Positive input ventilation (PIV)
Loft or wall units that gently push filtered air into the home to tackle condensation.
From £795 inc VAT per home
Guide
PIV or MVHR: which is right for my home?
PIV vs MVHR
PIV is usually the better choice for an existing home with general condensation, because it costs around a sixth of MVHR and fits in a few hours. MVHR is the better choice for airtight, well-insulated homes and new builds where heat recovery pays back.
How do PIV and MVHR differ?
PIV pushes filtered air into the home from one unit and lets stale air escape through the normal leaks and vents. MVHR both supplies and extracts through ducts and recovers heat from the outgoing air.
Which costs less?
A loft PIV unit typically costs £795 to £1,395 including VAT fitted. A retrofit MVHR system in a three-bedroom house is typically £6,450 to £9,450.
Which is better for condensation?
Both reduce condensation. PIV is very effective in typical older homes, especially with working extract fans in the kitchen and bathroom. MVHR controls humidity throughout an airtight home.
When is MVHR worth the extra?
When the home is airtight, you are renovating anyway, or you are building new. In those homes MVHR gives steady filtered air and keeps more of the heat.
Can I start with PIV and add MVHR later?
Yes. Many people fit PIV and better extract fans now, then consider MVHR as part of a future renovation.
Sources
Related services
MVHR installation
Whole-home heat recovery ventilation, designed room by room and airflow-tested at handover.
From £4,450 inc VAT per home
Get a guide price in two minutes
Answer a few questions for a price range, or send photos and we will come back to you with a written quote.