View Full Version : Daikin inverter running on/off

14-07-2016, 06:11 PM
I am interested in keeping the temperature of measuring equipment at 23 +/- 0.4 degrees. The heat load is variating from 0 to 10 KW depending on the surrounding conditions. The variation in heat load is slow and mainly related to season. However local disturbances may accrue (a door being opened and so on). At the moment I am running a Daikin FVQ100C + RZQSG100L9V1. The system cannot regulate to a suitable production level and end up in on/off operation with a period of approximately 25 minutes (23 +/-1.7 degrees). The situation is similar with high heat load and low heat load the on mode is just more intense. I was expecting that an inverter based system would be able to regulate smoothly to the need avoiding large temperature variations due to this.

The system is mounted on a well-insulated semi-trailer. We are measuring through some holes where hot/moist air enters. There is a limit to the power available (approximately 4.5KW)

I have tried to use the default temperature sensor (suction air) and a wireless sensor at various locations for control but canít get the system to regulate satisfying. I have high air velocities in the room so the regulation is infarct not so influence by the sensor location.

It will be helpful to get advice on how to optimize the current setup. It will also be interesting to get advice on more suitable hardware for the future.

Hope you can give me some constructive input.

The Viking
14-07-2016, 06:37 PM
So you got an application where you require +/- 0.4K stability.
That is well in to close control territory where you do need units built for the purpose.

No air-conditioning system will even come close to +/- 0.4K, by default they are for comfort cooling and at best can be expected to keep +/- 1.5K.

Sorry that I'm not able to give constructive input, it is just that this application is just like hooking an 30 tonne trailer up behind an VW Golf and wanting it to travel at 100km/h. Yes, I could tell you to start on the top of a steep high cliff and you would reach the 100km/h but it would end with a crash.

Looking ate better equipment for the task in hand... Personally I believe that even "off the shelf" close control units will struggle to keep +/- 0.4K and that the only way to reach that target would be with something bespoke made for your requirement. You haven't specified the size of your room but for that close tolerance you are really looking at some sort of environmental chamber. (If you Google [environmental chamber] you will see what I'm talking about)