A monoblock heat pump contains the complete refrigerant circuit in a single outdoor unit; only insulated water pipes cross the wall into the building. No refrigerant work is done on site, so the sealed circuit needs no F-gas certified installer. Under the EU F-Gas Regulation, new monoblock units up to 12 kW placed on the EU market from 1 January 2027 must use refrigerants with a GWP below 150 — which is why R290 propane models, such as Solimpeks' Varm Boost Series, are becoming the standard.
How does a monoblock heat pump work?
A monoblock ("one block") heat pump houses evaporator, compressor, condenser and expansion valve together in the outdoor casing, factory-sealed and factory-tested. Heating water is piped out to the unit, heated in the built-in plate heat exchanger, and returned through insulated pipes. Indoors, only hydraulic components remain: circulation pump, valves, controls and usually a buffer tank or hot water cylinder.
Because the refrigerant circuit is hermetically closed at the factory, installation is plumbing and electrical work — no brazing, evacuating or charging of refrigerant lines at the top of a ladder in winter. That shortens installation and removes an entire category of field workmanship risk. Most units pair with weather-compensated controls and a diverting valve for hot water, so the indoor installation often reduces to a cylinder, a buffer and wiring.
What is the difference between a monoblock and a split heat pump?
| Criterion | Monoblock | Split |
|---|---|---|
| Refrigerant circuit | Entirely outdoors, factory-sealed | Field-connected lines to an indoor unit |
| Crosses the wall | Heating water | Refrigerant |
| F-gas certified installer | Not required for the sealed circuit | Required |
| Frost risk | Outdoor water pipes need protection | None — water stays indoors |
| Refrigerant charge | Fixed and leak-tested at the factory | Set on site, leak-check obligations |
A split heat pump keeps the water circuit entirely indoors, at the price of field-made refrigerant joints. The full decision framework is in Monoblock vs split: which should you choose?.
Why do most monoblock heat pumps now use R290 propane?
According to the latest EU F-Gas Regulation 2024/573 rules, new monoblock and self-contained heat pumps up to 12 kW placed on the EU market from 1 January 2027 must use refrigerants below GWP 150, and F-gases are to be phased out of these units from 2032 — installed units keep running, and exemptions and national implementation are still being worked out. R290 propane has a GWP of roughly 0.02 (IPCC AR6), sits outside the HFC quota system and reaches flow temperatures of 70–75 °C.
R290 is an A3 flammable refrigerant, and the monoblock construction is precisely what makes it manageable: the whole charge stays outdoors in a sealed circuit, so indoor charge limits never come into play. Meanwhile the HFC supply squeeze is already priced in — the EU quota for 2025–2026 is 42.9 Mt CO2e, about 48% below the 2023 level, pushing service prices of high-GWP refrigerants steadily upward.
What are the advantages and limitations of a monoblock?
Advantages: single outdoor unit, faster installation, no on-site refrigerant work, factory-verified charge and performance, natural fit for R290, easy pairing with existing cylinders and buffers. European market data reflects the shift: heat pump sales grew 13% in 2025 to 2.88 million units (EHPA), with R290 monoblocks the fastest-moving air-to-water category.
Limitations: the outdoor water pipes must be protected against freezing — by glycol in the outdoor section, by antifreeze valves that dump water below about 3 °C, or by guaranteed pump circulation. Long outdoor pipe runs lose heat, so the unit belongs as close to the building as siting allows. All hydraulics being outdoors also means service work happens outdoors. The compressor and fan live outside too, so siting should respect distances to neighbouring windows and use a vibration-decoupled base — the two factors behind most noise complaints.
Solimpeks builds its monoblock air-to-water heat pump range — including the R290 Varm Boost Series — at its Konya factory and serves customers in 96+ countries.
Frequently asked questions
Does a monoblock heat pump need an F-gas certified installer?
Not for the refrigerant circuit — it is factory-sealed and never opened during installation. Hydraulic and electrical work follows normal trade rules. Servicing that does open the circuit requires certified competence, and from 12 March 2026 EU-wide training requirements also cover natural refrigerants such as R290.
How do you stop a monoblock freezing in winter?
Three standard methods: fill the outdoor section with a glycol mixture, fit antifreeze valves that automatically drain the exposed section near 3 °C, or rely on continuous circulation with backup power. One of them must be designed in — still water in outdoor pipes bursts them in one hard night.
Is a monoblock less efficient than a split heat pump?
No — the refrigerant circuit is the same technology, and factory sealing removes field workmanship variables. The only structural penalty is heat loss from outdoor water pipes, which good insulation and short runs keep to a few percent.
Can a monoblock heat pump be installed far from the house?
Keep water runs as short as practical: every metre of outdoor pipe adds standing heat loss and pumping resistance. Where distance is unavoidable, oversized insulation and a correctly sized circulation pump limit the damage.