Choose a monoblock heat pump when you want the entire refrigerant circuit factory-sealed outdoors, water-only connections into the house and R290 refrigerant — the configuration the market is moving towards as EU F-gas rules for small monoblocks tighten from 2027. Choose a split when the outdoor unit must sit 10–30 m from the indoor equipment or where a frost-safe water circuit is impractical. Heating performance is equivalent; installation logistics decide.
What is the difference between a monoblock and a split heat pump?
A monoblock heat pump contains the complete refrigeration circuit — evaporator, compressor, condenser, expansion valve — in one outdoor casing; only heating water crosses the wall. A split heat pump divides the circuit: the outdoor unit holds the evaporator and compressor, an indoor module holds the condenser, and the two are joined by refrigerant pipes made and charged on site. Thermodynamically the cycle is identical, so COP differences between comparable-quality units are marginal — the real differences are regulatory and practical.
| Criterion | Monoblock | Split |
|---|---|---|
| Refrigerant circuit | Factory-sealed and tested | Assembled and charged on site |
| Installer qualification | Plumbing/heating skills; no refrigerant work | F-gas certified refrigeration work required |
| Connections through wall | Heating water (insulated pipes) | Refrigerant lines up to ~30 m |
| Freeze protection | Required (glycol, valves or trace heating) | Not needed — water stays indoors |
| Indoor space | None beyond hydraulics | Wall or floor indoor unit |
| R290 (propane) use | Ideal — charge sealed outdoors | Restricted — flammable refrigerant indoors |
How does the EU F-Gas Regulation change the choice in 2027?
It adds a regulatory reason to favour R290. Under Regulation (EU) 2024/573, the rules for small self-contained heat pumps using higher-GWP refrigerants tighten from 1 January 2027, and the HFC supply quota was reduced for 2025–2026. According to the latest regulatory updates the detail — which product categories, capacities and exemptions apply — is still evolving, so check current requirements with your installer or with us before ordering. The industry's answer is R290 propane: GWP of about 3, excellent thermodynamics and flow temperatures up to 70–75 °C. Because R290 is flammable (class A3), it is far easier to certify inside a sealed outdoor monoblock than in field-joined split lines entering living spaces — which is why the European market is converging on the R290 monoblock as the standard product. EU-wide installer training rules covering natural refrigerants were due by March 2026, but a monoblock keeps that competence requirement off most residential jobs entirely.
Which is easier and cheaper to install?
The monoblock, in most cases. A heating installer connects flow, return and power — no vacuum pump, no leak test, no refrigerant certification — which typically saves several hundred euros of labour and one site visit. The split's advantages appear at distance: refrigerant lines lose far less heat than water pipes over long runs and can snake through tight routes, so a plant room 15–30 m from the only viable outdoor location favours a split. Either way, correct hydraulic design — buffer tank, hydraulic separation where zoning demands it — matters more to real performance than the monoblock/split question; see do I need a buffer tank with a heat pump.
How do you protect a monoblock from freezing?
The water in a monoblock's outdoor pipes can freeze during a winter power cut. Three proven safeguards: fill the outdoor loop with propylene glycol mixture (simple, at a 2–5% efficiency cost); fit antifreeze valves that dump the outdoor water when it approaches 3 °C; or use electric trace heating on the exposed pipework. Insulate outdoor runs generously and keep them short — under 5 m where possible.
Which should you choose in practice?
Default to an R290 monoblock for new residential projects: future-proof refrigerant, simpler installation, one warranty-holding factory-sealed circuit — the configuration of Solimpeks' Varm Boost Series, an R290 monoblock rated for operation down to −25 °C. Pick a split when distance, routing or zero outdoor water risk genuinely demand it, and budget for F-gas certified commissioning. In both cases confirm the noise and siting rules first — covered in how loud is a heat pump.
Frequently asked questions
Are monoblock heat pumps less efficient than splits?
No — the refrigeration cycle is the same and rated COP/SCOP values for comparable units differ marginally. Long, poorly insulated outdoor water runs can cost a monoblock a few percent, which is why short, well-lagged pipework is part of good design.
Why are R290 heat pumps almost always monoblocks?
R290 propane is flammable, so safety rules strongly favour keeping the whole charge factory-sealed outdoors rather than piping it into the building. The monoblock format makes the A3 refrigerant a non-issue for the household.
Can I still buy an R32 heat pump in 2026?
Yes. The tighter F-gas rules apply to products placed on the market from 2027, and installed R32 systems can continue to be operated and serviced. R32 remains a common, efficient refrigerant; R290 models such as the Solimpeks Varm Boost Series are the natural-refrigerant option for buyers who want the longest regulatory runway. Rules are still evolving, so check current eligibility with your installer or with us.
Does a split heat pump need more maintenance?
It adds the refrigerant circuit to the inspection scope: field-made joints are the main leak risk and checks require F-gas certified technicians. A monoblock needs only standard heating-circuit maintenance plus a glycol or antifreeze-valve check.