Pure cleanliness
Maximum hygiene
Comfortable indoor ventilation
+ Regular maintenance
+ Professional installation
Professional planning
= Optimum hygiene

Pure comfort with maximum hygiene

Zehnder stands for high demands, and not just when it comes to fresh air: with regard to hygiene, too, Zehnder develops products and services which guarantee that your Zehnder systems for comfortable indoor ventilation will always work in the most hygienic way possible.

Only three points must be considered for optimum hygiene:

1. Professional planning

A professional must plan the ventilation system.

  • This is the only way to ensure that the system for comfortable indoor ventilation consists only of system components, which are perfectly coordinated with one another to give flawless operation.
  • It guarantees that the system components are positioned correctly, thus ensuring constantly flawless and hygienic air quality.
  • It enables plans to be drawn up carefully and in compliance with the applicable regulations and standards. Zehnder trains the professionals for this job.

2. Professional installation

The installation must be performed by a trained installer.

  • Because a clean, standard-compliant installation to the manufacturer's specifications is indispensable for a flawlessly hygienic ventilation system.
  • If the system is installed carefully, you can be sure that no dirt will get into it because of issues that arose during the construction phase. The ventilation tubes must remain sealed with caps during the installation phase, for instance, so that no dirt from the building site enters them.
  • A professional will install the system in such a way that all important system openings remain easily accessible for carrying out maintenance work during subsequent operation.

3. Regular inspections and maintenance

Some simple maintenance work must be carried out to give the most hygienic system possible.

  • The user only has to follow a few simple care points and perform the Minor Service. That is, every three months the user has to check the filters and replace them if necessary. The filters must be replaced every six months at the latest. Original spare filters can usually be purchased from the installer or ordered easily from the Zehnder online shop.
  • Besides this, the system must be regularly inspected by a professional at longer intervals (Major Service).
  • And there's good news for allergy sufferers: if particulate matter and pollen are captured too, thanks to optional pollen filters, even they can breathe easily. The filters are very easy to retrofit and can also be obtained from the installer or the online shop.
  • If the comfort ventilation system should, contrary to expectations, become contaminated due to improper use, for example, the installer can clean it easily.

Practical tips and tricks for the professional:

Professional planning lays the foundation for a hygienic ventilation system.

Facts about hygiene and planning

The air outlets must be planned in such a way that they are easily accessible at all times.

The outside and exhaust air connections can be positioned either through the outside wall or over the roof. It is important to position the outlets in areas where no external influences (emissions, rubbish bins, etc.) could adversely affect the quality of the outside air that is drawn in. The exhaust air, which may contain odours (from the kitchen, for example), should be brought to a site where it cannot cause a nuisance. This means that it is not advisable to blow the exhaust air out onto a balcony, for instance. The outside air intake and the exhaust air outlet also have to be installed at a sufficient distance away from one another. In practice, distances of more than 3 m or a diagonally opposing layout have proven effective. The prevailing wind direction plays a crucial role here too. (Note: The prevailing wind direction is usually westerly.) 

The scope of delivery of every Zehnder ComfoAir ventilation unit always includes a filter of coarse particulate Class G4. A Class F7 pollen filter can be installed at any time as an option, which will provide a huge source of relief to allergy sufferers. To achieve a longer filter service life, we recommend installing a second filter housing or an optional component such as a ComfoFond-L brine-earth heat exchanger.

Filter arrangement in the unit: In the air direction, a prefilter is always installed first, followed by a fine filter in the fresh air branch.

As well as a socket or power supply cord and the air connections, the room where the unit is to be installed must also provide a connection to the wastewater system, since condensate can form in the Zehnder ComfoAir ventilation unit over the course of the year. This is not a defect; rather, it is a sign that the ventilation system is working particularly efficiently. In this regard, the condensate connection guarantees that any sewer gases or odours cannot enter the ventilation system. The condensate is collected and removed from the Zehnder ComfoAir ventilation unit immediately via the condensate connection. 

The extract air opening inside the kitchen should be positioned a sufficient distance away from the cooking area. Please note that extract air outlets in kitchens are used for constant air exchange; they do not work as an extractor hood at all. In practice, lateral distances of at least 1.5 m from the cooking area or the cooker have proven effective. 

Access panels must be installed for the manifold boxes for this purpose. The outside and exhaust air outlets, as well as the supply and extract air outlets must be easily accessible. In addition, there should be sufficient space in front of and underneath the ventilation unit to perform maintenance work. 

Generally speaking, all supply and extract air ducts should be planned inside the thermal building fabric. This prevents condensation from forming and energy being lost, plus the tubes remain flawlessly hygienic. 

Zehnder does not recommend planning to lay tubes in cold areas.

Zehnder ComfoPipe Plus meets the requirements of local norms regarding proper insulation with an insulation thickness of just 43 mm.

By "forcing" air transversely through the room, air-borne pollutants such as CO², VOC, radon, moisture and odours can be removed from the room and the building in the best way possible. In this way, rooms are provided with a continuous supply of fresh, clean air.

Generally speaking, the air outlets must be positioned diagonally in relation to the overflow openings (usually the door undercuts) in the room. 

If you use highly inductive outlets (Zehnder valves, Zehnder renovation valves) in the supply air, the outlet can also be positioned nearer to the overflow opening. 

When planning a construction project, you must include enough time for the building to dry out. If the ventilation system is used during the construction phase, this carries a risk of it becoming contaminated. Ideally, the system will not be commissioned until the occupants move in.

A clean, standard-compliant installation is the second building block on the way to a hygienic ventilation system.

Facts about hygiene and installation

For maximum hygiene, the system should not be positioned below ground level. Positioning in a light well is not permitted. In areas polluted with radon, it is also recommended to have the intake at least 1 m above ground level. You can find out whether your area is polluted with radon from your local health authority or at http://www.radon.de/.

Systems with a Zehnder ComfoWell filter box: 

On systems with a ComfoWell filter box, the Class G4 standard filter remains in the Zehnder ComfoAir ventilation unit even if an additional pollen filter is installed. The pollen filter is positioned in the filter box for this purpose. This pollen filter box is installed in the supply air (tube between the unit and the supply air manifold box). Thanks to Zehnder ComfoWell's modular construction, the filter box can also be installed directly upstream of the manifold box. 

Systems with a Zehnder ComfoFond-L ground source heat exchanger: 

On systems with the Zehnder ComfoFond-L brine-earth heat exchanger, the coarse dust filter (G4) from the unit can be installed in the Zehnder ComfoFond-L directly. The pollen filter is then inserted in the space that has been freed up in the unit.

The first siphon, the dry siphon, creates a barrier between the extract air side of the ventilation unit and the room in which it is installed. We recommend the Zehnder dry siphon here, as some operating times are free of condensate and the sealing water can dry there. 

The second siphon, a funnel siphon, is connected to the first via a vacant outlet of at least 40 mm. This closes the wastewater system off from the room in which the unit is installed. This measure also excludes the possibility of reduced heat recovery due to infiltrated air. The design is regulated by local norms. 

According to local norms, a filter must be inserted in extract air outlets located in kitchens. This makes sure that the ventilation tubes always stay hygienically clean and free of grease deposits, thus reducing the outlay for maintenance.

The filters are easy to insert in the outlets.

Access panels must be installed for distribution manifolds for this purpose. The outside and exhaust air outlets, as well as the supply and extract air outlets must be easily accessible. In addition, there must be sufficient space in front of and underneath the ventilation unit to perform maintenance work.

Please note that it is not permitted to integrate air outlets into wooden panelling, built-in units, suspended ceilings, etc., due to the poor access this would provide for cleaning. 

Generally speaking, all supply and extract air ducts should be installed inside the thermal building fabric. This prevents condensation from forming and energy being lost, plus the tubes remain flawlessly hygienic. 

Zehnder does not recommend laying tubes in cold areas.

We recommend using insulation that is sealed against steam diffusion or a tube system that meets this requirement, such as Zehnder ComfoPipe and Zehnder ComfoPipe Plus.

If you use a tube system which does not fulfil these requirements, additional insulation of local norms must be installed. Make sure that joints and connections are bonded in a way that creates a permanent seal by means of a mineral-fibre insulating layer.

By "forcing" air transversely through the room, air-borne pollutants such as CO², VOC and radon, excessive moisture and odours can be removed from the room and the building in the best way possible, plus the room is provided with a continuous supply of fresh, clean air.

Generally speaking, the air outlets must be installed diagonally in relation to the overflow openings (usually the door undercuts) in the room for this purpose. 

If you use highly inductive outlets (Zehnder valves, Zehnder renovation valves) in the supply air, the outlet can also be installed nearer to the overflow opening.

To stop additional cleaning being required, contamination must be prevented from entering the tubes during the construction phase. Ideally, the system will not be commissioned until the occupants move in.

All components are supplied in sealed packaging ex works so no dirt can get into the parts during the transport and storage phase. This condition should be maintained throughout the entire construction phase too. To this end, Zehnder has included enough end caps for the Zehnder ventilation tubes, enabling the Zehnder components to meet very high hygiene requirements right from the start.

Start-up is performed using a suitable measuring instrument to measure the volume flow and takes around two to three hours, including instrument adjustment. Measurements are taken at both the supply air outlet and the extract air outlet with a vane anemometer or a counterpressure measuring instrument with a funnel. An even balance is achieved in the relevant ventilation levels between the volume of supply air and that of extract air by adjusting the ventilation system. The air volume required to provide good hygiene according to room use and occupancy is not set until the individual outlets are adjusted either. 

We recommend a maintenance contract to ensure that the system will continue to function perfectly even after long operating times. Maintenance work is divided into tasks that are easy to perform, which the end customer or system user could carry out himself (Minor Service*), and tasks that must be performed by a specialist company (Major Service*).

If this work is done properly and at the stipulated intervals, your customer's system will always be flawless and hygienic. Offer your customer a maintenance contract to achieve this.

The outside and exhaust air outlets, supply and extract air outlets, and Zehnder ComfoAir ventilation unit must be accessible so the filters can be replaced.

Hygienic usage enables a healthy and comfortable indoor climate to be achieved for the long term.

Facts about hygiene as regards operation and maintenance

An installer can perform the Major Service* in just a few steps, thus ensuring that your customer's comfort ventilation system will work in a way that is energy-efficient and hygienic. Offer your customer a maintenance contract to achieve this.

Major Service: 
- To be performed every 24 months by an installer
- Removal and cleaning of the heat exchanger in the Zehnder ComfoAir ventilation unit. The enthalpy exchanger can be cleaned very easily with water
- Cleaning of the pre-heater filters in the unit (if present)
- Cleaning of the condensate siphon and checking of the drain routes
- Checking and cleaning of the fans
- Please check too whether your customer has performed the work included in the Minor Service* correctly

Minor Service:  
- To be performed every three months by the system user
- Checking of the filters in the system. If necessary, replacement of the filters if the contamination is too great:
1. Filters at extract air outlets
2. Filters (supply and extract air) of the Zehnder ComfoAir ventilation unit
3. Pollen filters in the supply air (if present)
4. Filters of the Zehnder ComfoFond-L ground source heat exchanger (if present)
5. Inspection of the outside and exhaust air designer grilles/roof housing

Performing this work at three-month intervals has proven effective. Just because the filters must be checked, this does not automatically mean they will need to be replaced. This will depend greatly on the system's location and the site of the outside air intake. Generally speaking, the potential for contamination is higher in urban areas than in the countryside and the load is heavier in a newly developed area than in a residential area built quite some time ago. Zehnder usually recommends replacing the filters at least once a year, regardless of the contamination.

Frequently asked questions:

- Can the filters be cleaned via extraction?
The filters can be cleaned by using a hand-held vacuum cleaner to extract dirt from their surfaces. However, the embedded, deep-seated dirt cannot be dealt with in this way. The embedding is necessary to give the filters an appropriate service life. Zehnder recommends replacing the filters at least once a year, regardless of the contamination.

- Can the filters be washed out?
Zehnder advises against washing out the filters. This will remove surface dirt, but it will also wash deep-seated dirt into the material all the more. The result is a blocked filter. Depending on the contamination, mould may also form, due to a lack of air throughput and the sponge-like properties of the filter.

- Where can the user buy filters?
As an installer, you should offer your customer the appropriate original filters. In addition, your customer has the option of ordering filters in the Zehnder Filter Shop.

 

The outlets must remain accessible at all times, as they must be checked for dirt and, if necessary, cleaned every two years. As an installer, you should make the user aware of this.

To ensure the most hygienic operation possible, the user must check the filters every three months and replace them after six months at the latest (Minor Service*). If any of the inhabitants of the house are allergy sufferers, it makes sense to retrofit inexpensive pollen filters, rather than using the standard coarse dust filters. These pollen filters provide a huge source of relief to allergy sufferers in the household.

As an installer, you should enquire about this during your consultation, make your customer aware of the relevant maintenance work and offer him the appropriate original filters. If necessary, you can direct your customer to the Zehnder online shop for spare filters.

The dry siphon acts as an odour trap between the Zehnder ventilation system and the wastewater system. As an installer, you should check this every two years as part of the Major Service*; check its function and for leaks, and clean it if there is any contamination.

Stale, moist air is continuously removed via the extract air outlets, along with kitchen odours, tobacco smoke and volatile organic compounds (VOCs).

As a result, the filters in them should be replaced every six months. As an installer, you should offer your customer the appropriate original filters or direct him to the Zehnder online shop.

All the relevant components of Zehnder ventilation systems already feature the access panels required to ensure hygienically flawless maintenance that is easy to master. 

The thermal insulation must be visually inspected to exclude any possible damage to the insulating layer.

If the system is used during the construction phase, this carries a very high risk of components becoming more contaminated than usual. This results in more cleaning being required before anyone can even move into the residential unit. Zehnder recommends only starting up the system shortly before it is commissioned and handed over to the user.

Since Zehnder components have an air-tight seal when delivered, maximum system hygiene and cleanliness can be ensured during the entire construction phase, as long as the system is only commissioned once all building work is complete. 

 

Start-up to local norms also covers handover of the comfort ventilation system to the developer. As an expert, you should explain the most important functions to your customer and make him aware of the maintenance procedures.

The system for comfortable indoor ventilation removes excess moisture and pollutants from the building. The constant flow of air that passes through the components in doing so keeps the ventilation system hygienically clean. Generally speaking, the ventilation system must always remain operational in order to guarantee this cleanliness at all times. Rather than switching off the system completely, the air volume should be regulated to suit requirements, either via a timer program on the control panel or by selecting the ventilation level manually.

But what air volume is the right one to choose if the property will be unoccupied for a long period of time? In this case, the lowest ventilation level will usually be enough to keep the indoor climate constantly comfortable and to meet all hygienic requirements. What's more, the amount of energy consumed by this level is so low that it is practically negligible.

Have you got any questions? Just ask us. We'd be delighted to answer them.

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