air fuel ratio


  #41  
Old 01-19-19, 04:32 PM
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p,
What is the .005 & .008 mean. You are looking for neg. .02-.03 breach draft. What is that extra zero. How are you measuring the draft. Sealing the damper should give you the most draft, ordinarily too much. Opening the damper is suppose to cut the draft down.

The 5 min. is correct. At least 5 min., this gives the burner time to heat up the chamber and pipe to it's peak. Before that everything is still climbing, must give it a chance to level off.

Overfire = .01-.02 is what you want. Any more than that the draft is pulling the heat out of the boiler and up the chimney.
 
  #42  
Old 01-19-19, 04:51 PM
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pa,
After rereading your post it sounds like you are saying you are getting almost no draft. Less than .01 which you should be getting ate the burner. What is your stack temp, what are you using for a nozzle. Since heat creates the draft, it doesn't sound like you are creating much heat. Are you under firing your boiler or do you just have a huge chimney or an extremely tight boiler.

Pics would be very helpful if possible. If .01 is all you can pull with a sealed damper you have a draft problem somewhere. Possible chimney height or too large a flue for your boiler.
 
  #43  
Old 01-19-19, 04:57 PM
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im looking for -0.02 to -0.035 at the damper. Im getting above -0.01 (-0.005 to -0.008). Yes sealing it gives me more (-0.008 to -0.01). I have a long flue. If I open the damper i get 0.0.

Im getting under 0.01 at the fire.

Im using a dwyer 400-5-gage. With new fluid, o rings, and shut off valves.
 
  #44  
Old 01-19-19, 05:14 PM
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Originally Posted by spott View Post
pa,
After rereading your post it sounds like you are saying you are getting almost no draft. Less than .01 which you should be getting ate the burner. What is your stack temp, what are you using for a nozzle. Since heat creates the draft, it doesn't sound like you are creating much heat. Are you under firing your boiler or do you just have a huge chimney or an extremely tight boiler.

Pics would be very helpful if possible. If .01 is all you can pull with a sealed damper you have a draft problem somewhere. Possible chimney height or too large a flue for your boiler.
Replaced nozzle and it's the called for size 0.75-70B.

This unit heats up the house faster then ever and I have had it tuned professionally many times and i never noticed any of them checking the damper draft. When i cut the air intake the fire got much bigger and hotter and the unit is on less time each time it cycles on and it blows out much hotter air. ive ordered smoke spot test setup. Until then Ive opened up the air to about 1/2 way between what is was set by the last "pro" and what you see in the videos below which was the max size fire i could make which did look like it was hitting the far wall of the chamber, which is why i cut it back and still it heats the house much faster then this unit ever has since installation.

yes flue is long and while less pressure at the damper would be better will this be an issue? I note that if it was less at the damper, then my already low over fire pressure might be lower.
 
  #45  
Old 01-19-19, 05:15 PM
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If you put your hand in front of the observation door are you getting burned. With 0 draft the heat should be almost coming back through the door.
 
  #46  
Old 01-19-19, 05:28 PM
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Originally Posted by spott View Post
If you put your hand in front of the observation door are you getting burned. With 0 draft the heat should be almost coming back through the door.
I feel a draft and need to remove my hand after 2 seconds because of the heat. The over fire draft feels less then the draft at the damper port.
 
  #47  
Old 01-19-19, 05:36 PM
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If you go back to my post #22 I explained the larger and smaller fire. The less air, the hotter the fire and the more air cools the fire which cuts the cuts the draft.

You have 2 air settings on your Beckett burner.

You have your air band with a tightening screw which you loosen and then open and close by the lever that holds the screw. It may be tight but it does move. The other one is the pointed lever with the numbers.

The basic setting is with the damper closed and the adjustment made with the numbers lever but if you open the damper up you will find it will shorten up the fire so it doesn't hit the wall and then adjust your number to get your trace smoke.

Another thing you mentioned is your nozzle at 70 deg. That will give you a narrower and longer flame. Are you sure that's the right nozzle. Usually warm air furnaces take an 80 deg.

What is the model number of your furnace. Again pics would be good.
 
  #48  
Old 01-19-19, 05:49 PM
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carrier air handler label: model 58cma105-12, serial 3400v23172 w/betkett afg f3 w/nozzle 0.75-70B
 
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  #49  
Old 01-19-19, 05:51 PM
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If you cannot get enough draft at the breach it's impossible to get it over the fire because besides the lack of natural chimney draft at the breach you also have the boiler section restriction. You definitely have a draft problem somewhere. Have you checked chimney flue and height.

By code they have to 2ft. I believe above the highest point of the roof but because of surroundings like trees and taller buildings sometime that's not enough.

My biggest problem with masons is they do just what is required and do not check for proper draft when done.

I put a furnace in and needed a chimney on a job I did so the mason built the chimney and was leaving. Fortunately I was there and asked him if he checked for draft. He didn't, said it wasn't his problem, chimney was built to code.

With my draft gauge I got no draft. Asked him to build higher. After a little discussion where I mentioned, no draft no pay he had to add another 2 sections before I got the proper draft because of the surroundings. Huge trees surrounding the house.

It worked out but only because I was there at the time.
 
  #50  
Old 01-19-19, 06:13 PM
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Your nozzle is the correct size and spray angle. Your pump pressure is suppose to be 130 PSI instead of the normal 100 standard pressure which gives your nozzle a .85 GPH rating. Has your pump ever been changed or checked for the proper pressure.

The sight below will give you the specs of what they are looking for. It will show you the options for your furnace. They are firing it for 119,000 BTU's You can go larger by changing the nozzle.

When they clean it are they removing those 2 round covers and cleaning in there, Dome do not. I cleaned a 20 year old furnace like your that was serviced every year. I took the caps off and the original tin foil factory covering was still in place.

https://www.manualslib.com/manual/74...?page=4#manual

PAGE 4 of manual.

The problem with warm air furnaces is they heat up so fast the chimney doesn't have a chance to get warm.

You have a furnace, not an air handler. They are different. Air handler has no burner.
 
  #51  
Old 01-19-19, 06:24 PM
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Do you have a pic of your smokepipe and damper.
 
  #52  
Old 01-19-19, 06:49 PM
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my carrier label says output BTUH 85,000 and pump pressure 100. flue too long to get a clear pic. I cant get far enough away to get it all in. Small garage with obstacles.
 
  #53  
Old 01-19-19, 07:22 PM
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85,000, they are looking for a .65@ 130PSI which will give you the .75. Why the raise the pressure is for better atomization which will give you a better burn. What you have is the .75@ 100 PSI which not what they want for some reason.

Only know what they are looking for according to the numbers you gave me. At least you have the info.
 
  #54  
Old 01-19-19, 07:51 PM
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I’d be very curious what your pump pressure and CO actually are.
A lot of the time raising the pump pressure will also improve CO due to the better burn.
I’m somewhat concerned about your draft. You need that barometric damper operational.
 
  #55  
Old 01-20-19, 05:00 AM
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Why does my label say different?
 
  #56  
Old 01-20-19, 11:39 AM
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The manual is likely more recent than the furnace.
 
  #57  
Old 01-20-19, 12:04 PM
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I sent carrier email asking. If they recommend change i will do.

Also considering an exhaust fan to lower the draft pressure.
 
  #58  
Old 01-20-19, 01:32 PM
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What’s your chimney like? Clay liner? Is it in good condition?
 
  #59  
Old 01-20-19, 01:43 PM
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no chim. just pipe. metal 5" dia
 
  #60  
Old 01-20-19, 02:53 PM
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why? im lost here. i think in the smaller diameter pipe he might get a positive number, not negative. Would not downsizing the pipe increase the pressure?

https://www.youtube.com/watch?v=4rOl8CYBAkg
 
  #61  
Old 01-20-19, 03:59 PM
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Think of it like a water pipe. You have a 1" pipe and you reduce down to 1/2". It increases the pressure because all the water from the large pipe is being squeezed into the small.

Unfortunately with smoke pipe even though you have good draft at the small pipe, it is too small to properly remove all the heat from the big pipe so it leaks back into the furnace or in that case any available opening.

Exhaust pipe sizing is very important in removing exhaust from heating units or you get back draft causing CO2 leakage into the home.

You cannot chock down smoke pipe.

What do you mean NO CHIMNEY?
 
  #62  
Old 01-20-19, 05:48 PM
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so ur confirming what i said. smaller dia = more pressure. He said less.

why? because i dont. I dont know how else to answer that. My flue pipe just ends.
 
  #63  
Old 01-20-19, 06:23 PM
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How does it end, exactly? Once it leaves the furnace it should turn vertical and extend up past the roofline.
How high does it go? Is there a cap on it? B vent all the way?
 
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Old 01-20-19, 06:35 PM
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it angles up and goes thru the gable wall. we were going to turn it up vertical after that and make a chimney, but that never happened. its more wind resistant this way. i could still do that, but I think a draft fan might be a better idea.
 
  #65  
Old 01-20-19, 06:45 PM
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the down facing exit end is one of those adjustable 0 to 90 fittings. Covering the opening is 1/2" mesh wire screen. We were going to make the 90 face up add another pipe section, attach it to the gable fascia and bring it further up with another pipe section, then add a chimney cap. That might help lower my pressure slightly, but maybe not enough and it would be difficult and costly to make that hurricane proof.

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  #66  
Old 01-20-19, 06:59 PM
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That’s wrong, to have a horizontal termination like that a power venter is required.
Unless there’s specific documentation in the IOM saying otherwise.
You may want to pull the burner and make sure there’s no damage to the end cone or blast tube from poor draft.
 
  #67  
Old 01-20-19, 07:10 PM
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over fire draft is in spec.
 
  #68  
Old 01-21-19, 06:45 AM
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That is a miracle, with a venting setup like yours.
 
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Old 01-21-19, 06:58 AM
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That is why I concerned. If I install exhaust fan to lower my flue pressure, then over fire pressure will go lower too.
 

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  #70  
Old 01-21-19, 07:07 AM
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You’d have to select the correct oil burner rated horizontal vent fan. These can be very expensive.
And adjust the barometric to maintain correct overfire draft and breech draft.
 
  #71  
Old 01-21-19, 07:27 AM
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i understand that. I have already contacted carrier and other makers for info.

Im still not sure i need this. My over fire draft is fine, but my flue pressure is too high. If i lower my flue pressure, so lower goes my over fire pressure. Which may be ok.

most all sites and general info i read indicates that over fire should be negative, but mine calls for positive pressure.
 
  #72  
Old 01-21-19, 09:40 AM
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Some equipment does spec a positive pressure over-fire. If you are within manufacture's specs, I wouldn't loose any sleep over it.
 
  #73  
Old 01-21-19, 10:06 AM
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Grady,
You are correct in what you say but in this case the furnace smoke pipe is being vented out of a side wall with no chimney which is the reason for lack of draft.

This is a regular natural draft appliance which needs some type of chimney or power vent.
 
  #74  
Old 01-21-19, 10:10 AM
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over fire spec is +0.02" wtr max. no min. im just barely positive reading there with my flue pressure slightly to high.

i just turned the downspout on the flue exit to face up and it increased my negative draft just barely. With my barometric damper completely sealed Im at -0.012 With the damper not sealed but the weight set to let in least air, im right at -0.01" Spec is -0.02 to -0.35

If i install a draft fan, i can get more negative at flue, but that will bring my over fire down too, right?
 
  #75  
Old 01-21-19, 10:13 AM
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of note is that the label on my carrier is different then the paperwork that i got from carrier last year. It lists different flue draft and does NOT list over fire draft. Below someone found carrier spec sheet online which was different then my label and paper that i got from carrier last year.
 
  #76  
Old 01-21-19, 10:44 AM
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This is the sight that I previously posted but with different info. If you look at your table of contents at the venting section, pages 5 and mainly 6 on chimney venting.

If you look to the top right of the sight it will give you other options for info to check.

https://www.manualslib.com/manual/25...ier-58cma.html
 
  #77  
Old 01-21-19, 10:53 AM
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The barometric needs to be open and not sealed. To maintain proper draft.
There is no way you’ll ever get proper draft with that flue piped how it is. A vertical extension or power vent is a requirement.
 
  #78  
Old 01-21-19, 11:06 AM
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r,
With all due respect advising him to unseal that damper is only compounding his problem considering the circumstances. It's only going to lessen the little bit of draft he miraculously is getting at all. The damper is only used to control the draft if the chimney is producing to much wild draft to begin with.

He could remove the damper completely in his case. On another note I noticed he has had this so called professionally serviced. I cannot fathom any reputable service company servicing this without being vented to a proper chimney. What could this tech get for draft and never check it out or did he never even pull the smoke pipe down.
 
  #79  
Old 01-21-19, 12:31 PM
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I watch every one working in or on my home. None ever cked flue draft and there was not even a hole for the probe. Last year when I serviced it I found weight inside the chamber. There was also no weight on the baro drft door. None looked at my chimney unless it was before they knocked
 
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Old 01-21-19, 01:33 PM
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ok. see pics. i just extended it two more feet and now reading -0.015' wtr flue with barometric damper set to min and not sealed off. Then added two more feet (4' total added). see pics and now height above roof complies with NFPA211 and im getting just barely under -0.02" wtr.

with both above the over fire is 0" wtr.
p

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