Swimming pool open through winter
How a hotel or club with a 25 m outdoor pool and a small spa can keep them at 28 °C and 36 °C through winter with heat pumps, and what it saves against an LPG-fired pool boiler.
▶Video: Pools, spas and hatcheries
V12 · 2–2.5 minTitanium-exchanger heat pumps for pool and seawater heating
Video coming soon01Problem statement
- Pools close in winter. Water below 26 °C is too cold for most swimmers, so pools lose members and revenue for four to five months.
- Surface losses dominate. Most heat leaves through evaporation from the water surface, which is highest on cold, dry, windy nights.
- Gas heating is costly. Boilers sized for a large pool burn a lot of LPG, so many sites heat only partly or not at all.
- Losses between fuel and process. Burning LPG in a boiler or heater and distributing the heat loses a quarter or more of the fuel's energy before it reaches the process.
- Compliance, safety and handling. Fired equipment brings boiler inspections, fuel storage and unloading, flue emissions and an attendant on every shift.
02Use case
The reference site is a club in north India with a 25 m × 12.5 m outdoor pool holding about 470 m³ and a 10 m² spa pool. Without heating the pool closes from November to March, when water falls to 15–18 °C.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Pool surface losses | 28 °C held | 312 m² × 120 W/m² average with night cover × 24 h | 900 |
| Make-up water heating | 20 → 28 °C | 5,000 L/day backwash and evaporation, 20 → 28 °C | 46 |
| Spa pool | 36 °C held | 10 m² surface × 400 W/m² × 14 h | 56 |
| Total useful heat | 1,002 | ||
Averaged over 20 running hours, the heat pumps need about 50 kW.
03P&ID
Tags: HP heat pump, TK tank, SG steam generator, P pump, PHE plate heat exchanger, TCV temperature control valve, TIC temperature indicating controller (panel), TT temperature transmitter, MT moisture transmitter, PT pressure transmitter, LT level transmitter, FS flow switch, NC normally closed. Process fluids are heated through their own exchanger, coil or jacket.
04Solution
System description
- 1 × SE-SP-65U (65 kW) (SE-SP pool heat pump) delivering 40 °C, covering the day's 1,002 kWh in about 15.4 running hours.
- The LPG-fired pool boiler stays connected behind a normally closed valve as standby.
- Heat pumps heat pool water through a titanium exchanger placed after the filter and before chlorination.
- A second, smaller exchanger off the same hot water loop keeps the spa at 36 °C.
- A night cover on the main pool cuts evaporation, which is the largest loss.
- Heat pumps run through the night and day with the pool itself as the heat store.
Selected equipment
| Model | SE-SP-65U × 1 |
|---|---|
| Heating capacity | 65 kW each, 65 kW total |
| COP | 6.7 at A25 °C / W30 °C (data sheet T1) |
| Power input | about 9.7 kW total at rated conditions |
| Rating | titanium-in-PVC exchanger, R410A |
| Supply temperature | 40 °C |
Ratings from the Sunniva TDS 2026 data sheets.
Control philosophy
TIC-201 holds the pool at 28 °C, starting the heat pumps when water falls below 27.5 °C. The spa has its own valve and sensor set at 36 °C. Heating stops if the filter pump stops. The existing boiler can be kept for quick warm-up after a refill.
05Energy saving and ROI
Change any input to match a customer's site. Defaults are typical Indian prices for October 2026. The installed cost is a placeholder; replace it with the actual quotation.
| Existing | Heat pump | |
|---|---|---|
| Daily consumption | – | – |
| Annual energy cost | – | – |
| CO₂ per year | – | – |
06Benefits
Pool open all year
Members and guests can swim through winter, which adds months of use.
Low running cost per month
Heat pumps work well at the low lift a pool needs, so monthly cost is a fraction of gas heating.
Simple and safe
No gas, flue or burner near the pool deck.
Lower energy cost
Each kWh of electricity delivers about 6.7 kWh of heat at the required temperature, against well under one kWh of useful heat per kWh of fuel burnt.
No flame on site
No burner, flue or fuel tank for this duty, and no fuel deliveries to schedule.
Solar-ready
Running hours can be placed in daylight so rooftop solar supplies much of the electricity, which also cuts CO₂ further.
07Engineering pointers
Site data to collect
- Pool and spa size, depth and volume
- Indoor or outdoor, and use of a cover
- Target water temperatures and season
- Filtration flow rate
- Lowest winter temperatures at site
- Present fuel or electricity use and monthly bill
- Sanctioned electrical load and spare capacity
- Space for the heat pumps and storage, with service access
- Winter minimum ambient at site
Design notes
- Pool chemistry. Chlorinated water is corrosive. Use titanium exchangers and dose chlorine after the heater.
- Cover the pool. A night cover can halve heating demand. Without it, size for much higher surface losses.
- First heat-up. Raising a cold pool from 18 °C takes several days. Start heating before the season opens.
- Electrical. About 10 kW of heat pump input at rated conditions, plus pumps and fans. Check spare sanctioned load before ordering.
Service and warranty
Sunniva has supplied 5,000+ heat pumps since 2012, with nine service technicians across India, including remote sites such as Leh. All components carry a one-year warranty.
Talk to us
Swimming pool open through winter
How a hotel or club with a 25 m outdoor pool and a small spa can keep them at 28 °C and 36 °C through winter with heat pumps, and what it saves against an LPG-fired pool boiler.
▶Video: Pools, spas and hatcheries
V12 · 2–2.5 minTitanium-exchanger heat pumps for pool and seawater heating
Video coming soon01Problem statement
- Pools close in winter. Water below 26 °C is too cold for most swimmers, so pools lose members and revenue for four to five months.
- Surface losses dominate. Most heat leaves through evaporation from the water surface, which is highest on cold, dry, windy nights.
- Gas heating is costly. Boilers sized for a large pool burn a lot of LPG, so many sites heat only partly or not at all.
- Losses between fuel and process. Burning LPG in a boiler or heater and distributing the heat loses a quarter or more of the fuel's energy before it reaches the process.
- Compliance, safety and handling. Fired equipment brings boiler inspections, fuel storage and unloading, flue emissions and an attendant on every shift.
02Use case
The reference site is a club in north India with a 25 m × 12.5 m outdoor pool holding about 470 m³ and a 10 m² spa pool. Without heating the pool closes from November to March, when water falls to 15–18 °C.
| Heat user | Process temp. | Basis | Heat, kWh/day |
|---|---|---|---|
| Pool surface losses | 28 °C held | 312 m² × 120 W/m² average with night cover × 24 h | 900 |
| Make-up water heating | 20 → 28 °C | 5,000 L/day backwash and evaporation, 20 → 28 °C | 46 |
| Spa pool | 36 °C held | 10 m² surface × 400 W/m² × 14 h | 56 |
| Total useful heat | 1,002 | ||
Averaged over 20 running hours, the heat pumps need about 50 kW.
03P&ID
Tags: HP heat pump, TK tank, SG steam generator, P pump, PHE plate heat exchanger, TCV temperature control valve, TIC temperature indicating controller (panel), TT temperature transmitter, MT moisture transmitter, PT pressure transmitter, LT level transmitter, FS flow switch, NC normally closed. Process fluids are heated through their own exchanger, coil or jacket.
04Solution
System description
- 1 × SE-SP-65U (65 kW) (SE-SP pool heat pump) delivering 40 °C, covering the day's 1,002 kWh in about 15.4 running hours.
- The LPG-fired pool boiler stays connected behind a normally closed valve as standby.
- Heat pumps heat pool water through a titanium exchanger placed after the filter and before chlorination.
- A second, smaller exchanger off the same hot water loop keeps the spa at 36 °C.
- A night cover on the main pool cuts evaporation, which is the largest loss.
- Heat pumps run through the night and day with the pool itself as the heat store.
Selected equipment
| Model | SE-SP-65U × 1 |
|---|---|
| Heating capacity | 65 kW each, 65 kW total |
| COP | 6.7 at A25 °C / W30 °C (data sheet T1) |
| Power input | about 9.7 kW total at rated conditions |
| Rating | titanium-in-PVC exchanger, R410A |
| Supply temperature | 40 °C |
Ratings from the Sunniva TDS 2026 data sheets.
Control philosophy
TIC-201 holds the pool at 28 °C, starting the heat pumps when water falls below 27.5 °C. The spa has its own valve and sensor set at 36 °C. Heating stops if the filter pump stops. The existing boiler can be kept for quick warm-up after a refill.
05Energy saving and ROI
Change any input to match a customer's site. Defaults are typical Indian prices for October 2026. The installed cost is a placeholder; replace it with the actual quotation.
| Existing | Heat pump | |
|---|---|---|
| Daily consumption | – | – |
| Annual energy cost | – | – |
| CO₂ per year | – | – |
06Benefits
Pool open all year
Members and guests can swim through winter, which adds months of use.
Low running cost per month
Heat pumps work well at the low lift a pool needs, so monthly cost is a fraction of gas heating.
Simple and safe
No gas, flue or burner near the pool deck.
Lower energy cost
Each kWh of electricity delivers about 6.7 kWh of heat at the required temperature, against well under one kWh of useful heat per kWh of fuel burnt.
No flame on site
No burner, flue or fuel tank for this duty, and no fuel deliveries to schedule.
Solar-ready
Running hours can be placed in daylight so rooftop solar supplies much of the electricity, which also cuts CO₂ further.
07Engineering pointers
Site data to collect
- Pool and spa size, depth and volume
- Indoor or outdoor, and use of a cover
- Target water temperatures and season
- Filtration flow rate
- Lowest winter temperatures at site
- Present fuel or electricity use and monthly bill
- Sanctioned electrical load and spare capacity
- Space for the heat pumps and storage, with service access
- Winter minimum ambient at site
Design notes
- Pool chemistry. Chlorinated water is corrosive. Use titanium exchangers and dose chlorine after the heater.
- Cover the pool. A night cover can halve heating demand. Without it, size for much higher surface losses.
- First heat-up. Raising a cold pool from 18 °C takes several days. Start heating before the season opens.
- Electrical. About 10 kW of heat pump input at rated conditions, plus pumps and fans. Check spare sanctioned load before ordering.
Service and warranty
Sunniva has supplied 5,000+ heat pumps since 2012, with nine service technicians across India, including remote sites such as Leh. All components carry a one-year warranty.