Your MVHR filters should typically be replaced every 6 months, though this may vary depending on your location, system usage, and air quality. Homes in urban areas like Bristol, Cardiff, or Gloucester may require more frequent filter changes due to higher pollution levels.

Zehnder systems such as the ComfoAir Q (CAQ) and ComfoFlex automatically alert you when filters need replacing.

Order genuine Zehnder MVHR filters directly from our online shop – we offer some of the lowest prices on Zehnder CAQ filters in the South West.

A full MVHR service (recommended annually) ensures your system continues to provide clean, balanced ventilation and maximum heat recovery efficiency.

Our service includes:

• Cleaning and inspecting heat exchangers, fans, and internal components
• Checking and balancing airflow across your home
• Testing ducting and condensate drains
• Inspecting seals and filters for wear or blockages

If you own a Zehnder MVHR system, an annual service by a Zehnder UK Service Partner like us is required to keep your warranty valid (1 year parts & labour, 2 years parts, and up to 5 years extended warranty).

We provide MVHR servicing across Bristol, Bath, Somerset, South Wales, and Gloucestershire.

Neglecting your MVHR maintenance can lead to:

• Reduced airflow and efficiency
• Condensation, damp, or mould
• Increased noise from overworked fans
• Higher energy consumption

Zehnder systems use constant volume fans that automatically compensate for blocked filters, meaning the fans will run harder and wear out faster if maintenance is skipped.

You can perform simple home MVHR maintenance such as:

• Replacing filters
• Cleaning supply and extract vents

However, full MVHR servicing – including airflow balancing and component inspection – should always be done by a qualified MVHR engineer.

We’re fully trained Zehnder service partners offering professional MVHR servicing in Bristol, South Wales, Somerset, and the South West.

Louder-than-normal operation often means your MVHR unit’s filters are clogged or external vents are blocked, causing the fans to increase speed to maintain airflow.

Try this first:

• Check and replace filters (including any pre-heater filters)
• Clear external grilles of dust, leaves, or cobwebs
• Clean your internal air vents

 

If the noise persists, it could be due to worn fan bearings or incorrect commissioning – contact us for expert MVHR diagnostics in Bristol or South West.

Yes. Zehnder MVHR units such as the ComfoAir Q can be fitted with Active Carbon Filters that absorb odours and pollutants, improving indoor air quality.

If your MVHR system doesn’t support these, we can retrofit an external charcoal filter box to help remove unwanted odours from traffic or nearby wood burners.

Contact us to discuss MVHR air quality upgrades in the South West or South Wales.

During colder months, your MVHR system may dry indoor air because of the low humidity of incoming outdoor air.

Tips:

• Lower fan speed or use “Away Mode” when not home
• Add houseplants or a humidifier
• Upgrade to an ERV (Energy Recovery Ventilation) core, which retains moisture as well as heat.

We can retrofit ERV cores to Zehnder MVHR systems across Bristol and surrounding regions.

Not directly. MVHR units are designed to recover heat from extracted air but not redistribute it throughout your home. It’s normal to see temperature differences of 4 – 10°C between heated and unheated rooms.

This often points to a blocked or dry condensate trap.

Try this:

• Check the condensate drain for blockages
• Pour water into the trap to reseal it if dry

If water continues to leak, book an MVHR inspection – we’ll fix it before any damage occurs.

• If you own a Zehnder MVHR system and your touchscreen fails, listen for fan noise.
• If the fans are running, it’s likely just the screen.
• If the fans are silent, it may indicate a PCB (mainboard) issue.
• Check your power supply and fuses first.
• If the problem remains, contact us for Zehnder MVHR repairs

MVHR airflow can be subtle and difficult to detect.

Check:

• Is the MVHR unit powered and running?
• Hold tissue near a vent – it should move slightly. If not, your system may need recommissioning.

We provide MVHR performance testing and balancing in Bristol and surrounding areas.

For Zehnder MVHR systems with app connectivity:

• Enable Remote Support in the Zehnder app
• Send us your access PIN for secure remote diagnostics
• If your unit shows an ODA error, email hello@earthwiseconstruction.co.uk with your model, serial number, and location.

We’ll check with Zehnder for warranty coverage and arrange a repair visit.

Yes. If your Zehnder MVHR has app control, you can enable Remote Support and share your access PIN so we can safely log in to assess system data and diagnose issues.

This is normal, particularly in colder months when bathroom surfaces are cold. Your MVHR system will clear moisture over time. You can speed this up by activating the Boost mode or leaving the fan running longer after bathing.

If there’s a power cut, your MVHR unit will stop temporarily. You may notice the air feeling stale, but the system will restart automatically when power returns. If it doesn’t, check your fuse box and power supply before calling for assistance.