Heat Pumps for Cold Climate Applications

#Heatpumps will play a key role in the clean energy transition. The type of heat pump that is deployed (variable-capacity versus single-speed) will have a significant impact on grid resource utilization and resiliency during extreme cold weather.    Last year, the U.S. crossed a milestone as a record four million heat pump units were sold, surpassing sales of gas furnace. Because of the lower cost (~<50%), heat pumps installed today are mostly single-speed versus variable-speed. These single-speed heat pumps, with backup resistance strip heating, can add up to 10-20 kilowatts to peak demand (about twice the peak electrical load of an average house) when outdoor air temperatures become frigid. The grid needs to have adequate generation and T&D infrastructure to support this peak load a few times per year. These installed systems last for 15+ years and continue to contribute to higher peaks during cold weather events.   For example, during #WinterStormElliott in December 2022, grid demand exceeded some load forecasts by as much as 10-15%, partially driven by the accelerated adoption of single-speed heat pumps. The bomb cyclone produced both strong winds and outdoor temperatures more than 10 degrees colder than typical winter lows.   Coincidentally, the storm occurred during an EPRI research pilot with Tennessee Valley Authority to demonstrate the benefits of installing variable-capacity heat pumps with little-to-no electric strip heat to reduce winter peak demand. The TVA pilot focused on the #HomeUpliftProgram to address the significant energy efficiency and weatherization needs for low-income households. Preliminary EPRI analyses indicate that replacing the existing ~2M single-speed heat pumps installed in TVA’s service territory with variable-capacity heat pumps could have reduced peak demand by ~3 gigawatts.   Further EPRI analyses show cold climate, variable-speed heat pumps can perform at 0 degrees F with little-to-no backup heating. https://ow.ly/1gQ350PNfl5. Imagine a future where advanced heat pumps are more ubiquitous, and the additional margin they could provide society when the next cold weather event strikes.    It is critical that all stakeholders involved in accelerating deployment of heat pumps are aware of the significant differences in how each type impacts grid reliability and increases the overall societal cost to get the grid ready for the electrification of buildings and transportation.    I want to hear from you. How do we forecast this significant load spike that could happen several times per year with existing and increased single-speed heat pumps that are in the system? How can we increase the deployment of variable-capacity heat pumps even though today the cost of a variable-capacity heat pump to consumers could be 50% more than single-speed?    #heatpumps #grid #resiliency

Understanding the Defrost and Supplemental Heat Modes of a Heat Pump. Heat pumps are efficient systems for heating and cooling homes and commercial buildings worldwide. However, their efficiency can be challenged in cold climates where frost and ice build up on the outdoor unit, and extremely low temperatures require additional heating support. Heat pumps are equipped with defrost and supplemental heat modes to address these issues. Here’s how these features work together to maintain efficiency and comfort. Defrost Mode Time-Temperature Defrost: The most commonly used method for detecting frost involves a combination of a temperature sensor and a timer. The sensor is typically mounted on the tubes of the outdoor unit and activates when the coil temperature drops to a point where frost formation is possible. Once the sensor detects a cold enough temperature to trigger frost formation, it closes, signaling the defrost control board to begin tracking the accumulated run time of the compressor. Initiation of Defrost Cycle: The defrost cycle is based on specific temperature and time parameters. When the coil temperature falls below 30°F ±3°F, the defrost thermostat completes a circuit to the defrost board, which starts timing. The defrost cycle is initiated once the timer reaches the elapsed time set by a jumper on the board. If the defrost thermostat opens before this time, indicating an increase in temperature, the timer resets. The system will continue to monitor and can run for 30, 60, or 90 minutes with the coil temperature below the set point before initiating a defrost cycle. If the thermostat remains closed, the defrost cycle will end after approximately 10 minutes unless the manufacturer sets different specifications. Reversal of Operation: In defrost mode, the heat pump reverses its cycle, temporarily functioning like an air conditioner. The outdoor unit becomes a condenser and generates heat, melting the ice, while the indoor unit acts as an evaporator, releasing cooler air. You might notice a few things when your heat pump is in defrost mode: The outdoor fan stops running, a slight drop in indoor temperature (usually not significant), and as the ice melts, you might hear a hissing sound from the outdoor unit. Melting the Ice: The warm refrigerant circulates through the outdoor coil, melting any accumulated ice. This process continues until sensors determine that the coil is clear of ice. Supplemental Heat Mode Role of Supplemental Heat: Supplemental heat is essential during the defrost cycle and in extreme cold. It ensures that the indoor environment remains comfortable when the heat pump either cannot efficiently extract outdoor heat or temporarily blows cool air indoors during defrost. Integrating defrost and supplemental heat modes in heat pumps is crucial for operating in colder climates.

62-91% gas reduction: The game-changing tech you're overlooking 🏠🔥 While we obsess over EVs, a quiet revolution is happening in our HVAC systems. Cold-climate air-source heat pumps (CCASHPs) are redefining home electrification. A new study from the Greater Toronto Area shows CCASHPs slashing whole-home gas consumption by up to 91%. This isn't just an incremental improvement - it's a paradigm shift. Key insight: Replacing A/C units with CCASHPs is a low-hanging fruit for massive decarbonization. Here's why it matters: 1. Cost-effective: Near break-even on utility costs, with potential for long-term savings. 2. User-friendly: Homeowners report high satisfaction and comfort levels. 3. Policy-ready: Existing rebate programs make CCASHPs competitive with traditional A/C. This approach solves multiple problems simultaneously: • Tackles the largest source of urban emissions (buildings) • Provides a clear upgrade path for millions of homes • Protects homeowners from future gas price hikes The technology is here. The economics work. Now we need the vision and collaboration to make it happen at scale. Question: What barriers do you see to mass CCASHP adoption in your region, and how can we overcome them? #HomeElectrification #CleanEnergy #ClimateAction