"theCase" wrote in message
oups.com...
Why do gas water heaters require external venting while gas stoves do
not? Is there something fundamentally different in the combustions
byproducts (CO vs. CO2) that need to be vented for the water heater
and not the stove?

If the only reason is the volume (BTU rating) of byproducts, it
doesn't make sense. For example, a moderate water heater can have a
rating of 75,000 BTU, while a high end stove will have a total BTU
rating over 100,000.

Worse case, think about cooking a Thanksgiving meal, oven is on for
six hours and all the burners are going, all this is vented inside the
house. While downstairs the water heater just has a pilot light
going. Why is one required to have external venting while the other
one doesn't?

I think the difference is in the fact that the kitchen range generally
operates while being observed and the water heater operates day and night
where no one can observe whether the flame is burning at all, whether it is
burning yellow and creating lots of carbon monoxide, or burning too high
because of a regulator malfunction.

No one recommends leaving the kitchen range burning unattended all night
while the house occupants are asleep, which is what the water heater does.
People have been killed by improperly vented water heaters and by using gas
ranges for heating the house but they are both very safe when properly
installed and used.

Don Young