Ice build-up in an energy recovery ventilator (ERV) can occur when the temperature of the exhaust air stream is low, and the humidity level is high. The moisture in the air can condense and freeze on the heat transfer surfaces, leading to ice formation. Ice formation can prevent proper ventilation and could result in complete system failure. To prevent and minimize ice build-up in an ERV, the following measures can be taken.
Proper insulation of the ERV system can help maintain the temperature of the heat transfer surfaces above the dew point, minimizing the chances of condensation and ice formation.
Ensuring proper drainage of condensate and moisture from the ERV is essential. A well-designed system should have appropriate drainage mechanisms to remove collected moisture and prevent it from accumulating on the heat transfer surfaces.
The following frost control strategies can be implemented to prevent ice build-up in the ERV.
Proper control of temperature and humidity levels in the ERV system can help prevent ice formation. Adjusting the set points for temperature and humidity can minimize the likelihood of reaching dew point conditions where condensation and subsequent ice formation occur.
Incorporating bypass dampers in the ERV system can divert the airflow when conditions are not suitable for energy recovery. The bypass dampers allow the incoming and exhaust air streams to bypass the heat transfer surfaces, preventing ice formation.
In cold climates, preheating the incoming air before it enters the ERV system can help raise the temperature above the dew point and reduce the risk of condensation and ice formation. Similarly, in hot and humid climates, precooling the incoming air can help lower the moisture content and prevent condensation.
The direction of airflow is reversed periodically to melt the ice on the heat transfer surfaces. This can be achieved by temporarily stopping the ventilation process and running the ERV in reverse mode, allowing warm air to melt the ice.
Reduced Air Contact Time: Slowing down the rotation of the energy recovery wheel increases the air contact time with the wheel's surfaces. This allows more time for heat and moisture exchange between the exhaust and supply air streams. By prolonging the contact time, the temperature and humidity levels of the air streams can equalize to a greater extent, reducing the likelihood of reaching dew point conditions where condensation and ice formation occur.
Enhanced Moisture Removal: Slower rotation speed can improve moisture removal from the exhaust air stream. As the wheel rotates at a slower pace, it allows more time for the moisture in the exhaust air to be adsorbed by the desiccant material or transferred to the supply air. This can help prevent excessive moisture accumulation on the wheel's surfaces, reducing the potential for ice formation.
It's worth noting that the specific measures to prevent ice build-up may vary depending on the design and manufacturer's recommendations for the ERV system. Consult the manufacturer's documentation or seek professional advice for guidance on preventing ice build-up in a specific ERV installation.