Frequently asked questions on Retrofits

They will not consume more fuel when the Heat Exchanger has been properly designed to:

– Insure the minimum possible restriction to the air supply in the barn so the absorbed h.p. from fan’s motor is used to supply the tobacco with as much air as possible (during wilting -leaf drying stage) and not to overcome Heat exchanger’s extra restriction to the air flow.

– Insure high Combustion efficiency without restricting the air supply to the barn.
– Adjust the burner to proper output to run with long operating cycles instead of short ones .

Yes it happens in many cases (mainly when retrofitting with VCU® ).

– When curing in Direct fired barns with oversized atmospheric burners, farmer rarely takes good care of ventilation. Direct fired burners supply also water vapors in the barn so greater ventilation is required to drive out of the barn those extra vapors .
Since direct fired burners are usually oversized , no matter if farmer opens more than necessary the fresh air intake damper, the big burner will supply enough heat (more than necessary) to advance the cure and keep the temperature as required.
In other words the farmer may consume lots of energy just to heat the atmosphere.
Since direct fired burners supply also water vapors in the barn , air leaks from barn structure are not affecting tobacco’s quality which means that farmer rarely cares for the leaks. Air leaks result heat losses.

– When curing with Heat exchanger farmer has to follow better curing practices.
Heat exchanger produces what is usually called " dry heat “.
It does not supply the tobacco with extra vapors from fuel’s combustion but drives them out through the stack. So smaller ventilation is required during entire curing.
When heat exchanger is properly designed and burner properly adjusted according to barn’s air supply, just a small fresh air damper opening is enough to drive out of the barn tobacco’s moisture.
Since pressure burner cannot be oversized (for many reasons) if farmer opens more than necessary the fresh air damper, temperature in the tobacco will drop. This forces farmer to ventilate only as much as required (i.e. save fuel).
Since heat exchanger’s “dry heat" does not supply extra moisture to the tobacco, if barn has leaks it will loose moisture quickly and complicate coloring stage. This forces farmer to close all leaks.
In other words: when curing with heat exchanger farmer is obliged to follow better curing practices than before and service his barn both resulting considerable decrease in fuel consumption.