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From Wikipedia:

The main products of hydrocarbon fuel combustion are carbon dioxide and water vapor. At high altitudes this water vapor emerges into a cold environment, and the local increase in water vapor can raise the relative humidity of the air past saturation point. The vapor then condenses into tiny water droplets which freeze if the temperature is low enough. These millions of tiny water droplets and/or ice crystals form the contrails. The time taken for the vapor to cool enough to condense accounts for the contrail forming some way behind the aircraft's engines. At high altitudes, supercooled water vapor requires a trigger to encourage deposition or condensation. The exhaust particles in the aircraft's exhaust act as this trigger, causing the trapped vapor to condense rapidly. Exhaust contrails usually form at high altitudes; usually above 8,000 m (26,000 ft), where the air temperature is below −36.5 °C (−34 °F). They can also form closer to the ground when the air is very cold and has enough moisture.

jsburger wrote:

ERLover wrote:Just look at a chimney when the furnace is running in the winter and you can see the water vapor. High efficient furnaces that use the pvc piping for exhaust also plus they have a condensate drain off of the heat exchanger.
Just happen to have my Combustion Engineering Inc had book here with me at moms.
I was wrong on the kerosene, cant find a moisture content listed in flue gas
In Propane it is 1.634lbs of H2O in 22K BTUs, just under a pint, real close for natural gas which is 78% Methane is 2.246lbs H2O per 24K BTUs.
Based on some of the charts the H2O comes from a high amount of H in those gases,where kerosene has a very low amount.

All you are quoting is fuel type and BTUs. No mention of time for the supposed amount of water or the amount of water in the ambient air. The fuel does not have that amount of water in it. OK, there are chemical conversions but the humidity is 19% in my house tonight with the open flame NG furnace on. How does that equate?

Bad 'Assumption' re venting ER.

We heat our shops out here by turning off the air conditioning.

OK, there are chemical conversions but the humidity is 19% in my house tonight with the open flame NG furnace on. How does that equate?
John I dont know what you mean as an open flame furnace.
I am going by a manual for fossil fuel power plants that use up to a million lbs of air, it does not say what part of flue moisture comes from humidity in the air, but in the composition of h2o in propane and methane gas, witch methane makes up 77% of NG gave me those figures. I think we are splitting hairs here. The point is fossil fuels give off h2o when burned and if not vented are in the air in your shop. Now if it is a problem in yours or not is up to you to decide. I know HVAC people will tell you in a furnace for every 100K of btus burned you get approx 1 gallon of condensation.

ERLover wrote:OK, there are chemical conversions but the humidity is 19% in my house tonight with the open flame NG furnace on. How does that equate?
John I dont know what you mean as an open flame furnace.
I am going by a manual for fossil fuel power plants that use up to a million lbs of air, it does not say what part of flue moisture comes from humidity in the air, but in the composition of h2o in propane and methane gas, witch methane makes up 77% of NG gave me those figures. I think we are splitting hairs here. The point is fossil fuels give off h2o when burned and if not vented are in the air in your shop. Now if it is a problem in yours or not is up to you to decide. I know HVAC people will tell you in a furnace for every 100K of btus burned you get approx 1 gallon of condensation.

An open flame furnace has a flame you can see when you look inside. Yes it is vented but the flame is still open to the ambient air in the house. A closed flame furnace has a closed combustion chamber and gets its air for combustion from an outside source and exhausts all the products of that combustion outside. It uses a fan (same as the other type) to blow heated air into the house.

You said for every 100K BTU you get a GALLON of water. That has nothing to do with the definition of a BTU. My torpedo heater runs about 1/2 hour in the beginning to heat the shop. After that about 5 minutes every hour. Normally, once the shop gets warm I turn it off unless I will be out there more than 4 hours. It is 55K BTU. By your numbers that is a quart of water. In that time the heater burns less than a half pint of fuel. Where does the water come from??? Certainly not from the fuel. It is water in the ambient air that was already there. If it was already there it was already there. What is the problem. There is NO problem here in 15 years in my garage and the 30' X 40' shop.

John at this point I dont know or really care, its been a long day, as I said if you have not had a problem, God bless ya.

Sorry John B, a trying day with mom

The water that results from combustion was not already in the air. As Dennis quoted from wikipedia, the water is produced from the burning of hydrocarbon fuels. Ideally, when you combine a hydrocarbon with oxygen (fire), the result is carbon dioxide and water (H2O, dihydrogen monoxide). That only happens in a lab, if then. Most combustion results in many byproducts, including carbon monoxide, nitrogen compounds, and in the case of kerosene, diesel, jet fuel, etc., sulphur compounds as well. When you see a contrail, that is water that was produced during combustion. Next cold morning, start your car and go watch the water come out the tailpipe. That water was recently gasoline.

Mike

A pretty good animation of hydrocarbon combustion, except that the opening credits keep going for 45 seconds.

[youtube]https://www.youtube.com/watch?v=q7ZKnnXz5R4[/youtube]

Great analogy Mike, the car tail pipe, I had a car that had a drain hole in the muffler just for that.