Bard Bayrd Furnace 403293A - Manual (Page 29)

2. Remova outlet pressure tap plug from gas control.
3. Make sure shut-otf valve is in off position, then install
1/8”-pipe manual shut-off valve In hole vacated by
plug.
4. Attach "U" tube water manometer to 1/8"-pipe manual
shut-off valve just installed.
5. Turn on all gas appliances attached to gas supply
line.
cause lighting or burning problems on any of the
appliances.
2. Make sure gas control inlet pressure does not ex­
ceed 10.5 inches W.C. Use method in Section 19A
to check gas supply line pressure.
3. Make sura all other gas appliances are off. You may
leave pilots on. Start furnace following Operating In­
structions on front door or in Users' Information
Manual.
6. Open manual shut-off valve in gas supply line just
ahead of furnace. Start furnace following Operating
Instructions on front door,
7. Open 1/8"-pipe manual shut-off valve leading to ma­
nometer.
8. Read manifold pressure on manometer.
9. Make small changes in manifold pressure within al­
lowable range (3.2 inches W.C. to 3.8 inches W.C.)
by turning gas control regulator adjusting screw clock­
wise -> to increase pressure; turn counter-clockwise
<- to decrease pressure. Make major changes in flow
rate by changing main burner orifice size. See Sec­
tion 23.
10. Turn off gas at manual shut-off valve in gas supply
line just ahead of furnace. Install outlet pressure tap
plug in gas control. Turn on gas.
11. Check regulator adjustment cover screw and gas
control plug for gas leaks. Use a commercial soap
solution made for leak detection.
WARNINOs Never use an open flame to check
for gas leaks. A gas leak could cause a fire or
explosion resulting In damage, Injury or death.
SECTION 21 — CHECKING GAS INPUT.
Equipment Needed; Save time by getting these tools before
you start: Item number(s) 11,14,15,19 and 22 listed in Sectbn 10.
WARNING! Natural gas heating value (BTU/cu.ft.) can
vary significantly, therefore, it Is the installers* responsi­
bility to see that BTU Input to furnace Is adjusted prop­
erly. Failure to do so could cause heat exchanger failure,
asphyxiation, fire or explosion, resulting in damage, in­
jury or death.
Underfiring could cause inadequate heat, excessive conden­
sation or ignition problems. Overfiring could cause sooting,
flame impingement or overheating of heat exchanger.
A. Natural Gas.
NOTE; For operations above 2,000 feet elevation, follow in­
structions in Section 23.
Before starting natural gas input check, obtain gas heat value
at standard conditions from local supplier.
1. Make sure gas piping is large enough for all appli­
ances connected to it to operate at once without
lowering main line pressure. Failure to do so could
4. As furnace warms up, watch gas supply line (gas
control inlet) pressure using "U" tube water manom­
eter installed in gas control inlet pressure tap. Natu­
ral gas supply line pressure must still not exceed
10.5 inches W.C.
5. After verifying correct gas control inlet pressure, close
shut-off valve in gas control inlet pressure tap. Move
manometer connection to gas control outlet pressure
tap. See Section 20. Open shut-off valve in outlet
pressure tap. Let furnace warm up for 6 minutes.
6. Manifold pressure should be 3.5 inches W.C. Adjust
by removing regulator cover screw on gas control.
Save screw for reinstallation. Turn inner adjustment
screw counter-clockwise <- to decrease manifold
pressure; turn clockwise -> to increase manifold pres­
sure. Set correct manifold pressure. Install cover
screw and tighten to torque of 5 inch-pounds to pre­
vent gas leakage.
7. Locate gas meter. Determine which dial has the least
cubic feet of gas and how many cubic feet per revo­
lution it represents. This is usually one-half, one or
two cubic feet per revolution.
8. With stopwatch, measure time it takes to consume
two cubic feet of gas.
a. If dial is one-half-cubic foot per revolution,
measure time for four revolutions.
b. If dial is one-cubic foot per revolution, mea­
sure for two revolutions.
c. If dial is two-cubic feet per revolution, mea­
sure for one revolution.
d. After determining the number of seconds for
two cubic feet of gas to flow through meter,
divide this time by two. This gives average
time for one cubic foot of gas to flow through
meter.
Example:
If it took 58 seconds for two-cubic feet to flow, it
would take 29 seconds for one-cubic foot to flow.
9. a. Use this formula to calculate gas input:
Gas Input =
Gas BTU/CU.FT. x 3,600
seconds per/hour
Seconds for one cubic foot of gas
Btuh
27