Technical Data Sheet · Ultra High Temperature Heat Pump
SE-UHT Series
SE-UHT-25V
Cascade heat pump delivering hot water to 125 °C from ambient air alone. An R410A low stage lifts the air-side heat, an R245fa high stage takes it the rest of the way, and the two meet at a cascade heat exchanger.
Heating capacity
25kW
At T1 · A20 °C, / WB15 °C / W120 °C
Peak COP
2.2
At T1 · A20 °C, / WB15 °C / W120 °C
Max water temp
125°C
Rated outlet 120 °C
Hot water output
215LPH
At T1 · A20 °C, / WB15 °C / W120 °C
Performance
Rated output at each published test condition
T1
A20 °C, / WB15 °C / W120 °C
- Heating capacity
- 25kW
- Power input
- 11.2kW
- COP
- 2.2
- Hot water output
- 215LPH
T3
A−7 °C / WB-8 °C / W120 °C
- Heating capacity
- 18kW
- Power input
- 10.6kW
- COP
- 1.7
- Hot water output
- 120LPH
T5
A−20 °C / W120 °C
- Heating capacity
- 15kW
- Power input
- 10.5kW
- COP
- 1.4
- Hot water output
- 90LPH
Technical specifications
SE-UHT-25V| Parameter | Unit | Specification |
|---|---|---|
| Electrical supply | ||
| Power supply | — | 380~415 V / 50 Hz / 3 Ph |
| Maximum current | A | 50 |
| Refrigeration circuit | ||
| Compressor | — | Scroll (Copeland / Panasonic) |
| Number of compressors | Nos | 2 |
| Refrigerant | — | R410A + R245fa (cascade) |
| Heat exchanger (condenser) | — | Tube-in-shell / Brazed plate heat exchanger |
| Evaporator | — | Blue finned evaporator coil |
| Throttling device | — | Thermostatic / Electronic expansion valve |
| Water circuit | ||
| Rated water temperature | °C | 120 |
| Maximum water temperature | °C | 125 |
| Water flow | m³/hr | 4.3 |
| Water pipe size | inch | R1-1/4 |
| Unit & acoustics | ||
| Dimensions (L × W × H) | mm | 860 × 780 × 1780 |
| Net weight | kg | 225 |
| Noise at 1 metre | dB(A) | ≤ 58 |
Test conditions
- T1 — Ambient 20 °C, water outlet 120 °C
- T2 — Ambient 7 °C, water outlet 120 °C
- T3 — Ambient -7 °C, water outlet 120 °C
- T4 — Ambient -12 °C, water outlet 120 °C
- T5 — Ambient -20 °C, water outlet 120 °C
Installation requirement
- Protection device and cable size are not published for this model. Confirm both with Sunniva before wiring — the rated current above is not sufficient to size them.
- Maintain water flow of 4.3 m³/hr through the unit.
Built to order
Options available on this modelOptions
- Water connection — Coupling type to suit the site — threaded, flanged or grooved.
- Casing — Stainless steel or powder-coated finish.
- Circulation pump — Can be built into the unit instead of being fitted in the plant room.
- Condenser — Stainless steel or copper, in place of the standard build.
How to order them
- None of the above is the standard build, and none of it is included in the specification table on this page.
- Ask for it at enquiry and have it confirmed in writing on the order acknowledgement. Price, lead time and weight can all change with it.
The table above describes the standard machine. Options are quoted per order and are available across the range except on the All-in-One and Split units.
Site installation schematic
How the unit connects to the tank, pumps and piping on siteHot waterReturn to heat pumpCold water feedElectrical & control
- 1Heat pump unit
- 2RCC foundation with anti-vibration pads
- 3Insulated storage tank
- 4Primary circulation pump
- 5Y-strainer
- 6Non-return valve
- 7Isolation valve (typical)
- 8Automatic air vent
- 9Safety / pressure-relief valve
- 10Tank sensor to heat pump controller
- 11Drain valve
- 12Cold water feed
- 13Hot water to usage points
- 14Thermometer
- 15Power supply / MCB panel
Indicative hookup only. Static head, draw pattern and local code may call for additional components — confirm the final scheme with Sunniva before ordering.
Selection & site preparation
Recommended sizing derived from this model’s rated dataSystem sizing
| Storage tank volume | 430 – 1290 L |
| Tank sizing rule | Hot water output × 2 to 6 LPH measured at 20 °C ambient. Indicative range — stay inside it so the tank is neither undersized nor oversized. |
| Primary circulation pump | 5 m³/hr @ 10 – 12 m head |
| Primary pipe size | 25 mm (R1-1/4) to 10 m run; 32 mm beyond |
| Line insulation | 25 mm closed-cell, every line above 45 °C |
Civil & electrical
| Unit footprint & dry weight | 860 × 780 mm · 225 kg |
| Heat pump plinth | 1010 × 930 × 150 mm RCC, M20 |
| Plinth level | 100 mm above finished floor, ± 3 mm/m |
| Tank pad (1000 L) | 150 mm RCC, 200 mm larger each side ≈ 1150 kg filled |
| Clearances | 600 mm air-on · 1000 mm above fan · 800 mm service side |
| Electrical | MCB · |
Installation steps
Follow in order — a commissioning engineer should sign off before start-up- Cast the RCC plinth 1010 × 930 × 150 mm in M20 concrete, 100 mm above finished floor. Let it cure and check it is level within 3 mm per metre.
- Set the unit down on anti-vibration pads. Keep 600 mm clear at the finned coil faces and 1000 mm above the fan — the unit must breathe or capacity drops.
- Place the tank on its own level pad, as close to the heat pump as the site allows. Short pipes lose less heat.
- Pipe tank bottom → isolation valve → Y-strainer → primary pump → heat pump inlet, in that order. Fit the non-return valve after the pump.
- Pipe the heat pump outlet → tank top inlet. Fit an isolation valve at each end so the unit can be serviced without draining the tank.
- Fit the automatic air vent and the safety valve on the tank top. Pipe the safety valve discharge to an open drain — never cap it.
- Bring the cold water feed into the tank bottom through an isolation valve and a non-return valve.
- Fit the tank sensor into the tank pocket and run its cable back to the heat pump controller. Do not run it alongside the power cable.
- Insulate every hot line with 25 mm closed-cell insulation, pump body included.
- Power the unit from a dedicated MCB using .
- Fill and vent the system fully. Confirm the flow switch stops the unit when the pump is off, then start.
Process & instrumentation diagram
Refrigeration circuit, instrumentation and water connectionsInstrument schedule
Tags as marked on the diagram above| Tag | Device | Function |
|---|---|---|
| TT 01 | Compressor discharge temperature | Discharge superheat & high-temperature cut-out |
| TT 02 | Compressor suction temperature | Suction superheat monitoring |
| TT 03 | Water outlet temperature | Set-point control |
| TT 04 | Water inlet temperature | Return water sensing, ΔT calculation |
| PS HIGH | High-pressure switch | Discharge over-pressure cut-out |
| Tag | Device | Function |
|---|---|---|
| PS LOW | Low-pressure switch | Loss-of-charge / low-suction cut-out |
| PI HP | High-side pressure gauge | Discharge pressure indication |
| PI LP | Low-side pressure gauge | Suction pressure indication |
| FS 01 | Water flow switch | Interlock — no-flow lockout |
Cabinet reference drawing
Typical general arrangement — this model’s own dimensions alongside
Dimensions (L × W × H)860 × 780 × 1780 mm
Net weight225 kg
Reference arrangement only — V-coil cabinet, vertical discharge. Dimensions printed on the
drawing are indicative; the figures above and in the specification table are the ones that
apply to this model.
Operating envelope
The compressor’s permitted window, in refrigeration termsEnvelope limits
| Low stage — R410A | Te −25 to 25 °C · Tc 20 to 67 °C |
| High stage — R245fa | Te 22 to 75 °C · Tc 75 to 135 °C |
| Hand-over | 22 to 25 °C where the low stage’s condensing overlaps the high stage’s evaporating — the cascade heat exchanger sits in this band |
| Peak condensing | 135 °C high stage; the machine’s published water limit is 125 °C |
| Transient operation | Not applicable |
Reading the envelope
- Te (evaporating) follows the source the unit draws heat from — the colder the air or source water, the lower Te sits.
- Tc (condensing) follows the water leaving the unit — asking for 80 °C hot water puts Tc near the top of the envelope.
- A duty is valid only inside the shaded area. A cold source combined with very hot water pushes the point towards the top-left, which is exactly where the envelope closes in — that corner is the real limit on winter performance.
Two circuits, drawn on one frame. The low stage cannot condense much above 67 °C and the high stage cannot evaporate below 22 °C, so neither spans the lift alone — the shaded band between them is where the cascade heat exchanger hands the heat over. Envelopes redrawn from the Xecom / Embraco Nidec scroll compressor selection guide, “Operating Envelop”. Where a duty sits close to a boundary, confirm against the compressors fitted to the unit before finalising the design.
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Documentation
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SE-UHT-25V · Technical Data Sheet. Specifications are subject to change without prior notice.