John Wood Takagi - 320H-520H - Manual (Page 14)

14
Gas Supply And Gas Pipe Sizing
TO TURN OFF GAS
TO APPLIANCE
Turn off all electric power to the water heater if service
is to be performed.
Turn the manual gas valve located on the outside of
the unit clockwise to the off position. 1.
2.
WARNING
Ensure that any and all gas regulators
used are operating properly and provid-
ing gas pressures within the specified
range shown below. Excess gas inlet
pressure may cause serious accidents.
Conversion of this unit from natural gas
to propane or vise versa will void all
warranty. Contact your local distributor
to get the correct unit for your gas type.
The manufacturer is not liable for any
property and/or personal damage result-
ing from gas conversions. •
•
*Check that the type of gas matches the rating plate first.
1. The minimum and maximum inlet gas pressures are:
Gas type Inlet gas pressure
Natural Gas Min. 5.0" WC – Max. 10.5" WC
Propane Gas Min. 8.0" WC – Max. 14.0" WC
2. Gas pressure below this specified range for the 520H
and/or insufficient gas volume will adversely affect per-
formance. These pressures are measured when the
520H is in full operation.
3. Inlet gas pressure must not exceed the above maximum
values; gas pressure above the specified range will
cause dangerous operating conditions and damage to
the unit.
4. Until testing of the main gas line supply pressure is com-
pleted, ensure the gas line to the 520H is disconnected
to avoid any damage to the water heater.
Measuring inlet gas pressure
The 520H cannot perform properly without sufficient inlet
gas pressure. Below are instructions on how to check the
inlet gas pressure. THIS IS ONLY TO BE DONE BY A
LICENSED PROFESSIONAL.
Shut off the manual gas valve on the supply gas line.
Remove the screw for the pressure port located on the
gas inlet of the water heater shown in the diagram to the
right.
Connect the manometer to the pressure port.
Re-open the manual gas valve. Check to see that there
are no gas leaks. Open some of the fixtures that use the
highest flow rate to turn on the water heater.
Check the inlet gas pressure. When the water heater is
on maximum burn, the manometer should read from 5.0"
to 10.5" WC for Natural gas, from 8.0" to 14.0" WC for
Liquid Propane.
Pressure
port
Size the gas pipe appropriately to supply
the necessary volume of gas required for
the 520H models (199,000 BTU/h for both
Natural Gas and Liquid Propane) using
CSA B149.1 or local codes. Otherwise, flow
capabilities and output temperatures will be
limited.
Install a manual gas shut-off valve between the water
heater and the gas supply line.
When the gas connections are completed, it is necessary
to perform a gas leak test either by applying soapy water
to all gas fittings and observing for bubbles or by using a
gas leak detection device.
Always purge the gas line of any debris and/or water
before connecting to the gas inlet.
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