Daikin VRV III issue

[rude]

Hi guys

Just got an issue with a vrv. Basically i have a ducted unit in an office thats currently set on 23degrees on cooling and it doesnt seem to control the temperture very well and the clients arnt very happy.

Bit of a run down on the set up. The unit has 2 remote sensors that i assume average out and thats what the units uses to control the space temp. Remote control is in the plant room.

One of these
http://i35.photobucket.com/albums/d193/123MMM/Daikingwallcontroller.jpg

Now to my issue. The unit is set on 23 degrees cooling. The unit will get to around 24-24.5 degrees before it starts cooling which is fine. But it continues to cool down to 20.8 degrees and my complaints are that it gets to cold.

I know there is a way to check the actual return air temps from the controller but im unsure how to do it. Also if there is anything else that can cause this big flucuation in temp any information would be appreciated.


Cheers

[james10]

The fcu will be reading the air temp in the ceiling void you need to install a remote air temp sensor in the room these unit read temp from either controller or return air temp in your case the ceiling void temp

[install monkey]

setting 10 2 02-return air thermistor control.
To set the field settings, you have to change:

1

��

“Mode No.”

��

“First code No.”

��

“Second code No.”.

To change the field settings, proceed as follows:

Step Action

1


Hold down the INSPECTION/TEST button for at least 4 s during normal mode to enter

the “Field setting mode”.

2


Press the TEMPERATURE CONTROL button until the desired “Mode No.” appears.

3


�� If the indoor unit is under group control, all settings for all the indoor units are set at the

same time. Use the codes 10 to 15 to apply this group control and proceed to the next

step.

��

If you want to set the indoor units of one group individually or if you want to read out

the last settings, use the codes 20 to 25 which are displayed in brackets. Press the

TIMER SELECTION button to select the “Indoor unit No.” for which you want to adjust

the field settings.

4


Press the upper part of the PROGRAMMING TIME button to select the “First code No.”.

5


Press the lower part of the PROGRAMMING TIME button to select the

“Second code No”.

6


Press the CONFIRMATION button to confirm the changed setting.

7


Press the INSPECTION/TEST button to return to “Normal mode”.

[rude]

Thanks guys ill go and double check those settings to make sure it is reading from the correct sensor.

About a month ago i did get daikin out to check these settings because the temp was reading from the controller which was in the plant room and he said he changed for the unit to read the remote sensor.

If this is all correct what else could be causing this wide range of temperatures.

Is it possible to change the temperature differential as well?

[Tayters]

Is it 20.8*C all over the room or just where people are close to the supply air grills? Also I wonder as James has hinted at does the supply air come from the ceiling void or from the room?

Field code 12-2-01 is a diff of 1*C and factory setting. 12-2-02 is a diff of 0.5*C.

To check thermistor readings, hold test button for 4 secs this takes you to field set mode.
Hold test button again for 4 secs now you'll be in service mode with 40 on the display. Clock up & down button here will cycle through stored fault codes.
Use temp up and buttons to get to mode 41. Now use clock buttons to select thermistors.
0 - Sensor in remote
1 - Air on
2 - Liquid pipe
3 - Gas pipe
Sorry but not sure about checking the extra sensors though and not sure if when you check air on (1) which one that would be if there are 2 more added.

If all this fails then time to try the power of suggestion. Have a fiddle in the ceiling and tell them you've adjusted the setting to switch off at a higher temp. Rare to find people in offices that are happy with the AC. Some too hot, some too cold. Never please them.

Have you looked at the Daikin website? You'll need to register but once done there is some good stuff the on the VRVIII.

Cheers,

Andy.

[rude]

Thanks for your help! I can only get out to site next wednesday as we have a 5 day long weekend but i want to get as much info as i can before i head out.

This is the remote sensor located underneath the return air grill
http://i35.photobucket.com/albums/d193/123MMM/Daikinremotesensor.jpg

From what i can gather is that this sensor replaces the return air in the unit. Which i will have to double check to make sure it is actually connected properly. As for the other sensor in the room im unsure where that would be connected to i haven't checked yet.

I think what i might do is make sure everythings connected check that the unit is using the correct sensor and change the differential to 0.5 to see if it cuts the unit out sooner.

[AbsoluteWDJ]

Check the sensor has replaced return air sensor on indoor PCB, then position the extendable sensor kit around 1.3mtrs from floor level away from direct heat and set the field setting 10-2-02 for return air sensor only. This will achieve a realistic room temperature.

[JoeAT50A]

VRV or VRF or all indoor unit are based on return air sensor located at somewhere that so called realistic return air temperature cum room temperature to work but somehow as for ducted units, there are always the cases of over cooling due to sensor location was not right to detect the return temperature.
For my experiences, ducting design for return are very important area to look-out. short 90 Degree turn ductings have more issues than straight ducts. (see picture)
Alway you need to fine tune the locations (in red) of return sensor in order to get the realistic return temperature to match the space temperature.
If you stick on default location, .. there is no resolution for some cases.
Why not relocate your sensor? or use external sensor or extend the cable to place the sensor somewhere realistic that you measured.
Even free return cum ceiling return also need to watch out the return temperature. System is taking a higher side of return temperature, then compressor will be keep pumping running and ...for one of my case reaching 13, 14 degree C room temperature. Setting is 21 Degree C but return temperature has never changed from 28C.
Hope that will help.
6606

[rude]

Thanks everyone for their help but i think i have solved the issue.

After finding what codes do what i checked the return air temp on the controller and compared it to the temp on my thermometer next to the sensor and it was 1 degree difference. So what i did was plug the return air sensor from the unit back in and see if the unit controlled the room temp better. And sure enough after 1.5hours on site everyone in the office said it was very comfortable and the unit was cycling nicely between 22-23 degrees.

The only issue i may have now as per the above diagram is fresh air going over the sensor but so far its ok. I may have to get another sensor and replace the old one and see if it reads the air temp better and even move it into the duct.

Thanks again