I am working with a portable AC unit that needs to keep a small computer room cool.
If the power goes out to the building the AC will shutoff and won't comeback ON automatically.

My question is: can i bypass (jumper) the main ON/OFF switch so once the power turns back ON the AC will do as well.

Or is there a better solution?

The cost of a single central AC just for that room is way too expensive for this small start up company.

Is the on/off switch a momentary switch? If not, then leaving the switch in the on position should restart the unit when power returns.

Aside from the technical issues, do you really want to modify the equipment? I would think the LIABILITY INSURANCE would be rather significant if something did not go well.

The switch is a momentary.

Contact the manufacturer. There may be some sort of user menu where you can set the machine to start up after a restoration of power. The same idea but different application, as the sleep timer on a TV set.

Can the A/C be connected to a home automation system? If so, perhaps the connection point allows remote operation.

Does the A/C unit use a remote control? Perhaps the remote could be hacked?

I think Larry's first response is the only real answer for you. See what the manufacturer says. You really want to be using the approved solution. I am sure you can jumper something out to make it go but that might be outside the scope of your insurance.

Small UPS depending on how long the power is going to be off?

Actually being a AC it need a large UPS.
Contact the manufacturer and see if they make an 'auto restart' kit.

I contacted the manufacturer they could not help me. The unit doesn't have an auto ON function. I think i will push them to go to a small central AC unit just for that room.

Too bad the building owner doesn't allow a wall mounted unit.

Thank you all for your replies.

Are you samiliar with what is called a 'mini-split' system?

Niko:
You said a 'small computer room'?

Is that room a 'IT' classified room? (Article 645)

I suggest that you check into that Article. As you said a 'small start-up' company, but your building dept may have issues with that 'room'.

It all depnds on what it is 'called' and by whom.

A seperate system works in an 'IT' room by Art 645, but there qre other requirements.

Niko:
You said a 'small computer room'?

Is that room a 'IT' classified room? (Article 645)

I suggest that you check into that Article. As you said a 'small start-up' company, but your building dept may have issues with that 'room'.

It all depnds on what it is 'called' and by whom.

A seperate system works in an 'IT' room by Art 645, but there qre other requirements.

Use a wall mounted air conditioner -- say one-ton...

And have the condenser vent heat into some other space.

Just cut in a hole in the sheet rock and reframe it to hold the unit.

The last time I looked such units did not use a momentary switch.

A truly portable air conditioner works for people -- not machines.

You need to get the heat entirely out of the IT room.

I doubt very seriously that this would qualify as a 645 room.
Just because you put a computer in a room does not make it a "computer room". (645.4)

I doubt a mini split is going to do much for him either. They usually only have a wireless remote for the controls and the two I have come back from a power failure "off".

If I was really going to hack this, I would come up with a N/C point of a relay to provide the "on" pulse and pick the relay with a voltage generated inside the AC unit. That is how I kick started the MP3 player PCs in my cars that had ATX power supplies.
You still may want to do this in conjunction with an HVAC contractor for a little legal cover.

BTW one consideration is starting the compressor into a hydraulic lock. If you have an auto restart you should have a lock out time delay relay on the compressor so it won't short cycle if the power glitches. Those reclosers usually cycle faster than you would want to stop and start a compressor.

Liebert is a big name in data center cooling. They are not cheap, but if it's in the budget, I would probably look into one of their small data room cooling systems.

Liebert