Frequently Asked Questions - All FAQs

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Questions about the SolarVenti® solar air collector and the choice of model.

It makes it easier to position the system on the wall or roof, and it looks nicer.

The solar cell is more protected from plugs, footballs, wind and other types of weather when it is built into the panel.

When the system switches off on a hot summer day, the temperature in the absorber will not exceed approx. 80 degrees centigrade. According to scientists at DTU (The Technical University of Denmark), this regenerates the solar cell and actually lengthens its lifetime in comparison to a solar cell which is mounted on the outside of the solar air collector.

The frame and the back plates are made of salt-resistant aluminum. This makes the SolarVenti easy to lift, move and install. Due to its construction, the solar air collector is immune to corrosion – even in an aggressive environment.

The “glass plate” is not glass but UV-resistant Lexan (plastic) which has insulating properties and does not splinter if the SolarVenti is dropped during transport for example.

The Lexan plate is shockproof and will not even break if you kick a football at it. It is also very easy to replace.
The Lexan helps to keep the total weight of the system down. It is much lighter than glass which, by the way, does not insulate very well either.

All screws and rivets are made from stainless steel and salt-resistant aluminum

The regulator can reduce the speed of the ventilator (air) and, thus, increase the heat of the air while reducing the noise level. The regulator can also be switched off if you turn it to zero.

The on/off switch only has an ON/OFF function.

Based on the experience of Danish customers with the early version of the holiday house pack, in which the solar cell was positioned next to the panel, we expect the life expectancy for the solar cell to be 10 – 20 years. This is the most critical component in the panel. Our new solar cells – which are placed inside the solar panel – will presumably last longer.

The fan is one of the best and quietest on the market - a Sunon with double-row ball bearings and, in theory, 30,000 hours of operation which corresponds to approx. 25 years of wear and tear.

No, it is maintenance-free. Rain and snow wash dust, pollen and other impurities off the system.

When it is running at full capacity, the acoustic pressure is approx. 40 db (plus/minus 2 db, depending on solar radiation).
This corresponds to the noise from a very quiet extractor fan and we have not yet had any customers who have been bothered by the noise from the SolarVenti. Moreover, the noise level (air flow) can be adjusted using the fan’s regulator.

When the fan is turned down the temperature of the injection air will rise.

One possibility would be to set up a larger solar panel (SV30 is 3 m2). If you ensure that there is an air escape vent at the other end of the house, the air from the SolarVenti will automatically be drawn to it.

Another possibility would be to mount, e.g., 2 SolarVentis on the house, one at each end.

How does it work? What, how and why does it? Does dust enter the collector? Is it noisy? Does it consume electricity?

The system is free to run and is not connected to the main electricity supply. It is supplied with electricity via a solar cell.

When the sun shines it warms up the air in the absorber and the integrated solar cell produces electricity for the built-in fan which blows the heated air into the house.

Fresh air from outside is sucked / pulled in through a perforated back plate and a 2 mm layer of felt. The air velocity is so low that only extremely small amounts of dust, pollen etc. are drawn into the system.

When the system is running, air flow remains inside the panel. When the system is switched off, it cools itself down – even if there is bright sunshine. The heat rises inside the solar panel and exits via the felt and the back plate (open construction).

The main task is to dehumidify and ventilate the house. The aim is to improve the quality of the air and lower humidity. This makes the house better to live in and the air easier to warm up. In many cases, SolarVenti will result in significant savings in heating bills.

When a house is continuously ventilated with dry, warm air, the risk of damp, rot and mould will be reduced in the long term.
Many years of experience and use of the system have proven that SolarVenti reduces humidity significantly.
In practice, SolarVenti’s dehumidification/ventilation eliminates condensation on windows and doors which could cause them to bind.

Furniture, cupboards and duvets no longer feel and smell damp as there is no longer damp in the house.

And you can leave coffee, flour and salt in your holiday home without worrying about it forming lumps or going bad.

The SolarVenti system is an additional heat source, but it also an indirect source of extra warmth. It provides a supply of air which is warmer than the air already in the building. However, dehumidification provides an indirect source of heat: The heat supplied by the main energy source (central heating, wood-burning stove etc.) will be more efficient and distribution quicker when the air is not damp.

And a completely dry house makes better use of the heat from the sun through the windows than a damp house does.

Please contact one of our many distributors. See "Dealers & Fitters" to see list.

At our latitude, temperatures must be extreme before the system is not able to keep the house frost-free. However, we cannot guarantee that the system will keep the house frost-free. We also export to Greenland where temperatures of 45 degrees centigrade below zero are not uncommon. The situation is quite different here.

There is also a great difference in the way in which houses are insulated and there are other crucial factors. For example, the way in which the air circulates differs from house to house. It is also of significant importance that the system has the right dimensions and is positioned correctly. The system must also have enough time/sun to ensure thorough dehumidification. Once the system has had sufficient time to dehumidify existing damp in walls, floors, ceilings and inventory, and the house is thoroughly dry, it will be a lot easier to keep the building frost-free.

No, the air is filtered through the felt. The felt cannot get clogged as the air is drawn into the absorber through the whole of the rear of the panel.

A special filter can be used if you wish to filter the air more.

The air will automatically be drawn to the places where it is easiest to get out, e.g. to vents in kitchens and bathrooms or other vents and openings in the house. If possible, let the air blow directly into the most important room and open the doors to other rooms. You should be aware that a chimney damper in a chimney which is not in use will create an outlet for the air in the room. (There are further details in the answer to the question: “What happens when the system blows warm air into the house?”)

All models can be switched off. They all have a built-in on/off switch. A supplementary regulator enables you to adjust air flow and temperature on the larger systems if the people in the building are close to the air injection duct. The small systems can only be adjusted using the air injection vent on the ceiling or the wall. All systems have a switch so that they can be switched off completely.

In addition, most of the systems – apart from the SV3 – are supplied with a variable electronic regulator so that you can turn down the air flow. When the air flow is turned down. the temperature of the injection air will increase.

The SolarVenti dehumidifies a house over a period of time. During cloudy periods nothing will happen. When the sun shines again, the limited amount of damp which has accumulated in the meantime (and which you will probably not even notice) will be extracted relatively quickly.

Once the SolarVenti has been installed, there will be visible condensation on the Lexan plastic finishing coat on the inside of the solar air collector at regular intervals. This is quite normal and will in no way damage the system.

When the warm air in the solar panel meets the cold air – or at any rate colder air – outside the panel, the condensation will become visible. When two extremes in temperature meet, condensation will appear at the “dewpoint” which, in this case, is on the top Lexan plastic layer of the solar air collector.

Therefore, condensation will be most common when the solar air collector starts up after an idle period (short or long) due to cloudy weather. This is when the difference in temperature between the warm air in the panel and the cold air outside will be greatest. You can avoid the visible condensation by switching off the solar air collector for an hour or two depending on the weather conditions. When the panel cools down the condensation will disappear.

“A good indoor climate comes from outdoors”: Fresh air is only available from outside; but polluted air also comes from the outside. So, of course, it is possible to draw the smoke from your neighbor’s chimney into your living room but it could also come in through an open window if the wind is blowing the "wrong way".

The position of the SolarVenti determines which type of air you will draw into the house.
The SolarVenti “breathes” – takes in air – through the multitude of small holes on the panel. If the air intake is placed where the air is normally clean, the injected air will also be clean. In general, the cleanest and driest air will be at the top of the house. In practice, this means that you should not install the SolarVenti close to the ground.

You should concentrate on finding a position in which the solar panel can face south and where there is as little pollution as possible from wood-burning stoves, extractor fans etc.

Most people would say that it should be at floor-level. However, it appears that it is irrelevant whether it is on the ceiling or on the top, bottom or middle of the wall. The volume of injected air is of much more importance to the result.

Yes, it is easy to extend the system so that it blows cool air into the building. This requires an extra fan on the north side of the building and a room thermostat which switches between the fans.

We believe that the system must have an effect in relation to allergies and asthma. It dehumidifies and has a drying effect, which creates the worst possible conditions for fungus and mould. Also, the air the system blows through the building will usually be very clean. The only possible downside is the fact that the system may draw in pollen from outdoors. However, the air velocity of the injection air is so low that it would only draw in very small amounts of dust and pollen and, apart from that, the fresh air is drawn in through a perforated back plate and 2mm of special felt.

Many customers have told our installation engineers that they have noticed an improvement in allergic rashes and asthma after installation of a SolarVenti. In some cases, the symptoms have disappeared altogether.

If the system is under one year old, it will often blow in more air than expected. This results in lower temperatures and is due to the fact that the solar cell produces an extraordinary amount of electricity to begin with. After approximately one year, the solar cell’s electricity production will stabilize at the specified level.

The extra amount of air to begin with is usually an advantage as it dehumidifies the house more quickly. If you want warmer air, you can adjust the temperature by turning down the damper at the air injection duct, or by turning down the electronic regulator if the system has one.

When the sun shines, the air is warmed up and this is what produces the dehumidifying and warming effect. Otherwise, the system would just inject the air from outside directly into the house.

Frost and sun often go together. The sun tends to shine on really cold days. On a frosty, clear day almost all of the moisture will lie just above, and very close to, the ground. Therefore, all of the air above this is very dry and suitable for injection into the house.

No, if the solar air collector panel and the pipe through the wall are mounted correctly, there will be no draught through the air injection hole when the fan is not working at night.

Where do I install it? Is it better on roof or wall? Does it have to face south?

The solar air collector panel can be mounted vertically, like a door, or horizontally. The position is solely determined by what looks nicest and the limitations of the building itself.

The system should face as close to due south as possible and have as little shade, from trees or other buildings, as possible.

In theory, it is best to mount the system on a wall because the sun goes down at 21 degrees centigrade to the horizon (at our latitude) in the winter.

If you mount the panel on the roof, it must be tilted to 50 - 60 degrees centigrade in order to catch the winter sun. The pitch also ensures that dirt does not collect on the surface of the panel and snow does not lie on the light-permeable surface.

Lastly, the pitch is required to ensure that the solar air collector panel can release heat when the system is switched off, e.g. on a warm summer day.

Yes, we can always send our roof set on afterwards. All models are delivered with brackets for the wall.

If, for example, you mount an SV14 in a vertical position on the wall of a house, and a large overhang prevents the sun from reaching the upper third of the panel, this will still be alright. The solar cell is in the bottom/lower half of a vertical panel. The shade from the overhang will result in a slightly smaller amount of heat from the solar air collector in the summer, when the sun is high in the sky. However, in the winter, when heat is really needed, the sun will be low and the SV14 panel will not be in the shade.

If you mount an SV7 high up on the wall, under the overhang, this will cause problems. The solar air collector will probably remain switched off most of the time. The solar cell is in the middle of the SV7 panel and if it is mounted high up under a large overhang the cell will be in the shade for too long. The problem can be solved by mounting the SV7 a little further down the wall.

How is it installed? Do I have to connect the mains? Does it have to go horizontal or vertical?

Yes, anyone who is a little talented in the use of ordinary tools will be able to install a system. The SV14, which is the largest of the small models, weighs 19 kilos and is light enough for most people to handle. The SV30 is our heaviest model. The solar panel weighs 28 kilos. In this case, two people will be needed if it is to be installed on a roof and it would also be advantage if there were two people involved in the installation of the system on a wall.

In general, shorter pipes give a better utilization of heat.

If the piping must be longer than the lead-in through the wall, you should use smooth pipes in order to reduce resistance/pressure loss.

In the case of the SV3, 1 to 2 meters of smooth piping is the standard length.
In the case of the SV7 and SV14, 1 to 4 meters of smooth piping is the standard length (straight piece).
In the case of the SV20, 1 to 5 meters of smooth piping is the standard length.
In the case of the SV30, 1 to 5 meters of smooth piping is the standard length.
If you need longer piping than the above, of if you need to run a pipe downwards into a cellar for example, you will usually have to install an extra fan.

Yes, SV Regulator Unit works as a thermostat, a on/off switch and a regulator.

It is fairly simple to install a SolarVenti and anyone who is a little talented in the use of ordinary tools will be able to install a system.

The SV3 takes about 1 hour to mount on a wall. The SV7 takes about 2 hours to mount and the SV14 about 3 hours.
The roof model takes about twice as long in each case.

How is the equipment delivered?

The system is delivered in the form of a do-it-yourself pack in a shock-proof cardboard box. All accessories, such as flexible pipes, vents, valve frames, straps, brackets and screws, are packed in a components box which is packed in the large cardboard box.

The dimensions of the SV3 box are: 90 x 61 x 15 cm
The dimensions of the SV7 box are: 119 x 80 x 15 cm
The dimensions of the SV14 box are: 217 x 74 x 15 cm
The dimensions of the SV20 box are: 217 x 105 x 15 cm
The dimensions of the SV30 box are: 302 x 105 x 10 cm
The dimensions of the SV30 PV box are: 63 x 41 x 10 cm
The dimensions of the SV30 Air Kit box are: 40 x 26 x 21 cm

The dimensions of the box for the roof kit for SV7/14 are: 80 x 26 x 22 cm
The dimensions of the box for the roof kit for SV20/30 are: 110 x 26 x 22 cm

Sometimes it does not start to work until I give the fan a little nudge. Why is that?

The fan requires a certain voltage from the solar cell before it can start up. Once it has started it is easier for it to continue. If the sun is weak, for example if it does not directly hit the panel or the sun is behind a cloud, you might hear a low buzzing noise from the fan (which is trying to start).

It is difficult to define the best conditions for the system. A small cloud in a clear blue sky can cause more problems than even cloud cover. This is due to the fact that even cloud cover emits a lot of indirect radiation.

NB: Be careful not to put your finger in the fan when it is running. Even though the fan is small it is powerful when it is running - powerful enough to give you a nasty surprise.