Topic is now "boiler/temp" and the values "High" and "Normal".
This happens as soon as I open the serial monitor:
967643> MQTT: Recv type=PINGRESP id=0000 len=2; Pend type=NULL id=00
2160> CMD_parse_packet: cmd=1(RESET) argc=0 cb=0x00000000 ret=0
2160> CMD_Exec: Dispatching cmd=RESET
2160> CMD_Exec: no response (0)
3176> CMD_parse_packet: cmd=2(IS_READY) argc=0 cb=0x00000000 ret=1
3177> CMD_Exec: Dispatching cmd=IS_READY
3177> CMD_Exec: Response: 0x1, cmd: 2
3286> CMD_parse_packet: cmd=4(MQTT_SETUP) argc=9 cb=0x00000000 ret=1
3286> CMD_Exec: Dispatching cmd=MQTT_SETUP
3286> CMD_Exec: Response: 0xf00df00d, cmd: 4
3356> CMD_parse_packet: cmd=11(REST_SETUP) argc=3 cb=0x000003ac ret=1
3357> CMD_Exec: Dispatching cmd=REST_SETUP
3357> REST: setup #1 host=google.com port=80 security=0
3357> CMD_Exec: Response: 0xbeef0001, cmd: 11
3420> CMD_parse_packet: cmd=12(REST_REQUEST) argc=3 cb=0x00000000 ret=0
3420> CMD_Exec: Dispatching cmd=REST_REQUEST
3420> REST: request #1 method=GET path=/ bodyLen=0 hdrLen=146 totLen=146 data=0x3fff9188 hdrLen=133
3421> REST: pCon state=0
3421> REST: Connect to host google.com:80
3421> CMD_Exec: no response (0)
3502> REST DNS: found ip 172.217.21.238
3502> REST: connecting...
3522> REST #1: connected
3522> REST #1: sending 133
3654> REST: Sent
3655> REST: status=302, body=268
t: cmd=8(MQTT_SUBSCRIBE) argc=3 cb=0x00000000 ret=0
6585> CMD_Exec: Dispatching cmd=MQTT_SUBSCRIBE
6585> MQTT: MQTTCMD_Subscribe topic=boiler/temp, qos=0
6585> MQTT: Subscribe, topic: "boiler/temp"
6585> MQTT: Send type=SUBSCRIBE id=0007 len=18
6586> CMD_Exec: no response (0)
6587> MQTT: Recv type=SUBACK id=0007 len=5; Pend type=SUBSCRIBE id=07
6635> CMD_parse_packet: cmd=8(MQTT_SUBSCRIBE) argc=3 cb=0x00000000 ret=0
6636> CMD_Exec: Dispatching cmd=MQTT_SUBSCRIBE
6636> MQTT: MQTTCMD_Subscribe topic=boiler/temp, qos=0
6636> MQTT: Subscribe, topic: "boiler/temp"
6636> MQTT: Send type=SUBSCRIBE id=0008 len=18
6637> CMD_Exec: no response (0)
6637> CMD_parse_packet: cmd=8(MQTT_SUBSCRIBE) argc=3 cb=0x00000000 ret=0
6637> CMD_Exec: Dispatching cmd=MQTT_SUBSCRIBE
6637> MQTT: MQTTCMD_Subscribe topic=boiler/temp, qos=0
6637> MQTT: Subscribe, topic: "boiler/temp"
6637> CMD_Exec: no response (0)
6638> MQTT: Recv type=PUBLISH id=0000 len=19; Pend type=SUBSCRIBE id=08
6639> MQTT: Recv PUBLISH qos=0 boiler/tempHighpHigh
6677> MQTT: Recv type=SUBACK id=0008 len=5; Pend type=SUBSCRIBE id=08
6677> MQTT: Recv type=PUBLISH id=0000 len=19; Pend type=NULL id=00
6677> MQTT: Recv PUBLISH qos=0 boiler/tempHighpHigh
6677> MQTT: Send type=SUBSCRIBE id=0009 len=18
6679> MQTT: Recv type=SUBACK id=0009 len=5; Pend type=SUBSCRIBE id=09
6801> MQTT: Recv type=PUBLISH id=0000 len=19; Pend type=NULL id=00
6802> MQTT: Recv PUBLISH qos=0 boiler/tempHighpHigh