ComfoAir_Cert_70_enAirflow range
15-25 m³/h
(continuous operation)
15-40 m³/h 1)
(on-demand operation for
elimination of increased loads)
Heat recovery rate
ηHR = 85 %
Specific electric power
Pel,spec = 0.24 Wh/m³
Humidity recovery
ηx = 64 %
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CERTIFICATE
Certified Passive House Component
Component-ID 0826vs03 valid until 31st December 2024
Category: Air handling unit with heat recovery
Manufacturer: Zehnder Group AG,
Paul Wärmerückgewinnung GmbH
Germany
Product name: ComfoAir 70
Specification: Single room ventilation system with
optional second room connection
Heat exchanger: Recuperative
This certificate was awarded based on the product
meeting the following main criteria
Heat recovery rate ηHR ≥ 75 %
Specific electric power Pel,spec ≤ 0.45 Wh/m³
Leakage < 3 %
Performance number ≥ 10
Comfort Supply air temperature ≥ 16.5 °C
at outdoor air temperature of -10 °C
Passive House Institute
Dr. Wolfgang Feist
64283 Darmstadt
Germany
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2/4 ComfoAir 70
Zehnder Group AG, Paul Wärmerückgewinnung GmbH
August-Horch-Straße 7, 08141 Reinsdorf, Germany
+49 (0) 375 303505 - 0 | info@paul-lueftung.de | http://www.zehnder-systems.com |
2/5 ComfoAir 70
Humidity recovery
Indoor air humidity can be increased by using a system with moisture recovery in a cool,
temperateclimate, especially during the winter. These higher humidity levels will reduce evaporation
from building elements and furniture during the heating period and thus have a positive effect on the
building’s heating demand. In order to account for this effect, the heat recovery efficiency is increased
by a certain percentage, depending on the achieved level of moisture recovery.
Humidity recovery
ηx = 64 %
Adjustment of airflow by means of moisture control:
Since the moisture recovery of the heat exchanger exceeds a humidity ratio of 0.6,
humidity controlled volume flow adjustment is required in order to avoid damage due to
temporarily excessive indoor air humidity.
The device being tested does not provide this function.
Application of moisture recovery:
In cool temperate climates, heat exchangers with moisture recovery should generally only
beused if the moisture load inside the building is comparatively low (e.g. in a residential
building with an occupancy rate significantly below the average).
If moisture recovery > 60 % is to be used in a building with an average occupancy rate
and typical use, the energy balance of the building is to be calculated with an increased
airflow rate.
Adjustment of airflow by means of moisture control is required, even though that in case
of low internal moisture the increased airflow rate is not needed often.
Passive House comfort criterion
Temporarily lower supply air temperatures (14 °C) might occur due to the type of heat exchanger
and frost protection strategy. Once the frost protection is active, the supply air temperature increases
again to more than 16.5 °C.
Efficiency criterion (heat recovery rate)
The effective heat recovery rate is measured at a test facility using balanced mass flows of the
outdoor and exhaust air. The boundary conditions for the measurement are documented in the
testing procedure.
𝜂𝐺𝑅=
(𝜂𝐷𝑇𝐴− 𝜂𝐷𝐺𝐴) + 𝑃𝑒𝑙
𝑚̇ .𝑐𝑝
(𝜂𝐷𝑇𝐴− 𝜂𝑂𝐷𝐴)+0.08 .𝜂𝑥
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Component-ID: 0826vs03 3/5
with
ηHR Heat recovery rate in %
θETA Extract air temperature in °C
θEHA Exhaust air temperature in °C
θODA Outdoor air temperature in °C
Pel Electric power in W
𝑚̇ Mass flow in kg/h
cp Specific heat capacity in Wh/(kg.K)
ηx Humidity recovery in %
for ηx > 60 %, the heat recovery increase (0.08 . ηx) is limited to a maximum of 4.80 %
Heat recovery rate
ηHR = 85 %
Efficiency criterion (electric power)
The unit was examined with the following conditions, which correspond to the standard installation
situation of the unit: Outdoor air and exhaust air free air intake and discharge, extract air free air
intake, supply air side equipped with a ducting for connection of second room according to the
manufacturer recommendations (pressure difference 50 Pa).
Specific electric power
Pel,spec = 0.24 Wh/m³
Efficiency ratio
The efficiency ratio provides information about the overall energy performance of the respective
ventilation unit. It specifies the achieved reduction in ventilation heat losses by using a ventilation
unit with heat recovery rather than without.
Efficiency ratio
εL = 0.74
Leakage
The leakage airflow must not exceed 3 % of the average airflow of the unit’s operating range.
Internal leakage External leakage
0.64 % 1.88 %
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4/5 ComfoAir 70
Settings and airflow balance
It must be possible to adjust the balance between the exhaust airflow rate and the outdoor airflow
rate for all units.
This unit is certified for airflow rates of 15-25 m³/h (continuous operation) resp.
15-40 m³/h (on-demand operation for elimination of increased loads).
Balancing of the airflow rates of the unit is possilbe.
The standby power consumption of this device makes 3.0 W. The target value of 1 W was
exceeded. The device should be equipped with an additional external switch so that it can be
disconnected from the mains, if required.
After a power failure, the device will automatically resume operation.
Acoustical testing
Since it can be assumed that the unit will be installed in a functional or secondary room, the sound
pressure level in installation room should be restricted to 30 dB(A). The following sound levels for
the unit with second room connection have been determined depending on the airflow rate:
Airflow rate Sound power level LW
15 m³/h 25.7 dB(A)
25 m³/h 31.6 dB(A)
40 m³/h 43.6 dB(A)
65 m³/h 54.4 dB(A)
The criteria for the sound pressure level (30 dB(A)) in the specific installation room with an
equivalent room absorption area of 10 m² are met for the unit with second room connection
up to an airflow rate of 25 m³/h (continuous operation).
Indoor air quality
This unit is to be equipped with following filter qualities:
Outdoor air filter Extract air filter
ISO ePM1 50% ISO Coarse 60%
On the outdoor air side, the filter efficiency of ISO ePM1 50% (F7 according to EN 779) or better is
recommended. For the extract air side, a filter efficiency of at least ISO Coarse 60% (G4 according
to EN 779) is recommended. If not in standard configuration, the recommended filter is available as
an accessory part.
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Component-ID: 0826vs03 5/5
Frosts protection
Appropriate measures should be taken to prevent the heat exchanger and optional downstream
hydraulic heater coil from getting damaged by frost during e xtreme winter temperatures (−15 °C). It
must be ensured that the unit’s ventilation performance is not affected during frost protection cycles.
Frosts protection of the heat exchanger:
The frost protection strategy is based on reducing the supply air flow rate depending on
the outdoor air temperature. The frost protection strategy, due to the type of heat
exchanger with moisture recovery, starts operation at rather low outdoor air temperatures
(start of frost protection during the laboratory test at -8.2 °C). Down to an outdoor air
temperature of -10 °C, the misbalance is ≤ 25 %. Lower outdoor air temperatures will
cause higher misbalances and will finally lead to a supply air shut down (at about -13 °C).