Selecting the right hot water recirculating pump involves matching the pump's capabilities to your home's specific plumbing system and hot water needs.
A hot water recirculating pump provides instant access to hot water at your faucets without the wait, saving water and adding convenience. The selection process requires considering several factors to ensure efficiency and performance.
Key Factors for Pump Selection
Choosing the correct pump depends on understanding your system's demands. Here are the critical elements to evaluate:
1. System Requirements: Flow Rate and Head Pressure
- Flow Rate: This is the volume of water the pump needs to move, typically measured in gallons per minute (GPM). It's usually a relatively low flow for residential systems.
- Head Pressure: This is the resistance the pump must overcome to circulate water through the pipes. It's influenced by several factors:
- Pipe Length and Size: Longer pipes and smaller diameters increase resistance.
- The Number of Elbows: Elbows provide additional resistance to flow than what is in a straight pipe, significantly increasing head pressure requirements.
- Type of Pipe: The material and internal condition of the pipe (e.g., copper, PEX, older galvanized) affect friction and flow.
- Vertical Lift: Pumping water upwards requires more energy.
- Pump Start-up Time: Water has momentum and doesn't start moving immediately so this will delay the flow somewhat, meaning the pump needs initial power to overcome this inertia and establish flow quickly.
2. Pump Type
There are two main types of recirculating systems:
- Dedicated Return Line Systems: These systems have a separate pipe running from the farthest fixture back to the water heater. They are generally more efficient but require dedicated plumbing. The pump is typically installed at or near the water heater.
- Comfort Valve (Under-Sink) Systems: These systems use the cold water line as the return path. A valve is installed at the fixture farthest from the water heater, allowing hot water to flow into the cold line back to the heater when the pump runs. These are easier to retrofit but can slightly warm the cold water line.
3. Energy Efficiency
Recirculating pumps can run continuously, on a timer, or on demand.
- Timers: Allow the pump to run only during peak hot water usage times (e.g., morning and evening).
- Thermostats: Some pumps have built-in thermostats that turn the pump off once hot water reaches the fixture, preventing unnecessary circulation and heat loss.
- On-Demand Systems: Activated by a button or motion sensor, these only run when hot water is explicitly requested.
Consider the energy consumption (wattage) of the pump itself and the potential energy loss from continuous circulation, which is related to Heat absorption by the piping. This refers to the heat lost from the hot water as it travels through pipes, especially if they are uninsulated, which the pump must work to replenish.
4. Noise Level
Pumps can produce noise. Consider the installation location and choose a model known for quiet operation, especially if installed near living areas.
5. Installation and Maintenance
- Location: Pumps are typically installed at the water heater or the farthest fixture, depending on the system type. Ensure adequate space and access.
- Power Source: Verify the required voltage and access to a power outlet.
- Maintenance: Look for models with durable components and minimal maintenance needs.
Selection Checklist
Use this simple table to compare options:
| Feature | Consideration | Why It Matters |
|---|---|---|
| System Type | Dedicated Return Line or Comfort Valve (Under-Sink)? | Affects plumbing requirements and efficiency. |
| Flow Rate | How much water needed per minute? | Ensures sufficient hot water delivery speed. |
| Head Pressure | Pipe length, size, elbows, vertical lift, pipe type? | Pump must be strong enough to overcome resistance, considering pipe elbows and type. |
| Control Method | Timer, Thermostat, On-Demand, or Continuous? | Impacts energy use and convenience. |
| Energy Use | Wattage of the pump? How much heat loss (heat absorption by the piping)? | Affects electricity bills and overall system efficiency. |
| Noise Level | How quiet is the pump? | Important for home comfort. |
| Power/Location | Where will it be installed? Is power available? | Installation feasibility. |
By carefully evaluating these factors and considering the specifics of your home's plumbing, including the impact of pipe elbows, type of pipe, and the initial resistance related to pump start-up time and heat absorption by the piping, you can select a hot water recirculating pump that provides comfort and efficiency.
