[TheForge] forge flues

[Dan Brewer]

On the outside of your enclosure how much height do you have?  The top of
the stack should have at least two feet of clearance from any obstruction.
A cap on the flue is also a good Idea it keeps water out and  prevents back
draft.  A plus for a good cap that it will induce a draft no matter which
way the breeze is blowing.  They almost always have a spark arrestor on them
and some type of screening to prevent birds and other critters making there
home in the flue.

Dan in Auburn WA

-----Original Message-----
From: theforge-bounces at mailman.qth.net
[mailto:theforge-bounces at mailman.qth.net] On Behalf Of Peter Hirst
Sent: Wednesday, January 16, 2008 7:15 PM
To: GHS at execpc.com; Sponsored by ABANA
Subject: Re: [TheForge] forge flues

Good points.  Any idea how to calculate sufficient stack size and height? 
Mine is 8" pipe eight feet high from the thimble and that is inadequate. It 
draws just ok when the fire is at its hottest, but any thing less and  it 
spills smoke.   I know I have to add to it, but how much?

pgh
----- Original Message ----- 
From: "GRAF" <adveniam at att.net>
To: "Sponsored by ABANA" <theforge at mailman.qth.net>
Sent: Wednesday, January 16, 2008 7:13 PM
Subject: Re: [TheForge] forge flues


> If the flue is set up with enough size and height it will draw like a 
> banshee with just the room ambient heat to make it work.
> Kitchen vents in restaurants don't work without fans because they lack the

> stack height usually and have filters which restrict the flow.
>
> Mike Graf
>
>
> Peter Hirst wrote:
>> One more thought if you can stand it.  Something to watch out for: 
>> "positive ventilation".  I had a fire and health inspector come by 
>> recently who asked me if my forge was positively (power) vented (it 
>> isnt).   There is no specific standard in this jusridiction for forges 
>> (as there is for coal stoves, wood stoves and everything else), and the 
>> concern was that the flue gases  are NOT HOT ENOUGH to draw well.  Just 
>> like over a stove or gas grill in a commercial kitchen, the heat from an 
>> open fire mixes with a lot of ambient air on its way toward the hood, and

>> is not very hot at all as it travels up the flue.  That's why commercial 
>> kitchen hoods are POWERFULLY positive vented.  With a coal forge,   this 
>> usually means that significant smoke escapes the hood and the least back 
>> pressure stops the draft altogether.  How many of us with coal forges 
>> have shops as smokeless as a commercial kitchen?  Or as any room with a 
>> properly vented wood stove? Anybody?  I didn't think so.
>>
>> So I would soft pedal the idea that the flue gases don't get very hot. 
>> This could work against you and lead your inspector to conclude that the 
>> forge should have a high powered exhaust fan.  Which it probably should, 
>> but why press it?
>>
>> pgh
>>
>>
>>
>>
>> ----- Original Message ----- From: "john ortery" 
>> <bluestoneforge at gmail.com>
>> To: <theforge at mailman.qth.net>
>> Sent: Monday, January 14, 2008 7:36 PM
>> Subject: [TheForge] forge flues
>>
>>
>>> Thanks guys,This seems to be the thought all around.  Most of the people

>>> I
>>> talked to seem to think that as long as you have double wall pipe at the
>>> exit point and are insulated from any combustible material all should be
>>> well.
>>> Thanks again Allen Ortery
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