The questions British homeowners actually ask about MVHR.

Does my house have to be airtight for MVHR to be worth it?

It does not have to be Passivhaus airtight, but the leakier the building, the less of the brochure efficiency you actually see. In a typical British 3-bed retrofit you should expect comfort, quiet and reliable air changes rather than the 90% heat recovery figure on the data sheet. Even that lower outcome is usually worth the install, particularly where condensation has been a persistent problem.

MVHR or PIV, and how do I tell which I need?

PIV is the right answer in older, leakier British homes where ducting full MVHR would be invasive and the airtightness will never justify it. MVHR is the right answer in tight new builds and deep retrofits, where heat recovery is meaningful and the ducting can be designed in from the start. The middle ground is where most disappointment lives, so the test is honest about your fabric.

Will MVHR be audible in the bedroom at night?

A correctly designed and commissioned MVHR system runs at well under 25 dB(A) at the bedroom diffuser, which is below the threshold most people perceive overnight. Almost every complaint about MVHR noise traces back to undersized ducting, sharp bends close to the diffuser or the unit being mounted somewhere that transmits vibration into a structural wall. Commissioning is the fix, not the unit.

MVHR rewards thoughtful buildings. The household that does the airtightness work, picks a designer rather than a box-fitter and insists on a written commissioning report quietly gets the gold standard. The one that does not gets a fan in the loft.