How to Install a Heat Pump Water Heater

Heat pump water heaters combine the technology of a heat pump with a traditional storage-tank water heater. They extract heat from the surrounding air and transfer it to the water in the tank, making them up to three times more efficient than conventional electric water heaters. In this article, we’ll explore the installation process of a heat pump water heater with the This Old House plumbing and heating contractor Richard Trethewey.

How Heat Pump Water Heaters Work

A heat pump water heater operates by using a refrigerant cycle to capture heat from the ambient air. Here’s a simplified explanation of the process:

1. The heat pump’s evaporator coil absorbs heat from the surrounding air.
2. The refrigerant inside the coil is compressed, raising its temperature.
3. The hot refrigerant flows through a condenser coil wrapped around the water tank.
4. Heat is transferred from the refrigerant to the water in the tank.
5. The cooled refrigerant returns to the evaporator to repeat the cycle.

This process is much more energy-efficient than using electric resistance elements to heat water directly.

Benefits of Heat Pump Water Heaters

Heat pump water heaters offer several advantages over traditional electric water heaters:

• Energy efficiency: They use about 60% less electricity than standard electric water heaters.
• Cost savings: Lower energy consumption translates to reduced utility bills.
• Environmental impact: Reduced energy use means lower greenhouse gas emissions.
• Dehumidification: They can help reduce humidity in the surrounding area.
• Longevity: Many models have a longer lifespan than conventional water heaters.

Choosing the Right Heat Pump Water Heater

Before you can install a heat pump water heater, you’ll need to choose the right model for your home. We recommend considering the following factors.

Capacity and Size

Heat pump water heater capacity is measured in gallons and typically varies between 50 and 80 gallons. Consider your household size and hot water usage when selecting the tank size:

• Small households (1-2 people): A 50-gallon unit may be sufficient.
• Medium households (3-4 people): A 66-gallon unit generally works well.
• Large households (5 or more people): An 80-gallon unit is usually recommended.

Energy Efficiency Ratings

Energy efficiency ratings, like the Energy Factor (EF), indicate how efficiently a water heater converts energy into hot water. Higher EF ratings mean better efficiency. Look for models with an Energy Star label for optimal performance and savings.

Additional Features

Modern heat pump water heaters come with various features that enhance functionality and convenience, such as:

• Wi-Fi connectivity: Allows remote monitoring and control via smartphone apps.
• Warranty: Consider models with longer warranties for added peace of mind.
• Recovery rate: The time it takes to heat a full tank of water can impact your decision, especially in households with high hot water demand.

Preparing for Heat Pump Water Heater Installation

Before installing a heat pump water heater, you’ll need to do some prep and gather the necessary tools and materials.

Assessing Your Space

Heat pump water heaters require adequate space and airflow to operate efficiently. Consider the following factors:

• Room size: The unit needs at least 1,000 cubic feet of air space around it.
• Ceiling height: A minimum of 7 feet is recommended for optimal performance.
• Temperature: The room should maintain a temperature between 40°F and 90°F year-round.
• Location: Install near a drain for condensate removal and away from living spaces to minimize noise.

Tools and Materials Needed

Gather the following tools and materials before beginning the installation:

• Tube cutter
• Pliers and wrenches
• Propane torch
• Hammer
• Utility knife
• Copper pipes and fittings
• Solder and flux
• Electrical cable and connectors
• Condensate pump (if needed)
• Flexible plastic tubing

Heat Pump Water Heater Installation Process

Installing a heat pump water heater involves several steps, from removing the old unit to connecting the new one. Always consult the manufacturer’s instructions and local building codes before proceeding.

• Shut off the electricity and water leading to the old water heater.
• Drain the water from the old water heater.
• Disconnect and remove the old water heater.

• Install new shut-off valves to the hot- and cold-water pipes.

• Set new heater into place directly beneath the water-supply lines.

• Remove vacuum breakers and solder on the appropriate copper fittings.
• Connect new water heater to shut-off valves on the hot and cold water-supply pipes.
• Turn the water back on to fill the tank.
• Connect the existing electrical cable to the new heater.
• Run the heater’s condensate line to a condensate pump.
• Connect condensate pump to laundry drain using flexible plastic tubing.
• Turn the electricity back on.
• Install the heater’s air filter.
• Adjust water temperature at the heater’s electronic control panel.

Finalizing the Water Heater Installation

After completing the main installation, there are a few steps left to get your air pump water heater ready for use.

Filling and Testing the Tank

• Open the hot water faucets in your home to allow air to escape.
• Turn on the cold water supply to fill the tank.
• Check all connections for leaks and tighten as necessary.
• Once the tank is full and faucets are running smoothly, turn off the faucets.

Configuring Settings

• Turn on the electrical power to the water heater.
• Set the desired water temperature on the unit’s control panel.
• Choose the operating mode (typically “Hybrid” for optimal efficiency).

Installing the Air Filter

Most heat pump water heaters come with an air filter to protect the evaporator coil. Install this filter according to the manufacturer’s instructions and make a note to clean it regularly.

Heat Pump Water Heater Maintenance and Efficiency Tips

To keep your heat pump water heater running efficiently and extend its lifespan, follow these maintenance tips:

• Clean or replace the air filter every 2-3 months.
• Flush the tank annually to remove sediment buildup.
• Check the condensate drain line periodically to ensure it’s clear.
• Keep the area around the unit clean and free of dust and debris.
• Monitor your energy usage to ensure the unit is operating efficiently.

Optimizing Performance

Optimizing the performance of your heat pump water heater involves a few key practices:

• Adjust temperature settings: Lowering the temperature can save energy.
• Regular inspections: Schedule professional inspections to catch issues early.
• Upgrade insulation: Adding insulation around exposed hot water pipes reduces heat loss.

Troubleshooting Common Heat Pump Water Heater Issues

Even with proper maintenance, you may encounter some issues with your heat pump water heater. Understanding how to troubleshoot these problems can save you time and money.

Insufficient Hot Water

If your water heater isn’t providing enough hot water, consider the following:

• Check the temperature setting: keep it set to your desired temperature.
• Inspect the elements: Faulty elements may need replacement.
• Evaluate household usage: High demand may require a larger unit.

Unusual Noises

Unusual noises can indicate potential problems:

• Humming or buzzing: Tighten any loose parts and check the fan.
• Gurgling or boiling: This could be due to sediment buildup in the tank, requiring a flush.

High Operating Costs

If you notice increased energy bills:

• Inspect the air filter: A dirty filter reduces efficiency.
• Examine the location: Ensure proper clearance for airflow.
• Schedule professional maintenance: A technician can identify underlying issues.

Our Conclusion

Installing a heat pump water heater can significantly reduce your home’s energy consumption and lower your utility bills. While the installation process is complex and best left to professionals, understanding the steps involved can help you make informed decisions about your home’s water heating system.