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cool#9
29-03-2007, 10:30 PM
Hello high engineers !!!
Have a non constant problem with
REYQ14M7W1B+
12 INDOOR UNIT+
12 bsvq100m
The system is under my maintenance contract and i try to work "seriously" with daikin's product (with vrv checker, data recording, etc..).
i can describe as follow...
4 at 5 times in winter/ heating mode when outdoor temperature is between +2 / +5°c the system does not operate as to reach the targets and stays in "hot start" on indoor side during at least 3 hours !!!
I coudn't make a data recording but when you ask to the customer to shut down outdoor power supply then just after the problem disapear at the same outdoor temperature !!! i mean after the hot start least roughly from 8 to 10 mn max.
Of sure i've check everything i know i even recharge and made a re-comissioning.
Note that i have 3 hr vrv2 in this case with different combination as mentionned above.
I've heard from very far away it could be a problem with bs's 3 way valve or outdoor gaz valve or a wrong software...better change the whole system.!
I would have your opinion and share why not my experience with daikin's product.
Your advices are welcome !!!
cool#9;)

coolments
30-03-2007, 01:15 AM
Hi, hope i can help read the below.
turning power off to a Daikin VRV condenser forces it into oil recovery mode on re-start so the problem doesnt go away it is mearly delayed for a while. I know you said you checked the gas charge but double check it and make sure the extra refrigerant has been added. A sure sign gas charge is correct that the inverter compressor and fixed speed compressor will be running flat out during pre warm or when stat set points are in the extreem setting, here goes with what i can tell you.
1. if it was the 4way valve passing then i assume the unit would fault out on pipe temperature problems
2. If the problem is isolated to a few units then there maybe blockages caused by poor install, no nitrogen purging or 1/4 liquid lines not burred out properly when joined causing restriction....Nightmare....!!!.
3. If every things running flat out then the system maybe be over indexed (Daikin VRV systems can have an over capacity of around 30% put onto AHU duty, based on the fact that not all the units would need 100% all the time), added to the fact that maybe the system is under sized to start with would lead to long long and more frequent warm up periods, especially if the systems turned on in the morning and expected to warm a cold building up. If this is the case then try running the system 24/7.

If all the above doesnt help then more info is required, does the system perform in cooling, is the problem new or has it always been like this, if the gas charge is correct and the system is not over indexed or under sized and the compressors dont seem to be running flat out then i would be looking for restrictions in the pipe work, non condensables, blocked out door coil, faulty sensors or thyristors, there are to many factors to consider and with out being there its hard diagnose. Last resort is get a Daikin Engineer out to do a system health check....Good luck

cool#9
30-03-2007, 08:29 AM
Thanks to Coolments for this prompt reply.

I know i have to check everything once more...because one day of daikin engineer cost a year round maintenance contract for 3 systems !!!
Let's just say :
<there is no problem in cooling mode
<The system is sized roughly 110%
<We don't reach pipe lenght limit
<I checked pipe lenght and calculation of total charge ammont
<The building as goog insulation
<The problem exist since the first winter
<I didn't install the systems (that's why they ask me to follow it now !!!)
<refnet joints are on the right position

But... i can't tell about:
>the quality/result of comissioning procedure
>the quality of brazing, is it done under nitrogen gas?
>the quality of the VRV2 HR series, i don't know about Daikin's contremesure.

One conclusion first, VRV system are more and more installed since 20 years because it generate good and rapid profit and don't need to be enginneer to make a selection.. just a data book is needed.
But, you have to be a very good service man to assume a real after sales service even if you have experience and the last service manual that's what we trying to do day by day.

cool#9

Thermatech
30-03-2007, 04:55 PM
Hi
Q1 What is the room temperature / indoor unit air on coil temp when the system becomes trapped in hot start mode?
Q2 How many of the indoor units are running in heat mode when system becomes trapped in hot start mode?
Q3 Are the units operating in high or low fan speed?

The indoor units are the system condenser coil when in heat mode yes !
If the condenser is oversized, in your case 110 % index then hot gas temperature at indoor units will be reduced if all indoor units are in heating mode.
If the room temperature is very cold then the system will be overcondensing & the hot gas temperature pressure will be reduced further.
If the units are all in high fan speed then the system will be overcondensing even more & hot gas temp reduced even more!
As your system works ok in cooling mode & only gets trapped in hot start mode when winter weather is very cold then I would suspect very cold indoor unit on coil temperature & overcondensing typicaly during early morning warm up due to building becoming very cold over night or weekend.

Try switching off 50% of indoor units & see if system runs at higher discharge hot gas temperature & indoor units move out of hot start warm up mode into full heating.
If it does then wait untill those rooms get up to warm room temperature & then turn on the other units one by one.
If this works then suggest implement phased early morning warm up program to ceep condenser coil size smaller untill rooms get up to air temperature.

This can be a problem for any VRV/VRF system when consultants / contractor select system on based on cooling load & forget to consider what conditions the system will have to operate at heating mode.

cool#9
30-03-2007, 05:35 PM
Dear Thermatech
Your remarks are relevant. Many thanks.
Usually the systems starts at 5.00 am and there is a cold prevention setting for the night, setting: +17°c
These functions are made by an i touch controler DCS601B51.( fan force to low 'til the office open at 9.00 am).
So i've already checked by recording on checker and indoor temperature in the night is about 17/18°c.
I've also try to change start up 50% at 5.00 am and the other 50% at 6.30 am but even it fails one time!!!
As you said on VRV the condenser becomes greater in hot indoor side even if you're off at 50% cause the expansion valve's open 10%, 200pls...
I even try a special setting by closing some expansion valve during th off to reduce down under 100% of real condenser size...
That's why i think about a problem of valve or 3 way valve that bypass directly hot gas in the outdoor unit or into bs box.
They are 12 three valves on indoor side (1 in each BSVQ under insulation ) and two big valves on outdoor side.
I think i will install a temperature recording on the outdoor first coupled with service checker...and hope the problem will occur at the same time.
Thanks again.
cool#9

Obi Wan
30-03-2007, 11:52 PM
Hello Cool#9

I think I have a pretty good idea on what is happening. I am assuming that the refrigerant charge is correct and the indoor units are not short cycling, i.e. no indoor units is switching between heating and cooling mode rapidly.
You will need to check the software version on the outdoor unit main PCB. To do this enter the “Monitor Mode” and press the “Set” button 19 times then press “Return”
Read the binary number from right to left. This will give you the 1st digit on the software version. Then press the “Set” button once, and read the binary number, this will give you the 2nd digit of the software version. Press the “Set” button again to read the 3rd digit of the software version.
In the end you should end up with V X.X.X

Now then,

There were several software versions in the history on the VRV II Heat Recovery Systems.

Anything older the Version 6.1.2 will need to be updated.

Version 5.1.2
Possible heating shortage if the system was switched OFF for a long time. 3 Way Valve in the BS Box may not slide across all the way. Pressure difference between HP & LP not enough if ambient is lower the 5ºC and if outdoor unit is lower than indoor units.

Version 5.7.4
Solved the above problem by increasing the pressure differential timer from 15 sec to 60 sec. Possible problem in multi application (2 or more outdoor units on one system) If communication error occurred between master and slave outdoor units during oil return, system could not reset and system was locked on oil return.

Version 6.1.2
Solved the above problem. Heating shortage problem may seen in poorly insulated buildings when indoor and outdoor temps are low. Target evaporating temperature was set to 0ºC. Outdoor units will enter defrost mode easily.

Version 7.8.5
Solved the above problem by setting the target evaporating temp to -2ºC and speeding up of the loading up of compressors.

V7.8.5 is the latest version and it does work very well provided there are no installation errors. (refrigerant charge, short cycling and heat stratification affecting the return air sensors, no indoor units in comms room application)
If the software does need to be updated, you will need a Daikin engineer with programming cable and laptop or replace the outdoor PCB with a spare part PCB. This should have the latest version.

Hope it helps!!

Obi Wan ;)

cool#9
31-03-2007, 12:26 PM
Hi Obi Wan
I've read your answer and i'm glad to share experience with you.
So first i'll check the version by the binary code on the outdoor main pcb (orange single layer type).
<Ive already seen daikin technical manager made an update by the serial port on the pcb but i have not the special cable neither flash programm to do it as well (it was in 2005 on a different site )>.
So i think i'd better order a new pcb under warranty.!.:D
In addition i found in another forum that there is a problem with a filter on VRVII HR M series.
This could create another problem on one outdoor gas pipe that bypass hp to lp...looks like my problem also.
I'm actually waiting about explanation and i'll advise you if you're interesting of...Do you allow that i send you i private message in this case ???
Regards
cool#9

puddleboy3
31-03-2007, 12:56 PM
You should be able to tell if the filter on the discharge line is causing your problem. The wrong filter was fitted @ the factory. Problem being that it was not a two way filter and on heating mode was crushing the filter and causing restriction. Then when the system was on a full cooling mode the discharge line is used as a suction. This on a few occasions caused the filter to breakaway and become jammed in the SV causing discharge gas to pass to the low side of the system.

Hope this helps

P.S Obi do you have the latest software version?

Obi Wan
31-03-2007, 08:33 PM
Hi cool#9,

I know about the filter issue on the VRV II heat recovery, but I think if this was the problem on your site you would know about it. There will be almost no heating from the indoor unit, the high and low pressure are almost equalised and there is excessive noise on the outdoor unit. I have not seen one of these fail for a while.

Feel free to send me a private message, all information is good information.:)

Hi puddleboy3

Yes I have the latest software for the brown single layer PCB and for the green double layer PCB.:rolleyes:

Best regards

Obi Wan

cool#9
20-04-2007, 08:09 PM
Hi everybody
For this problem i finaly changed the sofware version
( upgrade to v785 ) but the weather condition are too warm to see any difference.
Thanks again to Obi Wan to guided me upon a software problem possibility...
Regards
cool#9