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.
SCOP 4.87
Peak efficiency
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.
