What is a venturi draft regulator?

Answer 1

A Venturi draft regulator is another device to control the overfire pressure in the fire box of a furnace or boiler.The standard draft regulator such as the Fields control uses the principal that hot gases are lighter than cold and therefor tend to rise.The Venturi Draft Regulator invented by Lionel Scott telephone #9o2-667-4133. This device uses the Bernoulli principal which the carburetor uses. When the hot gases move through the venturi tee where the Draft control door is located it causes a drop in pressure which causes the door to open .This is where it is hard to understand,to obtain the proper over fire pressure the weight on the door would have to be heavier than what it would be on the standard set up such as the Field control.The benefit of this is that when the fire is off the flue pressure has to be higher than the set over fire pressure before the regulator door will open,therefore less room air is exhausted up the flue.Also when the fire is on less room air is pulled into the gases and therefor the temperature of the gases is higher entering the flue.Thus more heat can be put into the home, the result is the A.F.U.E. is higher.