### CHPC: Cheap Heat Pump Controller v1.x The CHPC a minimal cost Heat Pump (HP) controller, which can be used as provided, or can be adopted to nearly all use cases due to open source nature.

## Real life installation. Works from ground heat collectors (loops) to radiant in-floor heating system. ![Installation example](./m_CHPC_i2.jpg) Driving: - EEV, - Heat Pump Compressor (1kW electrical power), - Circulating Pumps, - Compressor Heater. Temperature sensors installed: - Before/After Evaporator, - Cold In/Cold Out, - Hot In(used as Target)/Hot Out, - Outdoor temperature, - Compressor. Controlled via both RS-485 and 16x2 display with buttons. ## Changelog - 13 Apr, 2019: EEV support development started - 16 Apr, 2019: Standalone EEV (no thermostat) with only 2 T sensors written and debugged - 30 Apr, 2019: HP system updated to CHPC - 01 May, 2019: CHPC fully tested and released - 02 May, 2019: PCB rev.1.3 coming up, main feature: a lot of DS18B20 inputs - 17 May, 2019: PCB 1.3 tested, [assembly instructions added](https://github.com/gonzho000/chpc/wiki/assembly)

## Applications: | Usage. | Brief description. | Application examples | Available protections | | ---------- | ------------------ | ------------------ | -------------------- | | 1. Thermostat. | Precision thermostat. Simple and cheap. Only one relay and one temperature sensor required.
| Room heat control. A chicken coop climate control. Distillation column. Else. | N/A | | 2. Heat pump (HP) control. | Controller drives HP system components: compressor, Cold and Hot side Circulating Pumps (CP). Protect system from an overload, overheat and freezing up. Drives EEV to optimize running conditions. | DIY heat pump system. Repair module for commercial system. Water heater, house heating systems and same applications. | Compressor: cold start or overheat. Discharge and suction lines protection. Short-term power loss. Anti-freeze. Power overload protection. | | 3. EEV controller. | Only drives EEV, no relays. Require two T sensors. | Upgrade your system from capillary tube to EEV. | Protects from liquid at suction line by design. | For more information about Heap Pumps look at [Wikipedia about HP](https://en.wikipedia.org/wiki/Heat_pump)

## Features: - Up to 13 T sensors (see "T sensor abbreviations" for full list) - 5 relays (Compressor, Hot CP or Air Fun, Cold CP or Air Fun, Compressor Heater, 4-way valve) - 4 inputs - 5/6 pin EEV connection, - 1602 display support - RS485 or Serial(UART 5V) support - Automatically turns on/of system when heating required - Takes care of system components health - On board or off board power supply

## Control interfaces: None: Target temperature uploaded to board with firmware and not changed anymore. System used as an fixed thermostat. You can change target temperature with firmware re-upload.
0.96 OLED or 1602 LCD screen + buttons: Simple, local screen controlled system.
Remote computer terminal over RS-485 line. Target temperature and running conditions under remote control. A user can get stats from all T sensors. Up to 1.2 kilometer line.\*
Remote automated control/stats via RS-485. Firmware was written with python scripting in mind (and real scripts at the prototype 485 network).
Both screen + buttons and RS-485. Combination allowed. \* RS-485 specification. The hardware test succeeded on 400 meters line. Example: day/night setpoint control and data visualization with JSON communication way. ![graph example](./m_t_graph_example.png)

## Relays: ### "Thermostat": Only one Relay: drive an electric heater (any) ### "Heat Pump". Capillary tube, TXV, EEV: 5 Relays, drives all you need: * Compressor (relay can be used as external relay driver for High Power systems) * Cold Circulating Pump (CP) * Hot CP * Compressor Heater (optional, recommended for outdoor HP installations) * and one reserved to support 4-way Valve

## Temperature sensors: * Up to 13 temperature sensors can be connected to CHPC to control all processes that you want. * Only 1 sensor needed for "Thermostat" or "Heat Pump capillary/TXV" * 3 sensors needed for "HP with EEV" (absolute minimum scheme)

## Temperature sensors installation example (medium scheme) ![medium scheme](./m_HeatPump_t_sensors_med.png)

## Get your own CHPC: * download PCB Gerber file, *CHPC_v1.x_PCB_Gerber.zip* * search google [where to order PCB](https://www.google.com/search?q=order+pcb) or make your own at CNC machine * order electronic components, see BOM (Bill Of Materials) list, *CHPC_v1.x_PCB_BOM.html* * solder, [assembly instructions here](https://github.com/gonzho000/chpc/wiki/assembly) * install firmware *CHPC_firmware.ino* * install CHPC at your system * enjoy

## T sensor abbreviations: These abbreviations used in the interface during sensors installation procedure | Abbr. | Full name | Required for | | ----- | -------------------- | -------------------- | | Tae | after evaporator | EEV
Anti-liquid protection at suction line | | Tbe | before evaporator | EEV | | Ttarget | target | Thermostat
Thermostat+EEV | | Tsump | sump | Automatic Compressor Heater
Compressor overheat protection | | Tci | cold in | Antifreeze protection | | Tco | cold out | Antifreeze protection | | Thi | hot in | Hot CP automatic control | | Tho | hot out | Overheat protection | | Tbc | before condenser | Discharge overheat protection | | Tac | after condenser | | | Touter | outer (outdoor) | | | Ts1 | additional sensor1 | | | Ts2 | additional sensor2 | |

## Photos:
![v1.3](./m_PCB_v1.3_noscreen.jpg) ![v1.3](./m_PCB_v1.3_screen.jpg) ![v1.3](./m_v1.3_PCBdemo.png) ## Older revisions and prototypes:
PCB v1.1 ![proto3](./m_proto3.jpg) ![proto3 without screen](./m_proto3_noscreen.jpg) This is prototype 2 (PCB v1.0). 1602 is the best choice. ![proto2](./m_proto2.jpg) EEV development started here, PCB v1.0. ![proto2_EEVdev](./m_proto2_EEVdev.jpg) ![proto2 PCB](./m_proto2_PCB.jpg) Prototype 1. Say v0.0. History ) But worked well for a 2018-19 season. ![proto1](./m_proto1.jpg)

## Author: gonzho АТ web.de (c) 2018-2019 If you have any comments or questions, please do not hesitate to contact me.