HVAC Training – Low System Charge R22 TXV

by Ron Walker Here is a quick guide to help you diagnose and recognize a under charged, R22 HVAC system, with a TXV. Low System Charge – R22 TXV A system low on charge will have: Lowered cooling capacity. Lowered efficiency. A hot compressor motor Causes: Leaking system usually due to poor installation. Not properly…

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HVAC Training – Troubleshooting a Honeywell Smart Valve

by Ron Walker TROUBLESHOOTING SMART VALVE SYSTEMS The steps to correctly troubleshoot Smart Valves are as follows: Shut off the flow of gas to the appliance in question with the shut off valve. Make certain that the gas cock, located on top of the SV9X00 family of Smart Valves or later generations of Smart Valves SV9X01,…

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HVAC Training – Operating Principles of a Honeywell Smart Valve

by Ron Walker Let’s start with the Operating Sequence. The operating sequence of Smart Valve gas ignition and control systems is very similar to the older style, intermittent ignition systems which incorporate remotely mounted spark ignition modules. Those older systems use a 12,000 to18, 000 DC voltage source for ignition of the pilot gas. The Smart Valve system…

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HVAC Training – Basic Operation of Pressure Controlled Walk-in Coolers

by Ron Walker In this application, rather than controlling the cooler temperature with a thermostat, is is controlled by a low pressure cut-out switch. The low pressure cut-out switch is connected to the suction side of the compressor and is set to cut-out (or turn off the compressor) at 15-20°F below the cooler box temperature…

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HVAC Training Basic Operation of Temperature Controlled Medium Temperature Walk-in Coolers

by Ron Walker This system is controlled by a close on rise in temperature thermostat. The cooling thermostat will either be a mechanical type with a sensing bulb or a digital thermostat with a thermistor. Most of the walk-in coolers that require repair will be older and may have been retrofitted with a digital thermostat.…

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