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19
Gas Connection - Continued
Gas Valve Maintenance/Replacement
1. When checking or replacing a gas valve, the CO
2
percentage in the flue gas is the preferred measuring method to insure proper
combustion and firing rate. CO is used as the alternate.
2. Gas valve replacement for the HW 599:
The left hand gas valve (which is normally factory-set and sealed and must not be adjusted) must be set up to factory specifications
before any combustion related adjustments can be performed on the right hand valve. An electronic manometer must be used, as it
will be set to a scale of 0.01" WC.
The adjustment screw [1] (see Figure 3.3,) normally used for setting maximum flow rate must be turned counterclockwise until it
begins to click when turned. The screw will not fall out, but will be fully retracted at this point.
This is for Natural Gas, for LP gas,
close the left hand valve (clockwise) until it is closed down.
The digital manometer must now be connected to the outlet pressure tapping [4] on the left hand valve only (marked do not adjust in
Figure 3.3), and the appliance fired. It must be placed in the service mode and held at the minimum firing rate (
1653 rpm
fan speed).
With the appliance firing at this rate, adjust the offset (minimum firing rate) screw [2] to a pressure of “0” +/- .0.01" WC.
Be sure the
manometer has been zeroed out prior to making this setting.
Once this operation is complete, you may follow the instructions for setting the minimum and maximum firing rate as shown in the
Setting Maximum Load and Setting Minimum Load Sections for the
right hand gas valve only.
WARNING! Failure to follow all precautions could result in fire, explosion, or death!