HTP MC120 - Manual (Page 51)

51
LP-171 Rev. 4.10.14
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 high gas pressure regulator is used, it must be installed 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.
D. GAS VALVE
Figure 28 – LP-171-N
Do not do a gas conversion on this heater without an officially approved conversion kit and instructions supplied by HTP. Failure to use
a conversion kit when converting the heater to fire on Natural or LP gas will result in extremely dangerous burner operation, leading to
fire, explosion, severe injury or death.