Using 3rd party Mechanical timer on VRF Indoor unit

There is this home that recently installed Fujitsu VRF V2 airconditioning.
Hes got a server room where theres two 1hp wallmount aircons that he uses and would like to set up a timer for both the units working approx 12 hrs on/off
(as in one unit turns on, while the other is off, and the trend continues )

I know in hotels our systems are connected to a hotel key-card. Simple card that when the guest
inserts into the slot, would bring life (supply) to rooms lighting/air condioning/tv etc etc)

I would now want to propose a mechanical timer something like the SUL181H

http://www.sungko.com/SUL181H_SYN161...60A-Timer.html

I know the logic behind it is that the similar way it function for the hotel key-card, the mechanical timer would just replace it.

Im unsure about the wiring of the entire thing, some say
(Supply wires to mechanical timer - mechanical timer to relay - relay to indoor unit)

What relay are we talking about here?

From what I saw in the hotel type and keycard connetion,
I know the indoor unit aircond fujitsu, for eg: AUXB18LALH has an additional
3wires(red/black/yellow) from CN27(indoor PCB) to room MCB(I guess).

Im unclear about the whole thing, and would appreciate some help. :(
*The timer I intend to use would be battery powered, as the owner does not want the timing
set up to be screwed when theres a power trip.The SUL181H is a battery powered timer.
Could someone assist me please.

Allright, this would help you guys understand what I meant by CN27 external input on the Indoor PCB.
theres a diagram from installation manual.

Now the hotel wiring that i saw, I believe Cn27 from the indoor pcb goes directly to the rooms MCB or contactor,
that is triggered on or off when keycard in room is inserted or remove.

So how do i wire a battery powered timer to replace the keycard. :)Attachment 8759Attachment 8760

I think he's mad. I would set one unit at 20 c and the other at 22c and leave them both running.then every few months change the set points.

Stupid having back up and not using it

Quote:

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Originally Posted by r.bartlett

I think he's mad. I would set one unit at 20 c and the other at 22c and leave them both running.then every few months change the set points.

Stupid having back up and not using it

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what i meants: 1 goes on for 6 hrs, then shuts off while the other takes over... the trend follows each day..

Rash,

Typical Server room required one duty, one standby.
-12 or 24 hr changed over
-one breakdown/trip/error-one takeover
-high temperature takeover

You may need to consider having feedback cum status signals and as well as 3rd party temperature sensors as critical alarm to activate both air cond.

vrf,vrv systems shouldnt be used for server room cooling- a dedicated split unit/close control unit should be used
but if this cannot be achieved just run both units at the same setpoint- then if 1 struggles or fails the other will start up - otherwise if your gonna use the timer the switch contacts need to energise a 11 pin relay- so the timer powers the a1 a2 coil then as the 3 relays have a common no,nc contact-then use common and normally closed on 1 unit-switching ur cn27
and the other unit connected to common and normally open so as the timer cycles and energises the coil you will get auto changeover function.
then to get clever if you fit 2 hi limit stats to switch the cn27 contacts on each unit as your temp rises then both units will operate
i recommend run both continuously

Quote:

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Originally Posted by install monkey

vrf,vrv systems shouldnt be used for server room cooling- a dedicated split unit/close control unit should be used
but if this cannot be achieved just run both units at the same setpoint- then if 1 struggles or fails the other will start up - otherwise if your gonna use the timer the switch contacts need to energise a 11 pin relay- so the timer powers the a1 a2 coil then as the 3 relays have a common no,nc contact-then use common and normally closed on 1 unit-switching ur cn27
and the other unit connected to common and normally open so as the timer cycles and energises the coil you will get auto changeover function.
then to get clever if you fit 2 hi limit stats to switch the cn27 contacts on each unit as your temp rises then both units will operate
i recommend run both continuously

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m sorry mate, I did not get that at all...Im quite new .. rookie...
pretty much a rookie in my profession as well... but i'd wanna learn...

you mind explaining in detail... perhaps makin it alittle simpler for rookie ass like me... :(

Any idea on this issue :( ?

Fujitsu have an optional input card for the indoor units. You will have to talk to fujitsu about make and model and if it is compatable for your indoor unit. this allows you to have an external switch being a timer or normal on?off switch. we wire them up with a switch with a built in timer so the unit runs for 4 hours. You could just use a time switch using N/c and N/O contacs so it switches from one to the other daily or every 12 hours.
. give fujitsu a call. do they use a wired remote? if so you can set the timer on that so they run 12 hours a day each.

Good luck

Vrf A/C should not be used in server rooms as already said by InstallMonkey .
If part of a larger system and the only unit under demand is the server room unit the outdoor unit won't thank you for it, generally speaking VRF machinery should not be operated below 30% capacity for long periods as it causes issues with oil and refrigerant return .Which cause a lack of comp cooling and nuisance LP trips..
Cheers
Stu

wel yea... i get that..but the problem now that ... all installation/constructions works are done... so theres no taking a step back... just need a solution for the problem...by using the third party mechanical timer..
not an external switch controller...

i hav seen em using key cards b4..connected from the cn27 indoor pcb... justnot sure what type of timer and relay if built in or ? :(

I found this, a timer - could you guys help me explain this pls...

1. Does this have a dry contact, correct me if im wrong, see details - (switching capacity 10A)
from the installation manual i have: it says the external input for my indoor aircon CN27 terminal needs:

http://www.refrigeration-engineer.co...achmentid=8760

Output voltage - 12VDC
permissible current - 15mA



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The timer product and its specification:

http://www.theben.de/en/Products/TIM...gram/SUL-289-g

details:

Operating voltage 230 V AC
Switching capacity at 250 V AC, cos φ = 1 10 A
Switching capacity at 250 V AC, cos φ = 0,6 2 A
Switching output Potential-free and phase-independent
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Switching capacity says 10A, that means i cant use it with mine as mine permissible 12VDC and 15mA.

7 live to timer
8 neutral to timer
then you have 2 volt free switchen contacts
3 from your cn27 goes to your common connection 2 0r 5 depending on which channel you use
1 and 2 go from cn27 to 1,3 on your channel 1 or 4 and 6 if channel 2
be sure to have swapped connections on the 2nd channel as you want 1 unit to stop and the other to start.
good luck