Just in case you are wondering, MVHR systems usually come in 2 forms. One is the whole house system which draws air from all the kitchens and bathrooms, and puts fresh, warmed air into bedrooms and reception rooms. The other option is to use "hole in the wall" fans with MVHR combined, just in bathrooms and kitchens.
Michael's system, on the other hand, sits between the two. As the air tightness of Michael's house has been improved well beyond the norm for a house of that age, the MVHR system may save some energy from the heating bill by retaining the heat from the outgoing air.
The most efficient of these systems can cost less than £30 per year in electricity to run (even if on 24/7) and can take less energy to run than the heating energy that they save.
Here's Michael's review of his MVHR system to date."TITON - HRV-1.75 Q+ unit"Having installed this newly introduced unit 12 months ago, I am extremely impressed by the performance achieved to date.The system extracts warm damp air from three areas, bathroom, en-suite shower and kitchen. It operates on a "trickle" - 24/7 basis with switchable boost in the bath & shower areas.In the "trickle" mode, it is inaudible but obviously in action when on boost. The outlet vent in the dining room produces some noise & movement of air. This fresh air is pre-warmed by the outgoing stale damp air which is then vented through the roof, above the unit installed in the loft void. All loft trunking is contained in insulation jacketing to maintain efficiency. As the house has a good air-tightness, over & above current building regulations, this, too, aids to the total efficiency of the system.In summary, this efficient unit has produced a stable internal environment within our home.At present, no continuous monitoring of humidity levels has been instigated but it would be an interesting exercise to carry out.Perhaps one for the future!