Daikin VRVIII - refrigerant charge

[gwilliamson]

Hi Chaps

I wonder if any one can help.

I have an install with 2 VRVIII outdoor condensing units (REYQ12's) running 3 x 10 kw indoor ducted units each.

Although all up and running i have noticed what i feel to be excessive frosting outside on the condensor fins. First one side, then the other, swapping from one side of the unit to the other whilst one side defrosts, but this is happening at around 10 - 15 minute intervals. Is this correct?

I charged one unit using the automatic charge method which after working out the charge manually i feel is about 2 kg short. I also am a bit concerned as following the install guide to working out the additional refrigerant charge makes no reference to the ammount already pre charged. Which on the footplate states 10.5kg.

I also feel the air off temps inside are not high enough.

Any information or tips on charging and commissioning these units would be greatfully recieved.

Kind regards
Gareth

[gloucesterfridg]

Hi Gareth

In order to avoid all the hassle of recovering all the gas....and measuring....i recommend a magic trick.
1.I hope you weighed how much additional gas you put
never mind that it has been added automatically of in vacuum.
2.Go measure all the liquid lines and according to their size in your booklet you should manually calculate how much gas you need.
3.Compare what is charged automatically and top up the difference or remove the difference.
4.All the precharged gas is for the outdoor heat exchanger not for the additional feild pipe added by the
engineers.
5.While still in vaccum with the right calculations
charge the gas and you should not have any worries.


Pipe size from the top of my head:

1/4 - 0.0025 g

3/8 - 0.012 g

1/2 - 0,056 g..........(check your booklet supplied by DAIKIN)

and then multiply these grams by the meter+ the other pipe+ the other pipe+ the other liquid line pipe

and you got it.:D:D:D

Did you not read what he wrote?

GF

[nike123]

Did you charged when indoor temperature is between 10-32°C and outdoor between 0-42°C?
What is height difference between indoor units and outdoor unit (max difference)?
Does outdoor unit is situated above or below indoor units? Is it true that your indoor unit capacity is around 55% of outdoor units capacity?


I asking this, because there is certain conditions which must be satisfied in order to perform automatic charging. If any of them are not satisfied, then you must charge by weight. Could you confirm that you are familiar with all necessary conditions for automatic charging and that are, in this case, all satisfied?

[gloucesterfridg]

Just from curiousity:

Did you ever work at least on on VRV/VRF or even standing and looking what the others do?


What has my experience got to do with your reading?

GF

[The Viking]

DEEP BREATHS EVERYONE.

Then have a look HERE (http://www.refrigeration-engineer.com/forums/showthread.php?p=91756#post91756)

[frank]

The big RED button is ready - if required ;)

[Brian_UK]

Gloucesterfridg and MRcoolingMAGIC...

Please relax gentleman whilst in public.

[andy c]

If you have a controller connected to one of the indoor units, you can get into the service settings and see what the air on, air off and coil temps are, which will give you an idea of what it's doing. Phone Daikin Tech, they can talk you through the switch sequence at the outdoor unit to ensure none of the compressors have been manually switched off via the pcb, i've had that a couple of times in the past. I have a similar problem on a site but wont be going back for a couple of weeks. Andy C.

[transit 1]

Hi Chaps

I wonder if any one can help.

I have an install with 2 VRVIII outdoor condensing units (REYQ12's) running 3 x 10 kw indoor ducted units each.

Although all up and running i have noticed what i feel to be excessive frosting outside on the condensor fins. First one side, then the other, swapping from one side of the unit to the other whilst one side defrosts, but this is happening at around 10 - 15 minute intervals. Is this correct?

I charged one unit using the automatic charge method which after working out the charge manually i feel is about 2 kg short. I also am a bit concerned as following the install guide to working out the additional refrigerant charge makes no reference to the ammount already pre charged. Which on the footplate states 10.5kg.

I also feel the air off temps inside are not high enough.

Any information or tips on charging and commissioning these units would be greatfully recieved.

Kind regards
Gareth
bring back vrv 2 i say ? is air off 39 deg in heating then drops off even when room temp not achieved if so decant recharge was factory charge in????? make sure use right decant procedure same as vrv2 but dont kill outdoor power

[gwilliamson]

Thanks Chaps. Going back to site tomorrow to finally sort this out so will see how we go. Might be back online tomorrow night scratching my head!!

[andy c]

Hi Gareth,
How did you get on with the coil freezing up problem with this kit, i'm off to one sometime this week and would appreciate any pointers. Regards, Andy.C.

[Jase]

How the hell did you manage to put the vrv through the auto-charge function in these ambients?
Especially this time of year, unless of course the system is installed in Portugal:D

Jase

[SUBCONTRACTOR]

Exactly Jase

No matter how sophisticated the unit is .It relies on thermistors and ambient temp to calculate the subcool in order to determine the right charge and at this time of year it might of played a trick to the comisssioing engineer.That is why the best ever way is to measure the pipes.Add your gas then keep it minimum 6 hour on a crankcase heater to prevent damage to the compressor when it kicks in .:D


SPOT ON MAGIC:D

[gwilliamson]

Thanks guys for all your help. Got it all sorted. Back to traditional methods, measured the pipe work and calculated the charge.
All is working fine now, have decided in the future to pay no attention to Daikin toys such as auto charging and addressing. Its quicker in the long run to do it all manually.
Thanks
Gareth