thermoplus a/c thermostat wiring

[med-man]

can anyone please tell me how to properly install a hot/cold digital thermostat for my thermoplus 5 ton a/c

i have 4 wires, 4 colors. green , red, black, white. then the panel has 8 spaces, all with letters on em

sorry this is a double post. first time i have ever wired one of these units. always had air to air or swampers

thanks

med-man

 

[hvac guy]

The panel for the wallmount controller each letter corresponds to a color of wire, some hvac systems use all 8 wires, dampers, zone controls, signal/sensor inputs, etc.


Red = power from 24vac transformer
Black = common wire from transformer
Green = fan power
White = heat

The thermostat has corresponding terminals for each color wire. Hope that helps, if not just google and it will show you where eat wire goes on the thermostat and the AH and condensor unit.

 

[med-man]

hey hvac guy

thanks, i have it hooked up but the condenser kicks, chatters then dies. i was thinking maybe i had the thermostat connected wrong?

do they sell thermoplusses precharged with freon or dry? typically?

med-man

 

[hvac guy]

Is your AC unit three-phase, if it is, it may be wired in reverse, if the three phase wires are reversed, it will reverse the compressor. The contactor should be wired with red, blue and black wires and match them to the three phases. If you are single phase, it is probably the thermostat, the four wires from the AHU may be wired wrong. Can you indicate where the wires are connected.

 

[hvac guy]

Sorry Med-man, your ac unit is water cooled, that will be different wiring than a standard ac unit.

 

[med-man]

hey hvac guy

ya it is water cooled. the condenser kicks, but it doesnt seem like the water valve opens to let the flow cool it.

seems like there is a kill switch if the water doesnt flow. thats what seems like is happening?

med-man

 

[med-man]

Is your AC unit three-phase, if it is, it may be wired in reverse, if the three phase wires are reversed, it will reverse the compressor. The contactor should be wired with red, blue and black wires and match them to the three phases. If you are single phase, it is probably the thermostat, the four wires from the AHU may be wired wrong. Can you indicate where the wires are connected.

hey dude

i think you are right. it did come as 3 phase. anyway to wire it for 240?

here are the pics.

feedback is much appreciated

med-man

 

[med-man]

last pic

i called the guy that got it for me. he actually said it was 3 phase. let me know if more info is needed please

i have asparky but hes never installed one of these. any advice to proceed

med-man

 

[rives]

hey dude

i think you are right. it did come as 3 phase. anyway to wire it for 240?

here are the pics.

feedback is much appreciated

med-man

From the looks of the terminal block in picture #5 above, it appears that you are trying to hook the unit up to single-phase power. This will not work - the compressor motor is a 3-phase motor and will stall under single-phase conditions. There would be substantial work to convert it over - the motor would need to be swapped out and the wiring modified at a minimum.

There is both single-phase and 3-phase 240v power. Single-phase motors have start/run capacitors and a centrifugal switch to put the capacitors into the circuit at the appropriate time. 3-phase motors do not have this additional circuitry.

 

[med-man]

hi rives

thanks for the info

in the panflet it does say in can run single phase without mods

any comments? need me to take a pic of this writing?

med-man

 

[rives]

Are there any instructions on how to swap from one source to the other? The schematic in picture #4 shows three "T" leads going to the compressor motor. The rest of the circuit looks like it would function on single-phase, but I've never seen a motor that would run on both single or three-phase. Single-phase motors lack the starting torque to start up without the additional circuitry mentioned above.

*edit* In googling information on the unit, there are both single and three-phase versions of that model with different hookups for the compressor motor. I couldn't find anything about the 3-phase unit being convertible to single-phase.

 

[med-man]

hey rives

cool.

i will let my sparky read the info. i kind of understand what you are saying.

is there no such thing as a phase converter to put between the unit and the breaker

thanks again for the explanation

med-man

 

[hvac guy]

You'll need a phase converter that will allow you to run a three phase machine on single phase power. There are three basic types of converters: static, rotary and electronic. I would switch to a single phase unit if you can, less hassle than installing a phase converter.

 

[LEDfoot]

Interesting, I'm slightly familiar with rotary and electronic converters but not static.

http://www.phase-a-matic.com/StaticDescription.htm

 

[rives]

As HVAC Guy said, there is the option of putting a phase converter into the circuit, but they are relatively expensive, usually cannot source the level of power that you want on a 1-for-1 basis (they need to be significantly oversized), and it's one more piece of gear to go haywire. I would either change out the unit for a single-phase one or change the compressor motor/control circuit out.

 

[med-man]

hi guys cool

anyone know where these motor/control circuits are available? i have 2 weekes ti figure this out. just need it working by then then. i amlost died getting it up to where it is and i will be damned to get it down, ship it back pay the fees just to do and exchange lol

med-man

 

[rives]

You might get in touch with whoever you bought the unit from and get them to go through the parts list for each unit to round up everything that you would need. I imagine that it will void any warranty that you have on the unit, though. If the motor is mounted separately from the compressor (non c-face mount), then the alignment on the coupling is going to be both critical and difficult for a novice to accomplish. If it is a c-face arrangement, then it shouldn't be too much of a problem. Also, if your electrician was stumped by the single-phase vs three-phase issue, it is probably beyond his expertise to convert the unit over.

 

[med-man]

hey rives

he just wired it single phase is all.

he said we might just be able to pigtal something to close the circuit or something. he just set it up so air could circulate is all

thanks again man, much appreciated

med-man

 

[HidingInTheHaze]

Hindsight is always 20/20 but first thing to do is to always check is the buildings electrical supply. Different areas can have different voltages. Best thing to do is find a place with 480v industrial voltage so you could put in a transformers and derive any voltage you need.
Typically residential spots will be 240v/120v.

480v is the shit, you can transform that in to 277, 240/120, or 208v.