Why Is My Heat Pump Not Heating? Causes, Troubleshooting, and Maintenance

Heat Pump Not Heating

Thinking about why is my heat pump not heating? A heat pump that isn’t heating usually comes down to one of a short list of causes: a thermostat set wrong or out of calibration, a dirty air filter choking airflow, a frozen outdoor unit, a tripped breaker or an off power switch, a low refrigerant charge, or a failed reversing valve. 

About half of these you can resolve yourself in ten minutes. The rest involve the sealed refrigerant circuit or control board and need a licensed technician. Before assuming the worst, read our article to learn why heat pumps stop heating, the troubleshooting process, and how to maintain them to prevent future damage. Let’s begin.

Possible Reasons Why Your Heat Pump Is Not Working Properly

Here are the reasons why your heat pump is not blowing warm air.  

  • Check the temperature rise. A typical heating system may show roughly a 15–25°F rise between return and supply air, although exact values vary by equipment and conditions.
  • It may be in defrost mode. In cold, damp weather, the outdoor unit may temporarily reverse operation to melt frost. Steam and a temporarily stopped outdoor fan can be normal. Frequent or prolonged defrosting is not.
  • Restricted airflow. A dirty filter, blocked return, closed vents, damaged ductwork, or snow around the outdoor unit can reduce heating performance.
  • Low refrigerant. Heat pumps do not normally consume refrigerant. Low levels usually indicate a leak and can cause poor heating, long run times, or coil icing.
  • Electrical or mechanical problems. Failed capacitors, contactors, fan motors, reversing valves, controls, or compressors can prevent proper heating.
  • Thermostat or settings. Incorrect mode, calibration issues, or poorly configured backup heat can make the system appear ineffective.
  • Backup heat may not operate. A failed heat strip, sequencer, wiring issue, or incorrect lockout setting can prevent supplemental heat from engaging.
  • Outdoor temperature matters. Heat pumps lose heating capacity as temperatures fall. If the system consistently struggles in cold weather, the issue may be sizing or system design rather than a failed component.
  • Hydronic systems. Low water flow, trapped air, clogged strainers, or poorly adjusted outdoor-reset controls can reduce heat output.

Why Is My Heat Pump Not Heating? Expert Troubleshooting Process

Work through these in order. Stop as soon as heat returns. Before you reset anything, photograph any fault code on the thermostat or controller; resetting erases the best clue a technician has.

Incorrect Thermostat Settings

Start with the thermostat because this check is free and can solve many heating problems. Make sure it is set to Heat, the temperature is at least 2-3°F above the current room temperature, and the fan is set to Auto rather than On. When the fan stays on, it can circulate room-temperature air between heating cycles, making it feel as though the heat pump is blowing cold air. Also, check the programmed schedule and replace the batteries if needed.

Uncalibrated or Faulty Thermostat

A thermostat that reads the room temperature incorrectly can cause the heat pump to cycle improperly. Place a separate thermometer next to the thermostat and compare the readings after about 30 minutes. A difference of more than 2–3°F may indicate a problem. 

Poor placement, such as direct sunlight, an exterior wall, or a drafty area, can also affect accuracy. Clean the thermostat gently, recalibrate it according to the manufacturer’s instructions, or consider replacing an older unit with a heat-pump-compatible model.

Tripped Circuit Breaker

Check the electrical panel because the indoor and outdoor components commonly use separate breakers. If a breaker has tripped, reset it once by switching it fully off and then back on. If it trips again, leave it off and call a qualified technician. Repeated resets can indicate an electrical fault or compressor problem and may create a safety hazard. 

Indoor Unit Power Switch

Check the service switches near the air handler and outdoor unit. These can accidentally be turned off during cleaning, painting, or other work. Also check whether a condensate float switch has shut the system down because of a clogged drain or a backed-up drain pan. You can restore a mistakenly switched-off service switch yourself, but recurring float-switch shutdowns should be addressed rather than repeatedly bypassed.

Dirty Air Filter

A clogged filter restricts airflow and can significantly reduce heating performance. If little light passes through the filter, replace it rather than trying to clean a disposable pleated filter. Weak airflow, long run times, and overheating can all result from restricted airflow. Check the filter monthly during heavy-use periods and replace it according to the manufacturer’s recommendations, often every 1–3 months.

Frozen Outdoor Unit

Some frost on the outdoor coil is normal during cold, damp weather, but heavy ice covering the coil or fan is not. If the unit is heavily iced, use Emergency Heat if your system has it and allow the outdoor unit to thaw. 

Keep snow, leaves, and debris away from the unit, and never chip ice with a tool or pour boiling water over the coil. If ice quickly returns after defrosting, a defrost-control problem, airflow issue, refrigerant problem, or drainage issue may require professional diagnosis.

Low Refrigerant Charge

A heat pump with low refrigerant may produce insufficient heat, run continuously, develop ice, or show an unusually low temperature rise. Refrigerant is not consumed during normal operation, so a low charge generally indicates a leak. A qualified HVAC technician should locate and repair the leak before recharging the system.

Bad Reversing Valve

If the heat pump cools normally in summer but fails to heat properly in winter, a faulty reversing valve is one possible cause. This valve changes the refrigerant direction so the system can switch between heating and cooling. A stuck valve or failed solenoid can prevent proper heating. Because repairing the valve requires specialized refrigerant work, this is a professional repair.

5 Regular Maintenance Tips to Protect Your Heat Pump

Most no-heat emergencies are preventable. Follow these simple maintenance tips to protect your heat pumps and use them for a long time.

Change the Air Filter Every 1–3 Months

A clean filter keeps airflow strong and prevents the heat pump from working harder than necessary. A clogged filter can reduce heating and cooling performance, increase energy use, and contribute to overheating or system failures. Check the filter monthly and replace it sooner if you have pets, smoke indoors, or are renovating.

Keep the Outdoor Unit Clear

Maintain roughly 24 inches of clearance around the outdoor unit and keep leaves, grass, snow, and other debris away from the coil. In snowy areas, make sure the unit is elevated above expected snow depth and protected from roof runoff. Never cover or tightly enclose the unit because it needs unrestricted airflow and proper drainage.

Test Your Backup Heat Before Winter

Test the auxiliary or emergency heating system before the coldest weather arrives. A backup heat source that has failed or been disabled can leave you without adequate heating during a severe cold snap.

Keep the Home Well Insulated

Air sealing and improving attic insulation reduce heat loss and help the heat pump maintain comfortable temperatures with less effort. Lower heating demand also reduces reliance on expensive backup heat and can improve overall system efficiency.

Schedule Professional Maintenance Twice a Year

Have the system inspected in spring and fall because heat pumps operate throughout the year. A professional can check refrigerant levels, clean the coils, inspect electrical components, test defrost operation, and verify airflow. Finding a weak component early can prevent a more expensive breakdown later.

When Repair Isn’t the Answer

A heat pump that isn’t heating is rarely a mystery. Start by confirming it’s a genuine fault rather than normal behaviour: a heat pump’s air feels cool, defrost cycles interrupt heating for 5–15 minutes, and every system has a balance point below which it needs help. Then work through the process in order: thermostat settings, thermostat calibration, breakers, power switches, the air filter, the outdoor unit, refrigerant charge, and finally the reversing valve. The first five you can handle yourself; the last three belong to a licensed technician.

And if the honest answer is that your system has never kept up on the coldest days, no repair will change that. That’s a design problem, undersized capacity, a system chosen for its mild-weather rating, or emitters that need hotter water than the equipment can produce. That’s where we can help you. 

Arctic Heat Pumps has spent over 15 years engineering cold-climate air-to-water heat pumps for North American winters, tested in Winnipeg, where the weather doesn’t grade on a curve. Our EVI systems operate down to -35°C (-31°F) and handle whole-home heating, cooling, domestic hot water, and pool heating from a single outdoor unit, with built-in backup for the coldest days.

Every Arctic system includes a free heat loss analysis and custom hydronic design from our engineering team: precise load calculation, a schematic drawn for your floor plan, and matched components so the system performs from day one. You don’t have to believe our words, request your free system design, or run the numbers yourself with our free sizing tools. That’s all for today. Hope your heating pump works, and call us anytime you need professional help.

Frequently Asked Questions

Usually airflow restriction (a dirty filter or blocked ducts), low refrigerant charge, or operation below the balance point where it can no longer meet the load. In air-to-water systems, low water flow is the leading cause. Measure the temperature rise across the indoor coil; under 15°F indicates a real fault rather than normal behaviour.

Four common reasons: the fan is set to “On” instead of “Auto” and is circulating room-temperature air between cycles; the thermostat is on Cool; the system is in its normal 5–15-minute defrost cycle; or the reversing valve has stuck in the cooling position. The first three cost nothing to fix.

Turn the thermostat off, switch off the breakers for both the indoor and outdoor units, wait five minutes, restore power, then set the thermostat back to Heat. Photograph any fault code first. If the fault returns immediately, stop resetting and call a technician; repeated resets can damage the compressor.

Typically 5–15 minutes, occurring every 30–90 minutes when frost conditions exist. Steam rising from the outdoor unit during defrost is normal. Cycles that never end, repeat every 15 minutes, or leave ice behind indicate a defrost sensor, control board, or refrigerant problem.

Cold-climate models do. Conventional units lose most of their capacity below freezing, but cold-climate heat pumps using enhanced vapour injection (EVI) and inverter compressors maintain useful output well below 0°F, with some rated to -31°F (-35°C). What matters is correct sizing at your design temperature, a properly configured backup strategy, and emitters matched to heat pump water temperatures.

Yes, in cold weather. Modern inverter-driven heat pumps are designed to run long, low-output cycles rather than short bursts; that’s their efficient operating mode. Constant running in mild weather is the abnormal case, usually caused by a dirty filter, a dirty outdoor coil, low refrigerant, or a sizing mismatch.

Immediately for grinding or screeching noises, a breaker that trips repeatedly, burning smells, ice that survives defrost, or any suspected refrigerant leak. Anything involving the sealed refrigerant circuit legally requires a certified technician.

How Does a Hot Water Circulation Pump Work?

Hot Water Circulation Pump

You turn on the shower, then stand there waiting and waiting, while gallons of cold water run down the drain before the hot finally arrives. It’s a small daily annoyance that quietly wastes water, energy, and time. A hot water circulation pump is the device designed to make that wait disappear.
In this article, I will explain how does a hot water circulation pump works, what it’s made of, how long it lasts, and how to choose the right one for your home. Let’s begin.

What Is a Hot Water Circulation Pump?

A hot water circulation pump, often called a recirculation pump, is a small pump that keeps hot water moving through your plumbing so it’s ready the instant you open a tap. Instead of letting hot water sit and cool inside the pipes between uses, the pump continuously (or on demand) circulates it in a loop from the water heater to your fixtures and back again.

The result is simple: hot water arrives at the faucet or showerhead almost immediately, rather than after a long, wasteful wait. In hydronic heating systems, a closely related type of pump, the circulator, does the same essential job of moving heated water through radiant floors, radiators, fan coils, and buffer tanks. In both cases, the pump’s purpose is to keep warm water flowing where and when you need it.

Benefits of a Hot Water Circulation Pump

5 advantages you can get from using a hot water circulation pump.

  • Instant Hot Water at Faucets. The biggest draw. Because hot water is already waiting in the pipes, it reaches your taps and showers within seconds instead of minutes.
  • Reduces Water Waste. No more running the tap while you wait for it to warm up. Over a year, that adds up to thousands of gallons saved for a typical household.
  • Improves Convenience. Every hot-water fixture in the home becomes more comfortable and predictable, no cold surprises, no guessing games at the shower handle.
  • Saves Time. Those wasted minutes waiting at the sink or shower vanish, which is especially welcome during busy mornings.
  • Can Reduce Utility Costs (depending on system design). By cutting water waste and pairing well with modern timers, sensors, and efficient pump motors, a well-designed recirculation setup can trim your water bill. Efficiency depends heavily on how the system is configured; a continuously running pump uses more energy than one controlled by a timer or an on-demand trigger.

How Does a Hot Water Circulation Pump Work?

Learn the step-by-step process of how it works and get a better understanding.

  • The pump is installed on your hot water line, typically at the water heater or at the fixture farthest from it.
  • It creates gentle, continuous circulation, pushing hot water out of the water heater and through your home’s hot water pipes.
  • As the water travels the loop, any that has cooled is returned to the water heater to be reheated, keeping the line consistently warm.
  • Because hot water is always sitting close to your fixtures, it arrives almost instantly when you open a tap, no long wait, no wasted cold water.
  • Many pumps run on a timer, circulating water only during the hours you actually use it (mornings and evenings) to save energy.
  • Others use an aquastat/thermostat, switching on only when the water in the loop drops below a set temperature, so the pump isn’t running needlessly.
  • On-demand systems activate the pump only when triggered by a button, motion sensor, or smart control, delivering hot water on request while using the least energy.
  • In a dedicated return-line system, a separate pipe carries cooled water back to the heater. In homes without that extra line, a comfort valve at the farthest fixture lets the cold water cross over into the return path instead.

Hot Water Circulation Pump Components, Installation, and Maintenance Tips

Are you clear about how does a hot water circulation pump works? Now, let’s see what it’s made of, its installation process, and maintenance tips to help you use it safely.

Key Components

It’s made of 6 key components.

  • Pump Motor and Impeller: The motor powers the impeller to circulate hot water through the plumbing system. Modern ECM motors are quieter, more energy-efficient, and longer-lasting than traditional models.
  • Pump Housing: The housing protects the pump’s internal components and directs water flow. It’s typically made of cast iron, bronze, or stainless steel for durability and corrosion resistance.
  • Controller (Timer, Aquastat, or Smart Controller): The controller determines when the pump runs using schedules, water temperature, or smart automation to improve efficiency.
  • Check Valve: A check valve prevents backflow, ensuring water flows in one direction and maintaining efficient hot water circulation.
  • Isolation Valves and Flanges: These components allow the pump to be serviced or replaced without draining the entire plumbing system, making maintenance quicker and easier.
  • Return Line or Comfort (Crossover) Valve: A return line or crossover valve sends cooled water back to the heater, providing faster hot water while reducing water waste.

Simple Installation Process

The hot water circulation pump installation process is a bit tricky; however, it’s easy once you understand the process below.

  • Decide first whether you have (or can add) a dedicated return line, or whether you’ll use a comfort valve retrofit; this shapes the whole install.
  • Mount the pump on the correct line and in the correct flow direction (pumps are directional).
  • Install isolation valves on both sides so future maintenance doesn’t require draining the system.
  • Fit a check valve to stop backflow, and insulate the hot water and return lines to hold heat and improve efficiency.
  • Set the timer or control to match your household’s real hot-water schedule rather than running it around the clock.
  • Contact a professional, if necessary. Because installation involves plumbing and electrical connections, a licensed professional is the safest route for a leak-free, code-compliant setup.

Maintenance Tips

Maintain your hot water circulation pump regularly to use it for a long time.

  • Periodically check for leaks around the pump, fittings, and valves.
  • Listen for unusual noises like grinding or rattling, which can signal a worn bearing or trapped air.
  • Verify the timer or sensor is still triggering correctly, and adjust the schedule seasonally if your routine changes.
  • Confirm the check valve is holding and the pump isn’t short-cycling.
  • On systems with hard water, watch for mineral scale that can shorten pump life; a water softener helps here too.
  • Higher-end permanent-magnet circulators have bearings lubricated by the pumped water itself, so they’re essentially maintenance-free, but a yearly visual check is still worthwhile.

How Long Does a Hot Water Circulation Pump Last?

Most hot water circulation pumps last 10 to 15 years, depending on their quality, usage, and maintenance. High-quality pumps with ECM (permanent magnet) motors and smart controls, such as timers or thermostats, can often last 15 to 20 years because they run only when needed, reducing wear on the motor.

Several factors affect a pump’s lifespan, including build quality, water quality, installation, operating hours, and routine maintenance. Hard water can cause mineral buildup that strains the pump, while improper installation or continuous operation can shorten its life. Regular inspections, cleaning, and addressing small issues early can help maximize performance and longevity.

For example, a circulation pump that runs 24/7 in a home with hard water may need replacement after about 8–10 years. In contrast, a properly installed, high-quality pump controlled by a timer or smart thermostat and maintained regularly can continue operating reliably for 15 years or more, delivering consistent hot water while using less energy.

Choose the Right Hot Water Circulation Pump from Arctic Heat Pump

When it’s time to choose a pump that will last and run efficiently, quality matters more than the sticker price. That’s where Arctic Heat Pump’s hydronic circulation pumps stand out.

Arctic offers the Grundfos MAGNA1 series, high-efficiency circulator pumps built with permanent-magnet motors and simple, intuitive settings. These pumps are designed to fit heating, cooling, and domestic hot water recirculation applications alike, making them a versatile choice for almost any home or building project, new or retrofit.

Because the bearings are lubricated by the water they pump, they carry essentially no maintenance requirements and an extremely low life-cycle cost, exactly what you want in a component that runs for years. We ship with an insulation kit and are assembled in the USA.
Whether you’re adding a recirculation loop for instant hot water or building out a complete hydronic system, Arctic’s team can help you size and select the right pump for your setup.

Wrapping Up

A hot water circulation pump is a small addition with an outsized payoff: instant hot water at every tap, far less water and time wasted waiting at the faucet, and with the right timer or sensor control, the potential to trim your utility costs too.
Understanding how does a hot water circulation pump works, what it’s made of, and how to maintain it helps you get the comfort and efficiency it’s designed to deliver, with most quality units lasting a decade or more. Lastly, if you need any professional help, reach out to Arctic Heat Pumps anytime. We are available 24/7.

Frequently Asked Questions

It keeps hot water moving through your plumbing in a loop, so it’s ready the moment you open a tap. Instead of waiting for cold water to clear the pipes, you get hot water almost instantly, while wasting far less water in the process.

Generally no. Basic upkeep means checking for leaks, listening for unusual noises, and confirming the timer or sensor is working. Premium circulators with liquid-lubricated bearings are nearly maintenance-free, though a yearly visual check is always a good idea.

It can, but it depends on the setup. It reduces wasted water (lowering your water bill), and pumps controlled by a timer, aquastat, or on-demand sensor use much less energy than one that runs continuously. A poorly configured, always-on pump can actually add to your energy costs, so the control strategy is key.

Recirculation pumps work with most standard tank water heaters, and many are compatible with tankless and heat pump water heaters as well. It’s best to confirm compatibility and sizing for your specific system; professional guidance ensures the pump matches your heater and plumbing layout.

Not necessarily. Homes with a dedicated hot water return line get the most efficient setup, but if yours doesn’t have one, a comfort (crossover) valve installed at the farthest fixture lets the system use the existing cold line as a return path.

It’s strongly recommended. Installation involves both plumbing and electrical connections, correct pump orientation, valves, and sometimes a return line or comfort valve. A licensed professional ensures the system is leak-free, code-compliant, and configured for maximum efficiency.