System diagrams

Heat pump system diagrams: how each set-up connects

Where the pipes go, and at what temperature. Five set-ups we design most often for Philippine plants, drawn the same way so you can compare them.

How to read them. The heat pump sits in the middle. The cold side on the left takes heat in — from outside air, or from water you want chilled. The hot side on the right gives that heat out into your hot water. Four numbered connections, each with its temperature. Where both sides do useful work, one electricity bill buys your cooling and your hot water.

Jump to: Hot water loop · Hot + chilled water · 95 °C + glycol · Boiler make-up + chiller · Scalder + chiller

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.

Hot water only, heat taken from the outside air: cold side Cooler air out to outside, back 28–35 °C; hot side Hot water out 75 °C, in 60 °C. C HEAT PUMP Karnot iHEAT R290 air-source · several units share one loop 1 · Cooler air out to outside 2 · Outdoor air in 28–35 °C Outdoor air the free heat source 3 · Hot water out 75 °C 4 · Loop return 60 °C Hot water loop washing · CIP · laundry
  • 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.

Hot water and chilled water from one machine: cold side Chilled water out 6 °C, back 12 °C; hot side Hot water out 75 °C, in 30 °C. C HEAT PUMP Karnot iHEAT R290 water-to-water 1 · Chilled water out 6 °C 2 · Chilled water back 12 °C Cooling load air-handling units · process 3 · Hot water out 75 °C 4 · Cold water in 30 °C Hot water store washing · kitchens · showers mains or soft water
  • 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 R290 (water-to-water)

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.

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.

Near-boiling water and glycol below freezing, together: cold side Glycol out −2 °C, back +12 °C; hot side Hot water out 95 °C, in 20–30 °C. C HEAT PUMP Karnot iHEAT CO₂ water-to-water · CO₂ (R744) 1 · Glycol out −2 °C 2 · Glycol back +12 °C Glycol cooling cold rooms · product chilling 3 · Hot water out 95 °C 4 · Water in 20–30 °C Hot water store CIP · pasteurising from a stratified store
  • 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.

Pre-heating boiler make-up water, with a water chiller on the side: cold side Chilled water out 6 °C, back 12 °C; hot side Hot water out 90 °C, in 30 °C. C HEAT PUMP Karnot iHEAT CO₂ water-to-water · CO₂ (R744) 1 · Chilled water out 6 °C 2 · Chilled water back 12 °C Water chiller load process cooling · AHUs 3 · Hot water out 90 °C 4 · Make-up water in 30 °C Boiler feed arrives at 90 °C, not 30 °C make-up water
  • 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.

Poultry scalder with chilled water and a hot water store: cold side Chilled water out 2 °C, back 12 °C; hot side Hot water out 75 °C, in 30 °C. C HEAT PUMP Karnot iHEAT R290 water-to-water 1 · Chilled water out 2 °C 2 · Chilled water back 12 °C Chilled water carcass chilling 3 · Hot water out 75 °C 4 · Fresh water in 30 °C Store → scalder 9,000 L · scalder at 70 °C fresh water
  • 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 R290 (water-to-water)

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.

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?

When the hot water must go above 75 °C, or the cold side must go below freezing. R290 reaches 75 °C; CO₂ reaches 90–95 °C and beyond when the incoming water is cold, and can make glycol below 0 °C at the same time.

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 sketch

Related: All applications · Heat pumps in the Philippines · R290 vs CO₂ · Engineering Hub