Why Is My Circulating Pump Running Continuously?

You might find your circulating pump running continuously after installation. It would keep heating water continuously even when you don’t expect it. However, this could either be due to a faulty condition, or it might be designed that way. If you are not sure of what this means, here’s everything about the function of your circulating pump.

Circulating Pump Running Continuously

Do Circulating Pumps Run Continuously?

There are always-on circulator assembly installations for circulating pumps. This provides more even heat and keeps the heating system piping from freezing. So, depending on the design and the control of your heating system, the pump running continuously could be a normal situation. But if the system is not designed so but keeps on running without a break, there could be a problem with the system.

Why is the Circulator Running Continuously?

There are a few reasons behind a heating zone circulator that runs without stopping. Check the following possibilities in your system to troubleshoot the issue.

  • If the heat loss is greater than the heat provided into the boiler, then the thermostat detects this and chooses to keep the pump running continuously.
  • Another possibility is that the thermostat wires are shorted together between the thermostat and the zone valve or the circulatory result. As a result, the pump stays turned on.
  • This also happens if the circulator relay or the relay control board is damaged. 
  • If the heating zone is air-bound, the heat doesn’t reach the thermostat. So, the thermostat doesn’t identify the heat and continues to run the circulator.
  • Maybe the circulator is not actually running, but the heat cycles through heating pipes by convection. This could happen when the thermostat does not signal for heat generation. It is often caused as a result of a defective check valve or a zone valve latched in the open state.
  • The other possible reason for the circulating pump to run continuously is that it was deliberately wired to keep on running. This is the custom setting in some heating zones. It reduces the risk of pipes freezing and keeps even heat distribution throughout.

Should You Keep the Circulating Pump on All Summer?

You should keep the circulating pump on all summer as it increases the useful life. Pumps that run continuously usually last longer than otherwise. Another reason to keep the circulating pump on is that it will use less fuel to keep the pump on. When you use hot water in the house, cold water is added again to the hot water tank. Even in the summer, most well water and city water lines give water at around 52 degrees. So, heating this up to 110 degrees requires a lot of electricity, propane, or any fuel you use.

If you keep the pump on, the warm water in the outdoor wood stove will heat the water from 52 degrees to around 80 degrees for free. This reduces the fuel cost by about half if you keep it on during the summer.

Why is My Circulating Pump Not Working?

Circulating pumps stop working due to certain issues, such as a blown a fuse, a dead motor, or bad wiring. You can fix the issue by finding the exact cause behind it. Troubleshoot it systematically so that you can restore its function quickly. Here are some of the reasons behind a pump, not working and how you can fix them.

  • Motor not starting: This could be due to over-voltage, under-voltage, or over-current. Check the input voltages, motor resistance, and the possibility of electronic board failure. You might have to replace the circuit board or change the pump.
  • Processing unit failure: This happens due to the pump operating outside the duty point. Check the pump settings and the motor before you try updating the software. 
  • Display bank: Loose cables and faulty LEDs are the cause of this. Reconnect the cable and tighten it or change the display.
  • Communication failure: This is a result of loose contact. Check the display cable and replace it if needed.
  • Power module failure: High motor load, converter overload, and motor operating outside the range are the possible causes. Check for insulated-gate bipolar transistor (IGBT) faults. Also, check motor resistance and inspect it mechanically. Change the pump if needed.
  • Motor faults: There are various reasons for motor failures such as overloads, parameters outside the range, and converter overload. It requires various testing procedures to find the exact cause to fix the issue.

How Much Electricity Does a Hot Water Recirculating Pump Use?

Circulating pumps work with under-sink systems using large hot water tanks and tankless heaters. Assume that the cost of electricity is $0.12 per kW. Consider the pump with 250 feet of pipe on a timer to run 8 hours per day and has a sensor and a switch that runs 3 minutes per hour on average. This costs $1.40 – $1.59 a year for electricity.

How Do I Know if My Boiler Pump is Bad?

The following signs indicate that your boiler pump is not working:

  • Strange noises such as constant hums, come from the boiler.
  • The circulator pump running, but no heat in the water.
  • Water leaks from the pump.
  • The pump casing feels abnormally hot to the touch.
  • The pump runs constantly and doesn’t turn off.

How Much Does It Cost to Replace a Boiler Circulator Pump?

Replacing a bad circulator pump costs from $500 to $900. But it will cost lesser if you need to replace or repair only a certain component. If you need to fix a broken thermostat, you can expect to pay between $200 and $400. An expansion tank replacement costs are within the range of $300 and $600. Find the ideal parts compatible with the model of your pump when replacing any component. 


Some people face issues related to their circulating pump running continuously. So, if you figure out that it is the design itself that keeps the pump running, you can get a professional to change the system. It might be possible to do so in certain circulating systems by changing the connections. If you find that there could be some other issue related to the situation, get a professional to assist you.