most of the time you see the vapor cloud above the metal chimneys but
this one had a stream of water. nothing like it on the other similar
houses. maybe he's got a real humid envirnoment inside?


On Sun, 17 Dec 2006 22:37:08 -0500, "Edwin Pawlowski"
wrote:


"bill" wrote in message
.. .
whats the cause? just noticed my neighbor's roof. water is running
from the base of the chimney. outside temp is 30, its a hot air gas
fired furnace, in Maryland. i didnt notice this on other roofs.
ideas?

When gas burns, it does give of water vapor. At the right temperature, it
can condense in the chimney and drain down.

From http://www.naturalgas.org/overview/combust.asp

Combustion of NG is: CHI[g] + 2 O2[g] - CO2[g] + 2 H2O[l] + 891 kJ
That is, one molecule of methane (the [g] referred to above means it is
gaseous form) combined with two oxygen atoms, react to form a carbon dioxide
molecule, two water molecules (the [l] above means that the water molecules
are in liquid form, although it is usually evaporated during the reaction to
give off steam) and 891 kilajoules (kJ) of energy.