Double Flux VMC

Hi - does anyone have any experience of a Double Flux VMC (UK I believe these are Heat Recovery Ventilation Systems) in Southern France? We are interested because it appears you can reduce your heating bills by about 20% through retaining heat in the extracted air and also benefit from fresh cooler air during summer nights rather than air conditioning which is expensive to run.

Our architect doesn't seem to care much for them...could be they haven't put any in or they don't think they are worth the investment or just don't like them but I'd like to see your views on whether it's worth putting this system in or not.


Yep, it'll make no difference to an old place that isn't insulated. If you're after a passivhaus then it's part of the steps to insure that no heating is needed at all.

Suzanne, if you're having work done with diggers, fosse septique etc, then why not install a puit canadien/proven├žal. No running costs and cheap to install if you're already having other similar work done and have the space - 30m long 2 metre deep trench etc...

Some friends have had the system installed in an old stone house. Absolutely useless for an old house. However, it may work in a modern, insulated and draught proofed house.

Like Vic states other methods are much more effective.

no they're not cheap, Vic, depends what the overall project is and the desired result ;-)

I don't know about 20% reduction in heating bills as this infers that one loses the same amount if one has a normal VMC which is patently nonsense. I have a VMC used just for our 3 bathrooms. It runs normally on low speed to give house ventilation & I certainly don't notice any significant difference to the house temperature if I switch it off. The other thing I have done is to wire the high speed capability of the fan through a transformer & 24 volt coil relay operated by switches in the bathrooms. This is used when showering etc. The heat reclaim units are good but I couldn't justify the cost & extra work when I brought my ancient pile up to date(ish) If you can reclaim a lot of energy from a kitchen with a Aga or similar it would give better savings.

they're excellent if you don't mind the investment ;-)