34000 Autry Street, Livonia, MI 48150 • 800.968.5530 • Fax 734.419.0209 • www.hamiltonengineering.com • LIT91127 REV 3/09
GAS CONNECTION
PART 3. GAS CONNECTION
A. GAS CONNECTION
WARNING
Failure to follow all precautions could result in re, explosion or death!
(FIGURE 3-1) EVO GAS CONNECTION
The gas supply shall have a maximum inlet pressure of less
than 14” water column (1/2 PSI) (3.44 kPa), and a minimum
of 4” water column. The entire piping system, gas meter and
regulator must be sized properly to prevent pressure drop
greater than 1” as stated in the National Fuel Gas Code. This
information is listed on the rating plate. It is very important
that you are connected to the type of gas as noted on the
rating plate, “LP” for liqueed petroleum, propane gas or “Nat”
for natural or city gas. All gas connections must be approved
by the local gas supplier, or utility in addition to the governing
authority, prior to turning the gas supply on. It is mandatory
that a drip leg be fabricated, as per the National Fuel Gas
code. Once all the inspections have been performed, the pip-
ing must be leak tested. It is recommended that a soapy solu-
tion be used to detect leaks. Bubbles will appear on the pipe to
indicate a leak is present. If the leak test requirement is a high-
er test pressure than the maximum inlet pressure, you must
isolate the EVO from the gas line. In order to do this, you must shut the gas off using factory and eld-installed
gas cocks (following the lighting instructions in Part 6, Section B, Pages 23-24.) This will prevent high pressure
from reaching the valve. Failure to do so may damage the gas valve. In the event the gas valve is exposed to a
pressure greater than 14” water column, the gas valve must be replaced.
B. GAS PIPING
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The gas piping must be sized for the proper ow and length of pipe, to avoid 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” WC, the meter, regulator or gas line is undersized or in need of service. You can attach a manometer to
the incoming gas drip leg, by removing the cap and installing the manometer, see Figures 3-2 and 3-3 on the
following page. The gas pressure must remain between 4” and 14” 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 equivalent feet from
the EVO. 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 also in empty tank situations. This 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 con-
ventional gas valve under any circumstances. As an additional safety feature, this gas valve is easily de-coupled
from the fan inlet.
Refer to the following tables to size the supply piping to minimize pressure drop between meter or
regulator and unit.
