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cool it
28-11-2005, 07:31 PM
Hi hope you are all ok !
I have been doing some ppm at a huge building in lichfield,uk. They have 4 vrv systems across 2floors.
There are 2 main open plan areas and the rest are seperate offices.
The problem lies with 2nd floor, There are 6 indoor units mod-pefy100vmma. They are run from one controller, 5 of them are on one condenser and the other 1 indoor is on another system.
The condensers have been linked (daisy chain )
The problem that we are getting is that when the outside temp starts to creep up we do not get satisfactory cooling.
Now i must mention that the total pipe run does exceed the maximum but have been told that its not by much as to cause any major problems. and i have been informed that charge has been added accordingly.
I have had an air off temp of 13 today and been told that that is the best they have had for 3 years. but it just does not bring the room down lower than 22.
The stats are placed on the return air grilles and all units are ducted in hard drawn duct.
That is all I know so far about this system and was wondering if any of you guys have any suggestions as to what possibilities there are. it works in heating mode pretty well but just really struggles in cooling.
One more thing the other systems are identical and perform very well the only difference is that this one has a stray unit from another condenser.
hope this makes sense and any questions i will try and help you .
thanks fortaking the time to read and hope you can throw some things my way.
Cool it ;)

aeb200
28-11-2005, 09:00 PM
The stats are placed on the return air grilles and all units are ducted in hard drawn duct.

Cool it ;)

Dear Cool it

I know that daikin reommend fitting remote room stats (optional extra) to ducted systems as return air sometimes isn't same temp as room air, although I believe it would make the room colder not hotter.
Mitsi direct tel no. is 0870 300 3000 they may be able to help.

Is airflow adequate? are filters/ coil ok. - ducted systems aren't usualy maintained as well as other systems as you have to go into ceiling void or loft for access.
cheers aeb200

aeb200
28-11-2005, 09:03 PM
also are you sure that the systems are not undersized for the bldg!!!!

cool it
28-11-2005, 10:36 PM
Hi thanks for your replys!
The filters / coils are fine and seem to have been looked after very well!
They are sized correctly as all the other systems and areas are identical !
It certainly is a strange one !
Thanks again !

Peter_1
28-11-2005, 11:04 PM
Did you connected already a PC to the system and logged all the values some time?

cool it
28-11-2005, 11:17 PM
Hi i dont have use of that facility !
unfortunately

Peter_1
29-11-2005, 11:33 PM
You can program via the themostat if you want to measure the room with the thermistor in the inlet of the unit or with the thermistor build-in in the thermostat itself.
This is done in 1 minute and yo can see direct the result.

cool it
01-12-2005, 02:10 AM
Hi again thanks again for your replys .
yes if you send me the manual via email that would be great
its carlwragg@yahoo.co.uk.
Also peter sorry if i may sound a bit thick but i dont suppose you could explain your last message for me i dont quite understand and if poss how to do it ? :) :rolleyes:

Peter_1
01-12-2005, 08:00 AM
Switch off the unit.
Activate the setting mode by pushing Filter + ‘test run’ button for some seconds.
The 4 right stripes will start to blink.
Set the address with the 'Timer (On/Off)' button (the next 2 stripes will blink now)
Set the number of the unit with the ‘Timer set’ (Up down) buttons.
Confirm by pushing button 'Mode' (the button where you can chose between cooling, heating drying , fan..)
Now the 3 left stripes will start to blink.
Set with the ‘Temp Up/Down’ buttons the first two stripes on ‘02’
Confirm by pushing button 'Mode' (the button where you can chose between cooling, heating drying , fan..)
Now 3th digit will blink.
Set with the ‘Temp Up/Down’ buttons this digit on ‘01’ if you wants to measure the average between the two probes, on ’02’ if you wants to measure the probe of the indoor unit and on ‘03’ if you wanna use the probe in the remote control.
The setting is OK if display stops blinking.
Leave ‘Function Settin’ by pushing Filter + ‘test run’ button for some seconds.
You will see that a new icon will appear in the remote control (an icon of the remote control)
This way, you can change 21 different settings.

Hopes it helped you

cool it
02-12-2005, 12:08 AM
Thanks for that peter it is usefull to have this although i believe that way is more so on sinle split types.
for this system is a vrv , it is the sw1 no1 on indoor board that changes the sense temp on these ubits.
I appreciate the help and time though very much.

techguy
05-12-2005, 02:56 PM
Hi Cool,
! check the compressor discharge temp if it goes above 105 degrees C the inverter will back off to protect the compressor. So you will get high load conditions with the unit running at low or restricted level.
You say you have 6 pefy100 indoors this is a cooling load of 60 kw what size are your outdoors ?
one at least should be a 500 if not your undersized.

Every reading that the mitsu PC gives you can be checked through the outdoor display by setting the switch's on SW1 in differant configuration. Thers differ slightly for differant models if you get back to me with an address I could send you a disk with the revelant manual on it.
regards
T

Scooby
05-12-2005, 10:38 PM
hi,

not being funny or anything guys but dont you think it would be better to start with the basics...

what is the volume of gas in the system.....

we all know some peeps just keep on filling to errrrrrrr that feels about right...........

if you havent looked after this system from the start cool it i would recommend you just start at the start....

decant vac and then weigh in the correct volume ....
( check calculation of liquid line for volume of gas to be added - work it out yourself with formula )

same probs look for summit more complicated..

cheers
scooby

ps if i had some my clients premises any lower than 25c
id have my **lls kicked :):):)

martinpsullivan
06-12-2005, 11:16 PM
I work on a site covering 35 outdoor vrvs with 224 indoor units my main problems are dirty filters, clogged centrifugal fans, clogged coils or low refrigerant charge.
The classic is clean filter but clogged vanes on centrifugal fan.

Scooby
08-12-2005, 09:16 PM
roughly the same number of units here Martin
but my main problem is with the customer,
they think they should get more than the 15 years
they have had already from the units....

Main problem when i took the building over was filters etc
but now it is pipes weakening, flares leaking and a right pain in the ass........

There should be a legal time limit for keeping R22 systems going..... coz i hate to think how much R22 is floating up there .......from this one site alone......

Scooby