Heat Recovery Ventilation

[potiche]

Has anyone installed a wholehouse heat recovery unit in an old house?

[BRIGHT SPARK]

In older houses its difficult (but not impossible) to obtain the u values and air permeability ratings required to make mechanical HRV worth the investment.

[potiche]

Leaving aside the financial side of being worth the investment, if it's extracting air from shower, bathroom, kitchen & returning it to public rooms, will it improve humidity levels generally?

[buildersmate]

Yes it will, but no more so than decent extraction over showers and cooker hood, externally vented. What it does is run this warm moist air through a heat exchanger, that extracts most of the heat, passing it into fresh air from the colder outside, that then feeds into the house.
It's frankly one of the last energy improvement projects that I'd consider for a house, once everything else is done. Loft insulation, external wall insulation, double glazing, remove floorboards on suspended downfloors and put slab foam under them, etc. Etc. Then think about this.
The venting ducting is a pain to install unless one is building the house from scratch.
Not been buttonholed by an overenthusiastic salesperson, I trust.

[potiche]

No, not at all. In fact just the opposite. I need 3 new fans & i think this is an opportunity tol improve the health of the whole house. From all you mention Builder the only thing not done is underfloor insulation. Having moved from modern timber framed house, i feel stored textiles feel cold & bit damp so I'm reckoning high humidity. Ducting installation round eves of dormer bungalow so might not be too bad. Am i making sense or talking mince?

[buildersmate]

You can test humidity of course. Try Malkin for a reasonably cheap gadget to do this. Reasonably cheap compared to installation cost, or find a surveyor with a professional meter to do it for you.
You've obviously thought this out and the main hassle of installing the ducts should be a doddle because you have easy access to the rooms needing the ducting access. Good luck.

[buildersmate]

Maplin