Trickle Vents or Night Vents in Windows

19 posts in this topic

Hi there,

We moved into a new apartment building recently and after a few weeks noticed an interesting problem. Basically, when all the windows are closed and the bathroom extraction fan is on for a few minutes, it creates a pressure difference between the inside and outside of our apartment. This results in a strong whistling noise from all the windows as air is being forced in.

 

This effects nearly everyone in the new apartment building.

 

The construction company at first claimed there was nothing wrong on their part but after investigating into it, we found that without proper airvents in the windows, we will not only have this problem but also potentially one with mold if we are on holiday for a while or in winter when all the windows are shut most of the day.

 

The company has relented and is offering to install airvents in some of the windows, but they are the most horrible, large clip on things I have ever seen. To be honest, they would look terrible and spoil the clean lines of our new apartment. Of course, the company is trying to fix their error the cheapest way possible. After we all complained, they offered another cheap solution with smaller ones but said each window needs 5 of these and that would also look terrible.

 

I am also concerned at what they would do with the noise insulation that our windows provide. I have heard stories how bad ones can really let in a lot of noise.

 

Now, I am wondering if we should just do away with the free offering our building company has offered and get someone in to install a new frame with this built in.

 

Has anyone had experience with these? I never knew they existed until this problem and after going back to England a couple of months ago, I noticed my family's apartment has them installed as well as a friends. The friends place is also a new build and theirs are quite nifty in that they can be closed easily when wanted and look great.

 

What are they called in Germany and would it be terribly expensive to get one window frame replaced with a proper vent? We have a small window by the kitchen and this may be ideal. Would they need to replace the glass or just come in and swap the glass to a vented frame and reinstall?

 

I think one window vent would be enough for the suction problem with the fan, but would it be enough to prevent mold?

 

Help would be appreciated here, as I know nothing of these things.

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In Germany all buildings have to be leak tight to save energy.

And now the construction company plans to drill holes? WTF!

The correct solution would be the installation of a ventilation system (which most of the newer German houses have)

where the air going out of the building is used to warm the air going into the building.

I would say, the building is not constructed according to the German laws.

 

If you are afraid of mold, buy some hygrometers (the cost about 12€ ,Conrad) and put them in every room.

If the humidity exceeds 60% you need to vent. You should not have problems with mold then.

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Thanks for your quick reply :o )

Yes, it does seem that the building company has made a design mistake here. However, we are not at all sure how to address this. It is a 6floor apartment and so there are a few of us, but the construction company is one of the largest in Europe and have pretty much bottomless pockets if we dare challenge them in court.

 

We also suspect that we can't really fight to much as they have accepted to fix the problem, but in the cheapest way. They could so easily argue that in court that they are only required to fix the problem, not actually make it look nice.

 

The main reason we need to vent is that there is no incoming air into the apartment. When the extractor fans in the bathroom come on, so much air is sucked out of the apartment quickly that there is a pressure difference between inside and out when all the windows are closed. After a few minutes, we can hear whistling around the windows as air tries to force it's way in through what tiny gaps it can find. Once this happens, if you open the window, the force is strong enough to thrust the window strongly until pressure is equalized. This is clearly a design fault from the company.

 

The solution they offered is Trickle vents installed in the windows. I don't know much about this, but it looks like someone has to cut a hole it at least one window and install these vents. Although this sounds crazy, apparently it is not as uncommon as it sounds. In the UK anyway, they seem to be standard in new buildings and part of a recent code regarding energy saving and ventilation. I looked at these when last there and they can be opened and closed so you can stop air coming in if you want.

 

I don't think mold will be a terribly issue in our place, as we air the apartment daily by purging anyway and if a trickle vent was installed in one window I think we could expect the extraction vents to act as an exit for airflow even when the fans are off. Likewise, it is not a damp apartment. Currently the humidity is 14% inside, though it is a dry day anyway.

 

The thing is, the cheap solution offered by our building company is terribly ugly. As trickle vents is the only realistic solution on offer, I am hoping some people can shed some light on these.

 

* Does anyone know of any attractive vents for sale in Germany. Some of the ones I saw in the UK were really nice, at least on this inside. This is more important than on the outside of the building.

* Is it cheaper to simply have a new fame with a vent installed as I am guessing to install a vent in an existing frame the contractor would need to cut a gaping slot into the frame which would be quite time consuming.

* Has anyone had these installed and noticed significant changes in sound proofing?

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Why not just stop running the extractor fan if this is the only time you are having problems with the air and windows? Can you just not open the window in the bathroom a bit instead?

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A fan in a bathroom is a strong indication that the bathroom has no window.

 

14% humidity? I would expect this value in a desert, but not in Germany.

Something wrong with the hygrometer?

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@Moondancer, AnswerToLife42 answered that one. We have no windows in the bathroom or GuestWC, nor the Pantry, so all three rooms have extractor fans that come on a few moments after the light. The one in the bathroom does an exceptional job when in the shower. Afterwards, there is no steam anywhere else in the bathroom so even the mirror is totally dry and free of steam. I wouldn't want this changed.

 

As for the humidity, sorry about that, correction, 42%. We have weather three stations in the apartment and one appears to be faulty.

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Just one further question: You bought the apartment or are you a renter?

If it's your apartment I would suggest you to consult a lawyer.

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We bought, but a lawyer is not necessarily going to help us. The entire building has this problem and a lawyer has been looked at by other tenants. The cost of a legal fight compared to the cost of finding a solution do not really match up, especially since the building company can pretty much afford anything.

 

What I really need is potential and attractive solutions.

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Our Eigentümswohnung is one of seven in a Mehrfamilienhaus built in 2004.

The shower room, the bathroom and the utility room (for the washing machine & drier) are each equipped with a 2-speed extractor fan, each manually switchable to "high", "low" or "off" (this latter facility implemented by us after having moved in for reasons explained below).

Each window in the apartment is fitted with a "Zuluftelement" providing the means for outside air to enter when any of the extractor fans is running.

These "Zuluftelemente" operate whenever it's very windy outside i.e. whenever there is any great air pressure difference between inside or outside, and can on occasions 'whistle' a bit.

With all 3 extractor fans running, this system is supposed to refresh the air in the apartment every 2 hours, making for a constantly pleasant atmosphere even if nobody is at home even for weeks on end (it says here in the sales blurb), but we consider this an unnecessary expense (given the ~€30/yr max. electricity running costs for the fans, the open windows in summer and the wasted heating costs for the warm air being blown out all the time in winter).

This system of extractor fans and "Zuluftelementen" is supposed to provide protection against any danger of mould, and although its rumoured here in Sachsen to be required by building regulations, in our opinion it goes against the recommendations to "stoßlüften" (fling open your windows for 5-30 minutes a day depending on the season).

The "Zuluftelemente" cannot handle the airflow required by our kitchen extractor fan and to avoid a constant loud 'whistling' from them when this is running we have to tilt open a French window.

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Thanks AncientBrit, exactly information I was after. Can I ask what your Zuluftelementen look like and in how many windows? The ones on offer by our building company are uglier than can be imagined. I have seen some really nice ones in the UK but so far none at all in Germany.

 

And do yours still provide sufficient noise insulation?

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These Zuluftelemente are produced by "Aereco". On their website are different elements for installation in the wall, in windows or the roller shutter casing (Rollladenkasten). Some window producer offer windows with included air inlets in the frames, but they have a lower ventilation rate per hour than the Zuluftelemente. The air inlets are a reasonable price alternative to a ventilation system with heat recovery systems. It seems weird, but it works. And a new building in germany should at least have the air inlets, because airing just by opening the windows wide for 5-10min 2-3 times a day is a very tricky thing.

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Thanks AncientBrit, exactly information I was after. Can I ask what your Zuluftelementen look like and in how many windows? The ones on offer by our building company are uglier than can be imagined. I have seen some really nice ones in the UK but so far none at all in Germany.

And do yours still provide sufficient noise insulation?

 

All I can tell you off the top of my head is that the things are completely invisible until you go looking for them. They appear to consist of a non-return valve (air in not air out) and are built into or fitted into the uPVC frames. If you have wooden frames then it's a completely different matter, I suppose. Each of our windows and French windows is fitted with 'em.

We've never noticed any particular problem with external noise disturbing us inside.

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turn the bathroom extractor fan on for ages, i wonder what pressure you can get down to. You could use it to do kind of altitude training and increase your endurance and aerobic capacity. If your eyes start to pop and your lungs rupture, probably best to turn your mini vacuum pump off again.

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Are you the apartment owner? Or do you mean the owner is the "building company" and they also run the place?

 

If you are the owner, there will be a guarantee period to sort out defects and snags (five years I think). What happened with mine is that we had some issues - that's normal - and these were settled by arbitration and would have gone to law if needed. The managing agent ran the process for we owners (collectively not individually). If it's a "mistake", you will win and they will have to do the work. Can take some time to work through, though, wouldn't expect it sorted so fast.

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Did any of the other parties in the house consult an expert who calculated the costs for a proper solution that does not blight the appearance of the apartment and the building? Then you have a good idea about the potential costs of a lawsuit. While still being high the costs of a lawsuit are usually not prohibitive in Germany.

I would be exceedingly surprised if any judge considered a vent that has to be cut into the window an acceptable solution for an apartment in a new building. I have never seen anything of that kind either, and I have lived in apartments that relied on ventilation systems for the bathroom in the past.

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DIN 1946-6 regulates the requirement for fresh air supply of building. Basically the builder is required to ensure that the building has sufficient fresh air supply that does not require that windows are being opened.

You should not accept to be fobbed off with a cheap solution for the builder's mistake.

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Hi Oblomov, This is all new to us as none of us have lived in a new build before. Before this situation arose, I never even knew of these trickle vents. At the moment, we are all trying to look into this along with specifics. Thanks for the info on DIN1946-6, I'll pass this along to the other people.

 

I am quite wary though with this building company and their "third party" arbitration. Other buyers in the building had serious problems with their bathroom tiling which was clearly the fault of the construction company and their installation, yet the construction company won in the independent arbitration. We have since learnt that these independent arbitrators have professional ties to the construction company.

 

Thanks for your advise, it is much appreciated and something I will take to the others. I also don't think we have to accept a cheap solution considering this is a new build and one that was claimed to be of high standards.

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I don't suggest that you should go into some sort of arbitration. I was asking if someone has consulted with an expert (Sachverständiger)already. Obviously this expert will cost some money but you'll get a good idea about the potential success of litigation. As apparently the company has made mistakes as regards the ventilation this may also indicate problems you may encounter later on like e.g. mold. If you don't get a professional solution for this problems now it may very well reduce the value of the flat.

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