Here's the problem.

[Big maple]

Here's the problem, we are boiling on a 5x14 small bros with a ten foot flue pan (raised) and four foot syrup pan. Thi is the first time we have boiled on an evaporator this size with no forced draft. Our problem is no matter how hot we have the fire or where the draft gate is positiond we do not get the full hard boil in our syrup pan. The fire is hot enough,we have full boil on the flue pan after it is warmed up. I fired it for twelve hours yesterday, seven to ten minute intervals, tried loading differently, and everything I could think of. I'm just looking for some input on what you think it might be

[Haynes Forest Products]

Have you drawn off yet? How tight is the fire door are you getting alot of air coming in a blowing the fire away from the front pan. My syrup pan tends to boil slowly unt till the syrup is at the point of drawing off then its ripping.

[fred]

sounds like your draft is off .you may need to seal the front better and get the draft under the fire

[Big maple]

Yeah we made about thirty gallons before we shut down for the night but, the syrup wasn't making in the pan fast enough(not impatience just observation) the gradient is right but what we have in the flue pan already had the color it shoul normally have in about the third bay of the syrup pan. It was starting to make me nervous so we droped the level in the syrup pan from about an 1 1/4 to about 3/4 and subsequently made alot of syrup in a short time.But it still ain't right
One door is warped very little on the top center corner ,about a 1/4 of an inch gap, but I don't think it has a huge effect on the draft but I could be wrong.

[danno]

How about adding forced air?

How deep is your fire box? Sounds like the fire is staying to low in the fire box until it reaches the flue pan. If the fire box is very deep, experiment and set up a fire brick wall closer to the doors - thus forcing the heat up and under the syrup pan.

I know my set up boils soooo much nicer with forced air.