Pump FAQs: Hot Water Circulation Pumps

This Q&A provides a comprehensive overview of hot water circulation pumps, addressing common questions about operation, maintenance, and technical specifications. It also clarifies the definition and function of high efficiency circulation pumps which help buyers and users know better before choose.

Q1: Do circulation pumps run all the time?

The Circulation pumps are designed to run continuously in order to circulate fluids through a system.

In some cases, such as hot water circulation, the pump may only run when needed to circulate hot water to a particular location in the home, and may be controlled by a thermostat or timer. In other cases, such as with HVAC circulation pumps, the pump may run continuously to maintain the proper temperature or flow of fluids in the system. 

It is important to properly size and maintain circulation pumps to ensure that they run efficiently and do not waste energy.

Most economically, it may be possible to use a variable speed or demand-controlled circulation pump, which adjusts its speed and flow rate based on the actual needs of the system, rather than running continuously at a fixed speed. 

Q2: How do I get air out of my circulating pump?

To remove air, you can try bleeding the system, which involves opening bleed valves to release trapped air. Ensuring the pump is primed correctly and checking for leaks can also help.

Q3: What causes a circulation pump to fail?

Common causes of failure include motor burnout due to overheating, blockages in the system, wear and tear of parts, and power supply issues. Ensuring proper sizing, regular maintenance, and using quality components can prevent failures. 

A high efficiency circulation pump has lower temp.rise which can largely reduce the failures of motor overheating, and its auto-adapt control allows it to work on demand rather than working always at full speed, which reduce the tear and wear in a great degree.

Q4: How do you fix a noisy circulating pump?

Noise issues can be addressed by checking for debris in the pump or system, ensuring proper lubrication, balancing the impeller, and confirming that the pump is securely mounted to prevent vibrations.

Q5: How do you prevent freezing in winter? Are there any anti-freeze features or recommendations?

To prevent freezing, ensure the pump and system are adequately insulated, and that circulation is maintained to prevent water from stagnating. Some pumps may have built-in freeze protection features that stop the pump when temperatures drop below a certain point.

Q6: In countries like Russia, where environmental temperatures are very low, can condensation form inside the stator cavity, potentially causing damage?

Condensation occurs when the ambient temperature is higher than the liquid temperature. To prevent condensation, ensure the pumping liquid temperature is higher than the ambient temperature.

Q7: What's the working principle of a high efficiency circulation pumps?

Stream EA series high efficiency circulation pump is consisted of a pump body, impeller, permanent magnet motor and controller. The input 230V/50Hz power source is frequency-converted by the controller and supplied to the permanent magnet motor.  When the pump starts, the motor generates a rotating magnetic field due to the stator being energized, which drives the rotor to rotate in the stator cavity. Through the movement of the rotor components, the impeller rotates and the liquid flows into the pump body. The liquid is transported out through the centrifugal force of the impeller's rotation. Pumping media is used as lubrication between the shaft and thrust bearing. The circulating medium enters the pump body outlet from the low-pressure area at the pump inlet through the impeller and completes the pressurization. Different feedback signals from various stages are collected during different use modes and sent to the CPU on the controller, enabling various functions.

The intelligent control technology is adopted, and the motor armature current is detected to control the motor speed and achieve adaptive adjustment in changing conditions, solving the problem of high energy consumption of ordinary circulation pumps and achieving high energy efficiency and low noise economic operation.

Q8: Are variable speeds determined by heat (temperature) or pressure?

It depends. Different control modes has different logic.

For example, the proportional pressure mode is based on the temperature demand of the end-pipe, while the constant pressure mode maintains the same pressure and makes the water pump adjust its speed accordingly. However, the temperature mentioned here is not the direct water temperature in the pipe, which would require a temperature sensor. Instead, it refers to the heat demand of the end-use room.

Q9: What is EEI 0.23, and what does it require for a pump design?

EEI is energy efficiency index. It can be understood as the ratio of the actual input (consumption) power to the reference input power at several common operating points. When the actual input power changes, the EEI value also changes. The direct factor that affects the actual power consumption is the total efficiency of the pump.

In the theoretical design of a pump, the input power of the pump is the shaft power. While in the actual operating and testing of the pump, the input power is the power supply. So the efficiency of the whole pump should also include the motor efficiency and the drive efficiency.

Q10: What is PWM control? Who are the customer groups, and is it a common function?

PWM is short for Pulse Wideth Modulation. It is a method of modulating the width of a series of pulses, altering the signal by adjusting the change of the duty cycle and adjusting the speed of the water pump.

Application: the gas boiler system, heat pump system and other systems with PWM generators will need the PWM function.

Stream EA series has the PWM interface(GT and ST mode), but it is closed by default.

Q11: What are the main applications for energy-saving pumps?

Energy-saving pumps are widely used in gas boiler systems, urban apartments, suburban villas, residential water supply boosting, geothermal systems, hot water circulation, cooling systems, and air conditioning systems, as well as for boiler and solar water supply.

They are aimed to provide high performance curves on specific applications.

Q12: What is the noise level of a high efficiency circulation pump?

For Stream EA series, the noise level is below 42dB across the full power range under any operating conditions.

Q13: What are the maximum working environment and liquid temperatures for the your circulation pumps?

The ambient temperature ranges from 0°C to 40°C, and the temperature of the liquid being pumped ranges from 2°C to 110°C.

The max allowed environmental humidity is 95% RH. 

Q14: How do you choose pump body materials such as copper, plastic, stainless steel, brass, or bronze? What are they used for?

Cast iron is typically used for HVAC systems, while stainless steel, brass, or plastic are used for domestic water supply to avoid corrosion. Bronze or stainless steel is recommended for applications that require drinking water standards.

Q15: Are the coils in your circulation pumps Class H? What is the maximum temperature they can withstand, and how is the temperature rise controlled?

A standard qualified circulation pump is built with Class H coil.

Class H refers to the insulation grade of the coil, which can withstand a maximum temperature of 180°C with a temperature rise controlled within 125K.

Q16: Are impellers considered wear parts? What material are they made of?

Impellers are not considered wear parts. They are made of PPE, which is resistant to hydrolysis and alcoholysis.

Q17: What are the wearing parts of the circulation pumps?

The circulation pumps are designed to be maintenance-free with no easily replaceable parts. 

Q18: What are the key components of the high efficiency pump, and how is the quality of these parts ensured?

A18: Key components include the driver board, high-efficiency motor, and rotor magnet. Quality is ensured through ISO 9001 compliance, full inspection of the entire process, and stringent control of defects rate.

Q19: What is the defect rate of the energy-saving pump, and how are complaints resolved?

A19: The defect rate is controlled within 500 PPM. Complaints are addressed by analyzing the root cause and implementing corrective actions, such as redesigning components to meet specific environmental conditions and conducting extensive testing to ensure reliability.