Nortek O4HD-091A-12-FB, Installation, Operation And Maintenance Manual

IMPORTANT: 

SAVE THESE INSTRUCTIONS FOR FUTURE REFERENCE 

1.  INTRODUCTION 

Please read these instructions completely and carefully 
before installing and operating the furnace. 

MODELS O4HD-091A-12-FB,  O4HD-091A-14-FA-

DV,  AND O4HD-091A-V-FA

Models O4HD-091A-12-FB, O4HD-091A-14-FA-DV and 
O4HD-091A-V-FA are oil fired forced air up-flow furnaces 
with an output capacity range of 59,000 BTU/Hr. to 
86,000 BTU/Hr. 

DO NOT USE GASOLINE, CRANK CASE OIL, OR 

ANY OIL CONTAINING GASOLINE.

All models are CSA listed, (NRTL/C) for use with No. 1 
(Stove) and No. 2 (Furnace) Oil. Please refer to the 
tables in Appendix A for performance and dimensional 
data. 

In Canada, the installation of the furnace and related 
equipment shall be installed in accordance with the 
regulations of CAN/CSA - B139, 

Installation Code for Oil-

Burning Equipment

, as well as in accordance with local 

codes.  

In the United States of America, the installation of the 
furnace and related equipment shall be installed in 
accordance with the regulations of NFPA No. 31, 

Standard for the Installation of Oil-Burning Equipment

, as 

well as in accordance with local codes. 

Regulations prescribed in the National Codes and Local 
regulations take precedence over the general 
instructions provided on this installation manual. When in 
doubt, please consult your local authorities. 

All models are shipped assembled and pre-wired. The 
furnace should be carefully inspected for damage when 
being unpacked. 

2.  HEAT LOSS 

The maximum hourly heat loss for each heated space 
shall be calculated in accordance with the procedures 
described in the manuals of the Heating, Refrigeration 
and Air Conditioning Institute of Canada (HRAI), or by 
other means prescribed, or approved by the local 
authority having jurisdiction.  

In the United States, Manual J. titled, "Load Calculation" 
published by the Air Conditioning Contractors of 
America, describes a suitable procedure for calculating 
the maximum hourly heat loss. 

3.  LOCATION OF UNIT 

The furnace should be located such that the flue 
connection to the chimney is short, direct and 
consists of as few elbows as possible. When 
possible, the unit should be centralized with respect 
to the supply and return air ductwork. A central 
location minimizes the trunk duct sizing. All models 
may be installed on combustible floors. 

The minimum installation clearances are listed in 
Table 1.

Table 1:  Clearances – (Inches)

Clearance to Combustibles 

O4HD-091A-12-FB,          O4HD-
091A-14-FA-DV and         O4HD-

091A-V-FA 

Location 

Up flow 

Top 1 

Bottom 0 

S/A Plenum 

1 

Rear 1 

Sides 1 

Front 

   1** 

Flue Pipe 

  9* 

Enclosure Closet 

*18 in. in USA 
** 24 in. required for service clearance 

HEAT EXCHANGER SUPPORT SCREWS

Before final placement of the furnace, the heat 
exchanger support screws shown in the picture may 
be removed. This may be preferable if the furnace 
rear panel will be inaccessible after installation. The 
screws must be removed if the heat exchanger must 
be removed from the cabinet. 

3