Selectable efficiency versus comfort for modulating furnace
View Patent ↗A furnace controller for a modulating furnace that helps provide a balance between energy efficiency and occupant comfort across various burner firing rates and/or across various circulating blower speeds. In some cases, the furnace controller can be configured to permit a user to customize operation of the furnace in accordance with their particular needs and/or desires with respect to efficiency and comfort. A selection may be made between an energy efficiency setting and a user comfort setting. Then, a plenum parameter such as a discharge air temperature (DAT) or discharge air flow (DAF) may be regulated in accordance with the selected setting.
1. A method of operating a modulating forced air furnace, the method comprising the steps of:
accessing a defined relationship between a circulating blower speed and a plenum temperature, wherein the plenum temperature has a non-constant relationship with the circulating blower speed over at least a range of circulating blower speeds;
operating the modulating forced air furnace in accordance with the defined relationship between the circulating blower speed and the plenum temperature such that a substantially non-constant plenum temperature is produced over at least a range of circulating blower speeds.
2. The method of claim 1 , wherein operating the modulating forced air furnace in accordance with the defined relationship between a circulating blower speed and a plenum temperature comprises adjusting a burner firing rate.
3. The method of claim 2 , wherein operating the modulating forced air furnace in accordance with the defined relationship between a circulating blower speed and a plenum temperature further comprises adjusting the circulating blower speed.
4. A method of operating a modulating forced air furnace, the method comprising the steps of:
allowing a selection of an efficiency/comfort setting;
accessing a defined relationship between a burner firing rate and a plenum parameter, wherein the plenum parameter has a non-constant relationship with the burner firing rate over at least a range of burner firing rates, and wherein for a given burner firing rate, the corresponding plenum parameter is dependent upon the selected efficiency/comfort setting;
operating the modulating forced air furnace in accordance with the defined relationship between the burner firing rate and the plenum parameter.
5. The method of claim 4 , wherein operating the modulating forced air furnace in accordance with the defined relationship between the burner firing rate and the plenum parameter comprises controlling a circulating blower speed.
6. The method of claim 4 , wherein the defined relationship between the burner firing rate and the plenum parameter comprises a linear relationship with a non-zero slope between the burner firing rate and the plenum parameter.
7. The method of claim 4 , wherein the plenum parameter corresponds to a plenum temperature.
8. The method of claim 4 , wherein the plenum parameter corresponds to a volumetric plenum air flow measurement.
9. A method of operating a modulating furnace comprising a variable rate burner, a variable rate circulating blower and a furnace controller, the method comprising the steps of:
selecting between an energy efficiency setting and a user comfort setting;
the furnace controller operating the modulating furnace in accordance with a predetermined algorithm, and the selected setting alters the predetermined algorithm;
regulating a plenum parameter in accordance with the selected setting, wherein the plenum parameter is related to a discharge air temperature (DAT) of the modulating furnace; and
wherein regulating the plenum parameter in accordance with the selected setting comprises operating the variable rate circulating blower and/or the variable rate burner in accordance with the selected setting.
10. The method of claim 9 , wherein operating the modulating furnace in accordance with the predetermined algorithm comprises adjusting a speed of the variable rate circulating blower in order to obtain a plenum parameter that is related to a current firing rate of the variable rate burner.
11. The method of claim 10 , wherein the speed of the variable rate circulating blower is adjusted in order to obtain a plenum parameter in accordance with a linear relationship between the plenum parameter and the current firing rate.
12. The method of claim 10 , wherein operating the modulating furnace in accordance with the energy efficiency setting comprises operating the modulating furnace with a circulating blower speed profile that improves efficiency at the expense of user comfort.
13. The method of claim 10 , wherein operating the modulating furnace in accordance with the user comfort setting comprises operating the modulating furnace with a circulating blower speed profile that improves comfort at the expense of energy efficiency.
14. The method of claim 9 , wherein operating the modulating furnace in accordance with the predetermined algorithm comprises adjusting a firing rate of the variable rate burner in order to obtain a discharge air temperature (DAT) that is related to a speed of the variable rate circulating blower.
15. The method of claim 14 , wherein operating the modulating furnace in accordance with the energy efficiency setting comprises operating the modulating furnace with a burner rate profile that improves efficiency at the expense of user comfort.
16. The method of claim 14 , wherein operating the modulating furnace in accordance with the user comfort setting comprises operating the modulating furnace with a burner rate profile that improves comfort at the expense of energy efficiency.
17. The method of claim 9 , wherein regulating the plenum parameter comprises regulating a plenum temperature or regulating a plenum volumetric air flow.
18. The method of claim 9 , wherein selecting an energy efficiency setting or a user comfort setting comprises setting an input selector or making a software setting.