Heating medium circulation apparatus

Abstract

A heating medium circulation apparatus promptly detects an overheating abnormality, or local overheating of a heating medium caused by insufficient circulation of the heating medium in a circulation circuit. The heating medium is pumped by a circulation pump in a predetermined direction in a closed-loop circulation circuit connecting a heater that heats the heating medium and a heat dissipator that dissipates heat from the heating medium. The temperature of the heating medium flowing out of the heater is detected by an outgoing temperature sensor. Upon the start of a heat dissipation-based operation using heat dissipation with the heat dissipator, the circulation pump is activated, and the heating in the heating is started. An overheating abnormality is detected when the increasing gradient being the rate of increase per unit time of the temperature detected by the outgoing temperature sensor is higher than or equal to a predetermined determination gradient.

1 . A heating medium circulation apparatus for circulating a heating medium between a heater configured to heat the heating medium and a heat dissipator configured to dissipate heat from the heating medium, the apparatus comprising: 
 a circulation circuit being a closed-loop circuit connecting the heater and the heat dissipator;   a circulation pump configured to pump the heating medium in the circulation circuit in a predetermined direction;   an outgoing temperature sensor configured to detect a temperature of the heating medium flowing out of the heater;   a heating controller configured to control heating in the heater; and   an overheating abnormality detector configured to detect an overheating abnormality, the overheating abnormality being local overheating of the heating medium caused by insufficient circulation of the heating medium in the circulation circuit,   wherein the circulation pump is activated in response to a start of a heat dissipation-based operation and remains active during the heat dissipation-based operation, and the heat dissipation-based operation is an operation using heat dissipation performed by the heat dissipator,   the heating controller starts the heating in the heater in response to the start of the heat dissipation-based operation, and   the overheating abnormality detector detects the overheating abnormality when a detection condition is satisfied, and the detection condition is that an increasing gradient being a rate of increase per unit time of the temperature detected by the outgoing temperature sensor is higher than or equal to a predetermined determination gradient.   
     
     
         2 . The heating medium circulation apparatus according to  claim 1 , wherein 
       the heating controller temporarily stops the heating in the heater when the temperature detected by the outgoing temperature sensor reaches a heating stop temperature during the heat dissipation-based operation, and 
       the detection condition that the increasing gradient of the temperature detected by the outgoing temperature sensor is higher than or equal to the determination gradient includes a further condition that the temperature detected by the outgoing temperature sensor remains higher than an abnormality determination temperature for at least a specified time after the heating in the heater is stopped in response to the temperature detected by the outgoing temperature sensor reaching the heating stop temperature, the abnormality determination temperature is higher than the heating stop temperature, and the overheating abnormality detector detects the overheating abnormality when the detection condition including the further condition is satisfied. 
     
     
         3 . The heating medium circulation apparatus according to  claim 1 , further comprising: 
 a return temperature sensor configured to detect a temperature of the heating medium flowing into the heater,   wherein the detection condition includes a further condition that the temperature detected by the return temperature sensor remains below a return reference temperature until a predetermined return wait time elapses from a return specific time point, the return specific time point is after the start of the heat dissipation-based operation, and the overheating abnormality detector detects the overheating abnormality when the detection condition including the further condition is satisfied.   
     
     
         4 . The heating medium circulation apparatus according to  claim 3 , wherein 
       the return reference temperature is obtained by adding a return estimated increase to the temperature detected by the return temperature sensor at the return specific time point. 
     
     
         5 . The heating medium circulation apparatus according to  claim 1 , wherein 
       the heat dissipator is a hot-water supply heat exchanger configured to heat, through heat exchange with the heating medium, water supplied from a water supply to produce hot water, 
       the heating medium circulation apparatus further comprises a hot-water supply temperature sensor configured to detect a temperature of the hot water supplied from the hot-water supply heat exchanger, and 
       the detection condition includes a further condition that the temperature detected by the hot-water supply temperature sensor remains below a hot-water supply reference temperature until a predetermined hot-water supply wait time elapses from a hot-water supply specific time point, the hot-water supply specific time point is after the start of the heat dissipation-based operation, and the overheating abnormality detector detects the overheating abnormality when the detection condition including the further condition is satisfied. 
     
     
         6 . The heating medium circulation apparatus according to  claim 5 , wherein 
       the hot-water supply reference temperature is obtained by adding a hot-water supply estimated increase to the temperature detected by the hot-water supply temperature sensor at the hot-water supply specific time point. 
     
     
         7 . The heating medium circulation apparatus according to  claim 1 , wherein 
       the heat dissipator includes 
       space heating equipment configured to heat a space by dissipating heat from the heating medium, and 
       a hot-water supply heat exchanger configured to heat, through heat exchange with the heating medium, water supplied from a water supply to produce hot water, 
       the heating medium circulation apparatus further comprises a switcher configured to switch between a space heating operation in which the heating medium is circulated through the space heating equipment and a hot-water supply operation in which the heating medium is circulated through the hot-water supply heat exchanger, and each of the space heating operation and the hot-water supply operation is the heat dissipation-based operation, and 
       the determination gradient differs between the space heating operation and the hot-water supply operation, and the determination gradient is lower in the space heating operation than in the hot-water supply operation. 
     
     
         8 . The heating medium circulation apparatus according to  claim 2 , further comprising: 
 a return temperature sensor configured to detect a temperature of the heating medium flowing into the heater,   wherein the detection condition includes a further condition that the temperature detected by the return temperature sensor remains below a return reference temperature until a predetermined return wait time elapses from a return specific time point, the return specific time point is after the start of the heat dissipation-based operation, and the overheating abnormality detector detects the overheating abnormality when the detection condition including the further condition is satisfied.   
     
     
         9 . The heating medium circulation apparatus according to  claim 8 , wherein 
       the return reference temperature is obtained by adding a return estimated increase to the temperature detected by the return temperature sensor at the return specific time point. 
     
     
         10 . The heating medium circulation apparatus according to  claim 2 , wherein 
       the heat dissipator is a hot-water supply heat exchanger configured to heat, through heat exchange with the heating medium, water supplied from a water supply to produce hot water, 
       the heating medium circulation apparatus further comprises a hot-water supply temperature sensor configured to detect a temperature of the hot water supplied from the hot-water supply heat exchanger, and 
       the detection condition includes a further condition that the temperature detected by the hot-water supply temperature sensor remains below a hot-water supply reference temperature until a predetermined hot-water supply wait time elapses from a hot-water supply specific time point, the hot-water supply specific time point is after the start of the heat dissipation-based operation, and the overheating abnormality detector detects the overheating abnormality when the detection condition including the further condition is satisfied. 
     
     
         11 . The heating medium circulation apparatus according to  claim 10 , wherein 
       the hot-water supply reference temperature is obtained by adding a hot-water supply estimated increase to the temperature detected by the hot-water supply temperature sensor at the hot-water supply specific time point. 
     
     
         12 . The heating medium circulation apparatus according to  claim 2 , wherein 
       the heat dissipator includes 
       space heating equipment configured to heat a space by dissipating heat from the heating medium, and 
       a hot-water supply heat exchanger configured to heat, through heat exchange with the heating medium, water supplied from a water supply to produce hot water, 
       the heating medium circulation apparatus further comprises a switcher configured to switch between a space heating operation in which the heating medium is circulated through the space heating equipment and a hot-water supply operation in which the heating medium is circulated through the hot-water supply heat exchanger, and each of the space heating operation and the hot-water supply operation is the heat dissipation-based operation, and 
       the determination gradient differs between the space heating operation and the hot-water supply operation, and the determination gradient is lower in the space heating operation than in the hot-water supply operation.