Controls - Gas Control Valve, Orifice Chart - Bth 400/500 - A.O. Smith BTH 120 Series Service Handbook

CONTROLS – GAS CONTROL VALVE, ORIFICE CHART – BTH 400/500
The gas control valve has a built-in field adjustable pressure regulator. The regulator may be adjusted
by removing the cap screw. The adjustment screw is underneath. The gas control valve for the BTH 500
Natural gas model is shown below. This is a 24V. solenoid operated gas control valve.
For Series 100 and 101:
For Series 104:
ORIFICE CHART – BTH 120 thru 500
Model/Series 120
100/101
Natural 0.186"
Propane (LP) 0.121"
150 199
100/101 100/101
0.199" NA
0.136" 0.23"
Servicing should only be performed by a Qualified Service Technician
250 300
100/101 100/101 100/101
NA 0.274"
0.23" 0.189"
400 500
100/101
0.314" 0.347"
0.219" 0.241"
400/500
104
NA
NA
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