The Navien PEM750 is Navien's flagship R290 propane monobloc air source heat pump for UK residential properties. Available in five capacities from 4 kW to 17 kW — select the size that matches your calculated heat loss on the variant selector. Every variant shares the same platform: R290 refrigerant (GWP 3), flow temperatures up to 75°C, reliable operation down to -20°C ambient, MCS/Keymark certified, BUS grant eligible, and backed by Navien's UK warranty of up to seven years parts and labour.

4–17 kW

Output range

R290

Refrigerant (GWP 3)

Up to 75°C

Max flow temp

SCOP 4.87

Peak efficiency

-20°C

Min ambient

7 years

Warranty

BUS grant eligible

The Navien PEM750 is eligible for the UK Boiler Upgrade Scheme grant when installed by an MCS-certified installer in an eligible property. The grant is paid directly to your installer and discounted from your quote.

R290 outdoor unit siting

R290 is an A3 flammable refrigerant. UK installation requires minimum clearances from doors, windows, drains and ignition sources per Navien's technical manual. Most domestic gardens accommodate the unit easily — constrained sites need design review before ordering.

MCS-certified installer required

To claim the BUS grant and validate the full Navien manufacturer warranty (up to 7 years parts and labour), this heat pump must be installed and commissioned by an MCS-certified heat pump installer. Quality Heating can connect you with our trade network.

Choose your capacity

Heating output	Typical property fit	Navien part number
4 kW	Small, well-insulated 1–2 bedroom homes and flats	GPEM750004VGP01
6 kW	Typical 2–3 bedroom UK homes with average insulation	GPEM750006VGP01
8 kW	3–4 bedroom semis and detached homes	GPEM750008VGP01
10 kW	Larger 4–5 bedroom detached properties	GPEM750010VGP01
17 kW	Very large detached homes, older properties with retrofitted insulation, or small commercial	GPEM750017VGP01

Sizing tip

Always size a heat pump from a calculated room-by-room heat loss survey — not from bedroom count or existing boiler size. Oversized heat pumps short-cycle and lose efficiency; undersized units rely too heavily on backup heat. Quality Heating offers free heat loss calculations on request.

Why choose the Navien PEM750

R290 refrigerant — GWP 3

Propane refrigerant with a GWP of just 3 — close to one-thousand times lower than legacy split heat pump refrigerants. The most future-proof choice ahead of tightening UK F-Gas regulation.

Flow temperatures up to 75°C

Delivers 75°C flow temperatures — exceptional for radiator-only retrofits where existing emitters need to stay in place, and ideal for high-temperature DHW production.

Reliable cold-weather output

Rated operation down to -20°C ambient — dependable heat delivery through UK winter cold snaps, no supplementary heat required in typical conditions.

SCOP up to 4.87 — A+++ ERP

Top-tier seasonal efficiency for meaningful annual running-cost savings versus older split systems and, in most retrofit cases, versus running a gas boiler at current tariffs.

Sealed monobloc — no on-site F-Gas

Refrigerant circuit fully sealed at the factory. The installer only connects water pipes indoors — no F-Gas brazing required at install, reducing complexity and cost.

Smart touch display + app + web

Onboard smart touch display for setup, and dedicated smartphone app plus web platform for remote monitoring, scheduling, and fault alerts.

Shock absorption technology

Enhanced stability through shock absorption in the outdoor unit — reduces transmitted vibration and helps sustain performance across the warranty period.

Up to 7-year warranty

Backed by Navien UK's manufacturer warranty of up to seven years, parts and labour included — one of the strongest warranty offers on the UK heat pump market.

Platform specification (all variants)

Range	Navien PEM750
Type	R290 monobloc air source heat pump
Available capacities	4 kW / 6 kW / 8 kW / 10 kW / 17 kW
Refrigerant	R290 propane (GWP 3)
Maximum flow temperature	75°C
Minimum operating ambient	-20°C (rated); reliable operation in UK winter conditions
Peak SCOP	Up to 4.87 (35°C low-temperature output)
ERP energy label	A+++
Electrical supply	220–240V, 50Hz, single-phase (all variants)
Certifications	MCS certified, Keymark, BUS Grant eligible
Outdoor unit finish	Grey
Architecture	Sealed monobloc — no on-site refrigerant brazing
Compatible with	Radiators, underfloor heating, DHW cylinders
Smart control	Onboard smart touch display + smartphone app + web platform
Warranty	Up to 7 years parts and labour (Navien UK, MCS install)

What's in the box (every variant)

Navien PEM750 outdoor monobloc unit (capacity per selected variant)
Refrigerant circuit and integrated controls
Manufacturer installation and commissioning documentation
Navien UK warranty registration card

What you'll also need (sold separately)

DHW cylinder (heat-pump-suitable, indirect coil sized for low flow temperature)
Indoor hydraulic kit / wiring centre (Navien's dedicated wiring centre simplifies commissioning)
Outdoor wall bracket or floor stand
Anti-freeze valves on primary flow and return
Magnetic system filter on the primary return
Buffer tank if system water volume falls below Navien's minimum
Condensate drainage — piped to soakaway or gulley recommended

Frequently Asked Questions

Which kW should I choose?

Choose the variant that matches your calculated heat loss. As a rough guide: 4 kW for small well-insulated 1–2 bed homes; 6 kW for typical 2–3 bed homes; 8 kW for 3–4 bed semis and detached; 10 kW for larger 4–5 bed detached; 17 kW for very large or lightly-insulated properties. Always confirm with a proper heat loss survey — sizing by rule of thumb is the most common cause of poor heat pump performance.

Is R290 safe for a domestic installation?

Yes. R290 is widely used across Europe in domestic heat pumps and refrigeration. The refrigerant is sealed inside the outdoor unit, which sits outside the property. UK installation rules govern minimum siting clearances to ensure safety; a competent designer will ensure these are met.

Will my existing radiators work with the PEM750?

In most retrofit cases, yes — the PEM750's 75°C flow temperature means existing radiators sized for a gas boiler will usually deliver enough output without uprating. A heat loss survey identifies any coldest-rooms exceptions.

Do I need to be MCS-registered to install this?

The unit can be installed by any competent heating engineer, but to claim the Boiler Upgrade Scheme grant and to activate the full 7-year Navien warranty, the install must be carried out by an MCS-certified installer. Quality Heating can introduce you to trade partners if needed.

How loud is the outdoor unit?

Navien quote a low-noise floor of 42 dB(A), quieter than a typical gas-powered boiler. Sound power figures rise with capacity (larger units are inherently louder), but every variant is designed to meet MCS 020 boundary noise limits on a normal domestic install.

Is there a smart control included?

Yes — every PEM750 includes a smart touch display onboard, plus a dedicated smartphone app and web platform for schedules, monitoring and fault alerts. No extra Wi-Fi module needed.

NAVIEN