Shop Ventilation

J

John L

Joined
Oct 28, 2004
Messages
1,330
What type ventilation is required for a smallish propane forge indoors? If I use a large exhaust fan...there goes all my heat. If I don't, do I end up gone too?:eek: Don't want to wait for spring to show up to usee my new forge. Thanks.
 
Very bad idea, but if you do continue with this you'll need to mount a good updraft exhaust fan, CO moniter and notify your next of kin.Really not a smart move. Sorry .Dave:rolleyes:
 
Bigtime no-no, man... CO is heavy, and sinks to the floor and builds UP, rahter than flowing up and out. Propane forges throw off so much CO and CO2 (as well as eating up O!!!) that it's a really bad idea.
Besides, you can tell everyone how tough you are because you forge outside in 5 degree weather -- that is, if that's what you really do!
 
One of the reasons that I may never have a forge :grumpy:
There is really no place on my property that I could put one
outside without insane levels of risk. Basically all significantly
sloping with lots of oak trees all around the small yard.

It's either indoors (with good home insurance from a company
that knows what they're insuring) or no forge for me :thumbdn:
 
I know a very very VERY easy fix to this common problem MANY people have with gas forges.





USE COAL;).
 
I use my propane forge in my garage. I have a large ceiling fan, and I crack my garage door open about 2-3 feet. I've run it for a couple of hours at a time with no ill effects. The fan is set on downdraft, and the CO2 sinks, and pushes out the bottom of the door.

Insurance is another story, but I have nothing combustable anywhere near my forge. It's on a rolling metal cart, and it sits in the middle of the garage.

I guess everything has it's risks, but I do try to minimize them.
 
I forge outside down to 0F and tend to sweat. Set up some 2x4s and plywood to stop the wind, wear some car-harts, and you will be set for working outside. That is unless your farther north than northern NY.

As for setting up the forge inside, I wouldn't do it because of the fire risk, CO risk, and the insawool.

-Dan
 
I can't help but wonder if an air to air heat exchanger couldn't be set up on the exhaust system.

If you take a heat exchanger out of a large shop furnace, route the hot air through where the gas flame was and use a fan to recover the hot air where the regular fan would go it might work but access to the forge could be more difficult because of the shielding required to prevent exhaust leaks.
 
For those who didn't know George's uncle, Rube Goldberg, was one heck of an inventor.
Stacy
 
CO monitor and a exhaust fan running form outside to inside, don't try to suck the shop out. Use air flow principals. Duct the air to your head space and set everything up so the pressure from the fan causes any gases from the forge to move away and out. Use smoke to tell you what is happening with gases.

But then I open the garage and personnel doors wide open and have a fan. I grew up in Eastern Montana where it hits 40 below at times (not counting wind chill) and now live in Western Washington and never wear a coat unless it is a ways below freezing, which is seldom or if I am going to just stand around in the weather. I don't do that so much anymore. LOL
 
I can't help but wonder how many knifemakers have graduated from high school after looking at the misinformation in this thread.

I may have taken physics from old Uncle Rube but the principles are still valid.

A forge is nothing more than a high temperature fireplace.

Fire burns. O2 is consumed. Heat and hot exhaust air is produced.

Hot air rises. Fireplaces burn 24 hours a day without poisoning anyone if the chimney is not plugged because the hot air produced is vented outside the home.

Furnaces burn 24 hours a day without poisoning anyone if the chimney is not blocked and the hot air is exhausted outside the dwelling. Unfortunately losing the heat produced is not desirable so a hot air to air heat exchanger is
employed to avoid mixing exhaust fumes with recirculated air from inside the dwelling.

Furnaces are normally placed in basements around here with no outside air makeup except what comes in at doors and windows (leakage). So why does the basement not fill up with CO2 if it is heavier than air?

The answer is basic physics, hot air rises, cold air sinks. The heated exhaust rises up the chimney because it is warmer than the normal basement air.

If you need further proof that the exhaust of a propane burner is lighter than air I would refer you to the hot air balloon phenomena. Propane burner burns, hot exhaust from burner rises into the interior of balloon, with enough hot air balloon rises into air. Exhaust from propane burner contains CO2, it follows that hot CO2 must rise or the balloon would collapse on the ground instead of taking off.

Neither the furnace nor the fireplace require a fan to exhaust the exhaust.

A simple hood over the forge will serve to exhaust the forge to the outside air though a full surround would be more effective to collect all but a small percentage of the exhaust gas. This setup is used in almost all old blacksmith shops, metal melting and casting shops and other high heat operations to take advantage of the hot air rising principle.

The two primary considerations would be to ensure outside ventilation is present, both incoming for complete combustion and a chimney for the exhaust.

School is out.

George
 
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