TomC

PSDkevin,
Sorry for the short reply. I did not intent to offend you. I don't know what part of the country you are in or your local temp/humidity in the winter heating season. Our humidity runs lower here than summer. This morning the temp of my shop was 50 degrees and a rh of 56 percent. The outside temp was in the high 40's. I started my propane heater and with the air filtration unit running my shop was 64 degrees in about 15 to 20 minutes. The relative humidity did increase to 58 percent. I just don't believe I could add enough moisture to cause a condensation problem by heating up to fast in this part of the country.
Tom

TomC

Mike,
What if any precautions do you have to take on the combustion exhaust? I have two nat gas furnaces in my house and the exhaust gas is not hot. It exhaust through PVC piping. The furnace for my basement exhaust through the side wall and the exhaust pipe is turned downward.
Tom

PSDkevin

I wasnt offended. I just wanted to make sure you werent.

Hell it could be just my crazy set up. When I say condensation It's like a fog on a bathroom mirror not like a cold drink by the pool.

jimmomech8

I guess I don't understand any of this "condensation" stuff. I live in Minnesota and have a natural gas fired furnace in my home and a Mr. Heater 45,000 BTU nat gas heater in my shop. I have a remote sensor in the shop and reciever in the house to monitor temp and humidity. The furnace power is hooked to a switch in the house so I can turn the furnace on before I go out there. The humidity in the shop in the winter is always between 20% to 35% out there heated or cold. I recently added a Aprilaire humidifier to my house furnace so that when I woke up in the morning I didn't feel like I spent a night in Death Valley. So where is all this "condensation" you guys are getting coming from?

PSDkevin

Im not sure. I am most definitely getting condensation. All that discussion above is just my theory.

TomC

A gas furnace in a house uses a heat exchanger that a blower moves the inside air across to heat it. The moisture produced by it does not go into air inside the house. The propane heater I am using in my shop is an open flame with the shop air in direct contact. Any moisture produce will go into the shop air.
Tom

firehawkmph

Hi Tom,
The furnace vents through a double pipe setup that comes with it. The inner pipe is the exhaust and sticks out a little past the outer one which draws in the combustion air. The pipes are galvanized metal with a termination cap that goes over both of them. So no exhaust gets in the shop. The burner is completely sealed so there is no danger of an explosion from any flammable gases or dust.
Mike Hawkins

jimmomech8

You evidently did not read my post to close. I was talking about the furnace in my shop seperate from the house which also draws air within the shop.

TomC

If you have a natural gas flame in direct contact with the air it heats you will get some moisture added to the air. Sorry, I did not understand what you said because mainly I do not know what a Mr heater is.
Tom

Carvel Loafer

I heat my shop with a wood burning stove, just like the guys 150 years ago. I agree with the earlier comment that back then it was more chips and shavings. The dust levels do have me concerned so I refrain from cutting too much ugly stuff like mdf when the stove is going. I don't know what the explosive level is either but like was said, I don't want to find out the hard way.

Heating with direct fired propane is dangerous because of the exhaust. I did that for a while and actually got sick from the CO.

Good question and responses.

__________________
"Workin hard at loafin!"

Fsucraigk

I'm not sure on the size of the shop, your dust collection capabilities or placement of furnace unit. On a practical experience side of the coin, during numerous attempts to create 'dust initiator' charges for military applications we found it INCREDIBLY difficult to produce the conditions necessary to cause proper detonation of the air creating a larger explosion than our initiating charge. Without too much detail we had completely sealed environments with dust medium ranging from fine saw dust from furniture production factories, grain dust, even flour and coffee creamer.

Based on my experience with that, to include using c-4 explosives, TNT, and fires to attempt to create the conditions and not being successful, I would use a wood fired system in a shop without undue stress based on dust and explosion hazard. I would be more concerned with the location of the burner element and combustible material like scrap lumber that an ember or ash could catch fire.

I know my answer isn't from woodshop experience, but hope it helps. At the end of the day, check local building code, or contact the unit manufacturer to find out their recommendations.

davelindgren

The husband of a lady I work with was just in an explosion and was burned on 67% of his body. As of right now it's touch and go.
He was spaying poly in a 1 car garage, finishing the walls which were wood. The general had an electric heater in the garage. When the helper exited the garage the heater kicked on, igniting the fumes.
I know it's not dust related, but should give everyone pause to think. If he survives he's looking at months of surgeries and therapy. Thank God he was wearing a full face respirator and his lungs were'nt burned.
This man has lots of experience spraying. Sometimes comfort leads to contempt? Something to think about.

jharris

Sorry I haven't responded for a while guys. I've been to busy to get the darn thing installed.

Thanks for all of your input. I think that I'll invest in an air cleaner for the shop, install the FAU on the exterior of the exterior wall of my shop keeping cumbustion out of the shop entirely and piping the heated air into the shop.

Hopefully I can get this done over the summer and be toasty next winter.

I'll keep ya posted on the process.

RetiredLE

Thoughts and prayers for him and his family. A sobering reminder to be safe in what we do.

__________________
--
When you think about it, God has to be the best inventor of all time. He took a rib from Adam and made a loudspeaker.

Rwelch

Have you checked out the Modine hot Dawg line of external combustion heaters I have a 75,000 btu unit mounted in my shop and it is fabulous and extremely safe.

jharris

RWelch, Thanks for the suggestion. The budget is a a bit tight right now but hopefully not for long.