Freus, water cooled, change gas?

[Dennis Williams]

I installed a Freus, with a built in cooling tower, on a workshop. The sump water is in the low seventies. The pressures are 175/70. It never condenses water out of the air. I want to change from R-22 to 404a or 410 & am willing to change the oil to POE. My theory is I'd get an evaporator cold enough to dehumidify the air & reduce the enthalpy. What is wrong with this idea?

[mohamed khamis]

I installed a Freus, with a built in cooling tower, on a workshop. The sump water is in the low seventies. The pressures are 175/70. It never condenses water out of the air. I want to change from R-22 to 404a or 410 & am willing to change the oil to POE. My theory is I'd get an evaporator cold enough to dehumidify the air & reduce the enthalpy. What is wrong with this idea?

Hi Dennis Williams

From ur data, the evaporating temperature is 0.2°C i.e. coil dew point temperature of almost of 3 to 6°C and condensing temperature of 30°C with R-22. It sounds the system is undercharging case or the evaporator blower is oversized and blows a high flow rate of air than required. Although u can find the coil surface temperature is very small but u did not find considerable condensate flow rate, the dehumidification process depends on the coil surface temperature plus the cooling capacity as well the entering air humidity. could u cite more data for help.

cheers

[Gary]

For starters, you have way too much evaporator airflow. Kick the blower down a notch.

Ideally, the blower speed should be adjusted so that at thermostat cutout the supply air temperature (measured close to the coil) is about 21F lower than the temperature at the thermostat.

IOW, if the thermostat is set to cut out at 75F, the supply air temp should be about 54F when the system shuts off.

The lower the airflow, the colder the supply air... and vice versa.