Rolling Thermal Labs: Cooling a Work Van with an EV Battery and a Hydronic Heart
Rolling Thermal Labs: Cooling a Work Van with an EV Battery and a Hydronic Heart
Rolling Thermal Labs: Cooling a Work Van with an EV Battery and a Hydronic Heart
May 3, 2025
Introduction: Curiosity Meets Ingenuity
This is a story about curiosity, an electric truck, and a lot of hose clamps.
Showing someone the impressive capabilities of water-based heating and cooling typically involves bringing them to a home or building. But what if the home could come to them? With that question in mind, we had the slightly crazy idea of taking hydronics on the road.
What started as a back-of-the-envelope sketch quickly evolved into a live demonstration showcasing how distributed thermal systems can radically simplify mobile comfort delivery. At Portland's Buildright conference, we demonstrated how an EV battery-powered heat pump could effectively cool and dehumidify an unconditioned electric van using only hydronic loops.
The Vision: Mobile, Electric, and Resilient
Sweating through summer installations in sealed vans sparked a question: Could we harness an EV’s onboard battery to power a heat pump and condition a workspace using just hydronic lines and water?
Why hydronics? Hydronic systems uniquely demonstrate energy efficiency, quiet operation, and versatility. Our demonstration aimed to prove that this concept was not only possible but practical and visually compelling.
System Design: Building a DIY Thermal Lab
Our goal was straightforward: condition a fully electric workspace using an external hydronic system. Here's the setup we created:
EV Power Source: 2023 Ford F-150 Lightning, providing onboard 240V power output.
Heat Pump: 3-ton air-to-water combi heat pump (R32 refrigerant, 4.89 SCOP).
Thermal Storage: 40-gallon buffer tank mounted on a trailer hitch platform.
Hydronic Distribution: Twin insulated line sets running approximately 40 feet into the van.
Fan Coil Units: Two compact, wall-mounted fan coils inside the BrightDrop electric van.
Controls: Onboard thermostats and external temperature sensors.
Power Routing: 60A breaker routed from EV to heat pump and pump relays.
We welded a sturdy bracket for the buffer tank and routed hydronic lines through flexible conduits into the van, sealing everything tightly. Fan coils were mounted high to maximize airflow and comfort.
Performance Testing: Surprising Efficiency
Our real-time field tests yielded impressive results:
Ambient Temperature: 84–92°F
Van Interior (Before): 101°F
Van Interior (After): Stabilized at 76°F within 35 minutes
Relative Humidity: Reduced from 61% to 46% in just over an hour
Energy Usage: 2.3 kWh/hour (Heat pump: ~2.1 kW; Fan coils and pumps: ~120W)
Noise Level: Approximately 42 dB (quieter than a mini-fridge)
Runtime: Up to 3 hours without noticeable performance drop
EV Battery Drain: Approximately 7% per hour
Findings and Lessons Learned
What Worked Well
Rapid Cooling: Quickly and quietly reduced interior temperatures.
Stable Hydronic Delivery: No internal compressor noise or refrigerant leakage.
Grid-independent Operation: Efficient use of EV battery power.
Surprising Insights
Minimal ramp-up time needed for fan coils.
Thermal storage provided continuous cooling during fluctuations in EV power.
Line insulation was critical; minor leaks significantly impacted performance.
Challenges Encountered
Hose clamp failure mid-demo—a memorable (if damp) moment.
Pump cavitation due to unprimed system.
Interference from the van’s built-in HVAC complicated airflow readings.
Why We Did This
The primary goal was to visibly demonstrate the remarkable efficiency, simplicity, and flexibility of hydronic systems. Instead of just talking about theoretical benefits, we created a rolling thermal lab that builders and homeowners could see, touch, and experience firsthand.
This hands-on approach helps make hydronics relatable and demonstrates its real-world potential.
Final Thoughts: From Concept to Reality
Engineering isn’t just math and diagrams—it’s hands-on problem-solving and a willingness to innovate on the spot.
This project reminded us of the joy in creating something new and functional—right in a parking lot. Thanks to everyone who made this possible, from the collaborative crew to a surprisingly tolerant EV battery.
I hope our experiment inspires builders, engineers, and dreamers alike to ask, "What if we just tried it?"
Introduction: Curiosity Meets Ingenuity
This is a story about curiosity, an electric truck, and a lot of hose clamps.
Showing someone the impressive capabilities of water-based heating and cooling typically involves bringing them to a home or building. But what if the home could come to them? With that question in mind, we had the slightly crazy idea of taking hydronics on the road.
What started as a back-of-the-envelope sketch quickly evolved into a live demonstration showcasing how distributed thermal systems can radically simplify mobile comfort delivery. At Portland's Buildright conference, we demonstrated how an EV battery-powered heat pump could effectively cool and dehumidify an unconditioned electric van using only hydronic loops.
The Vision: Mobile, Electric, and Resilient
Sweating through summer installations in sealed vans sparked a question: Could we harness an EV’s onboard battery to power a heat pump and condition a workspace using just hydronic lines and water?
Why hydronics? Hydronic systems uniquely demonstrate energy efficiency, quiet operation, and versatility. Our demonstration aimed to prove that this concept was not only possible but practical and visually compelling.
System Design: Building a DIY Thermal Lab
Our goal was straightforward: condition a fully electric workspace using an external hydronic system. Here's the setup we created:
EV Power Source: 2023 Ford F-150 Lightning, providing onboard 240V power output.
Heat Pump: 3-ton air-to-water combi heat pump (R32 refrigerant, 4.89 SCOP).
Thermal Storage: 40-gallon buffer tank mounted on a trailer hitch platform.
Hydronic Distribution: Twin insulated line sets running approximately 40 feet into the van.
Fan Coil Units: Two compact, wall-mounted fan coils inside the BrightDrop electric van.
Controls: Onboard thermostats and external temperature sensors.
Power Routing: 60A breaker routed from EV to heat pump and pump relays.
We welded a sturdy bracket for the buffer tank and routed hydronic lines through flexible conduits into the van, sealing everything tightly. Fan coils were mounted high to maximize airflow and comfort.
Performance Testing: Surprising Efficiency
Our real-time field tests yielded impressive results:
Ambient Temperature: 84–92°F
Van Interior (Before): 101°F
Van Interior (After): Stabilized at 76°F within 35 minutes
Relative Humidity: Reduced from 61% to 46% in just over an hour
Energy Usage: 2.3 kWh/hour (Heat pump: ~2.1 kW; Fan coils and pumps: ~120W)
Noise Level: Approximately 42 dB (quieter than a mini-fridge)
Runtime: Up to 3 hours without noticeable performance drop
EV Battery Drain: Approximately 7% per hour
Findings and Lessons Learned
What Worked Well
Rapid Cooling: Quickly and quietly reduced interior temperatures.
Stable Hydronic Delivery: No internal compressor noise or refrigerant leakage.
Grid-independent Operation: Efficient use of EV battery power.
Surprising Insights
Minimal ramp-up time needed for fan coils.
Thermal storage provided continuous cooling during fluctuations in EV power.
Line insulation was critical; minor leaks significantly impacted performance.
Challenges Encountered
Hose clamp failure mid-demo—a memorable (if damp) moment.
Pump cavitation due to unprimed system.
Interference from the van’s built-in HVAC complicated airflow readings.
Why We Did This
The primary goal was to visibly demonstrate the remarkable efficiency, simplicity, and flexibility of hydronic systems. Instead of just talking about theoretical benefits, we created a rolling thermal lab that builders and homeowners could see, touch, and experience firsthand.
This hands-on approach helps make hydronics relatable and demonstrates its real-world potential.
Final Thoughts: From Concept to Reality
Engineering isn’t just math and diagrams—it’s hands-on problem-solving and a willingness to innovate on the spot.
This project reminded us of the joy in creating something new and functional—right in a parking lot. Thanks to everyone who made this possible, from the collaborative crew to a surprisingly tolerant EV battery.
I hope our experiment inspires builders, engineers, and dreamers alike to ask, "What if we just tried it?"