Chpc

CHPC: Cheap Heat Pump Controller v1.x

<b>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.</b> <br><br>

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: <b>PCB 1.3 tested, assembly instructions added</b> <br><br>

Applications:

| Usage. | Brief description. | Application examples | Available protections | | ---------- | ------------------ | ------------------ | -------------------- | | 1. Thermostat. | Precision thermostat. Simple and cheap. Only one relay and one temperature sensor required.<br> | 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 <br><br>

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 <br><br>

Control interfaces:

<b>None:</b> 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.<br> <b>0.96 OLED or 1602 LCD screen + buttons:</b> Simple, local screen controlled system. <br> <b>Remote computer terminal over RS-485 line. </b> Target temperature and running conditions under remote control. A user can get stats from all T sensors. Up to 1.2 kilometer line.*<br> <b> Remote automated control/stats via RS-485.</b> Firmware was written with python scripting in mind (and real scripts at the prototype 485 network).<br> <b> Both screen + buttons and RS-485.</b> 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. <br><br>

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 <br><br>

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) <br><br>

Temperature sensors installation example (medium scheme)

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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 <br><br>

T sensor abbreviations:

These abbreviations used in the interface during sensors installation procedure

| Abbr. | Full name | Required for | | ----- | -------------------- | -------------------- | | Tae | after evaporator | EEV <br>Anti-liquid protection at suction line | | Tbe | before evaporator | EEV | | Ttarget | target | Thermostat<br>Thermostat+EEV | | Tsump | sump | Automatic Compressor Heater<br>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 | |

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Photos:<br>

Older revisions and prototypes:<br>

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.

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Author:

gonzho АТ web.de (c) 2018-2019

If you have any comments or questions, please do not hesitate to contact me.