Universal Controls for Today’s HVAC Technician w/ Jim Fultz
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Universal components work across all systems, such as modern thermostats; you can see thermostats on gas furnaces, heat pumps, straight-cool A/Cs, and more, and they’ll all serve the same purpose. The “Universal” identifier merely indicates a part that works across several systems regardless of OEM. Universal controls aim to be easy for technicians to use when OEM parts are too expensive or impractical to order; customers also appreciate being given alternatives.
On furnaces, a common burner component that can usually use a universal replacement is the gas valve. White-Rodgers aftermarket components can work for hot-surface or direct-spark ignition.
In the blower compartment, we have the 24v transformers, which are critical components that allow universal components to work on systems. The “control circuits” that a 24v transformer connects with are the thermostat circuit, limit circuit, pressure switch circuit, gas valve, and ECM Speed Tap selection circuit. The integrated furnace control (IFC) is another critical component, as it fully controls all furnace operations; each control has specially designed functions for one or two-stage equipment, various blower motor types, direct-spark or hot-surface ignition, and OEM or universal options.
Nowadays, universal kits typically have adapters to multiple furnaces, so they can work across several different manufacturers’ models. You just have to verify the cross-reference of the voltage of the universal control to the IFC (such as via the WR Mobile app). After that, the installation instructions should tell you which harness you need for the conversion.
Whereas the IFC is the heart of furnace controls, the defrost control is the heart of a heat pump system’s controls. The defrost control manages the condensing fan motor, contactor, reversing valve, and coil temperature. It may also operate and monitor the high-pressure switch, low-pressure switch, outdoor air temperature, and backup heat.
The defrost control may use one of two strategies: timed defrost or demand defrost. Of the two defrost strategies, demand defrost is favorable because it can result in longer equipment life, more cost savings ($200-400 annually), and offer better compression protection. White-Rodgers defrost controls can upgrade units from timed defrost to demand defrost with the Matrix LED by using thermostat and heat pump harnesses and thermistors.
Contactors are components that require frequent replacement nowadays, which is ironic because they used to be the most durable part of the system. Contactors may come in the 1-pole, 1.5-pole, and 2-pole varieties. Most manufacturers tend to use 1.5-pole contactors nowadays. The SureSwitch universal part is a 1.5-pole contactor that can replace all three types.
Contactors commonly have electrical arcing issues. Pitting and welding occur during arcing, which prevents contactors from opening or closing. Pitting and welding may also happen due to voltage drops or insect damage. The SureSwitch contacts are sealed, so it is an appealing replacement because bugs cannot access the contacts and cause welding or pitting. The SureSwitch also comes with protection against brownouts and short cycles; those benefits will lead to improved equipment longevity.
The SureSwitch also comes with coil voltage options. The red cap on the spade can allow the SureSwitch to work with 120v, 208v, or 240v applications.
Jim also discusses:
Common White-Rodgers applications
Furnace burner components
Furnace blower assembly and blower motors
Furnace operation sequence
Universal component usage for Carrier/ICP air handler boards
Time defrost vs. demand defrost
Setup and programming options with the 47D01U-843
State requirements for heat pumps
Using auxiliary (backup) heat
47D01U-843 benefits on heat pump systems
The anatomy of arc damage
White-Rodgers product warranties
Future three-phase universal contactors
SureSwitch compatibility with refrigeration systems
Mounting the SureSwitch
How WR Mobile works
Visit the White-Rodgers website.
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