HTP EL-399NVWH - Manual (Page 43)

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LP- 346 REV. 3.20.14
Never use an open flame (match or lighter) to check for gas leaks. Use a soapy solution to test connection. Failure to use a soapy
solution test or check gas connection for leaks can result in substantial property damage, severe personal injury, or death.
Use two wrenches when tightening gas piping at the heater: One to prevent the heater gas line from turning. Failure to prevent the
heater gas connection from turning could result in damage to the gas line components, substantial property damage, severe personal
injury, or death.
CSA or UL listed flexible gas connections can be used when installing the heater. Flexible gas connections have different capacities
and must be sized correctly for the connected heater firing rates. Consult with the flex line supplier to assure the line size is adequate
for the job. Follow local codes for proper installation and service requirements.
C. CHECK INLET GAS PRESSURE
The gas valve is equipped with an inlet gas pressure tap that can be used to measure the gas pressure to the unit. To check gas
pressure, perform the steps listed below:
1. IMPORTANT! Before you connect to the inlet pressure, shut off the gas and electrical
power to unit.
2. Loosen the pressure tap with a small screwdriver. Refer to Figure 24 for location.
3. Each unit is equipped with a needle valve that will accept a 5/16 ID hose to connect to
a digital manometer or liquid gauge to measure incoming pressure from 0-
35” w.c. See
Figure 24.
4. Turn on the gas and power up the unit.
5. Put the unit into manual test mode (details on test mode are in Part 10 Section D). In
service mode, monitor pressure to assure it does not drop below 1 inch from its idle
reading. If gas pressure is out of range or pressure drop is excessive, contact the gas
utility, gas supplier, qualified installer, or service agency to determine correct action that is
needed to provide proper gas pressure to the unit. If Gas Pressure is within normal range
proceed to Step 6.
6. Exit test mode, then turn power off and shut off gas supply at the manual gas valve
before disconnecting the hose from the gas monitoring device. Tighten screw on the
pressure tap and turn gas on. Check for leaks with soapy solution. Bubbles will appear on
the pipe to indicate a leak is present.
Ensure the pressure tap screw is properly tightened to prevent gas leaks. Failure to do so could cause substantial property damage,
severe personal injury, or death.
The gas piping must be sized for the proper flow and length of pipe to avoid pressure drop. The gas meter and regulator must be
properly sized for the total gas load. If you experience a pressure drop greater than 1" w.c. (.87 kPa), the meter, regulator or gas line
may be undersized or in need of service. You can attach a manometer to the incoming gas drip leg after removing the cap. The gas
pressure must remain between 3.5" (.87 kPa) and 14" (3.5 kPa) during stand-by (static) mode and while in operating (dynamic) mode.
If an in-line regulator is used, it must be a minimum of 10 feet from the heater. It is very important that the gas line is properly
purged by the gas supplier or utility. Failure to properly purge the lines, or improper line sizing, will result in ignition failure.
This problem is especially noticeable in NEW LP installations and empty tank situations. This situation can also occur when a utility
company shuts off service to an area to provide maintenance to their lines. This gas valve must not be replaced with a conventional gas
valve under any circumstances.
DO NOT adjust or attempt to measure gas valve outlet pressure. The gas valve is factory-set for the correct outlet pressure and
requires no field adjustment. Attempts by the installer to adjust or measure the gas valve outlet pressure could result in damage to the
valve and cause substantial property damage, severe personal injury, or death.
Figure 23 – LP-205-W