Seperate Circuit Required??

[CLoSeR]

Hi All,

Im looking to get AC installed in my apartment, and have had a couple quotes.

First quote was for a Daikin Multi Split, serving 2 indoor units:

External Unit: 3MXS52EVMA
Indoor Unit 1: FTXS25 (2.5Kw)
Indoor Unit 2: FTXS50 (5.0Kw)

Now in the quote, it was stated to "loop off existing 10Amp" to power the External Unit. And the guy explained that they will power off the GPO in one of the rooms.

Now, this seems a little dodgy to me, and I dont think this is safe, or upto the requirements to run a Multihead Unit.

I should also mention that installing a new circuit is an almost impossible task, as this apartment has rendered solid core walls, with no cavity. Other than running an ugly piece of tracking from the mainboard to the external unit its pretty much a no go.

Second quote was from a friend of mine, he said the most I can run off the existing loop is a Single Split 1.5HP (3.5Kw Cooling). He cannot believe the previous quote, says its not possible, and will not install a Multi for me on the existing circuit.

Now, Ive checked the mainboard, and can see that infact the existing circuit is on a 20Amp fuse.

Can anyone shed some light on this? Of course I would love to have 5.5 and 2.5Kw babies installed, but I dont wanna burn the place down.

[frank]

I can see a couple of problems here. If you want a 2.5kW & a 5kW unit installed, you should get a quote for a different multi outdoor unit. The indoor units you want add up to 7.5kW but the outdoor unit is only rated at 5.3kW, What this means is that, at peak times, you will only get partial capacity out of each indoor unit.

The second problem is the 10Amp supply.

Here in the UK, the regs say that you should install a separate dedicated supply as it is fixed equipment. Without checking the manufacturers paperwork in the office, I would say that a 10Amp supply is undersized. The smallest supply I can recall is 16Amp for the smaller units and 20Amp for the mid sized units. This would need a 20Amp supply. I may be wrong without checking, but I'm sure I won't be far out.

[multisync]

Daikin recommend 10a for their 2.5 and 30a for the 5,2
(Check the book: these are MAX fuse ratings not suggested or recommended, a lot of people miss that point!)

However I bet the twin would run off a 10a. I will not get into the rights and wrongs esp if the electrics are dodgy but the worst that could happen is the fuse blows..

This maybe a front room and bedroom set up which means both are unlikely to be on at the same time. If so a 5.2 could be ok in such a situation. (we once fitted 2 x 2.5 on a 4 for this very reason)

[CLoSeR]

I actually called the 1st company back, and queried them on the setup. They said that the 5Kw and 2.5Kw are the cooling KW, and not the actual Kw the devices will pull.

They said it will use somewhere between 2.2 - 2.4 Kw.

Im not gonna go with them, too expensive and seem a bit dodgy.

Instead im gonna have 2 Fujitsu Inverter Splits installed.
Living Room
3.5 Kw Cooling (1.5HP) <<< Wont put anything in higher than 1.5HP.. Should still be ok, may take an extra 20 minutes to cool the room.
Bedroom
2.6 Kw Cooling (1.0HP)

Since they'll both be on the same circuit, which incidently is running on a 20Amp Fuse. We have been told that theres a good chance we wont be able to run both at the same time.

If we have to use one at a time then thats fine, the one in the bedroom is mostly for nights, which recently in Sydney have been bloody warm.

[eggs]

I think a 10a supply will be more than safe.
I don't know how everybody else commissions their kit, but i always put on an amp probe and put the system through it's paces. I have never seen a 5/6 kw inverter system pull more than 6.5 amps.
Recently i installed a 10kw inverter system and commissioned it on a 13a plug top (sparky wasn't ready for me) even at -2degC outside, the system on full heating never broke 10 amps.

Whats the problem ?

Eggs

*Edit the MCB/Fuse is to protect the cable, not the kit*

[CLoSeR]

My AC mate who is gonna do the deal on the Fujitsu units said they would pull around 4Amps each when running.

Ive just checked the specs on Fujitsu site, and are as follows:

Fujitsu ASTA09LCC Inverter 2.6Kw
Running Current Cooling: 3Amps
Running Current Cooling Rang: 6Amps Max

Fujitsu ASTA12LCC Inverter 3.5Kw
Running Current Cooling: 4.1Amps
Running Current Cooling Rang: 7Amps Max

Im pretty happy with this, being that its a 20Amp Circuit, and I do have other appliances on it. Major devices are a PC, TV, and some Router/Switch. Im thinking they'll all play happily together. Might even get away with both AC's on at the same time.. Will have to wait and see.

[frank]

What's the problem ?

There's not a problem, but, if the manufacturers recommended size of MCB is not fitted then there may be warranty issues.

The manufacturers size the MCB's for a reason.

[multisync]

There's not a problem, but, if the manufacturers recommended size of MCB is not fitted then there may be warranty issues.

The manufacturers size the MCB's for a reason.

Daikin down rated their small splits from 16a to 10a in the UK for a 'reason' alright-err because they were losing a lot of sales to others who'd spec'd 13a!

The 'reason' was that Daikin Europe said 16a simply because they hadn't kept up with the times. They just didn't bother to amend because the UK is the only ones with 13a fuses in plugs-Till the salesmen told them to change the UK literature.

However as I say check the spec - a 10a is the MAX fuse not the minimum or recommended.
A unit which draws 3-4a should not be fitted to a 16a fuse !

[Karl Hofmann]

This is something that does drive me nuts... A manufacturer can state that the maximum current draw is 9 amps and the start current is 3 amps yet will require a 20 or 30 amp protection device... To my way of thinking, this is just plane wrong... Surly a 10 amp protection device is far safer... And so this is what I fit.

I have looked and looked in the wiring regs, but I cannot find the reg that states that a fixed appliance is to be on its own circuit.. Indeed a 13 amp plug and unswitched socket seem to satisfy all of the criteria. That said any appliance that may interfere electrically with the other equipment on that circuit must be on its own circuit.. so I would conclude that fixed speed kit must be on its own circuit and smaller inverters may be connected to the ring via a three pin fused plug.

[eggs]

As i have stated, i always go with the 17th edition. Bllx to the the manufacturers instructions, the destruction book says "must be installed to current local regulations"

THE FUSE IS TO PROTECT THE CABLE, nothing else, period.

Eggs

[nike123]

D
A unit which draws 3-4a should not be fitted to a 16a fuse !

Fuse on main distribution board doesn't have role to protect equipment and it has only role to protect installed cable.
Therefore it is perfectly OK to fit unit of 3-4A consumption to 16A fuse.
Please, bare in mind that fuses on distribution board are only for protection of installations, not equipment. If equipment need protection, it is installed in equipment.

That is common misunderstanding from non-electrical technicians.

[nike123]

As

THE FUSE IS TO PROTECT THE CABLE, nothing else, period.

Yep, exactly that!!

[nike123]

This is something that does drive me nuts... A manufacturer can state that the maximum current draw is 9 amps and the start current is 3 amps yet will require a 20 or 30 amp protection device... To my way of thinking, this is just plane wrong... Surly a 10 amp protection device is far safer... And so this is what I fit.

Please give us example of model# where such specification and demand is stated.
Maybe with full insight we could explain manufacturer view.

The selection should be as follow:
You find allowable voltage drop for unit. According to that you size cable cross section. Then you size fuse according to chosen cable.

[frank]

However as I say check the spec - a 10a is the MAX fuse not the minimum or recommended.

................

Without checking the manufacturers paperwork in the office, I would say that a 10Amp supply is undersized.

[Debonair Spain]

Hi All,

Im looking to get AC installed in my apartment, and have had a couple quotes.

First quote was for a Daikin Multi Split, serving 2 indoor units:

External Unit: 3MXS52EVMA
Indoor Unit 1: FTXS25 (2.5Kw)
Indoor Unit 2: FTXS50 (5.0Kw)

Now in the quote, it was stated to "loop off existing 10Amp" to power the External Unit. And the guy explained that they will power off the GPO in one of the rooms.

Now, this seems a little dodgy to me, and I dont think this is safe, or upto the requirements to run a Multihead Unit.

I should also mention that installing a new circuit is an almost impossible task, as this apartment has rendered solid core walls, with no cavity. Other than running an ugly piece of tracking from the mainboard to the external unit its pretty much a no go.

Second quote was from a friend of mine, he said the most I can run off the existing loop is a Single Split 1.5HP (3.5Kw Cooling). He cannot believe the previous quote, says its not possible, and will not install a Multi for me on the existing circuit.

Now, Ive checked the mainboard, and can see that infact the existing circuit is on a 20Amp fuse.

Can anyone shed some light on this? Of course I would love to have 5.5 and 2.5Kw babies installed, but I dont wanna burn the place down.

Hi Closer i install a lot of Daikin here in Spain which have similar temperatures, i have to use plug sockets as a means of supply and base the sizing of a system on approx 150 watts per square meter and the individuals using the system. Are you likely to use the bigger unit which i suppose is for your lounge at the same time as the bedroom unit, if not you will not lose capacity.

Daikin also have an 2MXS50G which will also house a 5.0KW system.