boiler flue

Mitch_4

Draft diverter, albeit a real old one. Sliding the tin in/out to is how you adjust the draft (slice damper) .See them a lot on old gravity furnaces too.

Mike

dave_43

boiler flue

I have a cast iron low pressure steam boiler(1922),first use coal, converted to gas in the 1960's (695,000 BTU). At the rear of the boiler is a 12" flue-3'horizontal, one elbow- going into a tin box about 2' square with a COMPLETELY OPEN bottom. Inside the box is a single piece of tin directing the flue gas up and into a new 10" flue (4' horizontal, one elbow, 40' vertical). There is no flue damper anywhere. I am concerned about satisfactory draft - the boiler room gets very hot, though there is 0% CO. Two questions - What was the purpose of the the tin box?(It's more than 35 years old, though not original). Also, should the box be replaced or reworked to improve the draft?

Mark Hunt

\"Draft diverter\"


They were designed to keep pilot lights from being blown out by the wind.

They will also allow the equipment to keep running even if the chimney is blocked. They "divert" the flue gases into your home.

They also provide dilution air for the exhaust gases and cool them down.

Somehow, they are supposed to balance the amount of air being pulled through and across the burner.

Oil units use barometric dampers and the amount of "dilution" air CAN be adjusted with these.

"Draft diverters" cannot.

Mark H

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Unknown

Is this an Atmospheric

conversion burner? If it is then any attempt to put a barometric damper would present problems.

If it is a power burner then you can probably replace the draft hood with a barometric.

There is no need for any flue damper and the opening on the bottom of the draft hood should be left open.

If this unit has not been serviced for sometime it is probably not running very efficiently. If you can find a qualified gas technician who knows and understands how to refurbish the boiler and do a combustion analysis it should be done.

Mark Hunt

Update

I received my copy of P&M magazine today and with it came a copy of GAMAzine.

On page 24 they have a "Glossary Of Terms Concerning Venting".

The definition of "Draft Hood" is as follows:

"A non-adjustable device built into an appliance, or made a part of the flue or vent connector from an appliance, that is designed to: (1) provide for the ready escape of the flue gases from the appliance in the event of no draft, back draft, or stoppage beyond the draft hood. (2) prevent a back draft from entering the appliance, and (3) neutralize the effects of stack action of the chimney or gas vent upon operation of the appliance."

(National Fuel Gas Code 2002 54-8)

So the "draft hood" will allow the unit run if: There is no draft, there is a back draft, or there is a "blockage beyond the draft hood". Hmmmmm..........

It will also keep the pilot from being blown out.

It will also allow the appliance to run in the event of too much draft.

And they are a good idea because......????????????

Just quoting scripture here folks. That is what the good book says.

You do the math.

Mark H

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dave_43

boiler flue

This is a power conversion burner. Will follow up on your recommendation . thanks

Unknown

What is the make

of the burner? It is probably a good idea to look at redoing the conversion boiler preperation and removing the draft hood and going to a barometric. It is important to maintain the flue size reduction however so that the unit will not have condensing problems.

dave_43

boiler flue

Tim Thanks for your response. I should have been more complete in my description. The power comversion burner is a Burnomatic, made years ago in Minneapolis rated 550,000 to 750,000 BTU, currently clocked at 695,000. It fires a cast iron sectional steam boiler about 5' square. I had a new flue liner(10") installed this fall because the flue tiles (16") were cracked and falling down. They did pin the remaining tiles. The supplier sized the pipe at 10". The unit heats a 10 unit apartment building. I'm just trying to be sure there's adequate draft not knowing any thing about draft hoods.

Unknown

That system would surely work

better with a double swing barometric. You would then be able to control draft. Set it up with a combustion test and you should be fine.