Field controls WMO-1 User Manual

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BLOCKED VENT SWITCH

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The WMO-1 Blocked Vent Switch is

Model: WMO-1

recommended for installation with an
oil fired appliance that normall
operates with its vent system under a

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negative pressure. This device is
intended to detect a blocked ven
system, responds to hot flue gases
backing up through its heat transfe

TEMS SUPPLIED IN THIS KIT:

1-Blocked vent switch assembly
1-Gasket
1-Instruction sheet

tube, and can be wired to shut off the
oil burner. It requires manual resetting.

This device MUST be installed by a qualified agency* in accordance with the manufacturer’s installation instructions.

The definition of a qualified agency is: any individual, firm, corporation or company which either in person or through a
representative is engaged in, and is responsible for, the installation and operation of oil appliances, who is experienced
in such work, familiar with all the precautions required, and has complied with all the requirements of the authority
having jurisdiction.

WARNING: Read the installation instructions carefully and completely before proceeding with the installation.

WARNING:

Do NOT reset the device or restart the appliance unless the cause has been identified and corrected by
a qualified agency. Insure the switch appliance combination has been cleaned by a qualified a gency before placing
back into service. Annual inspection and cleaning by a qualified agency is required.

• Wiring MUST be in accordance with the current Canadian Electric Code and any other applicable federal,
provincial and local code requirements.

• For installations in the USA, all wiring shall be in accordance with the National Electrical Code and applicable local
codes.

• For continued safe operation, the appliance-switch combination is required to be inspected and maintained annually
by a qualified agency. Failure to properly maintain the appliance-switch combination can lead to Death, Personal
Injury and or Property Damage.

INSTALLATION
M

OUNTING IN THE VENT PIPE

SEE THE APPLIANCE MANUFACTURER’S INSTRUCTIONS FOR THE SPECIFIC LOCATION.

IF THE APPLIANCE MANUFACTURER DOES NOT SPECIFY A LOCATION

REFER TO FIGURE 1.

1. Drill or pierce a clean hole (about 3/4” diameter) in the vent pipe near the appliance outlet. (See Figure 1)

2. The heat transfer tube must have the fiber gasket installed against the mounting plate before attaching the unit to the
vent pipe

3. Insert the heat transfer tube with gasket into the 3/4” diameter hole placed in the vent pipe during step 1.

4. Secure the assembly to the vent pipe with a minimum of 4 sheet metal screws. The channel must be mounted
horizontally, unless specified differently by the appliance manufacturer. (See Figure 1)

CAUTION:

WARNING:

Disconnect electrical power supply to the appliance when wiring the blocked vent switch.

Switch connection
channel must be
mounted horizontally,
unless specified
differently by the
appliance manufacturer.

Figure 1

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WIRING INSTRUCTIONS

IF THE APPLIANCE MANUFACTURER DOES NOT SUPPLY A WIRING DIAGRAM

FOLLOW THE APPLIANCE MANUFACTURER’S WIRING DIAGRAM.

5. Wire the blocked vent switch in
series with the limit control circuit to
the primary control or as an optional
location in series with the orange
wire from the primary control to the
burner motor. (See Diagram A and
B) Route all wiring with an
acceptable wiring enclosure in
accordance with the current CSA

C22.1 Canadian Electric Code
Part 1 and any other applicable

federal, provincial and local code
requirements. For installations in the
USA all wiring shall be in accordance
with the National Electrical Code
and applicable local codes.

6. The following are typical wiring
diagrams. Read and follow the
appliance manufacturer’s instructions
and wiring diagram.

MAINTENANCE:

REFER TO DIAGRAMS A OR B.

Diagram A

Honeywell R7184B & Carlin 60200-02

Note: For continued safe operation, the appliance-switch

combination is required to be inspected and maintained annually by
a qualified agency.

7. Disconnect power to the appliance.

8. Remove the two screws holding on the WMO-1 blocked vent
switch assembly cover.

9. Remove the cover.

10. Remove the two screws holding the control box to the heat
transfer tube assembly. The control box slides, unlocking it
from the heat transfer tube assembly.

DO NOT DENT OR SCRATCH THE SURFACE OF THE THERMAL SWITCH.

IF THE THERMAL SWITCH IS DAMAGED, REPLACEMENT IS REQUIRED.

11. Carefully remove any buildup from the thermal switch surface.

12. Clear and remove any buildup or obstruction inside the heat
transfer tube.

13. Remount, lock and refasten the control box with the two screws
removed in step 10.

14. Reattach the assembly cover with screws removed in
step 8.

15. Re-establish power to the appliance.

120 VAC
240 VAC

Diagram B

Riello

CURRENT RATING

10 FL AMPS 60 LR AMPS

5 FL AMPS 30 LR AMPS