VENTILATION

Persistent condensation, mould around window frames, or a bathroom fan that’s noisy, weak or simply not there — ventilation comes up often during bathroom refurbishments, kitchen refurbishments and general improvement work. Here’s how we approach bathroom extractor fans and whole-house ventilation (MVHR) for properties in Burgess Hill and Mid Sussex.

BATHROOM EXTRACTOR FANS

• Bathrooms with a bath or shower need a minimum extract rate of 15 litres per second under Building Regulations Approved Document F, or 6 l/s for a WC-only room without a bath or shower.
• Fans should keep running for a period after use — an overrun timer (commonly around 15 minutes) or a humidity sensor (activating above roughly 65–70% relative humidity) is standard practice.
• Ceiling-mounted fans in a bathroom need to be rated at least IP44, with a higher rating required where the fan sits within the zones directly above a bath or shower.
• Ducting should run as short and straight as practical to open air outside — venting into a loft space without ducting through to an outside vent doesn’t clear moisture properly and risks condensation in the roof space.

WHOLE-HOUSE VENTILATION (MVHR & PIV)

Where a property is well insulated and draught-proofed, a single bathroom extractor isn’t always enough to keep air fresh throughout the whole home. Mechanical Ventilation with Heat Recovery (MVHR) draws stale, moist air out of bathrooms, kitchens and utility rooms and supplies filtered fresh air back into living spaces and bedrooms, recovering somewhere in the region of 70–90% of the heat from the outgoing air in the process. Done well, this can meaningfully cut heating costs alongside reducing condensation and improving air quality — particularly useful for allergy sufferers.

Positive Input Ventilation (PIV) is a simpler, lower-cost alternative often suited to older, less airtight homes with ongoing condensation or damp problems: a single unit, usually sited in the loft, gently pushes filtered fresh air into the property to dilute and displace humid air.

We’ll talk through which approach makes sense for your property, budget and the problem you’re trying to solve — there’s no one-size-fits-all answer.

WHEN THIS COMES UP

Ventilation is often specified as part of a bathroom refurbishment or kitchen refurbishment, planned alongside extensions and loft conversions, or fitted as a standalone fix where an existing fan has failed, is underpowered, or a property is suffering from condensation and mould. If your current extractor fan is noisy, weak, or you’re not sure it’s doing its job, we’re happy to take a look.

Any questions about this or your job? Call us on 01444 682683 or email info@mlpelectrics.co.uk — we’re happy to talk it through.

Frequently Asked Questions

Do I legally need an extractor fan in my bathroom?

If your bathroom doesn’t have an opening window, Building Regulations require mechanical extraction — a minimum of 15 litres per second for a bathroom with a bath or shower, or 6 l/s for a WC-only room. Even with a window, a fan is usually worthwhile to control condensation.

What’s the difference between an extractor fan and MVHR?

A standard extractor fan removes moist air from one room, typically a bathroom or kitchen, and expels it outside. MVHR is a whole-house system that extracts stale air from every wet room and supplies filtered fresh air to living spaces and bedrooms, recovering most of the heat from the outgoing air in the process.

Will MVHR reduce my energy bills?

It can — by recovering roughly 70–90% of the heat that would otherwise be lost through ventilation, MVHR reduces the heating needed to warm incoming fresh air. Savings depend heavily on how airtight the rest of the property is, so it suits well-insulated homes and new builds best.

My bathroom fan is noisy or barely working — can you help?

Yes — this is often down to an old, underpowered fan, a blocked or badly routed duct, or a failing motor. We can inspect the existing setup and recommend whether a repair, like-for-like replacement, or upgrade makes the most sense.