Thermo Pride Gas/Propane Furnace Induced Draft Highboy/Counterflow/Horizontal MHA1 - Manual (Page 8)

All installations and services must be performed by qualified service personnel.
5
and MDA1-75; 100CA-BASE for MDA1-100; and 125CA-BASE for MDA1-125.
refer to Figure 1.
Figure 1: Counter flow Furnace Combustible Surface-Mounting Base
D. Standard Clearances
Definitions of combustible material and non-combustible as issued by the
National Fuel Gas Code are as follows:
Combustible Material:
Materials made of or surfaced with wood, compressed paper, plant fibers,
plastics or other material that will ignite and burn whether flameproof or not or
whether plastered or not plastered.
Non-combustible Material:
Material which will not ignite and burn; such materials consisting entirely of steel,
iron, brick, concrete, slate, glass, plaster or combination thereof.
Table 1: Minimum Clearances to Combustible Materials
Model No.
Sides & Rear
of Furnace
(in.)
Front of
Furnace
(in.)
Top of
Plenum
(in.)
Flue or Vent
(in.)
Sides of
Plenum
(in.)
All Models
Covered by
This Manual
0 6 1 *6 1
*6 in. clearance may be reduced to 1 in. with UL Recognized type B1 vent.
The minimum clearances are listed for fire protection. Clearances for servicing
and proper operation, the front of the furnaces and to all points on the furnace
requiring access must be 24 in.