VMC - Continuous running

[Alan Zoff]

I was told by the local electrician (now no longer in the village) that VMCs should run continuously. This seemed daft to me and a total waste of electricity so I have inserted a time-switch so that I can turn mine off evenings and when the house is not occupied. Works fine, as far as I can tell.

Anyone any idea as to why it should be designed to run continuously?

The extraction unit on the next-door property (a "cantine" used for preparing food for the local schools) is quite noisy and easily heard from our bedrooms. It nonetheless runs day and night, even through the summer holidays. (It was presumably installed by the now-departed electrician.)

The VMC unit in my house runs silently, any vibration avoided by suspending it on an elasticated cord, seemingly a quite common approach. The cantine's much bigger system will obviously be more rigidly installed and the extra power will mean it is bound to be louder than mine but this would not be a problem if it was turned off on a time clock at the end of each day.

[Clair]

As far as I am aware, your electrician is correct. It should be on all the time.

[Benjamin]

Alan

If you mean the extractors in the toilet, bathroon and kitchen we open our windows when neccesary and turn the bl&&dy things off at the fuse board switch thingy in the garage. I'm not paying for winter heating and then seeing it continuosly drawn away by these bits of gadgatry.  [:P]

[AnOther]

Alan, I'll send you an application form for the TLA society.

We campaign for the abolition of Three Letter Acronyms [:D]

[thunderhorse]

The question is:

[quote user="Alan Zoff"]I was told by the local electrician (now no longer in the village) that VMCs should run continuously...

[/quote]

AZ wants the answer, WHY?

It's totally irrelevant that others leave such stuff on all the time. The question is: WHY? If it was me, use it as you need it.

[thunderhorse]

[quote user="Clair"]As far as I am aware, your electrician is correct. It should be on all the time.

[/quote]

WHY, FFS, WHY?

Please don't make a statement without giving reasons.

[Clair]

[quote]Réglementation (logements

postérieurs à 1982)

La ventilation est une obligation légale (arrêtés

du 24/03/1982 et du 28/10/1983) pour tous les logements

postérieurs à 1982, collectifs ou individuels.

Elle doit satisfaire aux exigences suivantes : l’aération

doit être générale et permanente,

la circulation d’air doit se faire depuis des

entrées d’air situées dans les pièces

principales jusqu’à des sorties, dans les

pièces de service. Des débits réglementaires

sont exigés. La façon la plus sûre

de les obtenir est d’installer une VMC. Il est

en effet difficile de contrôler les débits

d’air renouvelés par ventilation naturelle.[/quote]

Although this applies to post-1982 housing, it stands to reason that when a VMC is fitted, it should be left to do its work.

EDIT: Réglementation relative à l’aération des logements (pdf)

[BJSLIV]

Why? To provide sufficient ventilation to meet the requirements laid down by law.

[Phil & Pat]

Someone told me that when an electrician commissions a VMC system he returns the product bar-code to a special EDF office.  He then gets a commissioning fee and an annual backhander provided that no on-off switch has been fitted.

[AnOther]

For god's sake will someone put me out of my misery and tell me what VMC stands for [:-))] [:D]

 

[Clair]

I thought you were joking!!![:D][:D]

Ventilation Mécanique Contrôlée

Search for it in this section, loads of threads...

[AnOther]

Only 1/2 Clair, I knew what was being talked about but not what the acronym meant.

Thank you [kiss]

[ams]

We have VMC's fitted in our houses. Once a tenant turned it off by turning off the electricity whilst on holidays, the system would then not operate and became filled up with water. The electrician than resolved the problem told us to ensure that they operate all of the time 24 HPD.

 

ams

[Alan Zoff]

I'll risk the consequences and keep my time-switch. (The outer vents are protected from water ingress.)

But looks as if I will get little joy if I ask the Mairie to arrange for a timer to be fitted next door.... Although why it should run for weeks on an end when no one is using the building seems just plain daft.

[Alex H]

As far as I know (and I don't have one of these fitted yet) they don't have the power of the standard UK extractor fan, therefore need to run longer to get the same effect. However, I believe, they are very low power (50 watt?) and so are not consuming the same amount of 'leccy.

[Alex H]

[quote user="ErnieY"]

For god's sake will someone put me out of my misery and tell me what VMC stands for [:-))] [:D]

 

[/quote]

Try here http://www.acronymfinder.com/

[Phil & Pat]

[quote user="Alan Zoff"].... Although why it should run for weeks on an end when no one is using the building seems just plain daft.

[/quote]

Probably the same reasoning that required a fully-automated (no occupants) warehouse to have full access for the disabled, them's the regulations.

[La Guerriere]

I suppose it's a bit like the UK. They recommend that you do everything posssible to reduce draughts, then all new windows have to have trickle vents .....

[Albert the InfoGipsy]

For all those of you talking about 'wasting heat', try looking up 'VMC double flux'. Basically, it uses a heat exchanger to warm the incoming air with heat from the exhausted air.

Have a look about half way down this page:

http://www.ademe.fr/particuliers/fiches/ventilation/rub4.htm

or the middle option on this one

http://www.climdatec.com/a_datec.htm

 

[Chancer]

Most French houses by their very nature of construction (including new builds) need every bit of help to evacuate the damp that permeates them from every direction, whether it be solid walls without DPC, concrete slabs without DPM, carrelage laid on sand on terre battu or tiled rooves without felt. You only have to view an unoccupied property where the electricity is off or return to a holiday home to see the effect of no VMC.

I have one in my maison secondaire in the UK, as it is basically a wooden chalet (OK shed[:)]) it used to have a significant damp problem which has been been 100% resolved since I fitted a VMC hygroreglable. I am sure (but will have to wait until I buy the next one to confirm) that mine only use 11 watts on the slower speed.

I do however think that switching one off during the night hours may be a good compromise especially if it can be heard from the bedrooms.

On the other hand........... my one in France seems to do most of its work at night and will usually switch to the high setting early in the morning and remain so for a few hours, but I do have a fairly unique situation of ground damp entering the dwelling and condensing above the ceiling insulation on a tole bac acier roof which is why I have 2 VMC evacuation pipes in the roof void.

[Alan Zoff]

Dear EY

I sympathise with your point but, before reading responses to this thread, I hadn't known what the letters stood for and as they seem commonplace devices in French houses I just used the term seemingly used by everyone else.

Regards,

AZ

[Jonzjob]

As a matter of interest the normal/rapid switch can be modified to an on/off switch bt removing the link that goes from on side of the connections to the other on the back of the switch. You will only have one speed for the fan though.

If you don't know anything about electrics then please get someone who does to remove it if you want to be able to switch it off!!!

Ours was noisey and it disturbed us overnight. This is why I modified it. I have since changed the bearings on the motor which has made it quieter, but still enough to disturb.

As far as venting our house is concerned we have a bloody great open chimney that does a good job of that!

I have been amused by the 2 biggest sellers over the winter here. One is parafin which chucks out a couple of pints of water for every gallon burnt and two is dehumidifiers that mop up the water again [:-))]! A song comes to mind about it all makes work for the working man to do??? Oh yes, the parafin is stacked in 20 litre plastic bottles just inside the checkouts of all the supermarkets. Usually there is a couple of thousand litres there at any one time! Health and fire safty [+o(]?????

[Le Plombier]

I am fed up answering this topic and the sarcastic comments that follow

It is law that the VMC should run continously, nothing to do with humidity but to comply with the gas regulations

If you have a gas cooker you are breaking the law interfering with the VMC

Not a problem unless you have a gas explosion or someone dies from carbon monoxide posioning and then you will find you may face criminal charges and your insureres will not pay out

Your electrician is absolutely correct

Le Plombier

[Chancer]

A wise man speaketh

Amen.

[Benjamin]

[quote user="Le Plombier"]

I am fed up answering this topic and the sarcastic comments that follow

It is law that the VMC should run continously, nothing to do with humidity but to comply with the gas regulations

If you have a gas cooker you are breaking the law interfering with the VMC

[/quote]

Thank you for the definitive answer. As an all electric household I now feel vindicated in turning this device off and conserving otherwise wasted heat.