Power supply for a 6.8 kW multi outdoor A/C

[Slateral]

I’m requesting quotes for installing a multi outdoor ac unit on the house wall to cool 2 rooms indoors. One quote received so far proposes installing a 20A mcb fitted to spare slot on box currently providing power to a workshop in the garden and seems a sensible way to go.

Another installer has proposed taking the power from a double socket (either in the lounge downstairs or in the bedroom upstairs ) on the ring main and drilling through the wall behind the socket to run power through the wall, and fitting a waterproof socket on the external wall to provide power. Downstairs ring main has a 32A mcb, upstairs a 16A mcb, so I am assuming upstairs is out anyway.
Is this approach worthy of any consideration at all? It’s less costly and avoids external cabling from my garage, hence my query.

 

[Murdoch]

If it’s really 6.8 kw then you need a dedicated 32A circuit

 

[johnb2713]

If it’s really 6.8 kw then you need a dedicated 32A circuit

Electrically it will be nearer 2.2kW or thereabouts, really need the make and model or a view of the rating plate. If it's a non inverter style it will need to be able to handle the startup surge of the compressor.

 

[binky]

20 amps is roughly 5kw, just for guidance.

 

[Marvo]

I think the 6.8kw rating will refer to the cooling capacity of the refrigeration system meaning it's just shy of 2 ton capacity in old units. I would personally suggest it would be better on its own 20A circuit. I'd also check manufacturers instructions regarding their power requirements and taboos before you go any further.

 

[Slateral]

Thanks for your replies and apologies for lack of info - please see attached pic.

thanks

 

[Murdoch]

So the MI suggests 20A - so a dedicated circuit is what I would install

 

[Sharpend]

We always give a separate supply to each outdoor unit, usually 20A for the smaller units such as these.

 

[SPECIAL LOCATION]

Another installer has proposed taking the power from a double socket (either in the lounge downstairs or in the bedroom upstairs ) on the ring main and drilling through the wall behind the socket to run power through the wall, and fitting a waterproof socket on the external wall to provide power. Downstairs ring main has a 32A mcb, upstairs a 16A mcb, so I am assuming upstairs is out anyway.
Is this approach worthy of any consideration at all? It’s less costly and avoids external cabling from my garage, hence my query.

Even if there is a 32A ring final circuit.. you would need to take account of what other loads also share that ring...
how much spare capacity and how evenly, (or-not), they are distributed around the ring...
e.g. is this ring also supplying a kitchen/utility?

The generic installation manual suggests that the 'model 24' requires a 20A overcurrent circuit breaker and a 30ma Earth Leakage breaker..
https://www.fujitsu-general.com/datafiles/W9319205465-0601_IM_En_AOYG36KBTA5.pdf

The PDF above was what resulted from putting your model No into these search option..
https://www.fujitsu-general.com/uk/support/downloads/search/index.html

I haven't fitted any of these.. But if I were.. I doubt I would be spurring off a ring...???
I would be considering the inconvenience factor if the ring supply trips the power off and you can't immediately reset the power?

So your dedicated 20A supply option, (even if a tad more expensive initially), would be the most economical long term option if taking reliability into account and the guidance suggested by the product manufacture.

I would NOT be recommend the ring option to any of my customers if I were quoting for the work.
hope that helps?

 

[Slateral]

Yes - that’s a great help - dedicated 20A supply here I come, then!
My thanks to you all for your advice.

 

[kerching]

I have never yet known an AC installation company give me the correct supply information, but I do/used to deal with a high portion of imbeciles

Just saying

 

[Murdoch]

Last one I looked at they had spurred off the upstairs ring with no OCPD except the 32A breaker