Home News VRV and Munters Handle Humidity in Springhill Suites

A new Springhill Suites just opened in Fort Worth, Texas with Daikin VRV handling the internal sensible loads and three Munters HCUc (DOAS) taking care of the ventilation and internal latent loads.

The idea, as supported by ASHRAE best design practices, is to decouple to internal sensible loads and allow the VRV system to be downsized while the DOAS system provides air dry enough to handle the external and internal moisture loads.

Just like you could deliver 55 degree dry bulb air to keep a room at 75 degrees, you can do the same with latent loads by delivering air drier than what you want to maintain in a space. If you want to maintain 75Fdb/50% rh in a space, your base moisture content will be around 67Gr/#.
You can estimate that people give off ~200 BTU/latent energy. Given this and some slight moisture infiltration, along with standard ventilation rates for a hotel, you can predict that by providing your ventilation air between 45 and 49 Gr/#, you can completely decouple the internal sensible with the internal latent and downsize your VRV system in the process.

However, 45-49Gr/# moisture would require a DX coil to drop the dew point of the ventilation air to around 45-48 degrees dry bulb, which is not possible with some DOAS systems and is not as energy efficient in those systems that can.

Thus, using the Munters HCU with the condenser reactivated desiccant wheel can reduce energy usage by 10-30% compared to conventional systems, while still providing the overly dried air. Benefits for the owner include a building that is always kept at 50% rh and a more efficient VRV system that will not run as long, or have to over-cool the space on those humid days to keep people comfortable.