A single room heat recovery unit (SRHR) is a compact decentralised ventilation system installed through an external wall. It works by extracting stale air from a room (like a bedroom, living room, or office) and simultaneously bringing in fresh outdoor air.

The key feature is its heat exchanger, which transfers warmth from the outgoing air to the incoming air, so you keep the heat inside while still getting fresh air.

How Does It Work?

• Stale, warm air is extracted from the room
• Fresh, cooler air is drawn in from outside
• Inside the unit, heat from the outgoing air is transferred to the incoming air
• The room receives pre-warmed, filtered fresh air

This process ensures continuous ventilation without the typical heat loss you’d get from opening windows.

Yes, installing a single room heat recovery unit can help you save money on your heating bills, especially when compared to traditional ventilation methods like extractor fans or simply opening windows.

In a typical home, stale air is often removed by letting warm air escape and replacing it with cold air from outside. This means your heating system has to work harder to bring the temperature back up, which increases energy use and costs.

A single room heat recovery system works differently. It captures heat from the outgoing air and uses it to warm the incoming fresh air. This process significantly reduces heat loss, helping your home stay warmer for longer without extra strain on your heating system.

A Single Room Heat Recovery (SRHR) unit is a more advanced alternative to a standard extractor fan. While extractor fans simply remove stale air from a room and replace it with outside air (often through gaps and vents), SRHR systems both extract and supply air simultaneously.

The key advantage of SRHR is heat recovery. As stale air is removed, the system captures much of its heat and transfers it to the incoming fresh air. This helps maintain room temperature, improves energy efficiency, and reduces heating costs.

In contrast, extractor fans can lead to heat loss, draughts, and less controlled ventilation. SRHR units also tend to improve indoor air quality more effectively by continuously supplying filtered fresh air with the additional benefit of heat recovery - lowering your heating bills. 

Yes, single room heat recovery units can be used in a “summer mode” to maintain comfort during warmer months.The units can be set to free cooling to prevent heat exchange when not needed, such as during the summer. There is also an integral LED light to indicate when the “free cooling” option is active. This mode can be activated using the remote included in the SRHR Elta Plus package or is manually set on the unit of the Vent-Axia Tempra. 

The answer is not always -  you don’t usually need a single room heat recovery unit in every room. These systems are designed to be flexible and targeted, so you can install them only where ventilation is most needed.

For the best results, single room heat recovery units are typically installed in:

• Bedrooms – for better sleep and fresh air overnight
• Living rooms – where people spend the most time
• Home offices – to improve focus and air quality
• Problem areas – rooms with condensation, damp, or poor airflow

In many homes, just one or two well-placed units can make a noticeable difference.

No, most units are designed to run very quietly, making them suitable for bedrooms and living areas.

Most single room units typically operate between:

• 21 - 45 dB depending on speed and model
• Around 24 - 38 dB in normal use (similar to a whisper or rustling leaves)

To put that into perspective:

• 20 - 30 dB = whisper-quiet
• 30 - 40 dB = very quiet background noise

This means many systems are barely noticeable during everyday use, especially on lower settings.

Yes, continuous airflow removes excess moisture, helping to prevent condensation and mould growth.

How Do They Reduce Condensation?

Condensation forms when warm, moist air hits cold surfaces like windows or walls. A single room heat recovery unit works by:

• Continuously extracting moist, stale air
• Bringing in fresh, filtered air from outside
• Balancing humidity levels in the room

By keeping air moving and moisture under control, it stops condensation from building up in the first place.

How Does It Help Prevent Mould?

Mould thrives in damp, poorly ventilated spaces. These units help by:

• Lowering humidity levels, making it harder for mould to grow
• Improving airflow, especially in problem areas
• Reducing damp conditions on walls, ceilings, and around windows

Over time, this creates a healthier indoor environment that is far less prone to mould issues.

A humidistat is a built-in sensor that monitors the moisture level (humidity) in the air. When humidity rises above a set threshold, such as during showering or cooking, the unit automatically boosts its ventilation rate to remove excess moisture.

Once humidity levels return to normal, the system gradually reduces back to its standard operating speed.

This automatic function helps:

• Prevent condensation and damp
• Reduce the risk of mould growth
• Maintain a comfortable indoor environment without manual adjustment

Our Elta units and Vent-Axia Tempra HTP both have a built in humidistat making indoor comfort easier than ever. 

No, they are energy-efficient and use very little power, often costing just a few pence per day to run.

How Much Do They Cost to Run?

Most units use very little electricity, typically:

• 20 - 40 watts (similar to a low-energy light bulb)
• Around £25 per year in electricity
• Roughly £2 per month for continuous operation

Because they run 24/7 at low power, they maintain air quality without significantly impacting your energy bills.

Do They Save You Money?

Yes, this is where they really stand out.

By recovering heat that would otherwise be lost through ventilation, they can:

• Reduce heating costs by 15 - 30%
• Lower the need to open windows in winter
• Improve overall energy efficiency of your home

In many cases, the energy savings offset the running cost, meaning the system can effectively pay for itself over time.

While some experienced DIY users may attempt installation, professional installation ensures compliance with electrical regulations and optimal performance.

The general process includes:

1. Wall Preparation
A core hole (typically around 150 – 200mm diameter depending on the model) is drilled through an external wall to allow airflow in and out.

2. Fitting the duct

A duct is inserted into the hole to form a sealed passage for the unit.

3. Installing the Unit
The SRHR unit is fitted into the duct on the inside wall, and an external grille is installed outside to protect against weather and debris.

4. Electrical Connection
The unit is wired to a power supply. This may include connection to a switched live, lighting circuit, or continuous supply depending on the model and control method.

Elta packages come with full set up of unit, duct and external grille.