Monobloc or split heat pump: which to choose?

In short

In a monobloc the whole refrigerant circuit is in the outdoor unit and only water enters the house. In a split the refrigerant runs through pipes to an indoor unit. A monobloc simplifies installation; a split keeps the water pipes better protected from cold.

Author: Climai Group technical teamTechnical review: Climai GroupUpdated: 19 October 2026

What is the difference?

Aspect	Monobloc	Split
Refrigerant circuit	All in the outdoor unit, factory-sealed	Between the outdoor and indoor units
What enters the house	Water pipes	Refrigerant lines
Indoor unit	Hydraulic module (sometimes combined with the cylinder)	Indoor unit with the heat exchanger
Frost protection	Water runs outside: it must be protected	Water stays inside the house
Installation	Water connections only	Refrigerant line connection, vacuum and testing

Why a monobloc with R290?

With refrigerants such as R290 (propane), which is flammable, the monobloc has a clear advantage: the refrigerant does not enter the house. Instruction IF-20 of the Refrigeration Safety Regulation (RD 552/2019) requires the unit to be outdoors or in a machine room, with safety distances. In addition, a compact monobloc whose refrigerant circuit is not handled can be installed by a RITE-authorised company.

When does a split make sense?

When the outdoor unit is far away and you would rather not run water outside.
In areas with frequent frost, where water outdoors is a risk. Rare in Ibiza.
When the chosen model or the indoor space calls for it.

What needs protecting in a monobloc?

The water section between the outdoor unit and the house must be well insulated and protected from cold with one of these solutions:

antifreeze (glycol) in the circuit;
anti-freeze valves that drain the outdoor section when the water approaches 0 °C;
the unit's own protection, which runs the circulation pump in cold weather.

In Ibiza the average January low is 8.1 °C and there is almost no frost (AEMET), but well-designed protection avoids surprises. See do heat pumps work in winter in Ibiza?.

How do you decide?

Where the outdoor unit goes and how far it is from the plant room.
Which refrigerant you want: R290 or R32.
How much indoor space there is for the module and the cylinder.
Which emitters you have: underfloor heating or radiators, which set the water temperature.
Each model's SCOP at that temperature. See SCOP: how to compare heat pumps.

Frequently asked questions

Which is more efficient?

It does not depend on monobloc or split, but on the model, correct sizing and water temperature. Compare each data sheet's SCOP at the same temperature.

Do monobloc water pipes get cold?

Water runs through the outdoor unit and the section to the house. Frost is very rare in Ibiza, but it is worth protecting with antifreeze, anti-freeze valves or the unit's own protection.

Who can install each one?

A compact R290 monobloc, without handling the refrigerant circuit, can be installed by a RITE-authorised company or a level 1 refrigeration company (instruction IF-20). A split requires connecting refrigerant lines, work for authorised refrigeration staff.

Which takes up less space indoors?

It depends on the model. There are monoblocs with a small hydraulic module and splits with a built-in cylinder. Space is mostly defined by the hot water cylinder.

Can the outdoor unit go far from the house?

In a monobloc the distance is limited by heat loss from the water and the pipe insulation; in a split, by the maximum refrigerant line length the manufacturer states.

What do you recommend?

It depends on each house: where the outdoor unit goes, the distance to the plant room, the refrigerant and the indoor space. We decide on the site visit.

Sources

Royal Decree 552/2019, Safety Regulation for Refrigeration Plants and Installations (IF-20) · BOE · 2026-10-19

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