This Is Part 2 Of a 4-Part Article:

To See Part 1 Click Here: AlsPlumbing.com Heat Pumps Part 1 of 4

This article is about Heat Pump problems — and normal operation.    Al’s Plumbing, Heating & A/C in Plano, Texas provides maintenance & repairs for all brands of Central A/C, Gas & Electric Furnace, and Heat Pumps.  Additionally we sell and install new HVAC Systems from American Standard (same company as Trane), Ameristar (same company as American Standard) and Coleman HVAC (same company as York HVAC).

Al’s also provides full-service plumbing maintenance, repairs, and replacements for every plumbing component in your home.  Al’s sells and installs Rheem Professional Series gas & electric water heaters, and tankless water heaters.  Al’s is near your home in Plano, TX; Allen, TX, and Frisco, TX.  We service all homes in southern Collin County, TX and Denton County, TX with no additional travel charges.   Call Al’s today to discuss any concerns or problems you have with your HVAC System or Plumbing.

Heat Pump Problems — And Normal Operation

Heat Pumps have operational-characteristics unique to them.  They look like a central A/C — and run in reverse when heating.  We will discuss some typical operational-characteristics — that are normal operation — and don’t indicate that the Heat Pump needs service.  

Heat Pump Frosting / Icing (During Winter)  — And The Heat Pump Defrost-Cycle

Photo Source: Shutterstock

A Heat Pump outdoor unit will likely form visible frost or ice at times (when temps are 35 or lower).   This is normal and part of typical Heat Pump operation.  Many HVAC Repair Services receive calls from Heat Pump owners, thinking they have heat pump problems, when they see frost or ice on the outside unit’s coils.  Light frost/ice occurs during normal operation during lower outdoor temps.  The Heat Pump will melt the frost or ice as needed.   During the defrost-cycle, steam may rise from the top of the Heat Pump outdoor unit.  This is normal too.

Click Here To See A YouTube Video Of A Heat Pump Defrosting: Heat Pump Defrosting Itself

As a Heat Pump extracts heat from the outside air, moisture the outside-air freezes onto the outdoor unit’s coils when outdoor temps are below 32.  The outside unit will go into defrost mode (every 30-60-90 minutes) as often as needed to melt the frost.

During the Defrost-Cycle, the compressor is running but the fan at the top of the unit does not be run.  The compressor creates heat to melt the frost/ice –and you may see steam rising or water dripping off the bottom edges of the outside unit during the defrost-cycle.  There will be notably more noise from a Heat Pump during a Defrost-Cycle (generated by the compressor in the outside unit),

NOTE:  The Heat Pump temporarily turns to cooling-mode during the defrost-cycle to heat the outdoor unit’s coils.  During this cycle — cold air may come out the vents inside the home.  To compensate for this — the heat-strip (inside the furnace) turns on.  During the defrost-cycle, air coming out of the vents will be cooler than during the heating cycle.  This is also normal operation.  The defrost-cycle runs for only a few minutes.

Heat Pumps Are Not Created Equal Regarding Noise While Defrosting

American Standard & Trane Heat Pumps & Central Air Conditioners use their own proprietary ClimaTuff brand compressor.  Nearly all other brands have a compressor made by Copeland.  Copeland compressors make notably more noise during a Heat-Pump Defrost-Cycle than ClimaTuff compressors.   Defrost-cycle noise can become a concern with neighbors, or if your compressor is located near a bedroom or living room.

Click On These Links To Hear The Difference In Noise-Level During Heat Pump Defrost-Cycles:

• American Standard & Trane Climatuff compressor during Heat Pump Defrost-Cycle:  American Standard & Trane Climatuff Compressor during Defrost-Cycle

• Hear a Copeland brand compressor during Heat Pump Defrost-Cycle:  Copeland brand compressor during Defrost-Cycle

• When Heating & Cooling — the noise-level is much closer between Climatuff and Copeland compressors.  The Db noise-level shown in product literature is during heating or cooling — not during he defrost-cycle.

• If you are bothered by any Heat Pump or A/C compressor noise, this product can help:  Quiet Fence Video Demonstrating Effectiveness

• You Can Also Add A Compressor Noise Blanket (if one is not present).

Click On Photo To: View Product, See Details, or Purchase from Amazon.com

SHOWN: A/C  & Heat Pump Compressor Noise-Blanket

Excess Frost Or Ice Indicates Heat Pump Problems

We have provided YouTube videos showing normal amounts of frost on a Heat Pump.  Excess frost or ice build-up prevents the transfer of heat from the outside air (into the refrigerant) and prevents proper Heat Pump operation. If it is not serviced promptly, the unit cannot perform as designed, and heating costs will rise dramatically.  If allowed to operate with heavy frost or ice build-up for an extended period of time, the outside unit will likely become damaged.

Click Here To See Frost Build-Up On A Heat Pump That Is Not Defrosting Correctly: Heat Pump Not Defrosting Correctly

If You See:

• the top of the unit has a heavy coat of frost or ice
• the coils on the sides are encased in ice that extends beyond the coils themselves
• the entire unit is covered with a thick sheet of frost or ice

Your Heat Pump needs to be serviced.

Heat Pump Problems — Troubleshooting For Excess Winter Icing

“EXCESS-ICING” HEAT PUMP PROBLEMS MAY BE:

• The unit is not defrosting. Under normal conditions, your heat pump periodically defrosts as needed.  This heats up the outdoor coils long enough to melt all frost and light ice.  Once the outdoor coil reaches around 57 degrees, the defrost-cycle stops — and the system goes back into heating mode.

• Defrost issues can be caused by faulty Electrical Relays, Controls, or sensors — or a problem with the Refrigerant Reversing-Valve.  This valve reverses the flow of the refrigerant during the defrost-cycle.

• The refrigerant reversing-valve, or its electrical-connection, can fail.  In either case, the outdoor unit may be stuck in heating mode  — and can’t reverse the compressor to defrost the outside unit.

• Outdoor fan problem. The fan motor or blades may have failed.  If the fan is not working properly during heating — excess ice accumulates.  A normal defrost-cycle won’t melt large build-ups of frost / ice.

• Low refrigerant.  With low refrigerant-level, eventually, the refrigerant can become so low that the outdoor unit can’t produce enough heat to melt the frost.
• If this is the case, the system can’t heat properly (just like an A/C that can’t cool properly).   This causes back-up electric heat to run & dramatically increases heating costs.  It overworks the heat pump & shortens its life.

• Water may be dripping onto the outside unit from another source. Water dripping onto the unit (from leaking gutters for example) can form a layer of ice on top.

• If a notable amount of frost or ice remains at the end of a defrost cycle — call for repair.  Thick ice build-up means something is wrong with your Heat Pump.

• Until repairs are made — set the system to “Emergency Heat”.  This will shut the Heat Pump off — and the electric back-up heat will provide all heat until the Heat Pump is repaired.  This stops the Heat Pump from running with excess frost / ice build up.  Call for service to get your unit operational again.  Heating with the electric back-up heat is up to 3 times more expensive than the Heat Pump (depending on outdoor temp.).

Normal Operation — And Heat Pump Problems Requiring Service

Heat Pump Running Constantly (Outdoor Temp Below 32 Degrees) – Normal Operation

In DFW, during below freezing temps — a Heat Pump may run constantly.  This is normal, and how it’s designed to operate.  Heat pumps produce lower heat temperatures than a furnace, so they must run longer.  The colder the outside temperature — the more the Heat Pump must run — because the outdoor air contains less heat for the Heat Pump to extract.

“Running Constantly” Heat Pump Problems (outdoor temp above 32) May Be Due To:

Photo Source: CanStockPhoto

SHOWN: Clogged Furnace Filter On Left.  New Filter On Right.

• clogged furnace air filter
• HVAC System outside unit is too dirty — and running poorly as a result
• HVAC System indoor coil is too dirty — and running poorly as a result
• low refrigerant level

Click Here To See A Very Dirty Outdoor Unit:  An Extremely Dirty HVAC System Outdoor Unit – Before & After Cleaning

Click Here To See A Very Dirty Indoor Coil With Black Mold Growth (coil inside the furnace and can’t be seen without removing a panel): Very Dirty HVAC Indoor Coil — Before & After Cleaning

Other Factors:

• poorly insulated home requiring more heat than a properly-sized HVAC System can provide.

• HVAC System is too small for home’s size

NOTE: If the outside temperature is above freezing, and the Heat Pump is running all the time — you likely need service.

NOTE: If your attic does not have at least R-38 Insulation (roughly 12″ of blown insulation) — you are overworking your HVAC System and you’re spending more than necessary to heat and cool your home.

Heat Pump Sometimes Blows Air That’s Cool or Barely Warm

In the winter, a heat pump periodically goes into “defrost mode” and temporarily blows barely warm air inside the home.  This is normal and occurs during the defrost-cycle.  During this time, the electric back-up heat may turn on, but air coming out the vents will be notably less warm during the defrost-cycle.

TIP: Of the outdoor unit’s compressor is running and fan on top is not running — this means it’s defrosting.

Another Issue That Can Cause The System To Blow Air That’s Too Cool To Heat The Home (Normal Operation)

The outside temperature is too cold.  Cold air has less heat available.  The lower the outdoor temperature  — the less heat available (in the outside air) for a heat pump to extract.

In very cold weather, a heat pump may produce warm air at only 85-95 degrees (which is warm enough to heat your home).  As compared, a gas or electric furnace produces temperatures of 130 — 150°F. Compared to a furnace, the heat pump’s output-air may not feel warm enough — though it’s working correctly & is able to heat your home.

TIP: Measure the temperature of the air at the ducts before calling for service.

• NOTE: Supplemental Heat will operate (as needed) during very cold weather.

• NOTE:  With a Heat Pump, You Must Raise The Thermostat TWO (2) Degrees To Get The Supplemental-Heat To Turn On. 
• When the outdoor temp is mid 30’s or higher — you should not need to raise the thermostat more than 1 degree for more heat (so only the Heat Pump produces all heat).

• NOTE: Any time you want the home to heat up faster — raise the thermostat 2 degrees to turn the supplemental-heat on.   The home will heat faster, though the cost of heating increases notably while the electric supplemental-up heat is running.

TIP: During this time, it’s common for both the Heat Pump + Supplemental-Heat to be running.

Restricted Air-Flow To Outside Unit

Blocked air-flow to the outside unit will cause the heat pump to run longer, work harder, and produce less heat.   It also causes condensation and moisture to collect around the coils. The chances of your heat pump freezing are notably increased if air-flow is restricted (often due to overgrown landscaping).   Trim landscaping at least 2 feet away from the outdoor unit.

Your heat pump or central A/C needs a tremendous amount of air-flow to work properly.  The amount of air-flow required by a heat pump (heating or cooling) is 350 cubic feet per minute (CFM) for each 1 ton (1 ton = 12,000 BTU’s) of capacity.  A DFW 2,000 sq. ft. home needs a 3-ton Heat Pump HVAC system.  In both heating & cooling modes — just over 1,000 cubic feet of air passes through the outside unit every minute.

When air to the outside unit is reduced:  

• The efficiency of the unit diminishes
• Heating (and cooling) costs rise
• The HVAC System runs longer & harder than it would under normal operating-conditions — causing it to wear out sooner

• Keep the outside unit’s coils clean
• Maintain a minimum of 24″ between the outside unit and any nearby obstruction such as a building wall, shrub, or fence.  NOTE: The back side of the outdoor unit can be close to the house.

Click Here To See Landscaping That’s Too Close To The HVAC Outdoor Unit: Overgrown Landscaping Against House

TIP: If you can’t see the HVAC Outdoor Unit — The landscaping is too close to it.

Al’s Plumbing, Heating & A/C in Plano, Texas provides maintenance & repairs for all brands of Central A/C, Gas & Electric Furnace, and Heat Pumps.  Additionally we sell and install new HVAC Systems from American Standard (same company as Trane), Ameristar (same company as American Standard) and Coleman HVAC (same company as York HVAC).

Al’s also provides full service plumbing maintenance, repairs and replacements for every plumbing component in your home.  Al’s sells and installs Rheem Professional Series gas & electric water heaters, and tankless water heaters.  Al’s is near your home in Rowlette, TX; Wylie, TX; and Murphy, TX.  We service all homes in southern Collin County, TX; and Denton County, TX with no additional travel charges.

Call Al’s today to discuss any concerns or problems you have with your HVAC System or Plumbing.  We will arrange an appointment at your convenience.