Frequently asked questions about SEVi ductless Heat Recovery Ventilation

What´s your HRV-System made for?

The SEVi HRV-System is made for any kind of buildings with a certain size, no matter if they used for residential or commercial purposes. Because of current building regulations for heat recovery ventilation (Part F), we do not recommend the SEVi ductless HRV-System for buildings with a total floor areas of more than 180m² (approx. 1,900 sq.ft)


Why should I use a HRV System? I can open the windows as well.

Especially in well insulated buildings you have to secure a permanent supply of fresh air. Sure could you do this by constant ventilation through your window openings (in the worst case every two hours all day and night to prevent condensation). But you´re losing heat/ energy by opening the window everytime.


Can I install your HRV-System during the refurbishment of my existing home?

Yes of course! The SEVi HRV-System needs no ducts and pipes - it´s the perfect solution for subsequent installation. There´s no need of additional work, to get the ducting installed.


How do I get a ventilation without ducts and a main HRV-Unit?

Each SEVi HRV-Unit blows the stale air for roughly 75 seconds out of the room. The air is passing the built-in heat buffer, made of special ceramic, which get´s heated by the warm air that leaves the building. Afterwards the SEVI-Unit changes the working mode and sucks fresh air into the building for another 75 seconds. This fresh, clean air passes the warmed heat buffer as well and gets heated.


What´s the difference between the SEVi HRV System and single room ventilation?

A single room system will just ventilate one room of your house by having very limited options for distinct adjustments. Some of these systems are running 50 minutes per hour on a passable ventilation mode but 10 minutes every hour on a so called boost mode, which is very noisy. Also, there´s no option of controlled interaction between these units whenever you have more than one installed.

By using the SEVi HRV System, you can also create a sophisticated single room ventilation which can be extended every time.


How many units do I need for my building?

It depends on the size of the building. You need at least a minimum of two SEVi HRV-Units because they´re working contrary. One unit blows the stale air out and the other one sucks the fresh, clean air in until they change their working mode after 75 seconds.

For an average 3 bedroom house, you should expect between 6 and 10 SEVi HRV-Units, depending on the size and proportioning.


How much do I have to pay for electricity to run your HRV-System?

Compared with a conventional, duct-operated pipe system you´re saving money on the running costs. The SEVi HRV-Units run on low Wattage - the average consumption of electricity for a complete system of 6 units is less than €30 per year (based on a unit price for electricity of 20ct/ kWh)


What about maintenance?

That´s the biggest advantage of the SEVi Ductless HRV System! Because it operates without ducts, there´s no need for expensive duct cleaning and sanitizing by using specialists with dry ice or other chemicals. The SEVi HRV-Units are made to maintain just by the user with conventional cleaning devices. For example the ceramic heat buffer is made for cleaning in an ordinary dishwasher.


Can I get bad air quality caused by germs and bacterias?

Because of  the short length of our  SEVi HRV-Units  and the permanently change of the air flow, there´s no chance of breeding germs. Just clean the SEVi HRV-System every 6 month and replace the filters constantly and enjoy the fresh and clean air every time.


Will the SEVi HRV-System influence my wellbeing?

By getting supplied with fresh and clean air constantly, you´ll feel much better especially when you awake in the morning.


Is the system suitable for allergy sufferers?

We supply different air filters for the SEVi-HRV Units. Beside the standard one, you can get a special pollen filter to reduce the risk of hayfever. Or you can choose a charcoal absorber to protect yourself against the most of the enviromental toxins. Our filters are easy to reach and replaceable without hassle. A small light on the control panel will give you notice when it´s time to change the filter.


Will your HRV-System influence the humidity inside of my building?

Due to the permanent air change, you´ll get a decrease of humidity inside of your building. You can check this fact usually in the winter time at your window panes, by having no more condensation there.


What kind of noise produces your HRV-System?

Every SEVi HRV-Unit runs on a noise level of less than 20dB on the lowest fan mode. You can compare that sound with a cooling fan as installed in your computer.


Will I get drafts by using your HRV-System?

No, because the SEVi HRV-System is engineered to operate almost unnoticed.


Does your HRV-System infects the usage of my stove or chimney?

In some exceptional cases it could happen that you have to install a separate pressure monitor for fireplaces. This device will switch off the SEVi HRV-System during the operation time of your fireplace, to prevent dangerous lack of air pressure inside of your building. Please ask your fireplace dealer/ installer if you´re in need of that monitoring system.

Generally we highly recommend the use of stoves / chimneys with an external air supply.


Is your HRV-System certified?

Every SEVi HRV-System is designed and manufactured in Germany, that´s why it´s certified and approved by German authorities like DIBt. Please ask for copies of the certificates in case you´re interested in more details. The certification contains the CE label as well.


How long will your HRV-System last?

The first SEVi HRV-Systems were built more than 15 years ago and they´re still running, because of the usage of high quality parts like EBM-Papst fans or high-end ceramic heat buffers. And in worst case, the part exchange is very easy to handle.


What kind of warranty will I get?

You´ll get a full 24 months warranty against manufacturers faults and a 10 years warranty for the performance ot the ceramic heat buffer units. The warranty excludes all damages, you´re responsible for on your own.


I need more than six HRV-Units for my building, how can I control them?

Our standard control units SEC 20 and SEC 20 basic operate up to 6 SEVi HRV-Units. If your system consits of more than 6 SEVi HRV-Units, you´re in need of 2 (or more) SEVi standard control units.

Since 2015 we supply the new SEC-Touch, a touch screen operated control unit which operates up to 12 SEVi HRV-Units. This new unit offers much more comfort, because you can adjust different ventilation zones for your building.


What about the extraxt ventilation of bathrooms?

We offer a wide range of matching extract fans as well as a special single room ventilation unit with heat recovery. Please ask for the SEVi Duo Mini, in case you want ventilate your bathroom in a high efficient way.


What do I have to prepare for the installing of your HRV-System?

If you want to install the SEVi 160 HRV-System, you need core drillings of 165-180mm. The external diameter of every unit is 160mm but you should leave a joint arround, which has to be proper sealed afterwards to prevent thermal bridges or sound transmission. If the blockwork is not finished or you have to do massive changings on your external walls, we highly recommend the use of our pre-fab casings (Mounting Aid) instead of core hole drilling.


What´s the advantage for the use of your Mounting Aid (pre-fab casing)?

The Mounting Aid is mostly made for new buildings and will be installed during the blocklaying. When it comes to the second fixing of our SEVi HRV-System, you just have to put the unit in the existing opening of the Mounting Aid. It fits perfect and ensures a proper insulation arround. By using the Mounting Aid, you don´t need a seperate core drilling.


Can I extend your HRV-System in case of house extensions or changings?

Of course. You only have to connect the new SEVi HRV-Units to your existing control panel or to install another SEVi Control Panel, in case you already run the maximum amount of SEVi HRV-Units on the existing SEVi Control Panel(s).

If you want to built your SEVi HRV-System stepwise, we recommend the usage of our Background Ventilation Kit "ALD 160".


What does your Background Ventilation Kit mean?

Our Background Ventilation Kit is similar to a conventional vent but offers various advantages.


1. You can upgrade the Kit into a full SEVi HRV-Unit, just by installing the Finishing Kit afterwards. All you need is the wire connection to the (existing or prospective) SEVi Control Panel.

2. The Preparation Kit contains the same external hood and  internal cover like the complete SEVi HRV-Unit. You get the same high-quality parts and the intake of air in a controlled manner.


By using the Background Ventilation Kit in conjunction with a pre-wiring, you can upgrade from a Passive Ventilation System (which is needed to ensure the standards for well-insulated homes) into a ductless SEVi HRV-System step by step.



Any questions left?

Please contact us directly