Midco Unipower A-Series - Manual (Page 2)

Part 1 Installation
I Specifications Burner Style Power Type
Flame Safeguard Instantaneous electronic type
with flamerod detection (flame rectification).
• Provides pre-purge and intermittent pilot operation on UL listed models up to 2500 MBH
maximum input.
• Provides pre-purge and interrupted pilot operation on UL listed models over 2500 MBH
max.
Pilot Spark Ignited
Fuel Natural or Propane Gas to 14" W.C. Pressure
Controls 120 Volt, 60 Hz., 1-Phase
Burner Capacity Chart page 12
In U.S.A.: UL Listed, In Canada: ULC (A5 Series only)
Burner
Model Minimum*** Maximum H.P. Phase Volts
Burner Input Capacity*
Natural or Propane Gas MBH**
Motors
3450 RPM. 60 Hz.
A50G
A52G
A53G
A55G
A73G
A75G
A77G
1
1
1
1
3
3
3
1 /
3
1 /
2
3 /
4
3 /
4
1 1 /
2
2
2
115
115
115/230
115/230
230/460
230/460
230/460
420
840
840
840
1,680
1,680
1,680
1,500
2,000
2,500
3,000
4,200
5,000
6,000
Table 1: Burner Specifications
* Values given based on -0.1" W.C. to +0.1" W.C. firebox pressure, altitudes to
2,000 feet. Derate burner for altitudes over 2,000 feet by 4% for each 1,000
feet over sea level. (One gallon fuel oil=140 MBH).
** Refer to Burner Spec Plate for Inlet and Manifold gas pressure required.
*** Modulating and High-Low-Off burners are limited to a 3 to 1 turndown
ratio.
All models are capable of full input start. However, in some cases, (i.e. restricted draft or induced
draft) optional low fire start may be necessary. Specify On-Off, Hi-Lo-Off or Full Mod as required.
■ ■ ■ ■ A permanent means must be provided to supply an ample volume of fresh air for combustion
and boiler room ventilation. A direct opening to the outside air for combustion and boiler room
ventilation. A direct opening to the outside air should be provided sized on the basis of
1 /
2
square
foot of free opening for each 1,000 MBH of burner input when the flue pipe is equipped with a
barometric draft control, as is commonly used on burners of this size. If the ventilation opening is
screened, it should be of 1
1 /
4
" mesh. The opening should be located at least six feet over ground
level to prevent accidental obstruction. If a direct opening to the outside air is not available, an
amply sized air duct can be run to the nearest outside air source.
■ ■ ■ ■ While the Unipower A Series burner will perform successfully under moderate or momentary
back draft conditions, it is not intended for operation under sustained reverse draft, as might be
encountered in building with large ventilating fans but with insufficient make-up air. Even if
burner operation is successful under these conditions, they must be corrected to prevent the
hazard of drawing flue gases into the building.
■ ■ ■ ■ The entire heating system should be inspected, cleaned and repaired as necessary to provide
proper heating.
■ ■ ■ ■ Remove all grates and obstructions from the firebox, clean thoroughly, and seal all joints and
cracks. Complete sealing of the firebox is required where the combustion chamber pressure will
be positive during burner operation. It is also beneficial where the pressure is negative as it
promotes combustion efficiency.
■ ■ ■ ■ Firing door catches should be filed off or otherwise arranged so that the door will open easily
to relieve excess pressure. No positive catches should be used. The use of a spring-type door
holder is recommended.
■ ■ ■ ■ If the appliance has been designed for automatic firing and contains no firing doors, an
observation port should be provided that will allow inspection of the main flame and pilot.
II Ventilation
III Preparation of the
Heating Appliance
2