Building a DIY air conditioner for your tiny house using scrap parts can be a fun and rewarding project. With some basic mechanical skills and readily available components, you can construct a simple yet effective AC unit to keep your small space nice and cool even on hot summer days.
Gather the Necessary Materials
The great thing about this project is that many of the parts can be salvaged from old appliances or purchased very cheaply. Here's what you'll need:
Refrigerant Gas
- R-134a is readily available and is the most common type of refrigerant used in DIY air conditioners. You'll need about 1-2 pounds.
Compressor
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The compressor compresses the refrigerant gas as part of the heat exchange process. You can often salvage one from an old fridge or window AC unit.
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Look for a 1/4 to 1/2 horsepower compressor. Match the specifications to the size of your tiny house.
Copper tubing
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3/8" copper tubing is needed to connect all the components in the refrigeration cycle.
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You'll also need a short piece of 1/4" tubing for the compressor suction line.
Condenser
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The condenser coils condense the refrigerant gas into liquid as part of the cooling process.
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A condenser from an old fridge or AC works perfectly.
Evaporator
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The evaporator coils allow the refrigerant to evaporate and absorb heat.
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You can use a car AC evaporator or salvage one from an appliance.
Refrigeration oil
- A small amount of mineral oil is needed to lubricate the compressor.
Pressure switches, tubing, and fittings
- Pressure switches, tubing, hose clamps, threaded fittings, and other hardware are needed to join all the components.
Fan
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A squirrel cage blower fan will blow air across the evaporator to cool your space.
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Look for a fan that matches the BTU of your compressor.
Electrical components
- You'll need wiring, a start capacitor, and a relay to control the electrical supply to the compressor and fan motor.
Plumbing the Refrigeration System
Once you have all the parts, it's time to assemble the refrigeration system:
1. Compressor
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Mount the compressor on a sturdy platform with vibration dampening.
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Attach the suction line (1/4" tubing) to the compressor's low pressure inlet.
2. Condenser
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Mount the condenser above the compressor to allow gravity to pull condensed refrigerant downward.
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Connect it to the compressor's discharge port with 3/8" tubing.
3. Filter
- Install a filter drier in the line before the evaporator to keep contaminants out.
4. Evaporator
- Mount the evaporator on the platform and connect it to the condenser outlet with 3/8” tubing.
5. Refrigerant
- Once assembled, pull a vacuum and charge the system with R-134a refrigerant.
Adding the Fan
To blow air across the cold evaporator coils and into your living space:
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Mount the blower fan on the platform, positioned in front of the evaporator.
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Power the fan with an electric motor and wiring. It should turn on when the thermostat calls for cooling.
Thermostat Control
To turn the AC on and off automatically:
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Mount a thermostat on the wall at a comfortable height.
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Connect it to a relay that starts the compressor and fan when the temperature rises.
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Set it to your desired room temperature.
Powering the Unit
You'll need a power source to run the components:
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For off-grid tiny homes, use a sufficiently sized DC battery bank to run the 12V DC compressor.
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If connected to electrical grid power, install a 240V AC circuit with 30 amp breaker.
Performance Tweaks
To maximize efficiency and cooling power:
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Insulate all the cold refrigerant lines.
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Apply thermal paste between components.
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Adjust the expansion valve to fine tune refrigerant flow.
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Make sure all connections are thoroughly air-tight.
Safety First
Working with pressurized refrigerant, AC power, and heavy components requires caution:
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Wear protective eyewear when handling refrigerant.
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Discharge capacitors before disassembling AC units.
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Use gloves and lift properly when moving heavy objects.
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Follow all electrical safety codes.
Conclusion
Constructing your own tiny house air conditioner from scrap parts can be an extremely rewarding DIY project. By salvaging components and following basic refrigeration principles, you can build an efficient cooling system for a fraction of the cost of buying a new AC unit. Just be sure to do your research, work carefully, and prioritize safety throughout the process. Stay cool!