high stack temperture

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Old 12-16-07, 12:00 PM
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Angry high stack temperture

Hi i'm new to this forum and hope you guys can give me some advise. I have an oil fired boiler called Blue Ray III which is really just a Thermo Dynamics vtf 510 boiler and a Beckett AF mp1192 burner. I've brushed and vacumed the boiler,checked draft (.05) did a smoke test (0) and checked my pump preasure (was 110 lowered to 100). When I check my stack temperture reading is 750 deg f. The boiler room is 75-80 deg and book says stack should be 500 over room temp so i figure 600 deg is highest it should be. The plate on boiler says IBR burner capacity 1.00 80 deg hollow which is the size nozzle i'm using. My questions are is that the size nozzle to use or ithat just the max? How do you determine the right size to use should I be useing an .85 80deg hollow? Also is there anything else that would affect stack temp? Thanks for any help you guys can offer me.
 
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Old 12-16-07, 06:11 PM
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Vtf 510

You can try reducing the draft to about 0.03-0.04 & see what happens but I usually fire this boiler with a .85x80 hollow nozzle @ 100#. You will have to cut back on the air.
 
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Old 12-16-07, 07:13 PM
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0 smoke

also make sure that you are just at 0 smoke... you could be well beyond 0 smoke and that raises the exhaust temp and that you are at around 11 to 12 percent co and 4 to 7 percent 02
 
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Old 12-16-07, 07:41 PM
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I'd guess best way to do that is close the air till you get a trace then open the air to zero...
 
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Old 12-17-07, 07:00 AM
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NJ Trooper you are right on. Get a trace and lean it up. I believe Bacharach or Beckett says get a trace, add enough air to drop % CO2. Some of the problem here is excessive draft as stated above. When you exceed a -.04 w.c. draft the flame on flame retention burners start to leave the head thus causing soot. The draft should be taken overfire unless the boiler is pressure fired. Most pressure fired boilers will require a lower breech draft usually near 0 Set the proper CO2 and it should be clean.
 
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Old 12-17-07, 08:00 AM
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high stack temperture

Thanks for the help I will try changing the nozzle to a .85 80deg hollow and see how much that helps. If the manual calls for a .05-.06 stack draft is there any problem leaving it at .03-.04 if that also helps? Also what would be best for the over fire draft manual says .02? Once again thanks for your help.
 
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Old 12-17-07, 02:52 PM
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I'm not familiar with this boiler, but do know that some boilers have 'baffles' that you can use to adjust the stack temp. This old Vaillant that I have been nursing along for 25 years has 'em, but they don't tell you what they are for.

One year I accidentally left them out after I cleaned it and the stack was a LOT higher... don't know how much exactly, but it was higher.

Just wondered if that boiler has them or not ?
 
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Old 12-17-07, 03:07 PM
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Unhappy

My VanWert multifuel backup boiler was reaching near 700 degrees the other day when I fired up the oil burner (to get fresh oil through the filter and to nozzle.) I suspect the burner is set up incorrectly, since it was showing a trace of smoke when the service guy was here. (Older Becket AFG with the 1725 motor/pump.) Guess I need to order those parts for my smoke pump sooner than later.
 
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Old 12-17-07, 05:55 PM
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high stack temperture

This boiler just seems to have 8 tubes that go from the top down to the fire box. There dosen't appear to be any baffles in the tubes not sure if there should be and someone removed them or if this is just the design of this boiler.
 
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Old 12-17-07, 05:59 PM
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Baffles

Originally Posted by NJ Trooper View Post
I'm not familiar with this boiler, but do know that some boilers have 'baffles' that you can use to adjust the stack temp.


Just wondered if that boiler has them or not ?
Trooper,
Yes, it does have (or is supposed to have) baffles.
 
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Old 12-17-07, 06:44 PM
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Is this a vertical tube dry base boiler? Is fo it does require baffles and the OF draft would be -.02" w.c.. All baffles should be in. Make sure there is not a lot of debris in the combustion chamber.
 
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Old 12-17-07, 08:21 PM
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high stack temperture

If this boiler is supposed to have baffles I guess that means a previous service man must have removed them. Are they replacable and if so how would I go about finding them? I guess if it is missing the baffles this would add to the reason for high stack temperture.
 
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Old 12-18-07, 02:50 PM
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Baffles

Yes they are replaceable. Here is a link to Thermo-Dynamics web site. You will find contact information there.
http://www.thermodynamicsboiler.com/
 
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Old 12-18-07, 09:22 PM
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high stack temperture

Grady thanks for the link to their web site. I contacted them and they confirmed when new boiler came with baffles and that all of them should not have been removed. They told me to find a distributor of their boilers for the parts. I live in Long Island NY and so far had no luck finding the baffles ,but will keep on trying. I will also contact Thermo Dynamics again and see if they will sell them to me or at least give me a name of a distributor near me.
 
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Old 12-19-07, 05:53 PM
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Thermo-Dynamics

Look in the phone book for Sid Harvey. The are a wholesale supply house who does not sell retail but should be able to direct you to a service company thru whom you can order the baffles. What is your telephone area code? Sid's has about a dozen or more stores in NY. With your area code, I might be able to give you one or more near you.
 
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Old 12-19-07, 07:11 PM
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high stack temperture

I did go to a local Sid Harvey in Farmingdale and they said they did not carry but recomended a place called Acme Rasol which I will try tomorrow. Also tried a place i've used before called Patriot supply and they can order me generic baffels if I know the height and width. I'm pretty sure height is 17" but not sure of exact width without haveing old one to compare to.
 
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Old 12-19-07, 07:35 PM
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Baffles

Strange that Sid's didn't handle Thermo-Dynamics. My local Sid's does. Maybe Thermo-Dynamics will tell you the size or you could measure the hole into which the baffle goes.
 
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Old 12-20-07, 07:05 PM
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high stack temperture

Can you give me some advise on how the baffles should fit? Do they go the full length of the tube if it measures 17" is that what I order? As far as the width the tube is rectangle shape and measures 3" x 1/2" how snug should they fit? Would you order 3" wide or little less say 2-3/4" just not sure how tight they should fit? Thanks for the help.
 
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Old 12-20-07, 07:41 PM
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Baffles

Sorry, I was thinking that particular boiler had round tubes.
As far as I know, nobody makes aftermarket baffles for that boiler. The only aftermarket baffles I've see are for round tubes. You will likely have to order them from a Thermo-Dynamics distributor. Typically Thermo-Dynamics baffles are about 4-5" long & zig-zag shaped.
 
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Old 12-22-07, 08:05 AM
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high stack temperture

Grady thanks again for your help you were right on with the size of the baffles. I finally found a distributor who stocked them and they are only 4" long I thought they would be as long as the tube. First chance I get i'm going to reclean boiler install the baffles, readjust as needed and see how it affects stack temp. If necessary i'll change from the 1.0 to the .85 nozzle which I thought you suggested.
 
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Old 12-22-07, 02:45 PM
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Nozzle size

Usually the reason I downsize the nozzle is because of back pressure. I don't suggest this be done without test equipment.
 
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Old 01-14-08, 03:01 PM
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Smile high stack temperture

Hey guys

It's been a while but now that the holidays are over finally had time to work on my boiler. I gave it a good cleaning and installed the missing baffles which lowered stack temp from 750deg to 620deg. The manual calls for 500deg over room temp which would be 570deg-580deg is 620deg close enough or would you try going from a 1.0 nozzle to a .85 to lower temp a little more? Right now my o.f. draft is .02 and stack draft is .05 co2 is 10% with 0 smoke. Is it better to be a little high or a little lower on stack temp? Thanks for all the help.

Gary
 
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Old 01-14-08, 03:58 PM
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Lemmee jump in before Grady gets here ...

I can tell you that the .85 will lower your stack some more. Judging by your messages, you have the proper test equipment, so I would say to try it ! What have you got to lose ? If you don't like the way it runs with the .85, you can always crank the pump pressure up a bit to get back to the same firing rate, with a benefit of better atomization of the fuel ...

Lower stack temps means higher efficiency ... not much, but worthwhile.
 
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Old 01-14-08, 04:59 PM
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Originally Posted by NJ Trooper View Post
Lemmee jump in before Grady gets here ...

I can tell you that the .85 will lower your stack some more. Judging by your messages, you have the proper test equipment, so I would say to try it ! What have you got to lose ? If you don't like the way it runs with the .85, you can always crank the pump pressure up a bit to get back to the same firing rate, with a benefit of better atomization of the fuel ...

Lower stack temps means higher efficiency ... not much, but worthwhile.

The only concern would be stack condensation,
and you are a long ways from that happening.
My Biasi runs at around 350 degrees net when
it is clean.

Pete
 
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Old 01-14-08, 07:15 PM
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Nozzle

Hey Trooper, you been around long enough to be reading my mind?

Railmanm, Since you have the test equipment & know how to use it, go for it. Unless I miss my guess, you will drop the net stack temperature by almost 100 & be able to get around 12% CO2 with a clean fire & -0.02 draft overfire. I'll be watching for the actual data.
 
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Old 01-14-08, 07:38 PM
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Originally Posted by Grady View Post
Hey Trooper, you been around long enough to be reading my mind? ... I'll be watching for the actual data.
I dunno about that Grady, but I think I might be getting close to 'taking the grasshopper from your hand' ! wax on, wax off ...

I wanna see the final results too !
 
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Old 01-15-08, 04:48 PM
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Wax on, Wax off

Originally Posted by NJ Trooper View Post
I dunno about that Grady, but I think I might be getting close to 'taking the grasshopper from your hand' ! wax on, wax off ...

I wanna see the final results too !
You'd better behave yourself or you'll be relegated to painting the fence.
 
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