44
8. Ensure inlet pressure is within specied range. Minimum and
maximum gas supply pressures are specied in this section
of the manual.
9. If gas supply pressure is within normal range and no
adjustments are needed, proceed on to Step 11.
10. If the gas pressure is out of range, contact the gas utility, gas
supplier, qualied installer or service agency to determine
the necessary steps to provide proper gas pressure to the
control.
11. Turn the power switch to the “OFF” position.
12. Shut off the gas supply at the manual gas valve in the gas
piping to the appliance.
13. Remove the manometer from the pressure tap on top of the
gas valve. On Models 150 - 500 re-tighten the set screw
inside the pressure tap. On Models 600 - 800 remove the
1/8" (3 mm) eld supplied tting and reinstall the pipe plug
removed in Step 3.
When re-tightening the set screw, be sure to tighten securely to
prevent gas leaks. Do not check for gas leaks with an open ame
-- use the bubble test. Failure to use the bubble test or check for
gas leaks can cause severe personal injury, death, or substantial
property damage.
14. Turn on the gas supply at the manual gas valve.
15. Turn the power switch to the “ON” position.
16. Adjust the temperature Setpoint on the control panel of the
UIM to the desired water temperature so the appliance will
call for heat.
17. Check burner performance by cycling the system while you
observe burner response. The burner should ignite promptly.
Flame pattern should be stable. Turn system off and allow
burner to cool, then cycle burner again to ensure proper
ignition and ame characteristics.
Table 23. Natural Gas Pipe Size Chart
CAPACITY OF SCHEDULE 40 METALLIC PIPE IN CUBIC FEET OF NATURAL GAS PER HOUR
(BASED ON .60 SPECIFIC GRAVITY, 0.30" W.C. PRESSURE DROP)
Pipe
Size
(Inches)
Length of Pipe in Straight Feet
10 20 30 40 50 60 70 80 90 100 125 150 175 200
1/2 131 90 72 62 55 N/A N/A N/A N/A N/A N/A N/A N/A N/A
3/4 273 188 151 129 114 104 95 89 83 79 70 63 58 N/A
1 514 353 284 243 215 195 179 167 157 148 131 119 109 102
1 1/4 1,060 726 583 499 442 400 368 343 322 304 269 244 224 209
1 1/2 1,580 1,090 873 747 662 600 552 514 482 455 403 366 336 313
2 3,050 2,090 1,680 1,440 1,280 1,160 1,060 989 928 877 777 704 648 602
2 1/2 4,860 3,340 2,680 2,290 2,030 1,840 1,690 1,580 1,480 1,400 1,240 1,120 1,030 960
3 8,580 5,900 4,740 4,050 3,590 3,260 3,000 2,790 2,610 2,470 2,190 1,980 1,820 1,700
4 17,500 12,000 9,660 8,270 7,330 6,640 6,110 5,680 5,330 5,040 4,460 4,050 3,720 3,460
XP water heaters are typically shipped ready to re on natural gas. Check the water heater rating plate to determine which fuel the
water heater is set for. If set to natural gas, it may be converted to Propane (LP) by installing an orice or by making a gas valve
adjustment (see pages 15 and 16). In order to operate on Propane (LP) gas, an orice MUST BE installed or a gas valve adjustment
MUST BE made. Failure to comply could result in severe personal injury, death, or substantial property damage.
CHECK INLET GAS SUPPLY
CSA or UL listed exible gas connections are acceptable, but
you must exercise caution to ensure that the line has adequate
capacity to allow your water heater to re at full rate. Consult with
local codes for proper installation or service procedures.
DO NOT adjust or attempt to measure gas valve outlet pressure.
The gas valve is factory-set for the correct outlet pressure. This
setting is suitable for natural gas and propane, requiring no eld
adjustment. Attempting to alter or measure the gas valve outlet
pressure could result in damage to the valve, causing potential
severe personal injury, death, or substantial property damage.
The gas piping must be sized for the proper ow and length of
pipe, to avoid excessive pressure drop. Both the gas meter and
the gas regulator must be properly sized for the total gas load.
If you experience a pressure drop greater than 1 inch w.c., the
meter, regulator, or gas line is undersized or in need of service.
Perform the steps below when checking inlet gas supply:
1. Turn the main power switch to the “OFF” position.
2. Shut off gas supply at the manual gas valve in the gas piping
to the appliance.
3. On Models 150 - 500 loosen the set screw one (1) full turn
from inside the pressure tap on top of the gas valve. On
Models 600 - 800 remove the 1/8" (3 mm) pipe plug on the
inlet ange to the valve and install a suitable 1/8" (3 mm)
tting (eld supplied) for the manometer tubing. Place the
tubing of the manometer over the tap once the set screw is
loosened or the 1/8" (3 mm) tting is installed (depending on
model) as shown in Figure’s 66 thru 69 on Page 45.
4. Slowly turn on the gas supply at the eld installed manual
gas valve.
5. Turn the power switch to the “ON” position.
6. Adjust the temperature Setpoint on the control panel of the
Control Module to call for heat.
7. Observe the gas supply pressure as the burner res at 100%
of rated input. Percent of burner input will be displayed on
the control panel.
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