30
GKNE-SVX001B-EN
Gas Input Rate
Check the gas input rate as follows (Refer to General
Safety Information section for metric conversions).
1. Turn off all gas appliances that use gas through the
same meter as the unit heater.
2. Turn the gas on to the unit heater.
3. Clock the time in seconds required to burn 1 cubic foot
of gas by checking the gas meter.
Insert the time required to burn one cubic foot of gas
into the following formula and compute the input rate.
For example:
Assume the BTU content of one cubic foot of gas is
1000, and that it takes 18 seconds to burn one cubic
foot of gas.
Adjust the gas pressure as follows:
1. NATURAL GAS: Best results are obtained when the
unit heater is operating at its full rated input with the
manifold pressure of 3.5 inches WC (0.9 kPa).
Adjustment of the pressure regulator is not normally
necessary since it is preset at the factory. However,
field adjustment may be made as follows:
a. Attach manometer at the pressure tap plug
adjacent to the control outlet.
b. Remove the regulator adjustment screw cap,
located on the combination gas valve.
c. With a small screwdriver, rotate the adjustment
screw counterclockwise to decrease pressure, or
clockwise to increase pressure.
d. Replace regulator adjustment screw cap.
2. PROPANE GAS: An exact manifold pressure of 10.0
inches WC (2.5 kPa) must be maintained for proper
operation of the unit heater. If the unit is equipped with
a pressure regulator on the combination gas valve,
follow steps "a" through "d" above. If the unit is not so
equipped, the propane gas supply system pressure
must be regulated to attain this manifold operating
pressure.
3. The adjusted manifold pressure should not vary more
than 10% from pressure specified in Table 9.
*This schedule is for units at operating at normal altitudes
of 2000 feet (610m) or less.
When installed in Canada, any references to deration at
altitudes in excess of 2000 ft. (610m) are to be ignored. At
altitudes of 2000 to 4500 ft.(610 to 1372m), the unit heaters
must be field derated to 90% of the normal altitude rating,
and be so marked in accordance with ETL certification. See
Table 6A for field deration information.
Tubular unit heater high altitude deration
This Tubular Unit Heater has been manufactured utilizing
standard burner orifices and a normal manifold pressure
setting as per the specifications shown on your unit rating
plate.
All unit deration must be done through field adjustments
by a qualified technician. Once the proper adjustments are
made in the field, attach label #J17-06459 to the unit, and
CAUTION
Never over fire the unit heater, as this may cause
unsatisfactory operation, or shorten the life of the
heater.
NOTICE
If the computation exceeds, or is less than 95% of the
gas BTU/hr. input rating (see
), adjust the gas
pressure.
3600 Sec perHR
BTU
Cu Feet
Time Sec
-------------------------------------------------------------------------------------------------------------------------
InputRate
=
3600 1000
18
------------------------------------
200000
=
Table 9.
Main burner orifice schedule*
*
INPUT
IN
1000
BTU
TYPE OF GAS
NATURAL
PROPANE
NUMBER OF
BURNER
ORIFICES
HEATING
VALUE
1050 BTU/Ft
3
(39.1 MJ/m
3
)
2500 BTU/Ft
3
(93.1 MJ/m
3
)
MANIFOLD
PRESSURE
3.5-inch W.C
(0.87kPA)
10-inch W.C.
(2.49 kPA)
100
FT
3
/HR
ORIFICE
DRILL
93
42
40
53
4
125
FT
3
/HR
ORIFICE
DRILL
116
42
50
53
5
150
FT
3
/HR
ORIFICE
DRILL
140
42
60
53
6
175
FT
3
/HR
ORIFICE
DRILL
163
42
70
53
7
200
FT
3
/HR
ORIFICE
DRILL
186
42
80
53
8
250
FT
3
/HR
ORIFICE
DRILL
233
42
100
53
9
300
FT
3
/HR
ORIFICE
DRILL
280
42
120
53
10
350
FT
3
/HR
ORIFICE
DRILL
326
42
140
53
11
400
FT
3
/HR
ORIFICE
DRILL
372
42
160
53
12
