Jump to: Hot water loop · Hot + chilled water · 95 °C + glycol · Boiler make-up + chiller · Scalder + chiller · Stratified store
Hot water only, heat taken from the outside air
The simplest set-up. The heat pump pulls heat out of the warm outside air and tops a hot water loop back up from 60 °C to 75 °C. Nothing is cooled that you use — the free heat comes from the air.
- Cold side outdoor air, 28–35 °C
- Hot side Loop return 60 °C → Hot water out 75 °C
- Machine Karnot iHEAT R290 (air-source · several units share one loop)
Why it works: Philippine air sits at 28–35 °C all year, so an air-source heat pump gets roughly ₱4 of heat for every ₱1 of electricity. For bigger loads, several units feed the same loop through a plate heat exchanger.
Temperatures shown are a typical duty; every design is sized to measured flows.
Hot water and chilled water from one machine
The machine takes heat out of your chilled water (12 °C back, 6 °C out) and puts that same heat into your hot water (30 °C in, 75 °C out). One electricity bill buys both.
- Cold side Chilled water out 6 °C · Chilled water back 12 °C
- Hot side Cold water in 30 °C → Hot water out 75 °C
- Machine Karnot iHEAT CO₂ (water-to-water · CO₂ (R744))
Why it works: If you already run a chiller and a separate water heater, you are paying twice to move the same heat. Here the heat the chiller would throw away becomes your hot water. It is a CO₂ machine because the water arrives cold and has to leave hot in one pass — too big a lift for R290, which suits a warm source and a shorter step, like topping a loop from 60 to 75 °C.
CO₂ gives its highest outlet temperatures when the incoming water is cold. Temperatures shown are a typical duty; every design is sized to measured flows.
Near-boiling water and glycol below freezing, together
One CO₂ heat pump makes 95 °C water for cleaning and pasteurising while it cools glycol from 12 °C down to −2 °C for the cold side of the plant.
- Cold side Glycol out −2 °C · Glycol back +12 °C
- Hot side Water in 20–30 °C → Hot water out 95 °C
- Machine Karnot iHEAT CO₂ (water-to-water · CO₂ (R744))
Why it works: This is the job that decides between refrigerants. R290 reaches 75 °C and cannot make glycol below freezing at the same time; CO₂ can do both. CO₂ gives its highest outlet temperatures when the water coming in is cold — which is why the hot side is fed from the bottom of a stratified store.
CO₂ gives its highest outlet temperatures when the incoming water is cold. Temperatures shown are a typical duty; every design is sized to measured flows.
Pre-heating boiler make-up water, with a water chiller on the side
Fresh make-up water enters at 30 °C and leaves the heat pump at 90 °C on its way into the boiler. The boiler burns fuel only for the last step to steam. The heat comes out of a chilled water circuit the plant needs anyway.
- Cold side Chilled water out 6 °C · Chilled water back 12 °C
- Hot side Make-up water in 30 °C → Hot water out 90 °C
- Machine Karnot iHEAT CO₂ (water-to-water · CO₂ (R744))
Why it works: One rule sizes this machine: it only runs while there is make-up water to heat. Size it to the make-up flow, not to the boiler — oversizing buys a heat pump that sits idle.
CO₂ gives its highest outlet temperatures when the incoming water is cold. Temperatures shown are a typical duty; every design is sized to measured flows.
Poultry scalder with chilled water and a hot water store
The heat pump fills a 9,000-litre store at 75 °C that keeps the scalder topped up at 70 °C, and chills water for the carcass chill tanks with the same electricity.
- Cold side Chilled water out 2 °C · Chilled water back 12 °C
- Hot side Fresh water in 30 °C → Hot water out 75 °C
- Machine Karnot iHEAT CO₂ (water-to-water · CO₂ (R744))
Why it works: A scalder uses a lot of water at one steady temperature, all day. The store lets a modest heat pump run steadily and still cover the morning start-up, when the scalder is filled from cold. CO₂ because fresh water at 30 °C has to reach 75 °C in one pass while the cold side makes 2 °C chilled water — more lift than R290 will carry.
CO₂ gives its highest outlet temperatures when the incoming water is cold. Temperatures shown are a typical duty; every design is sized to measured flows.
Two tanks in series: how a store keeps the heat pump efficient
Two tanks piped in series, not side by side. Hot water leaves the heat pump along the top to the taps, with a tee into the top of tank 1. The bottom of tank 1 feeds the top of tank 2. The bottom of tank 2 — the coldest water in the building — is what goes back to the heat pump.
- Cold side outdoor air, 30 °C
- Hot side Cold water in 30 °C → Hot water out 75 °C
- Machine Karnot iHEAT R290 (air-source)
Why it works: This is why R290 and a store work so well together. A heat pump is only asked for a big step when the water coming back is already warm. Keeping the tanks in series means the machine always draws the coldest water in the system, so the step stays small, the COP stays high and the store still holds a full tank at 75 °C for the morning rush. Mix the tanks in parallel and you warm the return, shrink the saving and lose the top temperature.
Temperatures shown are a typical duty; every design is sized to measured flows.
Questions we get asked
Where do the pipes go on a heat pump?
A heat pump has two sides. The cold side takes heat in — from outside air, or from a chilled water or glycol circuit you want cooled. The hot side gives that heat out into your hot water. Each side has a flow and a return, so there are four connections, and each has a temperature.
Can one heat pump make hot water and chilled water at the same time?
Yes. A water-to-water heat pump takes heat out of the chilled water and puts the same heat into the hot water. One electricity bill buys both. With R290, hot water reaches 75 °C with chilled water around 6 °C.
When do you need CO₂ instead of R290?
Three cases: the hot water must go above 75 °C, the cold side must go below freezing, or the water arrives cold and has to leave hot in one pass. That last one is the lift — the gap between the cold side and the hot side. R290 suits a warm source and a shorter step, such as topping a hot water loop from 60 to 75 °C. CO₂ carries the big lift, and gives its highest outlet temperatures when the incoming water is cold.
How do you size a heat pump for boiler make-up water?
To the make-up water flow, not to the boiler. The heat pump only runs while there is fresh water to heat, so a machine sized to the boiler would sit idle most of the day.
Send us your flows and temperatures
A sketch of your plant, or just the temperatures and flow rates on each side, is enough. We draw your version and size the machine to it.
Send us your sketchRelated: All applications · Heat pumps in the Philippines · R290 vs CO₂ · Engineering Hub