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I Forge Iron

Useing forge to heat house


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I'm moving to a colder climate ,I am going to have a winter shop in the basement.
My propane forge puts off a lot of heat .but not sure how much oxygen it will burn up.
Does any buddy know how this will turn out? Will I need a window open or will I need to just bring in a 4" fresh intake?
Thanks Keith

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Although I love the idea of capturing "waste heat" for use, and wish our society did more of that (especially in industry), I'm pretty sure you'd be violating some fire code, or insurance policy clause so beware.  (boy, I HATE our lawsuit culture...) :angry:   I'm not saying don't do it, merely don't expect any sympathy or empathy from authorities in the event of an accident.

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Bad move. Home furnaces are made in such a way as to separate the heated air from the fuel gases and combustion by-products. Gas forges can put out A LOT of carbon monoxide and carbon dioxide, and should only be used outdoors, or in well ventilated areas.


To prevent flooding the shop, and by extention the living area with deadly gases, you will need to provide air flow thru the basement. This will probably mean a net cooling of the living area, as well as the shop.


If you decide to do this anyway, buy two carbon monoxide detectors, one for the shop, and one for upstairs.


You might want to consider knifemaking, where one sunny afternoon at the forge on the driveway will leave you with several weeks worth of grinding, polishing, handles and sheaths to complete inside. Or armour, or jewelry, or copper, or........

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When I use my propane forge I have two 10'x10' roll up doors on opposing ends of the shop open.  The shop also has the gable ends open


An enclosed space drastically increases the amount of CO produced as the forge can re-run exhaust through the burner(s)


When I live in a colder area I built a miniforge run off a plumber's torch and small bottles and used that in the basement---100 year old house with a VERY leaky basement airwise.

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These are good points the CO detector, and insurance.
I do have some hvac training .
I'm thinking maybe some type of exhaust vent that could reclaim the heat and get most of the CO out of the room.
It may work with some air pushingi n the front of the forge and an exhaust vent going out. The magic heat claimer on the exhaust may work .
A fan assisted forge instead of a aspirated forge would be more controllable.
I'm sure someone has done this already . Hope they will please tell how they did it .
Besides it may be time to clear the air that is in any structure we have our forges in.

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A gas forge can produce as much heat or more than a forced air gas furnace . Using that example I would not use an unvented gas forge in an a basement. The question of oxygen consumption is not the only question that needs consideration. Carbon monoxide is a likely product. So not only is there a need for fresh air supply but the gases produced by combustion need to be vented.

There are other issues that need to be addressed. You should consider your residential insurance and how having a propane forge might affect your coverage, especially if you plan to use bottled gas.

There may be ways to resolve all of these barriers such as placing your forge in some sort of vented sheet metal cabinet but I expect that even if there are effective ways to resolve these issues in a practical manner that insurance and code officials may still not agree. I gave up trying long ago. I just pull my forge outside when in service.

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There is a threshold limit to how many BTU's you can pump out of say an open flame propane or natural gas space heater  or fireplace before it has to be vented. Same applies to say a gas range/oven. A very small forge might come in under those limits, but I'd guess a decent sized one wouldn't.



As others have mentioned there are quite a few issues using gas heating appliances unvented in a home. Consequences can be very serious and many things like CO poisoning or O2 depletion can sneak up on people unawares. I remember a few years back where several guests at a local hotel died as a result of CO poisoning due to a propane job site heater the masons were using in the tent outside the rooms they were staying in.

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I'm not advocating the idea, but if one chose to go ahead with it one would need a co/fuel gas monito, a low o2 minister and a fire alarm. I would also recommend fire suppression equipment. I have no idea how much ventilation one would need.
If I was intertaining the idea of a forge indoors, I would look at charcoal. Again the same safety and protective gear as above, but fire places and charcoal grills are used in homes and restraints so the nessisary air quality and fire safty issues are easier to address.
Forges have been set up in basements, it wasn't uncommon practice in buggy shops.
That said. I wouldn't do it. Not in the basement. The fire danger of a stray piece of red hot steel is just to great.
Invest in a shed or trailer.

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B-A-D idea! Propane sinks in open air so when your forge ever springs a leak the propane WILL lay in your basement till it reaches a flammable ratio and the next spark will send it up. That will scatter burning pieces of your house for a surprising distance.


Even as out of the building codes zone as we live installing a propane boiler here had so many requirements attached it turned out to be far cheaper to burn oil. No insurance company would touch us with propane in the basement and we have a daylight basement so it's not airtight like a deep hole.


Not saying you can't do it, just be very VERY careful and have it done professionally so THEIR insurance will cover IT.


Frosty The Lucky.

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I agree with the comments by others of the dangers of using a gas forge indoors, insurance issues etc so will just comment on ventilation via a 4" duct. The most any standard low pressure fan or impeller can pull through a 4" diam duct is ~400 CFM. Higher pressure fans can force more air through a 4" duct but it will then scream like a banshee.


There is also a temptation to say, eg my cellar is 20 x 20 x 9 ft = 3600 cf so ~ 400 cfm should replace the air every 9 minutes. This can only happen if the air inlets and outlets are evenly distributed on opposite walls and something called laminar air flow is achieved which required nothing blocking the airflow path across a room. In practice, with say a doorway inlet on one wall and a 4" outlet one the other a 400 cfm extraction can at best achieve one complete room air replacement every 18 minutes and most likely every 30 minutes. 


6" ducting is better (limited to ~1250 cfm) provided that the driving fan also can deliver that but even that may not be sufficient.


FWIW I'm using a natural gas forge inside a ~3600 cf shop and even using a 1300 cfm squirrel cage fan, after about half an hour the shop starts to get hot have have to switch on additional ventilation. I really need to get myself some CO/NG sensors to keep a track of what is going on.

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