Handy with Lieberts????

[BatesTech]

Just started up 2 Mini Data 1 5 ton 1 8 ton both supply same small very small space with huge expected heat load well I need to perform a lead and lag alternate days keeping one as back up only for mechanical falt. Like a 5 degrees difference every other day. The control box schedule is not capable so I was going to put a honeywell 8000 in the cicuit somewhere and was hoping to interupt a circuit with Y1 and not set a alarm code onthe liebert. Anybody know of a circuit I can make and break. (DCV)

[ispip]

please don't do that. break the remote shutdown contact to turn the units on/off. If you can get a switch over panel to make things easier

[Domcort]

as stated, please don't do that

Liebert has panels that are designed to do that, Lead/Lag, changeover, temp staging. They are called AC4 and AC8, contact your local Liebert guy for advice.

[BatesTech]

Thank you thats what i want. Its just to bad the customer didnt know what he wanted. Cant read minds but I can back charge.

[ispip]

It is ok, it really happens all the time! I don't understand why you have 2 differant sized units and what to lead/lag them.

[The Doctor]

But with two different units, lead/lagging them is not exactly the priority, is it? Sure, sure, the guy with the money says, "lead/lag them". We've all been there, but how about you accent that he has two 5 ton circuits and one three ton circuit.
What's he going to balance...the two 5s?
What about the 3ton? It's now in the minority. Do we have to make a rule here? :)

How about just staggering the setpoints, with one unit set high enough away from the first unit's setpoint to be "the backup"?

But's it's still not going to balance out, unless all the planets are in alignment.

[david chamberla]

contact liebert.: the rm senor(controle pannel).. is dc volts and has a interface board most likely behind stat sensor.or can be remotely located that ties into 'unit interface that is capable of remotely being controlled ,that is up by unit before hooking up call 614 888 0246 or you might let the smoke out that engineers put in those componets.. let it out it wont work. L.O.L..... :LOL:.

[GoColts]

I have too argree with whoever ask why two different tonages here. First is the 5 ton system going to carry the load when it is the "Lead" unit? I would think you would want to put in two 8 ton units in. Then it dosent matter which unit runs, it can carry the heat load. Second, why not just run the 8 ton unit and have the 5 ton as a true back up? If either one of the compressors fail this unit comes on and picks up the slack.

[flange]

There are multiple reasons why two diffedrently sized units could be there, one such idea is to be more closely matched to the load during different seasons, winter and summer. Even though server rooms are supposed to be sealed environments, many are not. it could be that server use is anticipated to be higher at certain times, for example a call center at dinnertime with heavy dialing. whomever made THAT decision swhould be consulted as to why.

On to lead/lag, I too say get a panel. It can also give you alarm output, or in the case of one room we just did, it gave them a dialer they didnt know they bought. Probably an hour after I told them it was there, a phone line was waiting for us to tie in. a thermostat isnt the best answer.

[BatesTech]

as stated, please don't do that

Liebert has panels that are designed to do that, Lead/Lag, changeover, temp staging. They are called AC4 and AC8, contact your local Liebert guy for advice.

Cant figure out how to incorporate my smoke detecter and secondary pan float. The AC4 uses my remote shutdown terminals I originaly used. I need to have it show a alarm so the back up unit will kick in.

[Domcort]

Cant figure out how to incorporate my smoke detecter and secondary pan float. The AC4 uses my remote shutdown terminals I originaly used. I need to have it show a alarm so the back up unit will kick in.

Tie the smoke detector in series with the remote shutdown, so that if either of them open the unit will shutdown.
Check your units schematic for connection of the pan float switch, as you have condensate pump alarm input on the unit, or you can parallel this switch with the high water float switch in the unit.