runcyclexcski

Thanks, John. It's the heat-exchanger that one pulls out, I may have seen the term "cube" on some other forum. It looks like a beam splitter cube from my laser work. Another issue (I may be over-thinking this) is that I like my flat to be positively pressurized, whereas the MVHR will vent that pressure out. Oh well, I will see how it does. This is what I got from Boulder, they recommend keeping RH at 35-40% which is a bit too low for my liking (below). Quote from Boulder: >>>>>>>>>>>> "Ensure Proper Drainage: Please check that the drainage hose is installed correctly and is free from blockages. This ensures water from condensation is effectively removed. Adjust Ventilation Rates: Increasing the airflow slightly can help dry the heat exchanger cube more effectively and reduce the chances of moisture settling. Lower Indoor Humidity: While 45% relative humidity is comfortable, lowering it to around 35–40% during the winter can help minimise condensation. If needed, a dehumidifier can assist with this. Regular Maintenance: Clean the heat exchanger cube regularly as per the unit's maintenance guidelines. Removing dust and debris will improve performance and help prevent mould growth. Insulate Ductwork: Ensure the intake and exhaust ducts are properly insulated to prevent additional cooling and moisture build-up inside the system. Replacing the Heat Exchanger Cube If the above measures do not resolve the issue and mould persists, you may need to replace the heat exchanger cube. In heavy winter use, we would recommend inspecting the cube at the start of the season . You would need to replace it if signs of mould or significant wear are visible."

I just found this resource; peviously I periodically checked greenbuildingforum, but that may be going belly up. I have recently installed a basic MVHR unit (rated at 150 m³ hr⁻¹). TLDR: How do I make sure I do not get mould in the heat exchange cube due to condensation? I have attached a picture of the MVHR label. It gets to around 0C at night oudroors where I live, so condensation is an issue at my indoor humidity levels (which I maintain at around 50%). My unit does have a drain hose, and the pan appears to be "proper" (no dead spots in it), but from what I've read online mould can form anyway. Should I replace the cube every winter (can be problematic in the long term if the manufacturer discontinues the unit)? I could make a polycarb window in the unit, to periodically inspect the cube w/o opening the unit. Or, I have some high-power deep UV diodes lying around from other project, so I could potentially implant them inside, but I am not sure if the light can reach deep inside the cube anyway. Thank you all in advance!

I've been doing HVAC (filters and ventilation) for quite some time now. I am slowly getting better at it, but there are always new challenges. I live in rental flats, hoping to build my own passivehaus eventually.