Is MVHR feasible for my home? An honest triage

MVHR only pays back its running cost and installation disruption when the envelope is tight enough for the recovered heat to actually stay in the house. Without a blower-door test the household can approximate this by walking the property on a windy day and noting where draughts are obvious; skirting lines, loft hatches, floor edges, service penetrations behind kitchens.

If a first pass of draught-proofing, loft-hatch sealing and floor-edge attention is on the near-term list anyway, MVHR fits the roadmap. If the fabric work is not planned, the honest answer is that positive-input ventilation or improved trickle vents will deliver more comfort per pound spent than MVHR would.

The unit itself is the size of a small fridge and sits happily in a utility cupboard, an insulated loft or a boxed-in corner of a plant space. The design constraint is almost always the duct routing to each wet room and each habitable room, using continuous runs of one-hundred-and-twenty-five millimetre duct back to a central manifold.

Walk the house imagining a duct run to each bedroom, the living room, the kitchen and the bathrooms. Redundant chimney breasts, service voids from previous refurbishments, and dropped ceilings along a single corridor are usually the answer. If none of those exist and the household will not accept a bulkhead on a landing, the feasibility answer is honestly no.

MVHR runs continuously, drawing modest but steady electricity. Households used to a boiler that cycles on demand sometimes find the always-on nature of the fan uncomfortable in principle, even when the actual annual cost is small. That reaction is worth taking seriously before committing to install.

The counter-question is whether the same household is currently opening windows in winter to clear condensation from bathrooms or bedrooms. If yes, the heat lost through those windows already dwarfs the MVHR fan cost, and the feasibility answer is clearly yes.

If the three checks land as tight-enough envelope, workable duct routes and a household willing to accept continuous fan operation, the next step is a specialist MVHR designer rather than a general ventilation contractor. Insist on a designer who will produce a room-by-room flow-rate schedule, a duct-routing drawing and a written commissioning plan before any kit is ordered.

If any of the three checks fails clearly, the honest recommendation is to defer MVHR and address the failing check first; envelope work, refurbishment scope or a smaller decentralised extract system depending on which check said no.