Bringing the air volumes of the home to perfection with the help of a professional
It is advisable to let a professional measure the air volumes of the home if you suspect that there is something wrong with them. This was also noticed by a family of four that, in May 2021, moved into a house in Loimaa that had been built in 2016 and seemed to suffer from extensive underpressure.
Once settled in, the family noticed that there was, at times, even a very distinctive smell of soot in the indoor air of their new home, especially in the vicinity of the fireplace. The smell became more noticeable when the cooker hood was used, but was clearly detectable at other times, too. This puzzled the family and people visiting the house. The fireplace was not used in the summer and it was swept when the family moved in. The filters of the cooker hood had also been washed immediately after moving in and the filters of the Vallox 150 SE ventilation unit had been changed. The residents concluded that the ratio between the supply and extract air flows was incorrect and that the extract air volume was clearly higher than the supply air volume, because air tried to get in through the flue of the fireplace.
The next step was to call in the professionals, namely Loimaan IV-asennus, a local company that specialises in HVAC installations, measurements, and adjustments. The constructor of the house had installed the ventilation unit and ducts himself, but the air volumes had been adjusted by a professional, of which there was a measurement log available.
Measurements revealed a problem
Loimaan IV-asennus visited the location one morning in August. First, it was ensured that the unit had new filters when the measurements were taken. The filters had last been changed immediately after the move, i.e., 3 months previously, and the coarse extract air filter had collected dust from the indoor air during the summer, which was visible on the surface of the filter. However, the coarse filter that filters the supply air was relatively clean, which was surprising, especially when there are plenty of insects in the vicinity of the house, as well as trees that continue to produce large amounts of pollen in June.
Next, the unit settings were modified so as to be the same as when the original adjustment was made. It was observed in the measurements that the volume of the fresh supply air was significantly lower than what the valves had originally been set to. On the other hand, the extract air flow of nearly all the valves was slightly higher than recorded in the measurement and adjustment log in 2016. In other words, the position of the extract air valves has been changed at some point, suggesting that they have been opened wider in order to boost the ventilation.
The significantly reduced volumes of supply air made the owner of Loimaan IV-asennus Sami Pihlajasaari and the installer Nenonen wonder what could cause such a major change. As the house was relatively new, a blockage seemed to be the most likely culprit. The reason for the reduced supply air volume and excessive underpressure was detected roughly six metres above the ground on the exterior wall of the house, where an insect net had been installed in the fresh air grille. The high location made the maintenance and cleaning of the fresh air grille difficult, and therefore it had not been observed that the insect net had become dirty. The blocked insect net prevented the flow of fresh air to the ventilation unit and further on into the rooms.
“It should be taught already in the kindergarten that an insect net must never be used in fresh air grilles”, says Pihlajasaari, as he climbs high up on the wall of the house on a ladder to remove the net.
It was no longer a mystery why there was no fresh air flowing into the building, as the insect net was covered with a thick layer of dirt that halved the supply air volumes of the fresh air valves.
“As a matter of fact, the suspiciously clean supply air filter found in the unit helped to pinpoint the cause, as the volume of insects and other flying bugs is much higher in the filter if the mouth of the duct is not covered with a net”, explains Pihlajasaari to the residents.
According to Pihlajasaari, insect nets are still found in supply air grilles especially in older houses that are equipped with mechanical ventilation, and it is one of the most common causes of reduced supply air volumes.
A unit running at a high efficiency level increased the supply air temperature
The reason for the high temperature of the supply air, which had puzzled the residents, was revealed at the same time. For example, the supply air temperature was, based on the control panel of the unit, up to 8–10 degrees higher than the outdoor temperature on the day the measurements and the adjustment were carried out. It is probable that the supply air fan of the ventilation unit had to work hard to acquire outdoor air to the unit through the insect net. The supply air temperature sensor of the unit measured high temperatures, because the fan was producing large volumes of heat only a few dozen centimetres from it.
As the result, the ventilation was measured and readjusted to meet the needs of the family. Thanks to Loimaan IV-asennus and the Vallox ventilation unit, the family will be able to enjoy fresh and clean indoor air in the future, for as long as they keep on changing the filters regularly and sufficiently often, and will only use original Vallox filters.
Maintenance tips!
• It is recommended that the filters of the ventilation unit be changed at least twice a year, or more frequently where needed. You should also check that there is no insect net behind the supply air grille of your own home, but that air flows unobstructed into the duct.
• In addition, it should be kept in mind that the resident should never change the adjustments of the valves, as the control panel should be used to boost the ventilation. MyVallox units have integrated carbon dioxide and humidity sensors that boost the ventilation automatically. However, the supply and extract air valves in the ceilings of the rooms should be hoovered from time to time. Professionals usually lock the valves in place in connection to adjustments, and therefore their position should not be changed during hoovering or light cleaning.
• The original filters can be purchased easily for Vallox ventilation units online at valloxsuodattimet.fi
• Read more about maintenance measures: Regular maintenance ensures the correct operation of ventilation