Problem with Daikin RZQ100C7V1B

[mgpetkov]

In our server room there are 2 units. Our equipment generates from 5 to 6kW heat.
Humidity is very low, below 30%. When one of the aircons is switched off the other cannot maintain the tempreture. I tried code 16-02-3, but nothing happens. When only one unit is working the tempreture in the room raises constantly. As these units are 10kW rated I thought that only one of them would be enough. What could be the problem?

[The Viking]

First of all they are rated at 10 kW total capacity (i.e. when cooling humans that sweat and generate moisture), the sensible capacity will be around 7 kW (this is the value to be used when cooling equipment, like servers).

But your main problem is the lack of humidity, the air conditioners needs humidity in order to absorb the heat from the air. If the humidity drop too low the A/C system will stop working.
In the case of Daikin RZQ units they will slow their compressors down to protect themselves and if the humidity level stays low the compressor might even stop for 5-10 minutes.

The capacity values from Daikin is given assuming a humidity level of 50% and Daikin states a minimum humidity level of 37% for correct operation (below this the system will start ignoring temperature set points and demands to instead control on frost protection).

Now, where do you go from here?
Ideally you would install dedicated full function units designed for IT rooms but these are expensive. (3-4 times the cost of your Daikin systems)
Alternatively you could install a humidifier.
However, to start with make sure your units are set at maximum fan speed (the more air that passes through them the less they will dehumidify) and that they are set at a reasonable set point (~22 *C).
Remember, the set point is not an accelerator, the fan speed is.



.

[still learning]

i walked in a comms room one time to find a vey large planter with ivy in it.
the it guy said they filled the tub with water and let it evaporate, how this helped the humidity in the room i did not measure.
if only it guys or gals would use a set point off 22*c, most use 20 or some 18*c

[mgpetkov]

Thank you Viking, but the problem was ***** leakage. It has only 1.5l. After filling it only one unit was able to keep under 20C despite the low humidity.