Air Conditioner / Heat Pump Troubleshooting FAQs

Fix Air Conditioners & Heat Pumps Set #6

High Heat Pump Electricity Bill FAQs

My daughter lives in a 3 year old apartment with two Heat Pumps mounted in the outside walls below her picture windows. One heat pump is in her small bedroom and the other one is in her living room/kitchen area and runs the most I believe.

Her electric bills the past two months have gone through the roof, I am wondering if one of the heat pumps might be the cause? If so, how might I diagnose the problem and determine which heat pump is the cause.

Details: It is mid-winter here in NJ but the temperatures have not been too bad, a mild winter, very little snow. During past winters, her electric bill has ranged around $30 to $50 max. per month. However, her last month's electric bill was $65 and her current electric bill jumped to $103!

Her usage of her TV, lights, refrigerator and microwave remain constant and doesn't explain her much higher electric bills the last two months.

She keeps her Thermostats on each Heat Pump always set at 72 degrees.

I just learned that heat pumps might have an electric back-up heater built into them that comes on when the outside temperatures drops too low for the main Heat Pump Function to operate well to give sufficient heat inside. Might one of my daughter's heat pumps be malfunctioning resulting in higher usage of electricity and higher electric bills?

I can envision that if the main heat pump with its freon is not working or not working well, then the built-in back-up electric in the heat pump might be kicking in and doing all or most of the heating at a much higher cost.

Is my theory correct and if so, how might I diagnose the heat pump to verify the problem before calling and paying for a Heating and Cooling Repair Company or bothering the landlord to do the same? On 2019-02-27 by Gary

Reply by (mod) - measure current draw for abnormal amps; check easy causes of long on-cycles

Thank you for an interesting question Gary.

What you can do is

1. check for obvious mistakes that increase the heat pump operating cost in heating or cooling mode such as things that cause longer than needed run cycles

• dirty or blocked air filters
• dirty or blocked cooling or evaporating coil
• ductwork blockages, leaks, disconnected sections
• closed air supply registers
• closed duct dampers

2. ask the heat pump or air conditioning service technician to measure the current draw at the compressor units to see if there's an abnormal behavior indicating that there's something wrong with the equipment.

Adequate air flow for air handler in a closet?

I have an indoor air handler for a heat pump installed in closet with a louvered door.

Is there enough air flow for it? On 2019-02-20 by Kenneth

Reply by Mod: Unwanted airflow restriction may added by the louvered door; safety questions

I can't say accurately, Kenneth, just how much unwanted airflow restriction is added by the louvered door in front of your air handler return opening, but here are three key points:

1. For two openings of equal size, louvers on one of them will cut the airflow there by about 33% or more depending on louver details like angle, thickness, and spacing.

So if the opening in your door do the air handler is just about the size as the opening on the air handler itself, that door is probably cutting return air flow, increasing operating cost, and in some installations may also be unsafe.

Watch out: key in understanding your question and answering it is what is the purpose of the "air flow" about which you ask.

2. IF the main or central building return air to your air handler is through that louvered door and into a return air opening in that closet then the total air opening should be at least as big as the air inlet opening on the air handler itself.

3. Combustion air safety concern:

Watch out: if your air handler is not just for cooling but also for heating, and if the heater is fueled by oil or gas, then the unit needs to have an adequate supply of outdoor air to support safe combustion - otherwise the unit could be unsafe, risking (for gas burners particularly) a fatal carbon monoxide poisoning hazard or for an oil burner, insufficient combustion air, sooty operation and a puffback explosion.

So we need to know which sort of "air supply" is in question here.

Also see these diagnostic pages

AIR FLOW WEAK at SUPPLY REGISTERS FAQs

COMBUSTION AIR REQUIREMENTS