Hitzer Energy Master II 710, Owner'S Manual, Page: 9 / 17

Page 9
Supply Duct:
In order to achieve maximum performance it is important to have the correct size of duct work that
corresponds with your Hitzer ENERGY MASTER Stoker Furnace. Your furnace is equipped with a 1009
CFM Blower. In order to achieve maximum performance and heat, it is important to make sure the duct
work is sized properly and not too small for the blower assembly. If the duct work is too small your furnace
won’t achieve full potential. Duct sized excessively large will also be detrimental to the operation of your
furnace. NOTE: These calculations are based on a .10 static pressure.
Supply Duct Size
Shape Approximate Capacity(CFM)
6”
round 120
8
”
round 240
10”
round 420
12”
round 680
14” round 1000
8”x12”
rectangle 480
8”x16”
rectangle 700
8”x 20”
rectangle 910
8”x 22”
rectangle 1000
8”x 24”
rectangle 1200
Return Air:
Return air is very important and MUST BE incorporated into the system. Without adequate return air
supplied to your furnace the warm air distributed into your home will be restricted. This will decrease the
efficiency of your furnace. You could also cause the furnace to overheat because of reduced air flow
causing damage to your unit and voiding your warranty. If your furnace is installed in a basement or utility
room that is fairly air tight the blowers on the furnace could depressurize the room and pull toxic flue
gasses from the furnace or other burning appliance in the area. These toxic fumes could then be
distributed throughout the house causing a very dangerous situation.
The return air can be provided by installing a separate duct system or by tying into the cold air return duct
of the existing furnace. Without a return air system warm air will be drawn into your basement,
unnecessarily heating unused portions of your home.
The return duct should be a minimum of 16” x 20”
or equivalent (320sq.in.). The return duct may be attached to the rear of the stoker furnace. Make sure if
you are attaching the duct to the rear of the furnace you do not inhibit the removal and replacement of the
furnace filters. These filters should be checked and cleaned/replaced regularly to maintain the proper air
flow.
Combustion Air:
All fires need air to burn. The incomplete combustion that takes place
in an “air starved” situation causes
carbon monoxide (CO) to be produced in quantities that can be dangerous inside a well sealed house.
Having a source of combusti
on air from outside the home will prevent “air starvation” of the furnace. You
must provide enough fresh air to assure proper combustion. Outside air is required to replace air used to
take the byproducts of combustion out the chimney. Outside air is also required to replace air exhausted
by kitchen/bathroom fans, and any other furnace, or water heater chimneys or fans.
Outside air may be needed if:

The solid-fuel-fired appliance does not draw steadily, smell, experiences smoke roll-out, burns
poorly, or back-drafts whether or not there is combustion present.

Any of the above symptoms are alleviated by opening a window slightly on a calm day.

The house is equipped with a well-sealed vapor barrier and tight fitting windows and/or has any
powered devices which exhaust house air.

There is excessive condensation on windows in the winter.

A ventilation system is installed in the house.
Installation In A Confined Space:
When the furnace is installed in a utility/storage room or other enclosed areas you must install two open
grills. They should be placed in a wall or door opening into the rest of the house. One will supply
combustion air. Locate it near the floor. The other is for ventilation and be located near the ceiling. Each