HP500

Propane forge and CO detection options

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I live in the northeast and it will be relatively cold here for the next 4 months or so. I don't  have a shop, so I wheel all of my equipment from the garage out to driveway and back again. I would like to use my new propane forge in the garage throughout the winter in the evenings after work and when the weather is bad.

I have a two car garage and can forge with at least one of the large doors open. I can also get a cross breeze if I open the back man door. I assume that this will be enough ventilation to prevent CO poisoning, but I'd like to install a CO detector just to be sure. The problem is, all of the CO detectors I've found have a minimum temperature rating of 40 degrees Fahrenheit. We won't see temps above that here until April. 

Does anyone know of a low temp CO detector? I came up empty with an online search. Thanks.

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If you are talking about an attached garage, my recommendation is to put at least one CO detector inside the residence.  It certainly can't hurt to have one in the garage as well, but most likely with the cross breeze you mentioned you will have adequate ventilation there.  I also think you will find that once your forge gets going you will be heating your garage up to a point where conventional CO detectors will work, but that is hard to predict.

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Yes, it is an attached garage. Good idea, thanks!

Edited by Mod30
edit excessive quote

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Remember CO is heavier than air and will pool at the lowest point. If you're garage door is open to the house and there's a stairway by the door it could concentrate at the bottom of the stairs like a waterfall.

Pnut

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Propane is denser than air. CO is a bit lighter and hot CO even more::

Myth: Carbon monoxide is heavier than air, so CO detectors should not be placed on the ceiling or high on the wall.

Fact: CO is slightly lighter than air. However, studies have shown no significant difference in measurements based on what height CO detectors are mounted.... It is worth mentioning that CO indoors is usually generated from incomplete combustion (heat source) and therefore traveling in a warm air stream. Warm air is more buoyant and does rise.

(from:  https://healthybuildingscience.com/2013/02/22/carbon-monoxide-facts/)

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I stand corrected. I was confusing CO and propane 100%. Thank you Thomas, my file retrieval system is not what it used to be before the motorcycle wreck and the knock from the steel pipe.  I confuse similar things quite often like one gas for another. Oh, the joys of TBI.

Pnut

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I spend a whole lot more time double checking myself since my TBI----like on that.

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You should never "bet the farm." That is exactly what you are doing by running a forge inside your home. An attached garage is part of your house. Forget about any insurance coverage after a fire.

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I registered just to say thank you for that correction and information Thomas Powers; i've read a half-dozen threads this evening that have said CO is heavier so pools on the ground and i really didn't want to drill holes into the shed walls. Sorry to jump on a thread but to stop another similar post, a question; Shed is 10x10 breeze block, door has a 1/2" gap at the bottom and i can open the top half of the door separately. Roof is corrugated sheets with no foam ridge filler things. Will that be sufficient or should i replace one of the small windows with angled pallet slats as another venting area? 

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The smaller the building the easier it is to clean with fan powered ventilation. Whether you push fresh air in, or push polluted air out is only a matter of convenience.

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Do you often have 40 kph winds blowing through your forge?  Without knowing too many details it's hard to say what will work in your situation.

I over ventilate and don't have to worry about it. I'm putting a wood stove in my smithy as I am NOT going to have the gas forge "heating it". (CO production zooms the more you rerun the exhaust gasses through the burner!)

Note too that many people do not take count of the fact that the exhaust coming out of the propane forge is screaming hot and so lighter than ambient air---otherwise hot air balloons wouldn't work.

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On 11/29/2019 at 8:47 PM, Mikey98118 said:

Whether you push fresh air in, or push polluted air out is only a matter of convenience.

Unfortunately while this sounds correct under ideal conditions, it rarely is a true equivalent in the real world.  Due to room configurations you can have unusual airflow patterns inside of occupied spaces (like eddies, "short-circuiting" and stratification) which can concentrate fumes even with fresh air being mechanically introduced.  If possible I strongly suggest that you pull the polluted air out with either localized hoods, or substantial exhaust fans located in a good capture area (mine is a 30" diameter 1/2 HP sidewall fan located near the peak of my shop.  It does a good job of removing the heated exhaust gasses from my gas forge), and let the fresh air back in via doors or window openings that are located in the breathing zone. 

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Makeup Air---very important if you are pulling/pushing air out of your shop---how is air to replace it coming in to your shop?

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