We often get asked what the difference between the PAUL novus and the Zehnder ComfoAir Q ranges is.
In a nutshell: Both MVHR units are high performance systems, which are almost en-par in terms of their efficiency and functionality: Both are Passivhaus certified, both have an integrated defrost pre-heater, both have good insulated, thermal bridge free housing, a 100% summer bypass, excellent controllability, have volume flow constant, maintenance-free EC fans and have the patented PAUL heat exchanger without or with moisture recovery (CAQ 450 or CAQ 450E = enthalpy).
The advantage of the CAQ units is the summer bypass operation, as it is modulated and can therefore operate in external temperatures below 12 degrees C. The unit can also be controlled via iPad and Android phones/ tablets with a LAN module, thus offering a range of functionalities and display of live values. With the online control function comes an easy step-by-step commissioning guide. Via an KNX interphase, the CAQ units can also be linked in with home automation systems. The CAQ units have an integrated controller, which means that the wired remote controller can be left out, in order to save costs.
The advantage of the PAUL units is their nice stainless steel touch screen and their slightly better heat recovery rate according to the Passivhaus Institute. KNX integration is possible, but limited to a few functionalities. Unfortunately only the PAUL novus 300 has been tested for SAP (Appendix Q), not the 450. The CAQ family (350, 450 and 600) have all been tested and excel in their efficiencies with up to 95% heat recovery rates.
There are a few more differences:
1. The PAUL novus, focus and climos units are truely volume flow constant, e.g. they will compensate increasing or decreasing pressures through wind load or soiled filters. The Zehnder CAQ units compensate for soiled filters, but not for changing wind loads. This has been implemented in order to avoid the humming noise of varying fan speeds. However, with good noise attenuation we have never had any issue with humming noises.
2. The filter alert of the CAQ range is timed and also according to increased resistance, whilst with the PAUL units it is timed only.
3. The other difference is that the summer bypass in the CAQ range is controlled by an adapted comfort range (cool, normal or warm), rather than a set and adjustable temperature that controls the PAUL summer bypass. The adapted comfort range looks at the outside temperatures of the last 5 days and triggers the summer bypass mode e.g. at either 19, 20 or 21 deg. C. extract air temperatures, depending on how cold or warm it has been outside. The reason behind this is, that we do adjust to the external temperatures and feel more easily too hot at 21 degrees in winter, than in summer. Those who disagree with this reasoning can switch the bypass operation of the CAQ units back to a set and adjustable temperature.
4. Compared to the PAUL units, the heat exchanger for the CAQ units has been slightly changed in its shape for optimised pressure drops.
5. The way the summer bypass is achieved is also different in both systems: The novus range has got a 100% bypass flap, which bypasses the heat exchanger, the CAQ ranges gradually cover over opposite halfs of the heat exchanger, thus achieving a modulated summer operation without heat recovery.