Managing Your Beam MVHR System in the Summer Months

With the warmer weather arriving, keeping your home cool and comfortable becomes a priority. 

If you have a BEAM Heat Recovery Ventilation (MVHR) System, we're here to help you make the most of it, plus share some simple summer tips to keep your space feeling fresh. 

We often get questions about how BEAM MVHR systems work in warmer weather, especially when homes start to feel too hot.

Modern new build homes are built as airtight as possible for energy efficiency, which is great for winter heating but can trap heat on hot days. 

If your home has large windows or lots of glazing, you'll also be dealing with solar gain, which is basically the sun turning your house into a greenhouse! 

Let's break down how your MVHR system works in the summer and what you can do to stay cool. 

While MVHR (Mechanical Ventilation with Heat Recovery) does manage air changes, it’s not an air conditioning system. Its main job is to ventilate your home by providing clean filtered air into the home, whilst at the same time extracting stale moist air out from your wet rooms and kitchen.

Some BEAM MVHR units come with features like Summer Bypass, Summer Boost, and Summer/Night Cooling, which can help in warmer months. But they’re designed to ventilate - not cool.

Summer Bypass is an automatic feature on BEAM Counterflow MVHR systems. You don't need to switch anything on. 

When the indoor temperature gets higher than the outside, the system will start diverting air around the heat recovery cell. That means the incoming air won’t be warmed by the outgoing air.

Your home stays ventilated, but without that extra warmth being added. Once things cool down, the system goes back to normal automatically.

Summer Boost increases the fan speeds to bring more fresh air into your home and remove stale air faster. You’ll notice more air movement, which can help it feel fresher, even if it doesn’t technically cool the space.

Check your user manual for how to enable this, or give us a call if you're not sure.

Summer/Night Cooling is available on the HERU MVHR Range. These functions need to be manually activated using the controller. 

How it works: 

If it’s hotter inside (say 22°C) than outside (maybe 18°C), the system will help bring cooler outdoor air into your home. This is most effective overnight when outdoor temperatures drop. 

Please check your manual for further information on your specific model, or view Summer/Night Cooling instructions here. You can also get in touch with our helpful team. 

It’s absolutely fine to open windows in hot weather! Your MVHR system will continue to ventilate your home, even with the windows open. 

The only downside is that air coming through open windows won’t be filtered, which might be a factor for allergy sufferers.

We don't recommend turning your MVHR system off in warmer weather, but you can. If the system is turned off, you will lose the benefit of clean, fresh, filtered air. 

Following the steps above will be much more beneficial in creating a more comfortable home during the summer months.

This can be done, but only if it was designed in at the build stage. It cannot be retrofitted efficiently.

MVHR and air conditioning can work really well together.

MVHR is used to filter and change the air for clean, fresh filtered air in the home and the aim of air conditioning is to cool this air.

• With air conditioning and no MVHR you will have cool indoor air – but it will not be ventilated so while the air will be recirculated, it won't be fresh and will feel uncomfortable.
• With MVHR and no air conditioning – you will have clean fresh filtered air, but in the summer months you may find your home gets too warm.

In some homes, such as those with an increased amount of glazing, it has become popular to fit domestic air conditioning units into the master bedroom and kitchen/dining areas of the home. If you feel that the design of your house will raise the risk of overheating, then this is something to consider as well as your ventilation options.

As well as running your ventilation system appropriately using the functions just mentioned, it is advisable to:

1. Use your MVHR system as normal (at a higher speed if needed), until the inside temperature rises higher than the outside temperature.
2. Open windows and doors when the outside temperature is lower than inside.
3. Close curtains/blinds (especially on south facing windows) to block out strong sunlight and reduce solar gain.