What's up with my Heat Pump?

What's up with my Heat Pump?

by Mason PUD 3 on

April 15, 2016

Heat pumps work great in our mild winter climates, but when the weather turns super cold, you may get a higher electric bill that you're used to.

BBRRRRRRRR… It sure is cold outside!

Cold weather came a little later this year, but once it got here it made its presence known!

If you have a super-efficient heat pump, you may notice an increase in your electricity bill. During colder-than-normal weather, your heat pump, which is usually really good at pulling heat from the outside air, needs a little help from its backup heat unit to keep your home warm. Unfortunately, this isn’t very efficient and costs more to operate.

How does the backup heat work? It’s pretty much the same technology as a toaster:

  • The heat pump has two main parts: the outdoor unit (compressor) and the indoor unit (air handler). The outdoor unit contains a compressor which uses the magic of the refrigeration cycle and, when operating, is where your energy efficiency is found. The air handler is basically an electric forced air furnace that has a special connection to the outdoor unit’s refrigeration lines as the primary heating system.
  • The home’s duct work is connected to the air handler, that has a large fan to blow air across the refrigeration coils (if the heat pump is working properly) or the backup heat’s electric coils. This distributes heated air throughout your home.
  • If backup heat is on, the electric coils (the same as those that glow red-hot in a toaster, but much bigger and stronger) are energized. This is a very inefficient way to heat air. It uses more electricity and costs more money. You want to minimize the amount of time that these electric coils come on.
With a heat pump, this alternate form of heat is usually called “strip heat”, “aux heat”, or “backup heat”. You can see when it’s on by looking at your thermostat. It’s the same system found in an electric forced air furnace.

What Causes the Backup Heat to Turn On?

  • When gets too cold the heat pump can’t extract heat as normal from the outside air temperature. To heat your home, the electric coils are turned on.
  • If your thermostat calls for heat greater than about two degrees, the backup heat turns on and works with the heat pump to boost temperatures more quickly.
  • If your heat pump is not working properly, backup heat will become the primary way your home is heated. If you’re not aware of your heat pump’s status, this can be very costly. The first warning usually comes when people get a high electric bill. By then, they’ve been using costly backup heat for a month or more, and have to wait to get an appointment with their busy heating contractor.

What Can I Do to Reduce How Long Backup Heat Runs?

  • Make sure you have a well-insulated home. Heat loss speeds up when the temperature is colder outside. Insulation slows down heat loss and helps your home stay warmer for longer before your thermostat makes a call to the heating system for more heat. PUD 3 may be able to help increase your home’s insulation levels.
  • Check your thermostat schedule. You can save energy by setting your thermostat back at night with a heat pump. The key is to slowly ramp up the temperature over the course of an hour or so in the morning. This slow ramp up will allow your heat pump to increase the temperature in the house, without relying on the expensive electric coils for assistance. Most thermostats have a two-degree allowable step difference before the backup heat kicks on.
  • Be aware of how your heating system is working, especially throughout the winter. If you notice the outdoor unit (fan) never turns on or that your thermostat gives a regular message such as “aux heat” or “emergency heat”, get your heat pump serviced by a certified technician as soon as possible. Give your heat pump a check-up every year before the heating season begins.
  • A heat pump’s outdoor unit can run in reverse to defrost frozen coils. When it gets really cold, any moisture in the air will often freeze to the coils of the heat pump, creating an ice barrier. The heat pump uses the backup heat to keep you warm while defrosting the coils so it can return to normal operation.

Get Your Ducts in a Row!

Make sure your ductwork is in good repair, has no air leaks, and that the crawl space or the access to your ductwork is secure. Don’t allow critters to get under your home. They like to make their home in the ductwork insulation and can knock down and destroy ducts to get to the warm air. PUD 3 has a duct-sealing program that may be able to help with the cost of getting your ducts sealed.

Why Bother With a Heat Pump At All?

If a heat pump won’t help keep my house warm on the coldest of days when I need it the most, why bother with one at all? That’s a fair question, but let’s put it into perspective. Mason County winters are relatively mild, more wet than cold. Our cold temperature range is usually perfect for an appropriately sized heat pump in a well-insulated home. Of course, we also get the occasional cold snap, which is why heat pumps have the backup heat feature. Most of the time, super-efficient heat pump technology is a good fit for Mason County.

A ductless heat pump, which uses an inverter driven compressor, can extract heat from cold outside air at a lower temperature than a standard heat pump. The variable speed compressor is able to squash the refrigerant harder, and harvest additional heat from the surroundings; and run more efficiently while doing so! Learn more about ductless heat pumps here.

If you have questions about how your heat pump works, or want to discuss other ways to eliminate energy waste in your home, contact the Mason PUD 3 conservation department at (360) 426-0777, or your heating contractor.