy audits on homes over the years. While very tight homes do exist out there, the norm is most homes are still too loose. Even homes less than a year old, we have found to have double the amount of required air exchanges per hour. Homes should be built as tight as possible and provide mechanical ventilation to pick where that fresh air makeup comes from and when. BUILD IT TIGHT AND VENT IT RIGHT. I don't know if I ran off the point here, but just try to look at a home as a whole system. One thing affects another. As far as pump pressures go, I know for years Sid Harveys have handed out those little pump pressure conversion charts. I thought that the burner manufacturers all went to running at 140 psi for better atomiztion of the oil and thus a better burn. Of course if you are testing the products of combustion you will know if you have a problem anyway. Since we pick up the liability anyway, make adjustments if you need to. But you better be testing and knowing what is going on in that combustion process. If you don't, someone else might end up being the proud owner of your house.






Darin

Jim Davis_3

Air Intake-Pump Pressure

Piping cold air directly to a burner lowers the efficiency of the burner. Industrial engineers have known for years that if you heat your combustion air you can make major improvements to equipment efficiency. If any one ever checked the rating of oil nozzles they would fine they are only tested to atomize oil at 100# pressure if the oil is heated to 80 degrees. Brookhaven Labs at one of their annual conferences a few years ago discussed the possibility of making 150# pressure standard on all burners. The biggest augument was that too many field service people didn't do testing and this would cause problems. Three things make oil harder to burn efficiently- cold oil(two line systems can aggrevate this), cold combustion air and low pump pressure(less than 125#). If one would check they would see when an oil pump is set at 100# pressure, the initial light-off pressure is 75-80#. At shut-down the oil flows until the pump pressure drops back to 75-80#. At 125# these two pressure never drop below 100#. Higher pressure increases the output of a nozzle but it shortens the length of the flame. Smaller oil droplets burn quicker. Equipment is only certified to perform in lab testing and no equipment was ever approved for your installation. It is the contractors job, according to the manufacturers instructions to make necessary changes. If pump pressure, nozzle pattern, spray angle are so critical why does the same exact burner, installed in different equipment, with exactly the same size combustion chambers have different specs. One says 100#, another 140#, one says 70 degrees hollow, the other 80 degree solid? Its the same burner!! Does water and air need different pressures and angles and spray patterns. Anyone that works on oil that doesn't test pump pressure before changing nozzles or doesn't know that it affects capacity shouldn't be allowed in the field. Once had a commercial oil boiler that fired at 20 gph. It was supposed to light a 100# and then jump to 200#. Well at 100# the boiler tried to jump across the room. It is amusing to watch a service technician hide behind a wall when a boiler lights(I thought I was the only one that did that). We raised the light-off pressure to 150# and the boiler lit so smooth he thought it didn't light at all. Always nice to have a combustion analyzer in the flue that can indicate in seconds the equipment is firing. Those not familiar with digital combustion analyzers, CO testing oil are naturally going to have a problem knowing and making the right decisions and must rely on old information. Many of the instuctions developed by this industry are based on antequated testing equipment and procedures. By the way, combustion air needs to be brought into all equipment rooms with mechanical(fan powered)combustion air to that room, not the burner.

Rob_16

Thank You Jim a lot of good information

Jeff Krawic

Combustion air from outside

I just had to add my 2 cents worth today and maybe its only worth one penny but....... Tjernlund makes a nice little unit, available in multiple sizes from 40,00 BTU/Hr. up to 3,700,000 BTU/Hr. Inputs. This unit DOES bring in fresh air directly from outside the building and deliver it to the burner. (NOT directly booted) and the really cool thing is it mixes the incoming fresh air from outside, with the ambient air in the space. This in turn changes the temperature characteristics of the combustion air. (www.tjernlund.com) This unit is called the "Air In-Forcer" Models PA-I for those who want to look it up on the Net.
Now as for my other 2 cents worth, Yeah Brookhaven did alot in the past with pump pressures verses atomization etc. and the newest info from Brookhaven (and pump manufacturers) is to use solenoid valves on oil supply lines, with delays, thus eliminating the pump pressure cutoff spring as the "opening and closing pressure point" of the oil supply to the nozzle. They showed a reduction in CO, sooting and smoke by using this method. Now for my $1.00 worth of info: Any service tech out there, working on burners either commercial or residential, you durn well BETTER be using a combustion analyzer or you should talk to Rudy Leatherman about law suits. There is NO good reason to not have one on the truck in todays world. Lets all be safe out there.
Jeff Krawic

DaveC

Yes, very good...

One question, though - is a smaller nozzle at a higher pressure more, less or no more likely to clog than a larger nozzle at a lower pressure? I'm thinking about the smaller range of sizes, like .65 to .85 gpm.

Jim Davis_3

Nozzle plugging

Historically higher pressure has prevented nozzle clogging, especially in the .50 to .85gph range. Actually had an engineer from Delavan agree with this years ago.

DaveC

Thanks, Jim...

There's been some real good information here lately on oil burners, glad I'm "tuning in"! =|:^)

Jack_21

One more thing on the Enforcer Jim

If the intake, dilution air inlet or mixed outlet air of the Enforcer is plugged it will not allow the burner to fire. It is the only unit which offers this positive safety. If you are using mechanical comb air, you should guarantee that you are getting it before allowing the burner to run. the fan in a can and burner boots have barometrics as balancing devices between the intake and the burner. If the intake gets plugged it dumps the baro and continues to let the burner run. No safety!

The code on power venting says that you must prove movement of flue gases prior to releasing the call to the burner. I would like to see the code require the same for Comb air.

Jack_21

Oops, sorry,... \"Jeff\"

joe_14

field cas.



fields cas will not let the burner fire if it dosent bring the motor on to bring in fresh air



joe.g