# What should you expect from a new heat pump in its first summer?

> What to expect from a new heat pump in its first Memphis summer: longer cycles, humidity, thermostat settings, filters, the outdoor unit and when to call.

URL: https://blufflinememphisheatpumps.com/blog/first-summer-with-a-heat-pump/

Blog, Seasonal

Longer, quieter cycles, a drier house and a few settings worth checking. Here is what normal looks like from May to September.

Last Updated: November 12, 2026

The short answer

Expect longer, quieter cycles than an oversized old unit, a house that feels drier after a week of summer weather, and indoor humidity settling around 45 to 50 percent. Keep the fan on AUTO, change the filter on schedule, keep the outdoor unit clear and check the condensate drain. Call if humidity stays high or rooms can't keep up.

## Longer and quieter

If your old system was oversized, the first thing you’ll notice is longer cycles. A correctly sized heat pump runs for longer stretches on a July afternoon and shuts off less often. That is the point: long cycles pull water out of the air.

[Bluffline Memphis Heat Pumps](https://blufflinememphisheatpumps.com/) sizes every system from a load calculation, and this note covers what to expect from May to September.

### What normal looks like

| What you notice | What it means |
| --- | --- |
| Runs most of a hot afternoon | Correct size; doing its job |
| Shuts off less often | Fewer starts, less wear |
| Quieter outside | Especially on two-stage and variable speed units |
| Supply air a few degrees warmer at low speed | Variable speed running slow to dry the air |

## The house gets drier, slowly

Indoor humidity drops over days, not hours. Carpet, furniture and drywall hold water and release it gradually. After a week of real summer weather, a reading around 45 to 50 percent at your normal setpoint is a good result.

### If it doesn’t

Readings that stay above about 55 percent for days point to something worth a look: the fan setting, the airflow, a leaking return duct or, rarely, the size. The [humidity guide](https://blufflinememphisheatpumps.com/guide/heat-pump-humidity-control/) explains each.

## Settings to check

A few settings make the biggest difference in summer:

- **Fan on AUTO**, so water on the coil drains instead of evaporating back into the house.
- **Dehumidify mode on**, if your thermostat has it.
- **A steady setpoint**; big daily swings cause short catch-up cycles.
- **Cooling mode, or AUTO** with heating and cooling setpoints a few degrees apart.

The [thermostat setup guide](https://blufflinememphisheatpumps.com/guide/heat-pump-thermostat-setup/) walks through each menu.

## The filter

A new system’s filter clogs faster in its first months as it catches dust stirred up by the work. Check it after a few weeks and change it on schedule after that, more often in summer and with pets.

## Outside

Keep the outdoor unit clear: trim plants back to the maker’s clearances, keep grass clippings and mulch away from the coil, and don’t let a sprinkler hit it. A gentle rinse with a garden hose once or twice a season helps.

## The condensate drain

A heat pump pulls gallons of water out of the air on a humid afternoon. Check that the drain line outside is dripping when the system runs. On attic units, glance at the secondary pan; it should be dry.

If the system ever stops cooling and the pan has water, the float switch did its job and the drain needs clearing.

## Spring and fall are different

The hardest humidity weeks are often the mild, rainy ones in May and September, not the hot ones. On a 75-degree wet day the house needs little cooling, so a single-stage system runs short cycles and the thermostat is satisfied before much water comes out.

### What helps in those weeks

- Close the windows on muggy days, even if the temperature outside feels pleasant.
- Lower the setpoint a degree or two for a day, so the system runs longer.
- Use the dehumidify mode if your thermostat has one.

Two-stage and [variable speed](https://blufflinememphisheatpumps.com/variable-speed-heat-pump/) systems handle these weeks best, because they can run long at low output.

## Noise and the neighbors

A new outdoor unit usually sounds quieter than the one it replaced, especially at startup.

If you hear rattling, buzzing or a hum that wasn’t there on install day, a loose panel or a line set touching the wall is the usual cause, and it’s a quick fix.

## The bill

Compare the summer bill with the same months last year, not with the previous month, since July and August are always the peak. A higher SEER2 rating and correct sizing usually show up as a lower cooling bill.

[Reading your MLGW bill after a heat pump](https://blufflinememphisheatpumps.com/blog/reading-your-mlgw-bill-after-a-heat-pump/) shows how.

## When to call

Some things aren’t normal and are worth a call:

- Humidity stays above about 55 percent after a week.
- A room can’t keep up on the hottest afternoons.
- Ice forms on the indoor lines or the outdoor unit in summer.
- Water appears in the attic pan or on a ceiling.
- A new noise, smell or tripped breaker.

The [lifespan guide](https://blufflinememphisheatpumps.com/guide/heat-pump-lifespan-memphis/) covers the care that keeps a heat pump running for years.

## Questions about this post

### Why does my new heat pump run longer than my old system?

A correctly sized unit runs longer cycles than an oversized one. Long cycles keep the coil cold and pull more water out of the air, which is what makes a Memphis summer comfortable.

### How soon should my house feel drier after a new heat pump?

Give it about a week of summer weather. Carpet, furniture and drywall hold moisture and release it slowly, so the humidity reading falls over several days.

## Keep reading

- [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/)
- [Learn**How should a heat pump thermostat be set up in Memphis?** The handful of settings that decide whether a heat pump saves money: the equipment type, the outdoor sensor, the lockout, setbacks and the fan.](https://blufflinememphisheatpumps.com/guide/heat-pump-thermostat-setup/)
- [Seasonal**How do you read your MLGW bill after a heat pump goes in?** Kilowatt-hours, the fuel adjustment and the gas side. How to compare fairly and how to spot strip heat running when it shouldn't.](https://blufflinememphisheatpumps.com/blog/reading-your-mlgw-bill-after-a-heat-pump/)
- [Learn**How long does a heat pump last in Memphis?** Year-round running, humid summers and installation quality decide the number. Here is what to expect and what helps.](https://blufflinememphisheatpumps.com/guide/heat-pump-lifespan-memphis/)

## Get an estimate for your house

(901) 657-2200