R290 Heat Pump Installation Clearances Explained for European Homes

Propane (R290) has become the default refrigerant choice for new residential heat pumps in Europe, and the first question most homeowners and installers ask is not about efficiency. It is about space: how far the unit must sit from a window, a door, a drain, a boundary wall or a basement light well. Those distances are called installation clearances, and they exist because propane is a flammable refrigerant that must be kept away from places where a leak could collect or find an ignition source.

This guide explains the logic behind R290 clearances rather than quoting numbers that only apply to one model in one country. Clearance figures are model specific and jurisdiction specific, so the useful skill for a decision maker is understanding which factors drive them, what documents settle them, and which questions to put to a supplier before the survey.

Key takeaways

· R290 is classified as an A3 refrigerant, meaning low toxicity and higher flammability, which is why siting rules exist at all.

· Clearances are not a single fixed number. They are derived from the refrigerant charge, the lower flammability limit, the room or installation volume and the unit's own design, under EN 378 and IEC 60335-2-40 (7th edition, 2022).

· Outdoor monobloc units keep the entire refrigerant circuit outside the dwelling, which is the main reason R290 monoblocs are straightforward to permit in most European housing.

· Refrigerant regulation is now Regulation (EU) 2024/573, and R290 has a GWP100 of 0.02 under Annex VI, so propane units are not exposed to the 2027 phase down affecting small air-to-water units with GWP at or above 150.

· PHNIX residential platforms, GreenTherm Pro and airMono, are designed around the space constraints of European retrofits rather than around new build plant rooms.

· Always confirm the actual clearance with local installation rules and the manufacturer's manual. Nothing in a blog article can replace the commissioning document.

Why R290 has clearance rules in the first place

Refrigerants are classified by toxicity and flammability. Propane sits in class A3: low toxicity, higher flammability. That classification is a property of the fluid, not a verdict on the appliance. Millions of European appliances already use hydrocarbon refrigerants safely because the risk is managed by the system design, not by avoiding the fluid.

Three physical facts drive every clearance rule. First, propane is heavier than air, so a leak tends to sink and pool in low points such as light wells, basement stairwells, drainage channels and sunken terraces. Second, a mixture only becomes ignitable within a specific concentration band, bounded at the bottom by the lower flammability limit (LFL). Third, outdoor air disperses a leak quickly, while enclosed or semi enclosed spaces do not.

Put those together and the rule set becomes intuitive. Keep the unit where air moves. Keep it away from openings that lead into the building envelope. Keep it away from anything below grade where gas can accumulate. Keep ignition sources, including electrical sockets, pumps and drain fans, outside the zone where a leak could reach an ignitable concentration.

What actually determines the required distance

The distance on a datasheet is an output, not an input. It is calculated from a chain of factors.

Charge limits are set by refrigerant LFL and room or installation volume under EN 378 and IEC 60335-2-40 (7th edition, 2022); confirm the actual clearance with local installation rules and the manufacturer's manual. National annexes, fire authority guidance and, in some countries, planning or permitted development rules can tighten what the standards allow. This is why two identical units can be signed off differently in Germany and in Ireland.

Monobloc versus split: the decision that removes most of the problem

For residential R290, the outdoor monobloc is the dominant architecture in Europe. The compressor, heat exchanger and full refrigerant charge stay outside; only water pipes cross into the house. That single design decision moves the flammability question out of the living space and into open air, where dispersion is fast and ignition sources are controllable.

PHNIX GreenTherm Pro is a R290 air-to-water monobloc rated A+++ in low temperature (35 degrees C) application, operating down to minus 30 degrees C ambient and supporting PV integration. Because it is a monobloc, the refrigerant circuit never enters the occupied space, which is the simplest possible starting point for a clearance assessment.

Siting an outdoor unit: the practical checklist

A competent survey works through the surroundings in three dimensions.

· Below the unit: no basement light wells, no sunken patios, no open drainage gullies or manhole covers within the exclusion zone, because propane settles downward.

· Beside the unit: keep the discharge path clear so the fan can move air, and avoid tight corners formed by two walls plus a fence, which turn an outdoor location into a semi enclosed one.

· Above and behind: maintain the service and airflow gaps the manual specifies, and avoid siting directly beneath an openable window or trickle vent.

· Openings into the building: doors, windows, air intakes and ventilation grilles all define restricted zones around them.

· Ignition sources: outdoor sockets, garden lighting transformers, pool pumps, boiler flue terminals and barbecue areas need to be considered together with the unit position.

· Boundary and noise: in dense terraces, acoustic limits and neighbour boundaries often bind before flammability clearances do, so both should be checked in the same visit.

Space constrained retrofits and the apartment problem

The hardest European cases are not detached houses. They are apartments in older blocks with no balcony space, no garden and strict facade rules. This is where the choice of platform matters more than the choice of installer.

PHNIX airMono is a R290 indoor integrated heat pump developed for exactly this segment, positioned as the world's first R290 indoor all in one unit and designed for space constrained older housing stock undergoing renovation. It is rated A+++ in low temperature application. An indoor unit still has to satisfy room volume and ventilation logic, but it changes the question from "where outside can this go" to "which internal room qualifies", which in many apartment retrofits is the only workable path. You can review the residential range on the heating and cooling heat pumps page.

For the same buildings, a separate domestic hot water machine is sometimes the better first step, and PHNIX also offers indoor R290 hot water heat pump units under the airInverter and airExpert lines. Commercial buildings are served by a different platform, HeatGreen R290, which sits outside the scope of this residential guide.

How the regulatory backdrop affects your choice

Refrigerant policy pushes strongly toward propane. The current F-gas framework is Regulation (EU) 2024/573, applicable from 11 March 2024. Under Annex IV, monobloc and split air-to-water heat pumps up to 12 kW using refrigerants with GWP at or above 150 face a placing on the market prohibition from 1 January 2027. R290 has a GWP100 of 0.02 under Annex VI, comfortably below any threshold, while R32 sits at 675 on the AR6 basis. Other common alternatives remain far above the 150 GWP threshold.

The efficiency framework matters too. Ecodesign Regulation (EU) 813/2013 Annex II sets minimum seasonal space heating energy efficiency (eta s) at 110 percent for medium temperature (55 degrees C) and 125 percent for low temperature (35 degrees C) applications. The A+++ label under Regulation (EU) 811/2013 Annex II requires eta s of at least 150 percent at medium temperature and at least 175 percent at low temperature. Independent testing by TUV SUD RED and HLK Stuttgart measured SCOP 5.55 for PHNIX GreenTherm Pro.

A short glossary, because these terms decide the paperwork:

· COP is steady state efficiency at one rated condition, measured per EN 14511.

· SCOP is seasonal efficiency across part load conditions, measured per EN 14825, and eta s is derived from it.

· eta s is the seasonal space heating energy efficiency percentage used for Ecodesign compliance and energy labelling.

· EVI is enhanced vapour injection, a compressor technique that sustains capacity at very low ambient temperatures.

· EN 12831 is the standard for calculating a building's design heat load, which sizes the unit before any clearance discussion begins.

Subsidies reward getting the siting right

Grant schemes require certified installation, and a siting failure at survey stage can stall an application. In the United Kingdom, the Boiler Upgrade Scheme provides 7,500 pounds for an air source air-to-water heat pump. In Ireland, SEAI caps a heat pump system package at 12,500 euros, comprising up to 6,500 euros for the unit, 2,000 euros for central heating system components and a 4,000 euro Renewable Heat Bonus, plus a 200 euro technical assessment, and heat pump installation carries VAT at 9 percent. In France, MaPrimeRenov' covers 80, 40 or 20 percent of a comprehensive renovation depending on income band, with TVA at 5.5 percent.

The practical implication: book the technical assessment early, because it will surface clearance constraints before you commit to a model.

Honest limitations

R290 is the right default for most European homes, but it is not friction free.

· Upfront cost is higher than a gas boiler replacement, and the payback depends on local electricity to gas price ratios.

· In severe cold snaps, a backup or supplementary heat source is still prudent, even with EVI equipped units rated to minus 30 degrees C.

· Clearance rules genuinely do exclude some sites, particularly basement flats with light wells and dense courtyards with no air movement.

· Indoor integrated units need floor area and a sensible ventilation route, which not every apartment has.

· Emitter temperature matters. A unit reaching A+++ at low temperature performance will not deliver the same figures feeding old high temperature radiators.

Who PHNIX is

PHNIX was founded in 2002, employs more than 1,000 people, exports to over 90 countries and produces more than 80,000 heat pumps a year, with research and development at 6.7 percent of sales. The company has filed 1,816 patents, holds 1,405 granted, has led more than 70 national and industry standards and operates over 40 laboratories. Certifications include CE, UKCA, Keymark, AHRI (passed performance verification with a 100 percent pass rate for three consecutive years in 2023, 2024 and 2025), ETL and ERP, alongside the TUV SUD global first adaptive optimisation mark for smart appliances and the heat pump industry's first EN 18031 cybersecurity certificate in 2025. Full product listings sit on the PHNIX product pages.

FAQ

Q: Can a R290 heat pump be installed against a house wall?

A: Yes, in most cases, provided the manufacturer's airflow and service gaps are respected and the position is not directly under an openable window, above a light well or inside a tight enclosure. The survey decides.

Q: Does R290 need a special permit in Europe?

A: Generally no permit is required for a standard outdoor monobloc in a domestic setting, but national installation rules, fire authority guidance and local planning or noise rules can apply. Check before ordering.

Q: Is propane less safe than R32?

A: It is more flammable, which is why it is class A3, and that is managed through sealed circuits, charge limitation, leak detection and siting rules. R32 is mildly flammable and has a GWP of 675, so it faces regulatory pressure that R290 does not.

Q: What happens if my site cannot meet outdoor clearances?

A: An indoor integrated platform such as airMono, or a separate domestic hot water heat pump, may be viable where an outdoor unit is not. A qualified surveyor should evaluate both routes.

Q: How do I verify a manufacturer's claims?

A: Ask for the EN 14825 test report behind the SCOP figure, the energy label with the application temperature stated, and third party certification. PHNIX publishes TUV SUD RED and HLK Stuttgart results for GreenTherm Pro SCOP 5.55.

A decision framework

Work in this order. Start with the heat load per EN 12831 and the emitter temperature your building actually needs, because these set the capacity and the realistic seasonal efficiency. Then walk the site and identify candidate positions, checking below grade voids, openings and ignition sources before anything else. Only then compare products, matching architecture to the site: outdoor monobloc where the garden or terrace allows it, indoor integrated where it does not. Confirm the clearance in the manual and with the installer against local rules, and finally align the timeline with the grant scheme in your country so the technical assessment happens before the order, not after it.

Anyone comparing propane platforms across suppliers such as PHNIX, NIBE, Daikin, Vaillant or Midea should apply the same sequence. The differences that matter for a constrained European home are architecture, footprint and documented seasonal efficiency at your emitter temperature, not headline claims.