Dettson OMF154L20A, Installation Instructions And Homeowner'S Manual

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chimney into which a solid fuel burning furnace is already 
being vented. 

Before venting this furnace into a chimney, its condition must 
be checked and repairs made, if necessary. Also, the chimney 
lining and dimensions must conform to local and national 
codes. 

2.6.2  Factory Built Chimneys

Oil fired furnaces are approved for use with “L” type vents. The 
unit may also be used with an approved chimney of proper 
dimensions and temperature ratings as specified in the 
installation code. Refer to chimney manufacturer’s instructions 
for proper installation. 

2.6.3 Draft Regulator 

It is recommended that a draft regulator be installed in cases 
where the draft is either high or variable due to external 
conditions. Follow the instructions provided with the regulator.

2.6.4 Side-wall Venting 

The heating unit is approved for side-wall venting. This system 
includes model VTK-3 / KLAVT0201DET side-wall venter and 
a 5” insulated vent pipe, model IFV5 / KLAFVxx01DET. Refer 
to the installation instructions provided with the venting system. 

2.7 BLOCKED

VENT

SHUT-OFF

DEVICE

(BVSO)

FOR

CHIMNEY

VENTING 

CAUTION 

It is imperative that this device be installed by a qualified service 
technician. 

A positive pressure venting system (Sealed Combustion System 
or Direct Vent) 

MUST NOT

 use the BVSO. Follow the 

instructions supplied with the venting system. 

This device is designed to detect the insufficient evacuation of 
combustion gases in the event of a vent blockage. In such a 
case the thermal switch will shut down the oil burner. The 
device will then need to be re-armed MANUALLY. 

Refer to the detailed instructions and wiring diagrams supplied 
with the BVSO for the installation and wiring procedures. The 
length of wires supplied with the unit is such that the safety 
device must be installed between the flue outlet of the 
appliance and the draft regulator, as indicated in the 
instructions. 

It is also essential that the BVSO be maintained annually. For 
more details refer to the instructions supplied with the device 
itself, as well as Section 3. of this Manual. 
 

2.7.1  BVSO Performance Test 

The purpose of the following test is to check that the electrical 
outlet on the furnace, designated to the BVSO, is functional. 

1.  Start up the burner; 
2.  Remove the three-pole plug from the BVSO outlet on the 

furnace; 

3.  The burner must shut-off immediately, while the blower 

continues to run to the end of the cool-down cycle. 

If the test is not in line with the above, call a QUALIFIED 
SERVICE TECHNICIAN. 

2.8 COMBUSTION

AIR

SUPPLY 

AND

VENTILATION 

WARNING

Poisonous carbon monoxide gas hazard. 

Comply with NFPA 31 (U.S.) and CSA B139 (Canada) 
standards for the installation of Oil Burning 
Equipment and applicable provisions of local building 
codes to provide combustion and ventilation air. 

Failure to provide adequate combustion and 
ventilation air can result in death, bodily injury and/or 
property damage. 

Oil furnaces must have an adequate supply of combustion 
air. It is common practice to assume that older homes 
have sufficient infiltration to accommodate the combustion 
air requirement for the furnace. However, home 
improvements such as new windows, doors, and weather 
stripping have drastically reduced the volume of air 
infiltration into the home.

Refer to oil furnace installation codes relative to 
combustion and ventilation air requirements. Consult 
Section 2.2 in this manual, specifically for units installed in 
an enclosed space.  

Home air exhausters are common. Bathroom and kitchen 
fans, power vented clothes dryers and water heaters all 
tend to create a negative pressure condition in the home. 
Should this occur the chimney becomes less and less 
effective and can easily downdraft. In certain cases, 
mechanically supplied air, by way of a blower, interlocked 
with the unit, is necessary. It is the installer’s responsibility 
to check that. 

2.8.1 

Contaminated Combustion Air  

Installations in certain areas or types of structures will 
increase the exposure to chemicals or halogens that may 
harm the furnace. These conditions will require that only 
outside air be used for combustion. 

The following areas or types of structures may contain or 
be exposed to certain substances, potentially requiring 
outside air for combustion: 

a. Commercial 

buildings; 

b.  Buildings with indoor pools; 
c. 

Furnaces installed near chemical storage areas. 

Exposure to the following substances: 
a.  Permanent wave chemicals for hair; 
b.  Chlorinated waxes and cleaners; 
c. 

Chlorine based swimming pool chemicals; 

d.  Water softening chemicals; 
e.  De-icing salts or chemicals; 
f. Carbon 

Tetrachloride; 

g.  Halogen type refrigerants; 
h.  Cleaning solvents (such as perchloroethylene); 
i. 

Printing inks, paint removers, varnishes, etc. ; 

j. Hydrochloric 

acid; 

k. 

Solvent based glue; 

l. 

Antistatic fabric softeners for clothes dryers; 

m.  Acid based masonry cleaning materials. 

2.8.2  Burner with Outdoor Combustion Air Kit

Certain burners are designed to function with combustion 
air taken directly from the outside. Follow the instructions