# How should a heat pump thermostat be set up in Memphis?

> How to set a heat pump thermostat in Memphis: thermostat type, outdoor sensors, strip lockouts, setbacks, fan settings, humidity and dual fuel handoffs.

URL: https://blufflinememphisheatpumps.com/guide/heat-pump-thermostat-setup/

Learn

The handful of settings that decide whether a heat pump saves money: the equipment type, the outdoor sensor, the lockout, setbacks and the fan.

Last Updated: November 12, 2026

The short answer

Use a thermostat set up as a heat pump, with an outdoor temperature sensor. Lock the backup strips out above about 30 to 35 degrees, keep winter setbacks small or use adaptive recovery, run the fan on AUTO in summer, and turn on any dehumidify setting. On dual fuel, set the gas switchover where you want it.

Key takeaways

- The thermostat must be configured as a heat pump, not a furnace and AC.
- An outdoor sensor lets it lock strips out on mild days.
- Small setbacks or adaptive recovery keep mornings from running on strips.
- Fan on AUTO in summer lets the coil drain and keeps humidity down.
- Dehumidify modes and humidity displays help in Memphis summers.

## A few settings decide a lot

A heat pump can be efficient or expensive depending on how its thermostat is set. Most of the difference comes from a handful of settings in the installer menu and a couple of habits.

[Bluffline Memphis Heat Pumps](https://blufflinememphisheatpumps.com/) sets them with you at start-up on every installation and writes the key ones down.

### The settings at a glance

| Setting | What to choose | Why |
| --- | --- | --- |
| Equipment type | Heat pump, with auxiliary heat (or dual fuel) | Lets the thermostat run the reversing valve and stage backup heat |
| Reversing valve | O or B, to match the equipment | Wrong choice swaps heating and cooling |
| Outdoor sensor | Installed and enabled | Lets lockouts work |
| Aux heat lockout | About 30 to 35 degrees | Keeps strips off on mild days |
| Compressor lockout | Below the balance point, or off | Avoids running the heat pump when it can’t keep up, where configured |
| Recovery | Adaptive or slow recovery | Warms the house with the heat pump, not strips |
| Fan | AUTO | Better summer humidity |
| Dehumidify | On, if offered | Slower airflow when humidity is high |

## The equipment type

The thermostat has to know it is controlling a heat pump. A thermostat configured for a furnace and AC can run the system, but it won’t stage auxiliary heat correctly and may call strips when it shouldn’t.

### The reversing valve setting

Heat pumps energize the reversing valve in either cooling (the O terminal, most brands) or heating (the B terminal, some brands). If the setting is wrong, the system heats when you ask for cooling. It is set once, at installation.

## The outdoor sensor

Without an outdoor temperature, the thermostat can’t tell a 50-degree day from a 20-degree one. It brings strips on whenever the house falls behind, which on a heat pump is much of the winter.

### Sensor options

- **A wired sensor** on a shaded north wall, the most reliable.
- **The outdoor unit’s own sensor**, on communicating systems.
- **An internet weather feed**, on some smart thermostats; it works but reads the airport, not your yard.

## The strip lockout

With an outdoor sensor in place, the thermostat can keep strips off above a set temperature. In most Memphis houses, about 30 to 35 degrees works: above it the heat pump carries the house, below it the strips help.

### How to choose

The right lockout sits a little above the house’s balance point, the temperature where the heat pump alone stops keeping up. The load calculation and the heat pump’s performance data give that number. The [sizing guide](https://blufflinememphisheatpumps.com/guide/heat-pump-sizing-manual-j/) explains how, and the [electric furnace to heat pump](https://blufflinememphisheatpumps.com/electric-furnace-to-heat-pump/) page shows how strips are sized to match.

The [aux and emergency heat guide](https://blufflinememphisheatpumps.com/guide/auxiliary-emergency-heat/) explains why it matters on the bill.

## Setbacks and recovery

Setting the temperature back at night or while you’re away saves energy with a furnace. With a heat pump it can backfire. A big setback means a big morning recovery, and many thermostats bring strips on to speed it up.

### What works better

- **Small setbacks**, about 2 to 4 degrees.
- **Adaptive or smart recovery**, which starts warming early and slowly with the heat pump alone.
- **No setback** on very cold nights, when recovery would need strips anyway.

In summer, setbacks are less of a problem; a few degrees warmer while you’re away is fine.

## The fan

Summer is when the fan setting matters most in Memphis.

### AUTO

The fan runs only when the system runs. After each cycle, water on the indoor coil drips into the pan and drains away.

### ON

The fan runs all the time. Water on the coil evaporates back into the house between cycles, raising indoor humidity. Some owners use ON for air filtration or mixing; in a Memphis summer it usually costs comfort.

### Circulate

Some thermostats run the fan for a set share of each hour. It’s a middle ground, but in humid weather AUTO is still better.

## Humidity settings

Many newer thermostats show indoor humidity and offer a dehumidify mode that slows the blower when humidity climbs. In Memphis summers that helps, especially with two-stage and [variable speed](https://blufflinememphisheatpumps.com/variable-speed-heat-pump/) systems. The [humidity guide](https://blufflinememphisheatpumps.com/guide/heat-pump-humidity-control/) explains why.

## Dual fuel settings

On a dual fuel system the thermostat also chooses between the heat pump and the gas furnace. The key setting is the switchover temperature: above it, the heat pump heats; below it, the furnace does.

### Where to set it

On MLGW’s typical rates gas is cheaper at every temperature, so the switchover is a comfort choice. The [switchover guide](https://blufflinememphisheatpumps.com/guide/dual-fuel-switchover-temperature/) works through the options, and the [dual fuel page](https://blufflinememphisheatpumps.com/dual-fuel-heat-pump/) covers the system.

## Emergency heat

The emergency heat setting turns the heat pump off and runs backup heat alone. Use it only if the outdoor unit is broken or frozen. Leaving it on by accident is one of the more common reasons for a shocking winter bill.

## Heat, cool or auto?

Most thermostats offer HEAT, COOL and AUTO modes. In AUTO the thermostat switches between heating and cooling on its own to hold a range.

### When AUTO helps

Memphis springs and falls can need heat in the morning and cooling by afternoon. AUTO handles that without anyone touching the thermostat. Set the heating and cooling setpoints at least a few degrees apart, so the system doesn’t flip back and forth.

### When to avoid it

In the middle of summer or winter, fixed HEAT or COOL is simpler and prevents an unexpected switch on an odd day.

## Where the thermostat sits

A thermostat reads the air around it, so its location matters.

### Places that mislead it

- **A sunny wall**, which reads warm and under-heats the house.
- **Near a supply register**, which reads the air coming out, not the room.
- **An exterior wall**, especially an uninsulated one, which reads cool.
- **Near a kitchen, lamp or TV**, which add heat.
- **A hallway with no return**, which can sit in still air.

When a new thermostat goes in, the old spot often stays because the wire is there. If the old spot misleads it, moving it a few feet, or adding a remote sensor, can make the whole house more comfortable.

## Common mistakes

Most expensive heat pump bills trace back to one of these:

| Mistake | What it costs |
| --- | --- |
| Thermostat set up as furnace and AC | Strips run when they shouldn’t |
| No outdoor sensor | No lockout; strips on mild days |
| Emergency heat left on | Strip heat all day |
| Fan left ON in summer | Higher humidity |
| Big nightly setbacks in winter | Morning strip heat |
| Heating and cooling setpoints too close in AUTO | Constant switching |

## Communicating thermostats

Many variable speed systems use the maker’s communicating thermostat, which talks to the outdoor unit and air handler over a data connection. Those thermostats set much of the above automatically, but the lockouts, recovery and dehumidify settings still deserve a look.

## A start-up checklist

At start-up, every item below should be set and confirmed:

- Equipment type and reversing valve set correctly.
- Outdoor sensor reading checked against a thermometer.
- Aux heat lockout set with you.
- Recovery and setback settings chosen.
- Fan on AUTO; dehumidify on if offered.
- On dual fuel, switchover set and written down.

The [commissioning checklist](https://blufflinememphisheatpumps.com/guide/heat-pump-commissioning-checklist/) covers the rest of start-up, and the [Memphis buying guide](https://blufflinememphisheatpumps.com/guide/memphis-heat-pump-buying-guide/) puts the decision in order.

## Questions about this guide

### Can I use a smart thermostat with a heat pump?

Most smart thermostats support heat pumps, including auxiliary heat and an outdoor temperature from a sensor or the internet. Some variable speed systems need the maker's own communicating thermostat to use their full range.

### What setback works best for a heat pump in winter?

Small ones, about 2 to 4 degrees, or a thermostat with adaptive recovery that warms the house slowly using the heat pump. Large setbacks often bring on strip heat in the morning and can cost more than they save.

### Should the thermostat fan be on AUTO or ON?

AUTO in most Memphis houses, especially in summer. With the fan running continuously, water on the indoor coil evaporates back into the house between cycles, raising humidity.

## Related service

- [Service**Electric furnace to heat pump** Strip heat makes the biggest winter bills in Memphis. A heat pump moves heat instead of making it and keeps strips for the coldest hours.](https://blufflinememphisheatpumps.com/electric-furnace-to-heat-pump/)

## More guides

- [Learn**What is the difference between auxiliary heat and emergency heat?** Two settings that both turn on the strips, why one is automatic and the other is a last resort, and how to keep the bill in check.](https://blufflinememphisheatpumps.com/guide/auxiliary-emergency-heat/)
- [Learn**What switchover temperature should a dual fuel heat pump use in Memphis?** The two numbers behind the setting, what MLGW's rates say about them, and how to pick a point you can live with.](https://blufflinememphisheatpumps.com/guide/dual-fuel-switchover-temperature/)
- [Learn**Does a heat pump remove humidity from a Memphis house?** Why 72 degrees can still feel clammy, where the water goes, and the four things that decide how dry a heat pump keeps the house.](https://blufflinememphisheatpumps.com/guide/heat-pump-humidity-control/)
- [Decision Guide**How do you buy the right heat pump for a Memphis house?** The whole decision in the order you meet it, from the system you have now to the readings you should get at start-up.](https://blufflinememphisheatpumps.com/guide/memphis-heat-pump-buying-guide/)

## Get an estimate for your house

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