Swimming pool heat pump calculator
How big a heat pump does your pool need?
Move the sliders. You get the capacity in kilowatts, the Sunniva model that covers it, and what it costs to run against an electric immersion heater or a diesel boiler. Every figure updates as you type, and nothing is hidden — the assumptions are listed at the bottom.
Your pool
Rough numbers are fine — surface area matters far more than depth.
Pool length
8m
Pool width
4m
Average depth
1.3m
Average, not the deep end — length × width × average depth is the volume.
Temperatures & heat-up
26 – 28 °C suits most swimmers; 30 °C and above for therapy or small children.
Target water temperature
28°C
Water temperature now
20°C
Hours to reach the target
48h
Longer heat-up needs a smaller machine. Once warm, it only replaces losses.
Where the pool is
Wind and an open sky drive the losses. A cover changes everything.
Indoor or outdoor
How exposed to wind
Air speed at the water surface — 0.3, 0.7 and 1.5 m/s. Much lower than the wind you feel standing up; walls and hedges on all sides count as sheltered.
Pool cover
Nearest city
A starting point only. Both figures below stay editable.
Design air temperature
22°C
The coolest daytime temperature you still want the pool warm in.
Relative humidity
60%
What you pay for energy
Change these to your own tariff — the comparison is only as good as the numbers you put in.
Electricity
9₹/kWh
Diesel
92₹/litre
Days of use per year
210days
Engineering assumptions change only if you know why
Ground & pipework allowance
5%
Added on top of the surface losses.
Electric immersion efficiency
95%
Diesel boiler efficiency
85%
Diesel energy content
10kWh/l
Whatever figure you have — ours or anyone
else’s, installed. Nothing is sent anywhere until you fill in the
form below.
Grid electricity carbon
0.71kg CO₂/kWh
The Indian grid average. Lower it if you have rooftop solar or a green tariff.
Diesel carbon
2.68kg CO₂/litre
LPG carbon
2.98kg CO₂/kg
PNG carbon
1.9kg CO₂/SCM
Coal / biomass carbon
1.8kg CO₂/kg
Swings hugely with grade. Set it near zero for biomass, which is usually counted as biogenic.
Required heat pump capacity
—
Smallest model that covers it
—
- Pool volume
- —
- Water surface area
- —
- Temperature rise needed
- —
- Heat-up load
- —
- Holding load, uncovered
- —
- Average load once warm
- —
- Heat needed per day
- —
Where the heat goes
Cost to run for one day
You would save
—
What it pays back, and what it stops
Pays for itself in
—
Carbon avoided
—
Want this sizing checked by an engineer?
Your name, phone and email go on the saved sheet and let our team confirm the selection against your actual site — cover, wind exposure, filtration and pipe runs all shift the answer. All three are needed before the sheet can be sent or saved.
How this is worked out
- Heat-up load = volume × 1.163 × temperature rise ÷ hours. That constant is water's heat capacity, 4.186 kJ/kg·K, in kWh per m³ per °C.
- Evaporation is the big one on an outdoor pool — usually well over half the loss. Calculated from the surface evaporation coefficient 25 + 19v kg/m²h, where v is the air speed over the water, times the humidity difference between saturated air at pool temperature and the actual air.
- Convection uses (3.1 + 4.1v) W/m²·K on the water-to-air difference; radiation uses a water emissivity of 0.95 against a sky 8 °C below air temperature outdoors, and air temperature indoors. A ground and pipework allowance is added on top.
- Payback is simple payback — the price you type in, divided by the annual saving. No finance, no maintenance, no discounting, and no price of ours is assumed or disclosed. Carbon is the displaced fuel’s emissions minus the electricity the heat pump draws, at the Indian grid average of 0.71 kg CO₂ per unit. Every factor is a slider, and the saved sheet records what was used.
- A cover is taken to cut evaporation to 5 % and convection and radiation to 35 %, for the hours it is on.
- The design air temperature is applied for all 24 hours. Real nights are colder than that, which would make the loss worse — but most pools are covered overnight or allowed to drift a few degrees, which is why the cover setting moves the daily figure so much. Set the ambient to your average day-and-night temperature if you want the running cost rather than the sizing case.
- Sizing uses the uncovered holding load plus the heat-up load, because the machine has to do both at once on the coldest day. Running cost uses the day-weighted average, because that is what the pool actually consumes.
- Capacity and COP are read off the chosen model's own published table and interpolated against your design ambient — not a fixed COP. Below 10 °C ambient the figures are extrapolated past the certified range and the panel says so.
- Indicative only. Static head, filtration, pipe runs, water chemistry and local code all affect the final selection — confirm with Sunniva Encon LLP before ordering.
Swimming pool heat pump sizing
Sunniva Encon LLP
Calculated for
—
What you entered
Result
Required capacity
—
—
Running cost & savings
How this was worked out
Talk to Sunniva
SalesWhatsApp our sales desk
LinkedInFollow Sunniva Encon
YouTubeSee the machines running
Review usRate us on GoogleContact
+91 93213 65103sales@sunnivaencon.com
www.sunnivaencon.com
Office
C‑443, Oshiwara Industrial Centre Premises CHS, New Link Road, Goregaon West, Mumbai© 2026 Sunniva Encon LLP. The design and code of this calculator are our copyright. Results are indicative and offered in good faith — the method is set out above. Confirm the final selection with us before ordering.
1
Swimming pool heat pump calculator
How big a heat pump does your pool need?
Move the sliders. You get the capacity in kilowatts, the Sunniva model that covers it, and what it costs to run against an electric immersion heater or a diesel boiler. Every figure updates as you type, and nothing is hidden — the assumptions are listed at the bottom.
Your pool
Rough numbers are fine — surface area matters far more than depth.
Pool length
8m
Pool width
4m
Average depth
1.3m
Average, not the deep end — length × width × average depth is the volume.
Temperatures & heat-up
26 – 28 °C suits most swimmers; 30 °C and above for therapy or small children.
Target water temperature
28°C
Water temperature now
20°C
Hours to reach the target
48h
Longer heat-up needs a smaller machine. Once warm, it only replaces losses.
Where the pool is
Wind and an open sky drive the losses. A cover changes everything.
Indoor or outdoor
How exposed to wind
Air speed at the water surface — 0.3, 0.7 and 1.5 m/s. Much lower than the wind you feel standing up; walls and hedges on all sides count as sheltered.
Pool cover
Nearest city
A starting point only. Both figures below stay editable.
Design air temperature
22°C
The coolest daytime temperature you still want the pool warm in.
Relative humidity
60%
What you pay for energy
Change these to your own tariff — the comparison is only as good as the numbers you put in.
Electricity
9₹/kWh
Diesel
92₹/litre
Days of use per year
210days
Engineering assumptions change only if you know why
Ground & pipework allowance
5%
Added on top of the surface losses.
Electric immersion efficiency
95%
Diesel boiler efficiency
85%
Diesel energy content
10kWh/l
Whatever figure you have — ours or anyone
else’s, installed. Nothing is sent anywhere until you fill in the
form below.
Grid electricity carbon
0.71kg CO₂/kWh
The Indian grid average. Lower it if you have rooftop solar or a green tariff.
Diesel carbon
2.68kg CO₂/litre
LPG carbon
2.98kg CO₂/kg
PNG carbon
1.9kg CO₂/SCM
Coal / biomass carbon
1.8kg CO₂/kg
Swings hugely with grade. Set it near zero for biomass, which is usually counted as biogenic.
Required heat pump capacity
—
Smallest model that covers it
—
- Pool volume
- —
- Water surface area
- —
- Temperature rise needed
- —
- Heat-up load
- —
- Holding load, uncovered
- —
- Average load once warm
- —
- Heat needed per day
- —
Where the heat goes
Cost to run for one day
You would save
—
What it pays back, and what it stops
Pays for itself in
—
Carbon avoided
—
Want this sizing checked by an engineer?
Your name, phone and email go on the saved sheet and let our team confirm the selection against your actual site — cover, wind exposure, filtration and pipe runs all shift the answer. All three are needed before the sheet can be sent or saved.
How this is worked out
- Heat-up load = volume × 1.163 × temperature rise ÷ hours. That constant is water's heat capacity, 4.186 kJ/kg·K, in kWh per m³ per °C.
- Evaporation is the big one on an outdoor pool — usually well over half the loss. Calculated from the surface evaporation coefficient 25 + 19v kg/m²h, where v is the air speed over the water, times the humidity difference between saturated air at pool temperature and the actual air.
- Convection uses (3.1 + 4.1v) W/m²·K on the water-to-air difference; radiation uses a water emissivity of 0.95 against a sky 8 °C below air temperature outdoors, and air temperature indoors. A ground and pipework allowance is added on top.
- Payback is simple payback — the price you type in, divided by the annual saving. No finance, no maintenance, no discounting, and no price of ours is assumed or disclosed. Carbon is the displaced fuel’s emissions minus the electricity the heat pump draws, at the Indian grid average of 0.71 kg CO₂ per unit. Every factor is a slider, and the saved sheet records what was used.
- A cover is taken to cut evaporation to 5 % and convection and radiation to 35 %, for the hours it is on.
- The design air temperature is applied for all 24 hours. Real nights are colder than that, which would make the loss worse — but most pools are covered overnight or allowed to drift a few degrees, which is why the cover setting moves the daily figure so much. Set the ambient to your average day-and-night temperature if you want the running cost rather than the sizing case.
- Sizing uses the uncovered holding load plus the heat-up load, because the machine has to do both at once on the coldest day. Running cost uses the day-weighted average, because that is what the pool actually consumes.
- Capacity and COP are read off the chosen model's own published table and interpolated against your design ambient — not a fixed COP. Below 10 °C ambient the figures are extrapolated past the certified range and the panel says so.
- Indicative only. Static head, filtration, pipe runs, water chemistry and local code all affect the final selection — confirm with Sunniva Encon LLP before ordering.
Swimming pool heat pump sizing
Sunniva Encon LLP
Calculated for
—
What you entered
Result
Required capacity
—
—
Running cost & savings
How this was worked out
Talk to Sunniva
SalesWhatsApp our sales deskLinkedInFollow Sunniva EnconYouTubeSee the machines runningReview usRate us on GoogleContact
+91 93213 65103sales@sunnivaencon.com
www.sunnivaencon.com
Office
C‑443, Oshiwara Industrial Centre Premises CHS, New Link Road, Goregaon West, Mumbai© 2026 Sunniva Encon LLP. The design and code of this calculator are our copyright. Results are indicative and offered in good faith — the method is set out above. Confirm the final selection with us before ordering.
1