Anti-freezing control method and system for failure of four-way valve of heat pump water heater

Abstract

The invention relates to an anti-freezing control method and system for failure of a four-way valve of a heat pump water heater. The method includes the following steps that firstly, whether the current water temperature T of the lower middle portion of a water tank is lower than the minimum temperature Tmin of the water tank in use or not is judged, if yes, the second step is executed; and if not, the first step is executed in a cycle manner; secondly, whether the descent speed Td of the current water temperature T is larger than or equal to the preset speed delta T or not is judged; or whether the current water temperature T satisfies the inequation of T<Tmin-a and is kept for the first time t1 or not is judged, wherein the a is the temperature difference limit value; if any judgment result is yes, the third step is executed, and if not, the first step is executed; and thirdly, a heat pump system is stopped and an electricity auxiliary heating system is started. By judging whether the descent speed Td of the current water temperature T is larger than or equal to the preset speed delta T or judging whether the current water temperature T satisfies the inequation of T<Tmin=a and is kept for the first time t1 or not, whether the four-way valve of the heat pump water heater fails or not can be judged precisely, and the error judgment situation is avoided.

Description

technical field [0001] The invention relates to the field of control of heat pump water heaters, in particular to an anti-freezing control method and system for failure of a four-way valve of a heat pump water heater. Background technique [0002] The existing heat pump hot water system has no failure mode to determine the four-way valve. If the four-way valve fails, refrigeration will be performed, and the low-temperature water in the water tank will be refrigerated into ice, causing ice blockage in the water inlet pipe of the water tank and blocking the water inlet, seriously affecting the use of users. ; In some existing cases, the failure of the four-way valve is determined by judging the difference between the temperature of the heat exchanger and the ambient temperature. In most working conditions, this scheme can determine whether the four-way valve is invalid. Under working conditions and low water temperature, this scheme will be invalid; it cannot be determined whe...

AI Technical Summary

Problems solved by technology

[0003] The present invention provides an anti-freezing control method and system for the failure of the four-way valve of a heat pump water heater to solve the above-mentioned technical problem of misjudgment when the four-way valve is invalid

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