In case of operating problems occurring at low outdoor temperature, perform the following troubleshooting. Perform the following checks in order 1-2-3.
1: Check efficiency
Run the unit in the operating mode normally used, usually comfort mode. Switch off the reheating coil, parameter 31 (AVC-02) or 240 (Evocontrol). Set the temperature to the highest value, parameter 21 (AVC-02) or user menu 1 (Evocontrol). Let the unit run for at least 15 minutes.
Important! Take your time!
Note the supply air, exhaust air and outdoor air temperatures.
Calculate efficiency
VG =
(Supply air temp - Outdoor air temp)
———————————————
(Exhaust air temp - Outdoor air temp)
Example:
VG =
10 - (-20)
------- = 30 / 40 = 75%
20 - (-20)
The efficiency should be about 65-75% for A70T and A50S. Other units about 75% or more.
If the efficiency is lower, e.g. 50-60%, there is an imbalance in air flows. Possible errors can then be incorrect adjustment of air flows, dirty filters, exhaust air grilles (ice, snow).
2: Check the electric battery
Note the supply air temperature. Switch on electric battery again and wait at least 5 minutes, take time, at least 5 minutes. Note the supply air temperature again when it stops rising but wait at least 5 minutes.
This test then shows how many degrees the electric battery raises the supply air temperature.
3: Check insulation
Exhaust air:
Read the extract air temperature. If it is 20 degrees in the house and the unit's exhaust air sensor shows 15 degrees, we lose 5 degrees on the way to the unit.
The unit recovers about 70-85% (depending on the unit model) of the heat in the exhaust air. Therefore, it is important that the exhaust air temperature is as high as possible.
Supply air:
Read the supply air temperature. If the unit's supply air sensor shows 20 degrees, and if the temperature in the supply air sensor is 15 degrees, we lose 5 degrees on the way and it blows cold.
It is therefore important that ducts in cold rooms are well insulated to avoid heat losses resulting in lower supply air temperatures.