Sizing in four steps
- Daily hot waterPeople × about 50 L at 55°C. Add more for bathtubs, rain showers or a kitchen.
- Peak demandEstimate how much is used in the busiest 1–2 hours, usually the evening.
- Tank sizeChoose a tank that holds most of the peak demand, so the heat pump can reheat slowly and efficiently.
- Heat pump capacityPick a unit that reheats the tank in about 3–4 hours: kW ≈ tank litres × temperature rise ÷ 860 ÷ hours.
Worked example
A family of six in a bungalow uses about 300 L/day, with 200 L used between 7 and 9 pm.
- Tank: 300 L, so evening demand is covered from storage.
- Reheat 300 L from 28°C to 55°C (27°C rise): 300 × 27 ÷ 860 = 9.4 kWh of heat.
- To reheat in about 2 hours: 9.4 ÷ 2 ≈ 4.7 kW, so a 5.1 kW WHP015HW-R4 fits well.
Rule of thumb: about 1 kW of heat pump capacity reheats roughly 30 litres per hour by 27°C.
Model capacity and dimensions
| Model | Heating capacity | Hot water output | Recommended tank | Dimensions (mm) | Weight |
|---|---|---|---|---|---|
| WHP010HW-R4 | 3.6 kW | 75 L/h | 150 L | 1000 × 350 × 620 | 40 kg |
| WHP015HW-R4 | 5.1 kW | 108 L/h | 200–300 L | 1000 × 350 × 620 | 46 kg |
| WHP020HW-R4 | 7.1 kW | 150 L/h | 300–400 L | 1000 × 350 × 620 | 55 kg |
| WHP025HW-R4 | 9.0 kW | 190 L/h | 500–600 L | 1000 × 350 × 620 | 62 kg |
| WHP030-R3DC | 9.7 kW (DHW) | ~210 L/h | 500 L+ | 1100 × 400 × 850 | 72–80 kg |
| WHP060-R3DC | 19.3 kW (DHW) | ~415 L/h | 1,000 L+ | 1100 × 400 × 1420 | 125–132 kg |
Hot water output at 15→55°C. Larger buildings: see commercial heat pump sizing.
Operating temperature range
Pecol DHW models work in ambient air from -7°C to 43°C and the DC inverter models from -30°C to 45°C, so Malaysian lowland and highland conditions are well within range. The warmer the air, the more output you get from the same unit.
Frequently asked questions
What size air source heat pump do I need?
For hot water, most Malaysian homes need 3.6–9 kW with a 150–600 L tank, depending on the number of users.
Is a bigger heat pump better?
Not always. An oversized unit cycles on and off more often. Size the tank for peak demand and the heat pump for a reasonable reheat time.
What is the largest air to water heat pump?
Pecol's commercial range goes up to about 103 kW for hot water, and several units can be combined for large buildings.