I wonder if type of generic(?) controller might also work with GSHPs?
eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices
KI&BNT
Air-source Heat Pump Water Heater Controller S-3330
The controller is a single system of air-source heat pump water heater dedicated controller, the wired remote and the control board composed of two parts. Wired remote control as a standard installation of 86 panels, the LCD screen displays temperature data, and can modify the control parameters through the keypad; control panel with three-way temperature sensor inputs: temperature sensor, evaporator sensor and exhaust temperature sensors, switch all the way external alarm signal input, the three control outputs:compressor, defrost and evaporator fans.
Specification
Power Supply: 220VAC +10% / -15%, 50/60Hz
Power consumption: less than 5W
Measuring range: -50 °C ~ +120 °C
Control range: 0 °C ~ 100 °C, adjustable
Resolution: 0.1 °C
Measurement Accuracy: ± 1 °C ± 0.5
Sensor fault delay: 10 seconds
Sensor type: NTC sensor, 10K/25 °C
Compressor Output: Contact capacity 30A/220VAC, direct drive and the following single-phase load 2HP/220VAC
Defrost output: Contact capacity 10A/220VAC
The remaining work output: Contact capacity 5A/220VAC
Wired remote control in front of protection: IP30
Package Content
1×Air-source Heat Pump Water Heater Controller S-3330
air-source heat pump water heater controller - Microcomputer Temperature Controllers - Products - Xuzhou Jingying Electronics Technology Co., Ltd.