Find the outdoor temperature where your heat pump stops saving you money.
For your weather, your exact model and your rates. Then see what your current thermostat setting is costing you.
Free · No account · Anywhere in the US
Your setting in four questions
About a minute. Everything else starts from a default you can change.
Three inputs. One temperature.
Your thermostat switches from the heat pump to your furnace or other heat at one outdoor temperature. We find the one that costs you least.
- 01
Your weather
Your local hourly weather history: how many hours each winter you actually spend at every outdoor temperature.
- 02
Your heat pump
Your exact model’s rated performance at each outdoor temperature.
- 03
Your rates
Your electricity and furnace fuel prices, including time-of-use pricing if you’re on it.
What you get
One lockout temperature with the range of settings that cost about the same, where to set it on your thermostat, and what your current setting costs compared with it. Sometimes that means setting the furnace to take over sooner.
In every result and chart:Heat pumpFurnace or other heat (boiler, strips)
More from the .blue family
Free tools, built by the same team.
- rebate.blueLook up the IRS manufacturer code (QMID) for your heat pump tax credit, and compare certified models. (opens in a new tab)
- calc.blueRoom-by-room Manual J load calculations on iPad, for contractors sizing a system. (opens in a new tab)
- spec.blueLook up an HVAC model and serial number: what the unit is and when it was made, sourced to the manufacturer. (opens in a new tab)
- forecast.blueAd-free US weather for where you are: how sure the forecast is, and what it means for your home. (opens in a new tab)
Questions
What is a heat pump lockout temperature?
The outdoor temperature below which your thermostat stops running the heat pump and heats with your furnace or other heat instead: a boiler or electric strips. Thermostats call it different things, such as compressor lockout, compressor minimum outdoor temperature or switchover temperature.
Is a lower lockout always cheaper?
No. A heat pump gets less efficient as it gets colder, so below some outdoor temperature your furnace fuel can cost less for the same heat. Where that happens depends on your weather, your model and your energy prices, which is why one rule of thumb does not fit every home.
Is the lockout the same as the balance point?
No. The balance point is about comfort: the temperature below which the heat pump alone can no longer keep up with your home. The lockout this tool finds is about cost. Your result shows both, labelled separately.
Is it free? Do I need an account?
It is free and there is no account. Your result is a link you can save or send to your installer.
Who runs heatpump.blue?
DotBlue LLC, a UniCo Group company. The tool is free and works anywhere in the US.
Does heatpump.blue track me?
Yes. We use Google Analytics, PostHog, umami and Cloudflare to see how the tool is used, so we know what to improve.