Pool swim season in Hartsville/Trousdale County, TN
When can you swim in an outdoor pool in Hartsville/Trousdale County, TN?
An unheated pool in Hartsville/Trousdale County reaches 78°F in Jul to Aug, about 2 months a year. The air allows up to 7 swimmable months with a heater (Apr to Oct).
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What each heater buys you in Hartsville/Trousdale County
| Option | Months | Swimmable | Energy/yr | All-in/yr |
|---|---|---|---|---|
| No heater | 2 | Jul to Aug | $0 | $0 |
| Solar cover only | 4 | Jun to Sep | $0 | $50 |
| Solar panels + cover | 5 | May to Sep | $0 | $283 |
| Heat pump + cover | 7 | Apr to Oct | $325 | $875 |
| Gas heater + cover | 7 | Apr to Oct | $521 | $946 |
For a 450 sq ft pool held at 80°F, at TN prices of 13.8¢/kWh electricity and $12/Mcf gas. All-in spreads the purchase over the equipment's life.
The cheapest way to the full season in Hartsville/Trousdale County
Heat pump + cover: 7 of 7 possible months for about $875 a year all-in, which works out near $175 for each month it adds.
Before you pay for any heater, buy a solar cover: on its own it adds 2 months here for about $50 a year (why a cover comes first). If you get quotes, ask for a heat pump sized to your pool's surface area; here it beats gas all-in (heat pump or gas).
Weather station: Hartsville, 1.8 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Hartsville/Trousdale County month by month: air, sun and pool water
| Month | Air high | Air avg | Sun kWh/m²/day | Water, unheated | Water, covered | Heat pump $ | Gas $ |
|---|---|---|---|---|---|---|---|
| Jan | 48° | 37° | 2.2 | 38° | 44° | – | – |
| Feb | 52° | 41° | 2.8 | 39° | 45° | – | – |
| Mar | 60° | 48° | 3.9 | 45° | 51° | – | – |
| Apr | 71° | 58° | 5.2 | 55° | 61° | $167 | $259 |
| May | 78° | 66° | 5.7 | 65° | 71° | $75 | $130 |
| Jun | 85° | 73° | 6.3 | 73° | 79° | $8 | $14 |
| Jul | 88° | 77° | 6.1 | 78° | 84° | – | – |
| Aug | 88° | 76° | 5.6 | 79° | 85° | – | – |
| Sep | 83° | 71° | 4.7 | 75° | 81° | – | – |
| Oct | 72° | 59° | 3.6 | 65° | 71° | $75 | $118 |
| Nov | 60° | 48° | 2.6 | 53° | 59° | – | – |
| Dec | 50° | 40° | 1.9 | 43° | 49° | – | – |
Heating costs most in Apr (about $167 with a heat pump, $259 with gas). Sunshine peaks in Jun at 6.3 kWh/m²/day (NASA satellite data, 32.9 km grid cell). Highlighted months are swimmable with no heater.
How Hartsville/Trousdale County compares with nearby cities
Hartsville/Trousdale County ranks 51 of 65 Tennessee cities for unheated swim months, and no nearby city gets a longer unheated season.
| City | Distance | Unheated months | Heat pump months | Heat pump $/yr |
|---|---|---|---|---|
| Lebanon, TN | 17 mi | 2 | 7 | $286 |
| Gallatin, TN | 17 mi | 2 | 6 | $183 |
| Mount Juliet, TN | 24 mi | 2 | 7 | $288 |
| Portland, TN | 25 mi | 2 | 6 | $136 |
| Hendersonville, TN | 25 mi | 2 | 7 | $296 |
| White House, TN | 29 mi | 2 | 6 | $140 |