Service manual

COMBAT
®
UH UNIT HEATER INSTALLATION OPERATION AND SERVICE MANUAL
12
Where local codes permit, a single section of type
B-1 vent material may be used at the roof or wall
penetration instead of a thimble. Ensure vent
manufacturer's clearance from vent material is
maintained. Seal annular space of the type B-1 vent
as well as all joints in the remaining vent.
6.9 Replacing an Existing Heater in a Venting
System
When replacing an existing heater in a venting
system, the venting system may not be properly
sized to vent the new heater. The following steps
must be followed with each appliance connected to
the venting system placed in operation, while any
other appliances connected to the venting system
are not in operation.
1. Seal any unused openings in the venting
system.
2. Inspect the venting system for proper size and
horizontal pitch, as required by the (US)
National Fuel Gas Code, ANSI Z223.1/NFPA
54 or (Canada) CAN/CSA B149 Installation
Code and these instructions. Determine that
there is no blockage or restriction, leakage,
corrosion and other deficiencies which could
cause and unsafe condition.
3. Close all building doors and windows and all
doors between the space in which the
appliance(s) connected to the venting system
are located and other spaces of the building.
Turn on clothes dryers and any exhaust fans,
such as range hoods and bathroom exhausts
so that they shall operate at maximum speed.
Do not operate a summer exhaust fan. Close
fireplace dampers.
4. Follow the lighting instructions. Place the
appliance being inspected in operation. Adjust
thermostat so that the appliance will operate
continuously.
5. For any appliance having a draft hood, test for
draft hood appliance spillage at the draft hood
relief opening after 5 minutes of main burner
operation. Use the flame of a match or candle.
6. After it has been determined that each
appliance connected to the venting system
properly vents when tested as outlined above,
return doors, windows, exhaust fans, fireplace
dampers and any other gas-burning appliance
to their previous conditions of use.
7. If improper venting is observed during any of
the above tests, the venting system must be
corrected by a contractor qualified in the
installation and service of gas-fired equipment
or your local gas supplier. If the venting must
be resized, use appropriate tables in (US)
Appendix G of the National Fuel Gas Code
Z223.1/NFPA 54 or (Canada) Appendix C of
the CAN/CSA B149 Installation Code to
determine minimum size. All vent corrections
must be in accordance with the appropriate
local codes and the (US) National Fuel Gas
Code Z223.1/NFPA 54 or (Canada) CAN/CSA
B149 Installation Code.
Figure 5: Vent and Roof Detail
Roof
Vent
Terminal
Listed Thimble
Flashing
or Rain Collar
Vent
2" Air Gap to
Combustible Material