(FIGURE 3-1) EVO
GAS CONNECTION
1/2"=1'
Dwg. By:
34000 Autry
Livonia, MI 48150
PH: (800) 968-5530
Fax: (734) 419-0209
Description:
Date:
Scale:
Customer:
HAMILTON
ENGINEERING
Dwg.
No.:
Checked.
By:
(2) HWD299's to HET 120
Gas
Supply
Drip
Leg
Gas
Shut-off
Valve
12
PART 3. GAS CONNECTION
PART 3. GAS CONNECTION
A. GAS CONNECTION AND INSPECTION
FAILURE TO FOLLOW ALL PRECAUTIONS
COULD RESULT IN FIRE, EXPLOSION OR
DEATH!
DANGER
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 liquefied 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 piping must be leak tested. It is
recommended that a soapy solution
be used to detect leaks. Bubbles
will appear on the pipe to indicate
a leak is present. If the leak test
requirement is a higher 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
field-installed gas cocks (following
the lighting instructions in Part 6,
Section B, Page 38.) 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.
Never use an open flame
(match, lighter, etc.) to check gas
connections.
B. GAS PIPING
The gas piping must be sized for the
proper flow 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 port 3 of the gas
valve (see Figures 3-2 and 3-3 on
the following page). Alternatively,
you can attach the manometer
to the incoming gas drip leg, by
removing the cap and installing the
manometer. 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 conventional 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.
