Open Source Heat Pump BOM

Open Heat Pump Module v1.0

This page documents an open-hardware heat pump module built from off-the-shelf HVAC parts. Design target: reversible ~2-ton (≈24,000 BTU/h) R-410A heat pump, suitable for air-to-water integration.

Goal

Create a modular, serviceable, repairable heat pump core using standardized refrigeration components easily sourced worldwide.

System Overview

Each module consists of:

• 2-ton R410A scroll compressor
• 4-way reversing valve
• Brazed plate refrigerant-to-water heat exchanger
• Expansion device (TXV or EEV)
• Filter/drier, accumulator, service valves
• Simple, open controls

Four modules ≈ 96,000 BTU/h.

Bill of Materials (per 2-ton module)

Compressor (2-Ton R-410A Scroll)

Primary: https://hdsupplysolutions.com/p/copeland-2-ton-r-410a-scroll-compressor-p252077 Alternative: https://www.ferguson.com/product/goodman-r-410a-208230v-single-phase-scroll-compressor-g50n6229vzakms/7347425 Budget surplus option: https://surpluscityliquidators.com/products/212-ton-achp-scroll-compressor-208230601-r410a-3?variant=41932566036525 eBay example (for cost discovery): https://www.ebay.com/itm/286682581692

Typical ratings: 2 ton capacity, R410A, ~208/230V single-phase, scroll type.

Reversing Valve (4-Way, Heat Pump)

Ranco V2-408060-170: https://www.supplyhouse.com/Ranco-V2-408060-170-1-2-x-3-8-Heat-Pump-Reversing-Valve-style-1 Budget Daikin compatible: https://www.partswarehouse.com/Daikin-Reversing-Valve-2Ton-R22-R410A-DAI-910198406-p/DAI-910198406.htm Alternative source: https://www.gsistore.com/products/ranco-v2-408060-270-reversing-valve Low-cost generic option: https://www.wilspecdirect.com/products/reversing-valve-2-ton

Typical line sizes: Suction ~ 3/4" Liquid ~ 3/8–1/2"

Refrigerant-to-Water Brazed Plate Heat Exchanger

(acts as condenser in heating mode / evaporator in cooling mode)

Bell & Gossett brazed plate heat exchangers: https://www.nationalpumpsupply.com/bell-gossett-brazed-plate-heat-exchangers/

General R410A plate HX listings: https://www.alibaba.com/showroom/r410a-brazed-plate-heat-exchanger.html Westermeyer / industrial quality: https://westermeyerind.com/products/heat-exchange/brazed-plate/

Requirements: Must be rated for R410A refrigerant pressure (typically 450-650 psi working). Water side stainless (316) preferred.

Other Refrigeration Components (standard HVAC)

Obtain from any HVAC wholesaler (Johnstone, Ferguson, SupplyHouse, etc):

• 2–3 ton R410A TXV (or EEV)
• Bi-flow R410A filter-drier
• Suction accumulator
• Service valves
• Schrader access ports
• Sight glass (optional)
• Copper lines and fittings

Hydronic Integration

(not included in refrigeration stack)

• Circulator pump
• Water manifold + PEX / copper
• Thermal storage tank(s) / IBC tote integration
• Fan coils OR radiant loops on load side

Refrigerant Circuit (Simplified)

Compressor discharge → reversing valve → Either outdoor air coil OR brazed plate HX → Liquid line with TXV/EEV → Evaporator (whichever is opposite role) → Suction accumulator → Compressor suction.

Use bi-flow filter/drier and appropriate check valves.

Line Sizes

Typical for 2 ton R410A: Suction: ~3/4" Liquid: ~1/2" Match compressor + valve ratings.

Controls

Sensors:

• Water in/out temperature
• Optional refrigerant suction/discharge pressure

Actuators:

• Compressor contactor
• Reversing valve solenoid
• Water pump relay
• Outdoor fan relay (if used)

Controller may be: PLC / ESP32 / relay logic.

Safety

All refrigerant work must be done by qualified personnel. Pressure test, evacuate, charge properly. Use components specifically rated for R-410A.

Open Hardware Intent

This design:

• Avoids proprietary sealed systems
• Uses catalog components
• Enables decades of maintainable operation
• Supports local fabrication and repair economy
• Serves as a building block for open thermal infrastructure