Expansion relief header for protecting heat transfer coils in HVAC systems

1. An HVAC heat transfer coil mounted within an air handler, the coil comprising:

a housing having a top, a bottom and opposed vertical sides;

a plurality of liquid tubes extending through the housing from one side to the other, each tube having a plurality of fins attached thereto for heat transfer;

a plurality of bends extending out of the sides, each bend connected to ends of adjacent liquid tubes to form a liquid passage there between;

one or more expansion relief headers extending vertically downward from the top of the housing toward the bottom of the housing, wherein each of the expansion relief headers is connected to a plurality of aligned bends, wherein the bends include holes in alignment with holes formed in the expansion relief header to enable liquid to escape from the bends into the expansion relief header; and

wherein at least one of the one or more expansion relief headers includes one or more relief devices mounted to the side or bottom of the relief header and configured to automatically open to release liquid and thereby to relieve excessive pressure in the respective expansion release header, bends, and connected tubes when a pressure within the expansion relief header exceeds a predetermined value or a temperature within the expansion header is below a predetermined value, wherein at least one of the relief devices is a valve that is mounted directly to the one or more relief headers at a location below the top of the relief headers and the top of the housing, and in direct communication with the liquid in the one or more relief headers at or below an uppermost bend during operation, and not in communication with an air pocket or expansion tank installed outside of the air handler, to thereby provide immediate release of liquid from the one or more relief headers when the valve opens without any release of air;

wherein the valve has an open position where liquid is allowed to flow out from the expansion relief header and a closed position where liquid is prevented from flowing out from the expansion relief header, the valve includes a first sensor that senses the pressure of the liquid for controlling the opening and closing of the valve, and a second sensor that senses the temperature of the liquid for controlling the opening and closing of the valve, wherein the valve is configured to open when the pressure within the expansion header exceeds a predetermined value, and is configured to close after liquid is released and the pressure within the expansion relief header falls below a predetermined value and the temperature within the expansion header is above a predetermined value.

2. The HVAC heat transfer coil according to claim 1 , wherein the expansion relief header provides an additional area or volume capacity that accommodates expansion of the liquid in the tubes.

3. The HVAC heat transfer coil according to claim 1 , wherein the valve provides an audible or visual signal after liquid has been released.

4. The HVAC heat transfer coil according to claim 1 , wherein the one or more expansion relief headers include vent connections for air removal and/or draining.

5. An expansion relief header to be utilized on an HVAC heat transfer coil, the expansion relief header comprising a main body to be secured to bends in liquid coils of the HVAC liquid tube system, wherein the main body includes holes at vertically spaced apart positions on the relief header and in alignment with holes formed in the bends to enable liquid to pass from the bends into the expansion relief header; and one or more relief devices mounted directly to the side or bottom of the expansion relief header and configured to open to release liquid and thereby to relive excessive pressure in the expansion release header, bends, and coils when a pressure within the expansion relief header exceeds a predetermined value or a temperature within the expansion header is below a predetermined value, wherein at least one of the relief devices is a valve that is mounted directly to the expansion relief header at a location on the expansion relief header below a top of the relief header and at or below an uppermost bend to which the expansion relief header is attached so that the valve is in direct communication at or below the uppermost bend with liquid in the relief header during operation, and not in communication with an air pocket or expansion tank installed outside of the air handler, to thereby provide immediate release of liquid from the expansion relief header when the valve opens without any release of air;

wherein the valve has an open position where liquid is allowed to flow out from the expansion relief header and a closed position where liquid is prevented from flowing out from the expansion relief header, the valve includes a first sensor that senses the pressure of the liquid for controlling the opening and closing of the valve, and a second sensor that senses the temperature of the liquid for controlling the opening and closing of the valve, wherein the valve is configured to open when the pressure within the expansion header exceeds a predetermined value, and is configured to close after fluid liquid is released and the pressure within the expansion relief header falls below a predetermined value and the temperature within the expansion header is above a predetermined value.

6. The expansion relief header according to claim 5 , wherein the expansion relief header provides an additional area or volume capacity that accommodates expansion of the liquid in the HVAC liquid tube system due to freezing.

7. The expansion relief header according to claim 5 , wherein the valve is configured to provide an audible or visual signal after liquid has been released from the expansion relief header.

8. The expansion relief header according to claim 5 , further comprising vent connections for air removal and/or draining.

9. An HVAC heat transfer coil with a relief valve, the coil comprising:

a housing having a top, a bottom and opposed vertical sides;

a plurality of liquid tubes extending through the housing from one side to the other, each tube having a plurality of fins attached thereto for heat transfer;

a plurality of bends extending out of the sides, each bend connected to ends of adjacent liquid tubes to form a liquid passage there between;

at least one expansion relief header extending vertically downward from the top of the housing toward the bottom of the housing, the expansion relief header mounted to the plurality of aligned bends through a plurality of liquid passages so that each liquid passage permits liquid to flow between one of the bends and the relief header, the relief header positioned on the coils so that the liquid fills a portion of the relief header during operation between a lowermost bend and an uppermost bend; and

at least one relief valve mounted directly to the side or bottom of the relief header at a location below the top of the housing where the liquid fills a portion of the relief header so that the valve is in direct communication at or below an uppermost one of the plurality of aligned bends with the liquid in the relief header during operation and not in communication with an air pocket or expansion tank installed outside of the air handler such that the valve will automatically immediately release liquid from the relief header, and thereby relieve excessive pressure in the bends, and connected tubes without any release of air when pressure within the expansion relief header exceeds a predetermined value;

wherein the valve has an open position where liquid is allowed to flow out from the expansion relief header and a closed position where liquid is prevented from flowing out from the expansion relief header, the valve including a first sensor that senses the pressure of the liquid within the expansion relief header for controlling the opening and closing of the valve, and a second sensor that senses the temperature of the liquid within the expansion relief header for controlling the opening and closing of the valve, wherein the valve is configured to open when the pressure within the expansion header sensed by the first sensor exceeds a predetermined value, and is configured to close after liquid is released and the pressure within the expansion relief header sensed by the first sensor falls below a predetermined value and the temperature within the expansion header sensed by the second sensor is above a predetermined value.

10. The HVAC heat transfer coil according to claim 9 , wherein the valve extends laterally from a side of the expansion relief header.

11. The HVAC heat transfer coil according to claim 9 , wherein the valve is configured to open when the pressure sensed by the first sensor is at or exceeds about 150 psi.

12. The HVAC heat transfer coil according to claim 9 , wherein the predetermined pressure value at which point the valve opens is at least about 150 psi.

13. The HVAC heat transfer coil according to claim 1 , wherein the valve extends laterally from a side of the expansion relief header.

14. The HVAC heat transfer coil according to claim 1 , wherein the valve is configured to open when the pressure sensed by the first sensor is at or exceeds about 150 psi.

15. An HVAC heat transfer coil according to claim 1 , wherein the predetermined pressure value at which point the valve opens is at least about 150 psi.