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VMC - ventilation extraction systems

Posted by Papi-10068015 - Created: 3 years ago
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9 replies (Showing replies: 1 to 9)

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Posted by orme2 - 3 years ago

We are in the process of installing VMC double flux in our house.  We have already insulated (thicker than requirements) and installed triple glaze windows, so without VMC we would have to throw the windows wide open for quite a long time every day to change the air.  That would cool down the air even more!

I don't know about the UK - maybe they are behind other EU countries on this - but when you go in a house which has good insulation and VMC, you notice the difference.

Our house was built in the '60s and we used to have big problems with black mould in a couple of rooms and even traces of damp and mould on clothes/bedding stored in some cupboards.  Good VMCs are expensive, but we think it'll be worth it in the long run.


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Posted by taxes - 3 years ago

we have one of those in all our houses and gites. they get rid of the humid air, and hot air is humid air :) it is also know that fresh air is a lot easier and quicker to heat, and of course more healthy!

a double flux works great too but need figuring out in what rooms to extract and what rooms to blow the warm air back in and cost a lot more then 50 euros (vmc) a double flux might cost you around 800 euros or more (depending on the type).

oh yes, the swith for the vmc is in our living room, so we can turn in on high when needed.

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Posted by JLJ-429896 - 3 years ago

I stand to be corrected, but my wife was talking to an old house builder (UK) friend and he said that heat recovery forced ventilation was mandatory on new build in the UK now.

We retro-fitted VMC simple flux i.e no heat recovery to a 1960s house and it's been marvellous. Can't detect any increase in electricity bills, can't say the house feels colder, but no condensation and no mould. It's long been known in France that good ventilation promotes good health; something recently discussed on the UK news.

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Posted by Papi-10068015 - 3 years ago

Thank you all for your replies. The running cost of the fan never concerned me, I was just thinking about the nice warm air inside the house being sucked out - and presumably being replaced by cold outside air, which can also be damp during winter months. In the UK I have never had a centralised system, relying on hob extractors and bathroom extractors, which always eliminate condensation. We never had condensation or mildew problems, though we know a number of people that do -but in each case it is through having no extractors at all.

If the French building regs specify VMC installation, you might have thought that the UK would go down the same route, especially with the generally damper and cooler climate compared to most of France.

I suppose that if the Belgians had discovered VMCs first, we would have an EU Directive for them by now.

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Posted by RHS35 - 3 years ago

if you set up the vmc properly , which includes a heat recovery system (around €500 extra) it takes all the heat calories from the air being extracted from the house and recycles this heat back into the house whilst extracting the humid air from the house through the vmc system, this negates the heay loss through the vmc and makes the heating of the house more efficient. Normally vmc will have a switch within the house to isolate the fan so it can be switched of for maintenance etc, it should also have its own breaker on the main fuse box.

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Posted by all4one-10057182 - 3 years ago

The whole system has been designed to run in modern double glazed, well insulated houses 24/7 and yes some have a "speedup" facility for occasional use - DO NOT switch them off, they use very little power and prevent mould/moisture build up.

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Posted by Mrs Agnes Brown - 3 years ago

It is designed to be on 24/7 but the switch should be placed in a central position - normally the kitchen for manual overide to fast speed if required - switch shoud not be placed in garage and the unit should normally be at or near the hightest point of the house.

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Posted by Mrs Agnes Brown - 3 years ago

There is a range of VMC's some - the better ones automatically speed up when they detect extra condensation through cooking, showering, etc.  Best thing you can ever install - better for your home and better for you.

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Posted by Cumbrian-440719 - 3 years ago

We have an airtight, double glazed, draught excluded house in the UK Since this has been done we have problems with condensation and are considering installing a similar system there,

 We humans and animals produce a  lot of moisture just breathing and it has to go somewhere. In our house it produces black mould on a cold north facing stone wall. The kitchen and bathroom extraction just does not get rid of it so a continuous gentle extraction which is effectively dehumidifying the air would seem to be the answer. A neighbour of ours  here living in a stone house with similar problems uses a dehumidifier and finds their house to be 2-3 degrees warmer as a result.

Apparently these units do not cost much to run.