Daikin VRV (was Air Conditioning by Ric)

[ric]

i have been to a daikin vrv in a office building a few times now.i am writing this thread on the of chance if anybody has had a problem like this.when the system ask's for full load on in door units the suction pressure is dropping to 30psi and riseing agian unable to hold around 60psi.all problems are saying unit is short of gas but i have checked this by recliaming charge no faults on that side.i have more information if needed

[frank]

i have been to a daikin vrv in a office building a few times now.i am writing this thread on the of chance if anybody has had a problem like this.when the system ask's for full load on in door units the suction pressure is dropping to 30psi and riseing agian unable to hold around 60psi.all problems are saying unit is short of gas but i have checked this by recliaming charge no faults on that side.i have more information if needed

Hi Ric

You can't just look at the suction pressures on a VRV to determine if it is working correctly.
Are you getting any fault codes? lack of cooling on the indoor units?
is it a 2 pipe or 3 pipe system?

[piston broke]

CORRECTION

I agree with Frank you should really get fault codes if there is a problem.

I'm assuming you have checked the basics like air flow across the indoor units eg. are the filters clean?

Also watch for low ambients. Some ppl in Scotland think and AC system is a fridge. Get some heat load on the evaporator.

Oh and just on the off chance are the pipe sizes and lengths correct?

Cheers

PIST

[frank]

Hi piston

Do you want to delete your first post?

if you make a mistake in your post then just click the EDIT button, bottom right, and make the corrections. After, just click on "save changes".

You don't need to retype the whole post.

[puddleboy3]

Hi there, can you please give model number of system? How many indoors connected? If system is heat pump does it have the same problems on heating as cooling. If system is running with low back pressure on a cooling mode the unloader compressor should not be on and the liquid injection will be open on the inverter to prevent overheat. In most cases when short of refrigerant all VRV systems right back to the G series will display F3 fault High discharge temp.

[Mr Memory]

The best and simplest way to tell if a VRV system is short of refrigerant is in heating mode. Check the head pressure at the outdoor unit (from the Schrader valve inside the condensing unit, not the service valve), and heating outputs of the indoor units. If the HP is 50-100 psig down from what it should be (depending on the type of refrigerant in the system), or the indoor units have a low heating capability then refrigerant shortage may be the problem. In cooling mode, if the indoor units are struggling to cool, turn them all off and start them one at a time. If the cooling capacity is okay to start with, and gradually gets worse the more units that are switched on, then once again refrigerant charge could be a problem. However, it could be something as simple as the return air filters on the indoor units need cleaning..... It is easy to mistake this for a refrigerant shortage problem!! Also, if there has been a leak and the system runs on R407C, composition change may have also taken place, which can make the system run erratically. Hope that helps.