control wire

[bori]

Good Afternoon, on low voltge control circuit Mr. Holt stated that the yellow control wire for compressor on A/C unit originates from thermostat, I am currently studying for my Electrical Journeyman license. I am however certified as a HVAC Technician,the yelow wire goes from thermostat to relay in Air Handler, from there it sends signal to compressor when T.S. calls for cooling. The graphic is incorrect and so is the explanation. The low voltage wire goes from T.S. to A/H and then to condenser,it activates compressor and condenser fan.:happysad: Than you

 

[kwired]

Good Afternoon, on low voltge control circuit Mr. Holt stated that the yellow control wire for compressor on A/C unit originates from thermostat, I am currently studying for my Electrical Journeyman license. I am however certified as a HVAC Technician,the yelow wire goes from thermostat to relay in Air Handler, from there it sends signal to compressor when T.S. calls for cooling. The graphic is incorrect and so is the explanation. The low voltage wire goes from T.S. to A/H and then to condenser,it activates compressor and condenser fan.:happysad: Than you

Can you post a link or copy of the material in question?

Often the "Y" conductor does physically run from thermostat to the air handler then to the AC unit, but it generally doesn't actually power anything in the air handler, there is just a terminal there for the convenience of splicing this conductor.

 

[bori]

yellow wire

yellow wire

the yellow wire is connected from T.S to a relay, this relay is energised when T.S calls for coling, insome older units the wire was spliced straight thru,in newer models that use 4 or 6 conductor wire for communication between condenser and air handler, and different stages or as heat pumps a relay is present by it self or in Pc board. The term A/C unit refers to entitre system, in a split unit you must refer to outside unit as the condenser or heat pump. Thank You

 

[kwired]

the yellow wire is connected from T.S to a relay, this relay is energised when T.S calls for coling, insome older units the wire was spliced straight thru,in newer models that use 4 or 6 conductor wire for communication between condenser and air handler, and different stages or as heat pumps a relay is present by it self or in Pc board. The term A/C unit refers to entitre system, in a split unit you must refer to outside unit as the condenser or heat pump. Thank You

I am very well aware of what you all mentioned. You are starting to see more units that maybe do have a load within the air handler that is energized by this conductor. There are still many basic systems that still do not have anything in the air handler except for a splice point for the "Y" conductor. About the only thing that really is needed from the air handler from this conductor is a signal to a variable speed fan control for telling the controller what the thermostat is calling for to determine fan speed. If you only have a single speed fan, there is not much need for the air handler to receive any kind of signal for the "Y" terminal from the thermostat, same thermostat will typically also send signal on the "G" terminal anytime the "Y" has a signal on it, which tells the air handler the fan needs to run.

 

[bori]

yellow wire

yellow wire

you are 100% correct. I still believe that the graphic neeeds to be changed, soit may reflect with todays wiring methods.. also on previous DVD Mike stated that if if the class 2 classification label on 24v transformer is marked over with sharpie it becomes a clas 1 and you may now run the control wiring with the power conductors. to do this you must bring wiring dirctly from A/H.Thank You for taking your time to correct me and instruct me,Thats what sets Mike Holt industries apart and in the forefront of the rest. My best Regards to Mr. Hutchings.

 

[kwired]

you are 100% correct. I still believe that the graphic neeeds to be changed, soit may reflect with todays wiring methods.. also on previous DVD Mike stated that if if the class 2 classification label on 24v transformer is marked over with sharpie it becomes a clas 1 and you may now run the control wiring with the power conductors. to do this you must bring wiring dirctly from A/H.Thank You for taking your time to correct me and instruct me,Thats what sets Mike Holt industries apart and in the forefront of the rest. My best Regards to Mr. Hutchings.

Again can you post the content in question so we can see and possibly explain better or even side with your concerns?

I will say there are cases where you can reclassify a class 2 circuit and run the conductors with class 1 or power conductors, but that means the entire circuit must be treated like class 1 or power conductors, which also means abandoning the typical class 2 thermostat and using a line voltage thermostat, and using class 1/power wiring methods for the entire control circuit.

 

[ronaldrc]

Mr. Holt is correct.

It originates from the thermostat because that is where it recieves its 24 VAC source.

Most units land this yellow control wire in the indoor unit probably because it is closer to the
thermostat.

on the newer units today most of the time the yellow conductor only energizes the compressor circuit.

 

[MarineTech]

Good Afternoon, on low voltge control circuit Mr. Holt stated that the yellow control wire for compressor on A/C unit originates from thermostat, I am currently studying for my Electrical Journeyman license. I am however certified as a HVAC Technician,the yelow wire goes from thermostat to relay in Air Handler, from there it sends signal to compressor when T.S. calls for cooling. The graphic is incorrect and so is the explanation. The low voltage wire goes from T.S. to A/H and then to condenser,it activates compressor and condenser fan.:happysad: Than you

I believe that Mike is referencing the common 4-Wire Thermostat low voltage (24 VAC) control wiring.

RSES training gives the basic 4-Wire Thermostat as follows:

Red (X1) 24VAC low voltage feed to TS.
Yellow (C1) Cooling request from TS to HVAC control board.
White (H1) Heating request from TS to HVAC control board.
Yellow (F) Fan request from TS to HVAC control board.

Generally the request signals energize control relays or opto isolators.

That being said, actual control for many larger HVAC installs have specialized wiring and controls.