View Full Version : Problem on DAIKIN's VRV REYQ36M8W1B

04-04-2007, 06:48 PM
Hi everyone
On a REYQ36M8W1B (16+10+10) with 20 indoor units and 19 BSVQ ive the following problem:
In total heating mode while the temperature is rising up to 35c on gas side of the indoor units (so at the startup) 2 bs box change suddenly the way of the 3 way valve as the result is cooling mode with Heat Mode selected !!!
After these boxes there are 3 indoor units, they are quite far from the outdoot unit ( 70 m ) and the level difference is 25m. These units and boxes are at the end of the refrigerant piping.
I checked the piping there is no mix between the 3 pipes.
I just wonder why the mode change suddenly maybe you've got an opinion about it.
If OBI WAN read this i've checked the software it's the 785...need some help
Thank you

04-04-2007, 10:14 PM
Strange!!!!! In total heating mode, indoor fan coil fans should not run and show pre heat symbol on remote controller until gas pipe is at least above 35 degrees C. Need more info on the system setup! Is there any form on centralised control! I Controller, I Manager or KRP? What is model of indoor fan coils and does each unit have its own remote controller?

Also what is the distance from the first refnet to the furthest fan coil?

Do you have a Service Checker reading from the system? I would be happy to have a look at it

Obi Wan
05-04-2007, 12:26 AM
Hello Cool#9 and Puddleboy3

To me it sounds like incorrect piping or wiring. Did the system pass the test mode? Note that not all wiring and piping faults are found with the test mode.
I think you should go back to basics and use the process of elimination.

Check the number of connected indoor units and BS boxes from the monitor mode on the outdoor PCB. (items 5 & 6)
If you read the correct number of units and BS boxes, then confirm this by forcing the indoor fans to high speed in setting mode 2 item 5. (dont forget to switch off all the indoor units from the remote controllers first) This will identify that the indoor units are at least wired to the same outdoor unit.

Are there more then one systems? (outdoor) Check there is no cross wiring between the outdoor units.

Are all the BS boxes in the same location? If yes than check for cross wiring between the BS box and the indoor units. The test function will not find this problem and you need to do this manually.

35C gas temperature in heating is very low. If the system is charged correctly, I would expect 60 to 70C on the gas pipe sensor and 35 to 40C on the liquid pipe sensor. The indoor fan operates on either/or logic. Indoor fan starts up if the liquid pipe temp is higher then 35C or 3 mins has lapsed since the compressor started.

Also check the 3 way valve on the BS box is wired to the correct terminals on the PCB. The BS Box PCB is the same as the K series PCB but with M series software. On the K Series there were 2 solenoid valves (suction and discharge pipes). On the M series its possible to miss wire the valve. If the BS Box PCB is replaced you need to make sure the correct terminals is used otherwise the 3 WV will work back to front. Normally the valve should energise for heating mode.

Check the pipe temperature on the 3 pipe side of the BS Box to make sure for correct field piping connections. There may be a cross pipe connection further back at the refnet joints.

Check the gas and liquid pipe sensors on the indoor PCB are connected correctly and are not back to front. ( plug in connectors are colour coded but you can fit them to the position)

Let us know what you find.

Obi Wan.

05-04-2007, 11:02 AM
Hi Puddleboy and Obi Wan
I found in check mode history "UF" default so i think there is problem since the first start-up.
The outdoor system is coupled by 1REYQ16M8(master unit) and 2REYQ10M8(slave unit).
We didn't took enough time to check the piping and the wiring between boxes and units.
So i'll try to make a complete re-comissioning on next tuesday and i'll advise you, of course.
Thanks again for your prompt and professional replies

05-04-2007, 08:30 PM
Hi puddleboy, Obi Wan, this is the last news...
Daikin's local service ask me for a expert appraisal
of the whole site on next tuesday.
It's true that maybe the piping is too long before the first branch and the last indoor unit (max 40m).
Also i've learn it's forbidden to put a lower size than 50 on a BSVQ250M due to possible liquid back by the BS box (sub-cooling control).
I confirm the 3WV is energized as we demand HEATING MODE but it change alone like a 4WV in deicing mode...maybe caused by pressure loss.
Ok, if you have no more remarks i put this problem on the side until next week...

PS/ i'll soon give you more information about one of my first post about " hot start problem on REYQ14M "

20-04-2007, 07:04 PM
Hi everyone
Just a message to give some good news from my problem.
I've checked the whole system and found the pipe lenght exceed 40 m from the first branch to the last indoor unit ( 55m eq. ) so i preconised to reduce the distance but the system didn' t work well so that the 3 WV was locked in cooling mode with heating mode on demand.
We decided to change the 2 last BSVQ100 and 250 by new ones and then the system run well !!!
In my opinion there is dirt in the small filter inside each BS BOX between the liquid side and the 3WV...or dirt inside the 3WV.
I'll soon open these boxes and remove insulation to find exactly where they failed because i never had this problem during the first comissioning of a such system... Feel free to contact me if you want more explanation and thanks again for your suggestions.

11-05-2007, 08:28 PM
Hi all
Just a new information about this post, i've change yesterday a bs box (M series) once again on another installation.
The problem still remain the same: the 3 way valve do not allow heating mode.
We had 3 boxes in 1 month with this problem, hope this one is the last

31-05-2007, 06:21 PM
About this topic does anyone's interesting by what we've finaly found ?

31-05-2007, 06:48 PM
I am, dont want you to feel like you were talking to yourself

31-05-2007, 07:58 PM
I am, dont want you to feel like you were talking to yourself
Thanks a lot...
Last week i completly remove insulation from a BS BOX trying to find some failure.
I had to cut the 3 way valve to find a broken part inside it: it's a steel part that link up the two pistons...
I remind the 3WV is the same concept as 4WV so the pressure could not strike this piston as well.
That's why we had problem in heating mode due to pressure leak inside the 3WV.
I hope nobody have to repair a BS BOX but if the same symptoms occurs you'll spend less time...
From Daikin it never happens...

10-06-2007, 02:31 AM
thanks cool9

10-06-2007, 10:12 AM
thanks cool9
Hi wolf
If you pay attention to this problem i think maybe you had it, or you maintain HR system.
I have pictures if you want, send me a private message with email if you're interesting of.
Kind regards