Heat pump advice from an expert
During extreme cold, switching to ‘emergency’ heat reduces energy savings but may increase your comfort
When temperatures drop below freezing, the number one question we hear from heat-pump owners is whether to switch to resistance heat. Most HVAC contractors recommend turning thermostats to “emergency” or “auxiliary” heat – essentially switching off heat pumps and turning on the furnace – during a cold spell.
Since that practice costs energy rather than saves it, we called Rod Van Hoven, longtime HVAC contractor and partner at Central Washington Heating of Wenatchee, to find out why.
“From a strict energy-savings standpoint, run it all the time,” Van Hoven said about heat pumps. But most of his customers are inquiring about how to increase their comfort, he said, which sometimes conflicts with energy efficiency.
“When you have 120-degree air (the temperature of air heated by electric coils in a furnace) and you put your hand over the register, the air feels warm. But air off a heat pump at 80 to 90 degrees feels cold. So if you’re sitting by the register or in your house taking a shower, it’s a comfort issue. This is where we start differentiating between a comfort standpoint and an energy standpoint.”
Van Hoven said recommendations differ between contractors, but “if people ask me at what temperature they should turn it off, my answer is that if it’s going to be cold for a long period of time, maybe a week, where the high is about 15 degrees, I’d be inclined to turn mine to resistance heat.”
Van Hoven said he also wants to avoid wear and tear on the machines. “When your heat pump is running at 0 degrees, it’s running a lot. You’re putting hours on that piece of equipment but not getting a whole lot of gain out of it.”
He said the best advice is to make your house as energy efficient as possible with vinyl-framed double-pane windows and good insulation, and sealed against air leaks. “That’s what will make your house more comfortable at these temperatures. It’s comfort and efficiency together.”
