Midco HMA-2 & HMA-2A Series - Manual (Page 9)

Midco International Inc.
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The burner performance is highly dependent on its application and installation in the heater. Factors
such as airfl ow around the burner, positioning in the profi le , as well as, the profi le sizing have
infl uence on the fi nal emissions levels . Midco does not guarantee combustion results prior to
performing actual combustion tests.
The burner should be located in the center of the profi le. The profi le clearance from ends of the
burner should be kept at approximately 1 to 4-inches. Typically setting the profi le 2″ from the end
plates is recommended. Any reinforcements used on the edge of the profi le opening should be
on the downstream side of the profi le. The burner can be mounted either vertically or horizontally.
Since the airfl ow varies from unit to unit best results should be determined by actual testing.
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The HMA-2 & 2A Burners are designed to operate in an air heater and in an air stream taken directly
from outdoors for most applications. To avoid stratifi cation of the heated air, the burners should be
located on the intake side center to the blower. Such positioning will take advantage of the blower
mixing effect and ensure minimum temperature stratifi cation. It will also allow for a relatively uniform
airfl ow across the burner resulting in a clean combustion.
The total pressure of the blower must include allowance for the resistance of the heater and
pressure drop across the burner, together with pressure losses at the inlet screen, inlet louvers,
fi lters, plus the external pressure rating of the heater, if any. Contact equipment manufacturer for
proper information.
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The HMA-2 & 2A Burner will operate satisfactorily when located downstream of the blower. A
mixing plenum may be required at the heater discharge opening to insure minimum temperature
stratifi cation. Blower and motor selection must be made on the basis of corrections for the coldest
anticipated inlet temperature. In the push-thru system the heater outlet CFM will vary due to the
expansion of air.
Installation
Figure 2 - Pull-Thru System
Installation in a Heater
Screen
and
Filter
Air Inlet
Weatherhood
HMA-2 &
HMA 2A
Burner
Adjustable
Profile Plate
Outlet
Blower Inlet
Center Burner
to the Blower
x
2x
Pull Thru System
Push-Thru Systems
Push-Thru System
Air Inlet
Outlet
Blower Inlet
Center Burner
to the Opening
Figure 3 - Push Thru System
Burner Placement
in the Profi le
Continued