Comparing MVHR and PIV Systems: Which is Right for Your Home?

When considering ventilation systems for your home, Mechanical Ventilation with Heat Recovery (MVHR) and Positive Input Ventilation (PIV) are two leading options. Both systems aim to improve indoor air quality, but they achieve this in different ways and are suited to different types of properties. Let’s break down the key differences, benefits, and considerations for each system to help you make an informed decision.

What is MVHR?

Mechanical Ventilation with Heat Recovery (MVHR) is a whole-house ventilation system that extracts stale air from wet rooms (like bathrooms and kitchens) and supplies fresh, filtered air to living spaces. The system includes a heat exchanger that recovers heat from the outgoing air and uses it to warm the incoming air.

Key Features of MVHR:

1. Heat Recovery: Recovers up to 90% of the heat from outgoing air, reducing energy waste.
2. Filtered Air: Provides fresh air while filtering out pollutants, allergens, and dust.
3. Balanced Ventilation: Maintains consistent air circulation throughout the home.
4. Energy Efficiency: Works well in airtight homes with high insulation standards.
5. Advanced Technology: Airfi’s MVHR systems feature an AI-driven defrost system (AFPS™) that adapts to indoor conditions like humidity and filter dirt build-up, ensuring optimal energy savings and performance during extreme weather conditions. Learn more about Airfi MVHR systems.

What is PIV?

Positive Input Ventilation (PIV) is a simpler ventilation system that works by introducing fresh air into the home, typically from the loft. This positive pressure forces out stale, humid air through natural gaps or trickle vents.

Key Features of PIV:

1. Simplicity: Easy to install and maintain.
2. Cost-Effective: Lower upfront and operational costs compared to MVHR.
3. Humidity Control: Reduces condensation and mold growth by lowering humidity levels.
4. Less Intrusive: Ideal for homes with natural air leakage.
5. Moisture Prevention: Effectively prevents dampness and musty odors, especially in older properties.

Key Comparisons: MVHR vs. PIV

Feature	MVHR	PIV
Installation	Complex and requires ductwork throughout	Simpler, often limited to a single unit
Cost	Higher initial and operational costs	Lower upfront and running costs
Heat Recovery	Recovers heat from outgoing air	No heat recovery
Air Filtering	Advanced filtration for pollutants	Basic filtration, dependent on incoming air quality
Energy Efficiency	Highly efficient in airtight homes	May increase heating demand slightly
Humidity Control	Effective in all areas	Effective in most homes but relies on air leakage
Suitability	New builds or airtight homes	Older, draughty properties

Limitations to Consider

Which System Should You Choose?

Choose MVHR if:

• You have a modern, airtight home or are building a new property.
• Energy efficiency and advanced air filtration are top priorities.
• You are willing to invest in a long-term solution.

Choose PIV if:

• You live in an older property with natural ventilation gaps.
• You want a cost-effective solution to combat condensation and improve air quality.
• Simplicity and low maintenance are key considerations.