heat pump troubleshooting
Winter electric bill is much higher than expected
What it probably is, what you can safely check yourself, and the point where it becomes our job.
Nothing is at risk today. Worth solving before the next cold snap, when everyone else is calling too.
What is most likely going on
On a heat pump house the usual cause is electric resistance backup heat doing the compressor’s work, from an unlocked lockout setting, an emergency heat switch left on, or lost capacity. Envelope losses and deep setbacks account for the rest.
Likely causes, most common first
- 1
Emergency or auxiliary heat left engaged
A thermostat switched to emergency heat during a cold snap and never switched back runs resistance elements instead of the compressor, and the bill reflects it immediately. This is the first thing we ask about, because it is free to fix and it is remarkably common after the first real freeze of the season.
- 2
Backup heat not locked out properly
If resistance backup can satisfy the thermostat at mild outdoor temperatures, it will, because it responds faster. PSE’s rebate requires backup to be locked out via an outdoor sensor with a recommended lockout at or below 35°F, and the compressor lockout disabled or set at 0°F or below. Those settings exist precisely to prevent this bill.
- 3
Deep nightly setbacks on a heat pump
Setting back eight degrees overnight forces a full-power recovery every morning, which on a heat pump often calls in the strip heat and costs more than holding a steady temperature. This is genuinely different from how a gas furnace behaves, and it catches people who bring furnace habits to a new heat pump.
- 4
Lost capacity from a dirty coil, filter or low charge
A system that has quietly lost capacity runs longer and leans on backup heat more, so the bill climbs before the comfort complaint does. Coil cleaning, filter changes and a charge check are the diagnostic path. A leak repair is a repair; adding refrigerant annually is not.
- 5
The house itself
A 1950s rambler with an under-insulated attic and a leaky crawlspace hatch loses heat faster than any equipment can cheaply replace. PSE pays weatherization as an instant rebate: attic at $1.75 per square foot up to $3,500, wall and floor at $2.50 per square foot up to $5,000, air sealing at $0.20 per square foot. That is the cheapest kilowatt-hour available.
What you can safely check yourself
Work down the list before you book anything. Plenty of calls end here, and we would rather you keep the money.
- Check that the thermostat is not in emergency or auxiliary heat mode.
- Replace the indoor filter, and clear leaves, moss and needles from the outdoor coil.
- Hold a single steady setpoint for a week instead of using deep overnight setbacks, and compare usage in your PSE account.
- Compare this winter’s usage to last winter’s in the PSE bill history rather than comparing dollars, since rates change.
- Note whether any electric baseboards or wall heaters you kept as backup have thermostats turned up.
What is deliberately not on that list
Nothing above involves refrigerant, gas piping, or opening a live electrical panel. Refrigerant work is federally regulated and needs recovery equipment. Gas work done wrong kills people. An energised panel turns a $300 repair into a hospital visit. Electrical work on the circuit itself is done by a licensed electrical contractor. If a step you have read elsewhere involves any of those three, stop and call instead.
When to call us
Call us if usage jumped without a weather explanation, if the auxiliary heat indicator is on in mild weather, or if you want the backup lockout settings verified. A commissioning check on an existing system is cheaper than a season of resistance heat. Reach us at (360) 592-3824, Monday–Friday 8:00 AM–5:30 PM.
Monday–Friday, 8:00 AM – 5:30 PM · Emergency calls answered 24/7
Tell us what it is doing
Describe the symptom and we will tell you what it takes to fix, what it is likely to cost, and whether it is worth fixing at all.
Monday–Friday, 8:00 AM – 5:30 PM · Emergency calls answered 24/7