13
Furnace Section
Important !!
This section of the manual is only to supplement the furnace manufacturers manual.
You must thoroughly read this manual and the furnace manufacturer’s manual before
doing any installation, operation, or maintenance of the make-up air unit.
WARNING !!
If You Smell Gas:
1. Open all Windows.
2. Don’t touch electrical switches.
3. Extinguish any open flame.
4. Immediately call your gas supplier.
For Your Safety!!
The use and storage of gasoline
and other flammable vapors and
liquids in the vicinity of this
appliance is hazardous.
Gas Supply Pressure Requirements
All furnace sizes require the same amount of gas supply pressure. Single furnaces (furnace input 100 to 400 MBH)
have a single 3/4" connection, double furnaces (furnace input 500 to 800) have two 3/4" connections, and triple
furnaces (furnace input 1050 to 1200) have three 3/4" connections.
Natural: 6 to 14 in. wg
LP: 11 to 14 in. wg
For input rates see the furnace manufacturer's recommendations.
Furnace Maintenance
The following procedure should be completed before every heating season by a qualified service person.
1.
Remove and inspect burner. Check burner ports and burner mixing tubes for cleanliness. Also inspect
pilot assembly.
2.
While the burner is removed, use a mirror and flashlight to look at bottom of heat exchanger and inside
heat exchanger tubes. Check for any signs of corrosion, cracks, or soot. Also, inspect outside of heat
exchanger for any cracks or signs of overheating.
3.
Inspect main burner gas orifices in gas manifold to make sure they are not blocked with spider webs. Use
a toothpick for cleaning if necessary. Also remove and inspect pilot orifice. If dirty or damaged clean or
replace.
4.
Check combustion air openings and vent system. Clear of any debris.
5.
Run unit and check general operations.
6. Inspect pilot and main burner flames. Observe burner flames to ensure that they are burning straight and
clean and there are well defined inner cones. If an abnormal flame is observed, check furnace
manufacturer's manual for proper adjustments.
7.
Check for correct blower rpm.
8.
Check high and low manifold pressures.
