Blow through direct fired heating, A/C and ERV
According to various aspects, exemplary embodiments are disclosed of blow through direct fired heaters including evaporator coils and/or energy recovery ventilation.
1. A direct fired, blow through HVAC system comprising:
a burner configured to heat air circulated across an open flame of the burner;
a supply air blower disposed upstream of the burner;
an evaporator coil configured to cool air through direct expansion, the evaporator coil disposed upstream of the burner;
an air switching box configured to selectively direct air through or around the evaporator coil; and
a safety circuit configured to selectively turn off the burner;
wherein:
the safety circuit is configured to, while the system is operating in a cooling and/or air-conditioning mode, ensure the burner is off prior to any air being circulated across the evaporator coil; and
the air switching box is configured to, while the system is operating in a heating mode and the burner is on, direct a supply of air around the evaporator coil to the burner so the supply of air does not pass through the evaporator coil prior to entering the burner to ensure any potential leak of refrigerant will not pass through an open flame of the burner.
2. The system of claim 1 , further comprising one or more inlets configured to provide air for circulation through the system.
3. The system of claim 2 , wherein the one or more inlets are configured to provide:
recirculated indoor air combined with outdoor air while the system is in a cooling mode; and
outdoor air only while the system is in a heating mode.
4. The system of claim 2 , further comprising an energy recovery ventilation device configured to recover energy from conditioned air leaving an enclosed space and reintroduce the recovered energy into the air received at the one or more inlets for circulation through the system.
5. The system of claim 2 , further comprising at least one sensor configured to detect an operating parameter of the system.
6. The system of claim 5 , wherein the operating parameter includes at least one of carbon dioxide, humidity, indoor temperature, outdoor temperature, and dry bulb temperature.
7. The system of claim 6 , further comprising a controller coupled to one or more components of the system and configured to control at least one operating characteristic of the system, based on the detected operating parameter.
8. The system of claim 7 , wherein the at least one operating characteristic includes one or more of an operating airflow, a gas modulation, and a percentage of indoor and outdoor air combination.
9. The system of claim 8 , wherein the one or more inlets comprise one or more variable dampers, the variable dampers configured to adjust a mixture of outdoor and indoor air supplied to the system.
10. The system of claim 8 , wherein the supply air blower includes a variable frequency drive configured to adjust an amount of airflow through the system based on an operating mode of the system.
11. The system of claim 1 , further comprising:
a compressor configured to pressurize a refrigerant;
a condensing coil coupled to the compressor and configured to receive the refrigerant and convert the refrigerant from a gas to a liquid;
one or more condensing coil fans configured to circulate air across the condensing coil;
an expansion valve coupled to the condensing coil and configured to remove pressure from the refrigerant before providing the refrigerant to the evaporator coil; and
a controller coupled to one or more of the evaporator coil, compressor, condensing coil, one or more condensing fans, and the expansion valve, the controller configured to operate the HVAC in a cooling mode.
12. The system of claim 11 , further comprising one or more inlets configured to provide air for circulation through the system.
13. The system of claim 12 , further comprising an energy recovery ventilation device configured to recover energy from conditioned air leaving an enclosed space and reintroduce the recovered energy into the air received at the one or more inlets for circulation through the system.
14. The system of claim 3 , further comprising:
a compressor configured to pressurize a refrigerant;
a condensing coil coupled to the compressor and configured to receive the refrigerant and convert the refrigerant from a gas to a liquid;
one or more condensing coil fans configured to circulate air across the condensing coil;
an expansion valve coupled to the condensing coil and configured to remove pressure from the refrigerant before providing the refrigerant to the evaporator coil; and
a controller coupled to one or more of the evaporator coil, compressor, condensing coil, one or more condensing fans, and the expansion valve, the controller configured to operate the HVAC in a cooling mode.
15. The system of claim 1 , further comprising at least one sensor configured to detect an operating parameter of the system, wherein the operating parameter includes at least one of carbon dioxide, humidity, indoor temperature, outdoor temperature, and dry bulb temperature.
16. The system of claim 15 , further comprising a controller coupled to one or more components of the system and configured to control at least one operating characteristic of the system based on the detected operating parameter, wherein the operating characteristic includes one or more of an operating air flow, a gas modulation, and a percentage of indoor and outdoor air combination.
17. The system of claim 8 , further comprising:
a compressor configured to pressurize a refrigerant;
a condensing coil coupled to the compressor and configured to receive the pressurized refrigerant and convert the refrigerant from a gas to a liquid;
one or more condensing coil fans configured to circulate air across the condensing coil;
an expansion valve coupled to the condensing coil and configured to remove pressure from the refrigerant;
an evaporator coil configured to receive the refrigerant from the expansion valve and cool air circulated through the system through direct expansion; and
a controller coupled to one or more of the evaporator coil, compressor, condensing coil, one or more condensing fans, and the expansion valve, the controller configured to operate the system in a cooling mode.