How the price of an MVHR relates to quality and performance

Crushed and bent flexi-duct will increase noise in an MVHR

I’ve written before about the average price of a high quality Mechanical Ventilation Heat Recovery (MVHR) installation, which includes an itemised price for each detailed ductwork layout, materials supply, installation and commissioning (airflow balancing and client handover). Today I’m going to explain (with photos) why the cheaper MVHR units are a false economy, and can … Read more

Do we need to make homes airtight in the UK?

Level 2 airtightness testing with blower door fan

30 years ago house-builders in the UK would have never considered how airtight they were building new homes. “Aren’t all homes fairly airtight, once you put the windows and doors in and pump the gaps with insulating foam?” Well, not necessarily. Fireplaces used to be for both heating and ventilation Traditionally, homes built before our … Read more

Is a detailed MVHR ductwork layout design really necessary?

Poor MVHR detailed ductwork design 3D overview image

A Mechanical Ventilation with Heat Recovery (MVHR) ventilation system is a technology that requires pre-design before it can be installed into a home, office, school or boat. The MVHR may include any and all of the following schedule of services: Calculation of required boost airflow rate to meet or surpass Part F Building Regulations Sizing … Read more

How much duct space do you need around the house for an MVHR system?

MVHR with ComfoCool installed in a residential home showing spacing requirements

The most common question I’m asked by people interested in mechanical ventilation with heat recovery (MVHR), low energy building design or Passivhaus is: How much space do we need for the ducts in an MVHR ventilation system? Variations to the question include: How big is the MVHR unit itself? How big are the ducts? Will … Read more

FAQ about MVHR systems: Cleaning ducts, indoor air quality and maintenance explained

In my role as the lead MVHR technician at Heat, Space and Light Ltd we receive lots of questions and queries about MVHR systems. I’ve collected together my responses to some of the most pressing concerns that people have with a home ventilation duct system – from airborne spores to cleaning, maintenance, kitchen extraction and … Read more

Difference between a branch and radial MVHR duct system – and which is better?

Manifolds for a radial semi-rigid ductwork system mounted on concrete floor

When you have decided to specify a Mechanical Ventilation with Heat Recovery (MVHR) system for your home, it can quickly become confusing which type of ducting to use. There are two main types of MVHR ducting to choose from, explained below: MVHR ventilation ducting in a “branch” layout This is the classic ventilation system, also … Read more

When spacing for MVHR ducts is tight, a combined intake-exhaust grille may be the solution

MVHR combined intake - exhaust grille for close proximity of external air ducts

Building Regulations requires that an MVHR’s intake grille (bringing fresh air into the property) and the MVHR’s exhaust grille (exhausting air from the property) should be 1.5 metres apart from each other. This is to prevent the system from sucking in the warm, humid exhaust air back into the property, also known as “cross-contamination”. The … Read more

MVHR Commissioning of a Zehnder ComfoAir Q600 with ComfoCool unit completed

Complicated ducting for an MVHR system with ComfoCool

14 June 2017: Today we finished the final stage of what was a complete design, supply, install and commissioning of a Zehnder ComfoAir Q600 Mechanical Ventilation with Heat Recovery (MVHR) system – that also features cooling air-conditioning. Although we’ve commissioned many Zehnder and PAUL MVHR units in the past, this was the first time we … Read more

How to DIY your own MVHR ventilation duct system (16 steps)

MVHR in a loft with 50mm steel sound drum attenuators to help with acoustics

Mechanical Ventilation with Heat Recovery systems (MVHR) are actually very straightforward to install yourself, as long as you’re reasonably handy with a drill and you aren’t afraid of heights. Here’s a step-by-step process for how to install your own MVHR or HRV system, safely, without leaks and saving a lot of money. If you’d like … Read more

Internal view of a Mechanical Ventilation with Heat Recovery unit

Internal mechanism of an MVHR unit

We’ve been chatting with people at the 2016 Homebuilding & Renovating Show in London all this weekend, and one of the cool toys we’ve had on offer has been one of the newest, top-of-the-range MVHR units from German-manufacturer Zehnder. The HRV unit had its panels removed and mounted in plexiglass, and the unit’s internal heat exchanger was … Read more