FAQ

Question 1:

Which wall thickness is M-WRG suitable for?

Answer: The concealed version is suitable for wall 24 to 36,5 cm thick (brickwork, without plaster). At the same time, further thickening of the walls (insulation, for example) is possible. Other requirements will be handled by request. In the case of wall-mounted units the requirements are fully flexible.

Question 2:

Does there have to be a M-WRG ventilation device in each room?

Answer: Since this is a decentralized system, principally yes, there should be. However, there is little sense in ventilating every side room. Our recommendation is to ventilate the living room, dining room, children’s room, study/workroom with our devices. For the kitchen we recommend to use our fresh air hood with double walls for pressure-neutral operation.

Question 3:

How many M-WRG ventilation devices does a one-family house need?

Answer: The number of units depends on the number and dimensions of the rooms which will be equipped with M-WRG. In individual cases the layout can be done by us if we are provided with necessary data (house type, area of habitable rooms, floor plans, profiles, elevations, insulation certificate). However, you can calculate roughly as follows: Per 20 to 30 m² of floor area one M-WRG unit. (The desired use is also very important, as in living room vs. bedroom in respect to the noise level of the device.) A typical one family home will need at least 4-6 devices.

Question 4:

Which M-WRG ventilation performance levels are available?

Answer: The standard device M-WRF-S has 3 performance levels with 15, 30 and 60 m³/h. The comfort model M-WRG-K offers ten adjustable levels from 15 to 100 m³/h. If there are other performance levels desired by the customer other than the ten preset levels, we can adjust the levels accordingly before delivery (within 15 to 100m³/h.output) If you have such wishes, please let us know beforehand.

Question 5:

What is to be understood under “effeciency rate?”

Answer: The electrical efficiency ratio is the rate of the recovered heat energy to the electrical energy used including the electricity consumption of all electric auxiliaries (e.g. control).

Question 6:

How can a seemingly average heat recovery rate (such as 76%) mark an extremely effective and energy saving ventilation device?

Answer: The heat recovery rate in itself is not as important as the electric efficiency rate, which shows the relation between power consumption of the device, with regard to all electrical auxiliaries (e.g. also the control). With M-WRG we are talking about 73% heat recovery rate and power consumption (with all auxiliaries) for two energy saving EC-DC motors of 5,2 W (permanent operation in the recommended air volume current of 30 m³/h included). This results in a electrical efficiency rate of 21 (proven by TUVtesting). This means that one portion of electrical energy recovers 21 portions of heating energy. The rule is basically as follows: The higher the electrical efficiency rate the better is the efficiency of the system.

Question 7:

What do we understand under “air exchange 0,4 l/h”?

Answer: The relationship between fresh air supplied to air volume to be ventilated be ventilated. 0,4 air exchange therefore means, that the room volume is replaced with fresh air 0,4 times per hour.

Question 8:

Who plans a M-WRG system?

Answer: As a rule, the planning office for house technology or the architect. We will be glad to provide you with device-specific producer data and advice.

Question 9:

How can a planner include M-WRG in the energy consumption calculation?

Answer: Home ventilation is taken into account in the calculation of yearly heating energy requirements. It is recommended to consider ventilation devices according to DIN 4701-10.Exact data from the producer can be used and the values for the devices and so also for the yearly primary energy summary are better and more exact.

Question 10:

Where are the devices situated in the living room?

Answer: M-WRG has to be installed on the inner side of an outer wall. We recommend placing the devices on the wall with windows as high up as possible. The used warm air gathers at the ceiling and can be effectively taken away. The unit should be situated app. 30 cm beneath the ceiling.

Question 11:

Can M-WRG used also as a ceiling unit?

Answer: No, it cannot. The unit is designed for use in walls (vertical position). Proper dispensing of condensate which may gather on very cold days would not take place in case of ceiling installation. The reverse movement of the condensate could ruin the motors and electronics. In such cases all warranty is void.

Question 12:

Can I cover the M-WRG unit with a curtain or build it into a wardrobe?

Answer: In order to always ensure proper and full functioning of the unit all obstructions are to be avoided.

Question 13:

Since the intakes and outlets for used and fresh air lie close to each other could the two kinds of air get mixed up in the M-WRG (on the room side of the wall)?

Answer:Due to the fresh air being blown in and the exhaust air being sucked out (the vacuum cleaner effect) at the other opening, the chance of mixing both air streams is practically eliminated. This was proven by TÜV-Süd-Bayern and is documented by photography.

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Question 14:

Who installs the M-WRG?

Answer: As a rule an electrician does, or possibly a heating and ventilation installation company. If choosing the concealed installation, it is recommended that the wall boxes (assembly set M-WRG-M) be mounted already during the building phase, before the plaster is applied. The units themselves can then easily be placed at the desired point of time..

Question 15:

How about the actual noise of an M-WRG device?

Answer: At the recommended basic ventilation level for permanent operation (15 m³/h) the M-WRG with its 15,5 dB (A) (10 m2, concealed model) is hardly audible at all. Therefore, the device can easily be installed even in a bedroom.

Question 16:

Can all M-WRG ventilation devices be controlled from one spot in a flat or house or is there any possibility of connecting them to the house automation (such as EIB)?

Answer: Yes, the solution to both requirements is under development.

Question 17:

Are there any draughts when using the M-WRG?

Answer: This depends on the individual person and their subjective feeling to a great extent; therefore it is very hard to measure it objectively. The research has shown that there are no draughts at all if the ventilation planning is good.

Question 18:

What kind of maintenance needs to be performed on M-WRG?

Answer: The periodical filter replacements and sometimes cleaning of the heat exchanger are to be performed. The handy compact round filter cartridges are remarkable for their comparably very large effective filtering area (0, 12 to 0, 36 m2) and therefore also for their long life span. With regard to the guidelines on hygiene for ventilation devices (VDI 6022) the filters should be replaced at least once a year without regard to their physical state. The filter cartridges can be changed by a few manipulations due to a unique and easy to operate mechanism.To ensure the filtering of the used air as well the risk of pollution of the heat exchanger is eliminated. Should the need arise it can be cleaned with water or by using of a mild cleaning agent.

Question 19:

Why the need for two filters?

Answer: To prevent any pollution in the fresh air to enter the building and to protect the unit and its vital components (motors, heat exchanger and electronics)from any contamination.Research has shown that contaminants such as smoke, metal dust, pollen, viruses and bacteria can be found in the air. The size of these particles vary from 1 μm up to pieces of threads, leaves and insects. Many of these particles can cause allergy or even respiratory problems. It is important therefore to properly filtrate the air.

Question 20:

What about the M-WRG units ability to reduce noise levels?

Answer: M-WRG has a norm noise level difference D n, e, w of 50 dB. It is possible to reach a D n, e, w value of 53 dB in operation, if special noise reduction measures are applied. In individual cases it is very helpful if you can describe the special noise reduction requirements of your object (noise protection class of windows, the level of noise). We will be glad to help you.

Question 21:

How many litres of heating oil or m³ of NG can you save with M-WRG?

Answer: This depends on the building (e.g. on the insulation), on the geographical position of it, quality of the heating device, and on the important factor of user attitude. You can save roughly 30 litres of heating oil or cubic meters of NG per device and year (in conditions similar to German winter). For a typical one-family home with a floor area of 130 m² this would be app. 150 l or m³ per year.

Question 22:

How about the amortization time?

Answer: An exact estimation of the amortization time is not possible without the following. There are many factors (such as geographical position of the building, insulation, quality of the heating system, development of prices for primary energies (oil, NG) and perhaps the most important factor, attitude of the user. Considering current prices and positive development of the other factors the payback time is getting better all the time. You will need to consider pricing, (government incentives if applicable) in your locality. However this unit will, unlike many other purchases,pay for itself in time through energy saved,healthcare costs saved,damage to building substance averted.

Question 23:

Can the M-WRG be used in rooms with fireplaces dependent on the air in the room for their opperation?

Answer: Basically it can. The room, with respect to the airtight insulation, shall not have an under pressure of more than 4 Pa, so that no smoke or burned gas can escape into the rooms. We recommend you to contact the local chimney sweep as early on as the planning phase.

Question 24:

Does the M-WRG condensate eject itself?

Answer: At common living room temperatures and humidity it is possible that it might happen on very cold days. The condensate is then blown out through a condensate lead pipe together with the used air – no condensate collector is therefore necessary. There are many possibilities to prevent the water from falling on the façade.

Question 25:

Is it possible that the used and fresh air get mixed because their respective openings are so close to each other on the outer façade?

Answer: According to TÜV-Südbayern this is practically impossible. For one thing, the used air is blown out in a strong stream, and the fresh air is sucked in from a very narrow area. On the other hand, there is almost always a natural air movement at the façade, which works against the unmediated mixing of the two air streams. This was proven by TÜV-Süd-Bayern and is documented by photography.

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Question 26:

How economical is one M-WRG device?

Answer: Very. Permanent operation provided during a period of 185 days per year, 24 hours a day, recommended air volume stream of 15 m³/h – this depends on the actual size of the room – gross price of electric power: 0,159 €/ kWh January 2003, Tel.: 0180-2/660 660) the costs are only app. 3€ per year! The power consumption for two motors is only 3,8 Watt!

Question 27:

Is M-WRG suitable also for retrofits?

Answer: Yes, it’s excellent for them! You do not need any ducting. All you need is two holes 120 mm in diameter and the electric lead for each device.

Question 28:

Can M-WRG be employed also to dry buildings?

Answer: Yes, it can. After the building is finished it still holds many litres of moisture.The drying time of the residential building is reduced to a fraction of the norm due to permanent air circulation. M-WRG ventilation units should be ordered from the factory with higher air volume stream settings for this purpose. Afterwards it is advisable to set the air volume stream back to the recommended or desired value.