Load−tracking Variable Capacity FAQs (SLP98V only)
What is Load−tracking Variable Capacity? When an SLP98 Furnace is connected to an icomfort Wi−Fit thermostat, the thermostat takes complete charge of the variable capacity staging of the furnace. Load−tracking Vari- able Capacity is only available with icomfort Wi−Fi thermostats.
How is Load−tracking Variable Capacity different from Variable Ca- pacity? Load−tracking Variable Capacity will smoothly track the load (sensi- ble temperature changes) up and down and adjust the furnace heating rate both ways. Variable capacity only tracks the load upward (rising tempera- ture). Variable capacity uses the thermostats stage differentials but not stage timers. LVC disregards both stage differentials and stage timers.
What makes Load−tracking Variable Capacity work? With icomfortt Load−tracking Variable Capacity, the thermostat uses a Proportional Integral Algorithm (PIA) to control firing rates of the furnace. The algorithm in the Load−tracking Variable Capacity provides much more precise control over the furnace than the Variable Capacity algorithm.
Interesting points about the Proportional Integral Algorithm (PIA):
SThe further temperature is from the current set point, the higher PIA sets the heating rate.
SThe longer away from a programmed set point, the higher the heating rate.
SIf needed, PIA will turn heating on and off in short cycles when there is a heat demand that is lower than the lowest the furnace can provide.
SIf the heat demand is higher than the minimum the furnace can provide, the furnace will run without shutting off.
SAs the room temperature rises nearer the set point, the heating rate will decrease.
SAs the room temperature falls further away from the set point, the heat- ing rate will increase.
SThe stage differentials have no effect when running the PIA.
SThe second stage timers have no effect when running the PIA.
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