Refrigeration – Automatic control – Time or program actuator
Reexamination Certificate
1999-12-27
2001-10-09
Wayner, William (Department: 3744)
Refrigeration
Automatic control
Time or program actuator
C062S201000, C165S208000, C165S218000
Reexamination Certificate
active
06298677
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to reversible heat pump systems which condition water that is to be circulated through one or more heat exchangers downstream of the heat pump system.
Heat pump systems which provide heated or cooled water to one or more heat exchangers are typically not required to switch from a heating mode to a cooling mode very often. This is in part due to the inherent inertia of a heat pump in trying to heat water that has been previously cooled. In this regard, the compressor within the heat pump must process a sufficient amount of refrigerant over time that can give up the necessary heat to the water that has been previously cooled. The compressor is presented with a similar heavy load situation when it is required to process a sufficient amount of refrigerant over time to absorb heat from previously heated water so as to produce cooled water. This inability to switch between heating and cooling or vice versa has previously led to switching the mode of operation of the heat pump system infrequently. For instance, changeovers would be implemented on particular calendar dates indicating normal change of seasonal weather conditions. On the other hand, a changeover might be implemented depending on a separately sensed outdoor air temperature indicating whether the heat pump system should be in either heating or cooling for the day. The above described changeover controls do not allow a heat pump system to respond to heating or cooling demands that may change throughout the day. The above described systems moreover do not respond to different demands for cooling or heating throughout a building on a given day.
OBJECTS OF THE INVENTION
It is an object of this invention to provide a heat pump system with the capability to automatically change from one operating mode to another operating mode at any time regardless of outdoor air temperature or calendar date.
It is another object of this invention to provide a heat pump system that will be responsive to different demands for cooling or heating throughout a building on a given day.
SUMMARY OF THE INVENTION
The above and other objects are achieved by providing a heat pump system controller with control logic, which continually polls the spaces or zones in which heating or cooling may be demanded so as to determine whether there is a predominance of either heating or cooling being demanded. The polling also checks to see whether a determined predominance of demand for either heating or cooling meets certain minimum demand requirements. In the event that minimum demand requirements are met, then a system demand is set reflecting the polling results. For instance, the system demand would be set for producing heated water if the predominance of polled spaces reflected that more spaces requested heating than requested cooling and that the number of spaces requesting heating exceeded some minimum number of spaces required to implement a changeover from cooling to heating. The system demand does not, however, allow for an immediate changeover to heating in the event that a changeover to heating is being requested by the polling results. In particular, the controller will first check to see whether the current mode of operation of the heat pump has been in effect for a minimum time period before stopping the then active compressor. The controller will preferably thereafter inquire as to whether a particular water temperature in the water return line to the heat pump is within a range of temperatures. This will allow the zone controllers associated with heat exchangers that are still demanding cooling to continue giving up heat to the circulating water so as to thereby increase the temperature of the returning water. During this time, the compressor will remain off so as to not be presented with an otherwise heavy load of trying to heat low temperature water. The controller may also override the requirement of raising the return water temperature to a desired temperature level in the event that a particular changeover period of time has elapsed since the compressor was turned off. It is only after the return water temperature is within range or the changeover time period has expired, if the latter is required, that the controller will proceed to actually authorize the changing of the valve position of a reversing valve within the heat pump system so as to configure the heat pump system to a heating mode of operation. The compressor will also be turned on at this point in time.
REFERENCES:
patent: 5207070 (1993-05-01), Miyazaki
patent: 5245835 (1993-09-01), Cohen et al.
patent: 5303767 (1994-04-01), Riley
Carrier Corporation
Wayner William
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