Understanding the difference between a monobloc and a bibloc air-to-water heat pump
Monobloc: the whole refrigerant circuit outdoors, what this changes on site
On a monobloc heat pump, the refrigerant circuit is factory-sealed inside the outdoor unit. On site, you mainly install hydraulics, with two water pipes entering the home. Fewer refrigerant-related tasks, but one point of attention: the freeze risk on the outdoor lines, to be managed with antifreeze or heat tracing.
Bibloc: outdoor unit + indoor module, key points for your teams
On a bibloc, the outdoor unit exchanges heat with an indoor module via refrigerant lines. This is handy for keeping water out of the outdoor unit and improving frost protection, but it requires careful installation: line length, vacuum pull-down, leak-tightness. Plan for the right tools and refrigerant skills.
Hydraulic, refrigerant, electrical: who does what depending on the heat pump type
In both cases, hydraulics remain the heating engineer's job: heating and domestic hot water connections. The refrigerant part is almost absent on a monobloc, while on a bibloc it falls to an authorized technician. The electrical side, protections and power supply, is coordinated with your electrician and the manufacturer's manual.
Choosing based on the home and usage: the right criteria in 2026
Renovation with radiators or underfloor heating: compatibility and flow temperatures
A heat pump is chosen first based on the flow temperature your network needs. Underfloor heating often targets around 35°C. Radiators may need 45°C to 55°C, or even more in a poorly insulated home. The higher you go, the more consumption climbs. Hence the value of aiming for low temperature after insulation work, or of increasing the emitter surface area.
Domestic hot water, volume, noise, footprint: deciding without getting it wrong
If you want hot water, look at the hot water tank. 180 to 300L often covers a household, depending on usage. On the comfort side, also check the sound level of the outdoor unit and its location. A good compromise is to keep it away from bedrooms and property boundaries, without unnecessarily extending the lines.
Climate, freezing and siting: monobloc and bibloc against weather constraints
In a cold zone, the freeze risk matters. A monobloc puts water outdoors, so the network needs to be secured (antifreeze, insulation, shutoff, draining depending on the case). A bibloc limits this issue, since the water stays indoors, but it requires refrigerant lines and careful installation. Also consider defrosting, wind, and ventilation clearances.
Installation: what really differs between monobloc and bibloc
Site prerequisites: location, networks, condensate drainage and anti-vibration mounting
For a heat pump, most of the comfort is decided before installation. For both monobloc and bibloc, plan for a clear location, maintenance access, a clean route for the electrical supply, and condensate drainage. Add an anti-vibration mount and think about noise, neighbors, and the freeze risk on outdoor networks.
Connections: hydraulic only on monobloc, refrigerant lines on bibloc
The monobloc connects with hydraulics only from outside. This involves pipe insulation, antifreeze management (lagging, heat tracing or glycol depending on the case) and a water leak-tightness check. On a bibloc, refrigerant lines between units are added, with length constraints, vacuum pull-down, leak tests and regulated handling of refrigerants.
Commissioning, settings and balancing: securing performance
Commissioning isn't just about "it heats." Purging, pressure, flow rate, heating curve, backup, domestic hot water and defrost cycles all need to be set to maintain performance. Balancing the emitters prevents overheated rooms and returns that are too hot. On a bibloc, refrigerant checks are a mandatory step.
Costs, timelines and maintenance: comparing to help your client decide
Equipment, accessories and labor: where the price differences come from
The price of a heat pump mainly varies by type (air-to-air, air-to-water), power, and controls. Differences also come from accessories: hydraulic module, hot water tank, buffer tank, refrigerant lines, water treatment, sludge removal. This is often where the quote shifts.
Installation time and coordination (plumber, refrigeration technician, electrician): avoiding extra costs
A smooth job costs less. Coordinated penetrations, network routing, reserved volumes, and same-day commissioning. When the plumber, refrigeration technician and electrician cross paths without a schedule, time is lost and the bill grows.
Maintenance and common failures: parts, accessibility and field feedback
Plan ahead for maintenance. Access to filters, heat exchangers, circulator, sensors, and control boards. Common failures come from a flow-rate defect, a fouled heat exchanger, or a faulty sensor. Plan for simple monitoring and available parts.
Grants and rules to know in 2026 for an air-to-water heat pump
RGE, F-gas and certificates: staying compliant whether monobloc or bibloc
To unlock grants, the company must be RGE QualiPAC certified. On a bibloc heat pump, there's a refrigerant connection. The technician must therefore hold an F-gas capability certificate, and commissioning must be documented. On a monobloc, the refrigerant circuit is factory-sealed. You avoid handling refrigerant on site, but the electrical, hydraulic and commissioning rules still apply.
MaPrimeRénov' and CEE: points to watch on heat pump applications in 2026
In 2026, check the current scales and conditions (home, income, type of replacement). On the quote and invoice, specify the model, power, seasonal performance, controls and useful options (sludge removal if planned). On the CEE side, refer to the standardized operation sheet dedicated to air-to-water heat pumps. Watch the dates: the quote must be signed after the applicant's commitment, otherwise the file can be rejected.
Documents to hand over: commissioning report, manual, settings and usage advice
Hand over the commissioning report, the manual, the installed references and a summary of the settings (heating curve, curve slope, schedules, hot water setpoint). Add a simple memo: best practices, maintenance, antifreeze, what to do in case of an alarm. A clear file limits callbacks and secures the grants.
Key figures
no refrigerant indoors
Monobloc
refrigerant indoor/outdoor
Bibloc
needs antifreeze
Monobloc freeze risk
Frequently asked questions
For a monobloc air-to-water heat pump, since the refrigerant circuit is factory-sealed, you generally don't need to handle refrigerants: a certificate isn't required for the hydraulic/electrical installation. On a bibloc, the refrigerant lines, vacuum pull-down and leak test must be performed by an authorized operator with a capability certificate and qualified staff. Always check the manufacturer's manual and the exact scope of operations planned for the site.
Louis Airy
COO of Argile
