NIBE introduced the S735 Exhaust Air Heat Pump on 5 October 2023, the newest addition to its S-Series range, according to the Chartered Institute of Plumbing and Heating Engineering (CIPHE), which published the announcement1.
The S735 is described as NIBE's most powerful and energy efficient exhaust air heat pump to date, available in two sizes and designed to provide heating, hot water and ventilation within a compact internal footprint1. It uses the refrigerant R290, which NIBE says it has trusted in its heat pumps since 1998 and which has a Global Warming Potential of 3; the unit contains 420 grams of refrigerant, equivalent to 1.26kg of CO2 content1.
NIBE states the 3-in-1 design suits apartments and new build houses up to 160m2, or approximately 6kW peak heating load, with an inverter driven compressor that adapts to the property's needs1. For homes with a larger hot water demand, it can be supplemented with the NIBE VPB S200 hot water cylinder to give total stored hot water of 380 litres, which NIBE equates to an 8-person occupancy1. Because of how exhaust air heat pumps work, the S735 removes the need for an outdoor heat pump and a standalone heat recovery ventilation system1.
"NIBE is delighted to introduce their all-new S735 Exhaust Air Heat Pump"
The unit carries an A+++ energy rating, sound power of less than 49dB, MCS certification and a published SCOP of 4.29, and is listed under the SAP Product Characteristics Data Base as both an MEV and a heat pump product1. It uses the S-Series control system, and the S-Series Wi-Fi network supports NIBE's myUplink smart home accessories for demand-controlled ventilation and time and temperature-controlled heating zones, which NIBE says provides compliance with Part F and L of the building regulations1.
| Specification | Figure |
|---|---|
| Sizes available | Two |
| Suitable floor area | Up to 160m2 |
| Peak heating load | Approximately 6kW |
| Refrigerant charge | 420g of R290 |
| Refrigerant GWP | 3 |
| Stored hot water with VPB S200 cylinder | 380 litres |
| Energy rating | A+++ |
| Sound power | Less than 49dB |
| Published SCOP | 4.29 |
Why it matters for households
An exhaust air heat pump draws heat from the air a home extracts rather than from outside, so it replaces both a conventional boiler and a separate mechanical ventilation system in one unit1. For flats and smaller new builds, that removes the outdoor unit and the space and planning questions that come with it, and it means ventilation and heating are controlled together rather than as separate systems1. The published SCOP of 4.29 is a measure of seasonal efficiency, and the A+++ rating and MCS certification are the figures advisers and installers typically work from when assessing a property1. The R290 refrigerant's low global warming potential of 3 is a departure from the higher-GWP refrigerants used in older equipment, though the charge is small at 420 grams1. NIBE positions the S735 for compliance with Parts F and L of the building regulations and the Future Homes Standard, which is the framework new build ventilation and heating specifications are being written against1. Households in existing homes considering a NIBE heat pump should note the stated 160m2 and 6kW limits, above which the unit as described is not sized to serve the property1.
What happens next
No launch date, price or UK availability date beyond the 5 October 2023 announcement has been reported1.
Sources1 cited
- NIBE Exhaust Air Heat Pump, ciphe.org.uk