flue baffles

Weezbo

I myself find it difficult not to share some of thier more livid moments I would suppose you could INDEED baffle The heck outa someone with half a brick....

Rookie_3

flue baffles

Just wondering if anyone has any reasons not to baffle the flue on a power vented system. Pro's, con's, advantages or disadvantages? What I'm seeing is good OF and breech drafts,
good CO2, 0 smoke but higher than desired stack temps keeping efficiencies lower than they have to be. To set up a -.02 OF with a -.04 breech and a 12% CO2 and walk away with a 78 1/2% efficiency because of a 600*F net stack seems like a waste. I'd like to get it down to at least a
400*F net and leave with it 83 1/2% efficent. Would baffling 20% of the breech with a half brick do any good with a power vent or would it create unwanted variables?
Any thoughts are appreciated.............ROOKIE

Rookie_3

OK, lets call it a split brick. I haven't read the papers much since November but didn't you have a "SPECIAL VOTE" on the ballot in Alaska. I'm thinking maybe it passed?

ROOKIE

Weezbo

I am currently unappraised of the oucome....

however were i to find myself standing infront of a sophisticated boiler and considering putting a Brick in the flue, i belive i'd have a sudden, serrendipitous realization that it was time to go home and call it a day*~/:) )) put on my thinking cap again in the morning you know give the idea a chance to mellow before any rash decisions:))

Larry Weingarten

Dear Weezbo...

...We've never met, but I must tell you, your writing is incredible! When you write your novel, I'm buying it. Tom Robbins, move over!

Yours, Larry

Rookie

Why not?

That's great the guy is asking a question,obviously he put some thought into it and all he gets is flack.I wonder what the first guy thought when he wanted to make a coal stove efficient. I know some guy told him to go clean out the barn, and shovel some coal.

Constantin

I don't think that was the intention... at all.

Weezbo has a particular writing style. He's not the type to jump down throats and the like.

As for the baffle-question, I wouldn't do it simply because you'd like to think there was a good reason to design a unit the way it was. Perhaps the extra "head-room" accomodates gusts and other natural events that do not seem obvious now.

When I developed a free-standing outdoor gas water heater, we experiemented with the number of baffles in the flue. Obviously, the more baffles you have, the better the HX, but at a risk to shoot up in CO and other nasties when the wind comes from the wrong direction.

Unless you have a wind machine and can subject the terminal to winds of up to 50MPH from multiple direction and see if there is any effect on combustion, etc. I'd keep extra baffles out of the flue pipe.

Weezbo

Jeesh Rocky ....

by now rokkie knows for the most part if its closer to L.A. or by bus.

Rookie_3

Finding a baffle accross the top of the heat exchange isn't really a rarity, at least not around here. It's done to keep the combustion gas on the HX longer bringing the stack temp. down. Not to baffle more than 20% of the opening is what I was taught. My question was, although common on systems with chimneys, is there reason this would not be a good idea with a power vented system.

Thanks...........ROOKIE

Dale

Conversion burners

In the old days of gas conversion every one of the thousands we did had the vent connector chokes off with a sheet metal gillotine baffle, if you didn't you had really high stack temps and CO2. The key was to get a slight over fire draft and the correct CO2. These usually had barometric dampers. To be fair to the oil persons when we cleaned the heat xchanger surfaces before conversion most were caked with soot and probably would have been alot more effecient if just cleaned on a regular basis. If you are new to the biz and don't know why the restriction is there you will repalce the vent connector and not notice the restriction which will really lower output and raise fuel costs.

Steamhead

Another reason to use a baffle

is to deflect the flue gases against the water-backed surfaces inside the boiler. I've done a few of these on older boilers with very good results. In this application you'd use a brick or something similar inside the boiler's flueways.

And of course, don't use a baffle so big that you kill the draft.

For Rookie and anyone else who is interested, here's a post I wrote last January that evolved into a Hot Tech Topic. One of the things I did was to baffle this lady's boiler with bricks. It worked real well!

http://www.heatinghelp.com/newsletter.cfm?Id=151

To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"

Tony_8

What kind of power vent ?

A Category 1 or a 3 ? A cat 1 is under neg pressure in the pipe and boiler and a cat 3 is positive in the pipe. I wouldn't brick a 3, and a 1 usually has some sort of damper or regulator on it's inlet.

Oh, and pay REAL CLOSE attention to Weezbo, lest you miss his point

Weezbo

howdy.

your reasoning was sround a coal fired conversion ,correct?. Iwould say that makes sence to me as i have also done Rennovating ....i calculate the fire box blah bla blah...lashing a brick into a power venter ,welllllll now that is a horse of another course. dont get me wrong here Rookie was thinking that might work for him however if he has the wrong size vent on it what on earth does a brick in the works do for the whole deal? nah down size the vent pipe to the powerventor get the right one for the appliance(boiler) or put the brick down and call it a day.

Rookie_3

Good article Steamhead. I hate to see a good combustion go to waste even if I'm not paying for the fuel. In a case like yours it was a matter of keeping the system up and running and buying some time for the HO to plan for a new one. I just didn't know if there was some hidden factor in doing it to a power vented system. Neg. draft as Tony was wondering.

Thanks for the input and Merry Christmas to ALL......ROOKIE

Unknown

Rookie what is your

carbon monoxide reading? If it is high that may be why you have a high stack temp. What is your O2 reading? I am not an oil man but do know a lot about gas combustion and enough about oil to tell you not to baffle a power vented system. You need to take additional measurements and get back to us as they will tell what is happening.

If this is an Flame retention 80 + efficiency oil system the ball park figures should be:

CO2 12 to 13 %

O2 3 to 5%

Flue Temp 350 to 450

Oil pump pressure 100# to 140#

Draft -02 negative overfire.

Smoke #0 - #1

CO around 100 PPM