Great links guys!!
Here are a couple of things that contribute to the problem.
What did you guys see in that picture?
One is A vent in the return air duct within 10 FEET of the FAU… A MAJOR no no period .
Before any flue can adequately warm up the effective “draw” is weak but 10 minutes… :shock:
All these play a part in the equation in a natural draft , gas burning appliance:
Length of flue? Slope of flue to chimney?
Size of flue, Greater then 7 times rule? Also calculated for multiple appliances.
Size of chimney itself? Too large, Brick, Unlined?
Does the flue share a connection with any other appliance (gas or otherwise)? Bad if mixed fuels!
If so how is it connected? Larger on the bottom of breach or “tee” fitting into flue before breach into chimney?
Does the appliance fit into the orphan category?
Combustion air / dilution air requirements. Is the room sized to small or sealed off ?
Is that a closet where the return air duct “pulling” “gas” down the chimney for combustion instead of moving products of combustion up and out of the house?
Take a look at :
Go to “Venting Done Right”
If you have about ten minutes , it’s a great video!
My gas company training / certification on Natural gas appliances tells me this is NOT a safe operating appliance period…