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.
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
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
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.
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)
Get your own CHPC:
- download PCB Gerber file, CHPC_v1.x_PCB_Gerber.zip
- search google where to 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
- 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:
Older revisions and prototypes:
PCB v1.1
This is prototype 2 (PCB v1.0). 1602 is the best choice.
EEV development started here, PCB v1.0.
Prototype 1. Say v0.0.
History ) But worked well for a 2018-19 season.
Author:
gonzho АТ web.de (c) 2018-2019
If you have any comments or questions, please do not hesitate to contact me.