HVAC and Residential load Calculation

[ING23]

Any one could help clarifying how determine the load for HVAC with Gas Heater . I understand we have 3 motor , (Compressor , Condenser Fan and Blower )
Which one (motors ) should I must consider?
Which Parameters of the motor I must use?
What chapter the code support your answer?

Every example online always mention the AC load , but not how to get it or just analyze the HVAC with the electric heater (usually with higher demand and they just use that value on load calc because the load is the higher than the load of the AC. )
here is the Specification:
Thanks for your help

 

[mtnelect]

This might help to explain.

 

[ING23]

Is RLC the same as RLA ?
LRC the same as LRA ?

 

[mtnelect]

Is RLC the same as RLA ?
LRC the same as LRA ?

This is an outside cooling only condensing unit. Please read the attachment for explanation on terms.

The inside unit Installation Manual will have different sizes of Emergency Heat if added to the gas furnace. For Electric Load Calculations you will have the following:
1) Dedicated Circuit for Condensing Unit
2) Dedicated Circuit for Forced Air Furnace
3) Dedicated Circuit for Emergency Heat if used.

 

[Crash117]

If you are unfamiliar with terminology, please hire a professional to handle this for you. A proper hvac installation will give you a much more comfortable home as well as be properly efficient for the size of your home.

 

[ING23]

If you are unfamiliar with terminology, please hire a professional to handle this for you. A proper hvac installation will give you a much more comfortable home as well as be properly efficient for the size of your home.

This is not my house, I am just a student and this is part of my subject. Thanks for your response .

 

[ING23]

This is an outside cooling only condensing unit. Please read the attachment for explanation on terms.

The inside unit Installation Manual will have different sizes of Emergency Heat if added to the gas furnace. For Electric Load Calculations you will have the following:
1) Dedicated Circuit for Condensing Unit
2) Dedicated Circuit for Forced Air Furnace
3) Dedicated Circuit for Emergency Heat if used.

No emergency heat, and FAU breaker is 15A. This is getting more confusing.....

 

[Crash117]

The information you have provided so far indicates this a traditional hvac system with an indoor gas fired furnace that has a cooling coil on it with is for the ac portion of it. In this scenario, the indoor furnace is treated as its own circuit with its own dedicated circuit. The outdoor condenser part (ac) is also treated as its own circuit with a separate curcuit. The electrical requirements for each part, furnace and ac, will have their electrical requirements listed on the equipment. The info tag you provided in the first post has all the info you need for the condenser(ac) circuit. Also posted that the furnace(FAU) had listed a 15 amp circuit required. That is all the information you need to set your circuits up properly.

 

[suemarkp]

You calculate the higher of gas heat versus cooling. Gas heat will be minimal electricity and uses the same air blower that cooling uses (evaporator fan). So ignore the heat.

The outside cooling has a compressor and an condenser fan. There may be an electronics load too. In the real world, they give you an MCA rating you use to size the wires and a max fuse/breaker to size the overcurrent device. If that isn't provided, it is compressor RLA * 1.25 + the condenser fan RLA.

The furnace should also have an MCA nameplate because most furnaces have electronics and power for the 24V for controls. But again, if a test question you use fan FLA * 1.25 if nothing else is given.

LRA is locked rotor amps, this is usually used to make sure the supply transformer and/or generator can supply that current to get the motor started.

 

[ING23]

The information you have provided so far indicates this a traditional hvac system with an indoor gas fired furnace that has a cooling coil on it with is for the ac portion of it. In this scenario, the indoor furnace is treated as its own circuit with its own dedicated circuit. The outdoor condenser part (ac) is also treated as its own circuit with a separate curcuit. The electrical requirements for each part, furnace and ac, will have their electrical requirements listed on the equipment. The info tag you provided in the first post has all the info you need for the condenser(ac) circuit. Also posted that the furnace(FAU) had listed a 15 amp circuit required. That is all the information you need to set your circuits up properly.

Yes , you are correct . That label has so many information and I cant figure out what number should I multiply by 240 to get the VA. On the other 440.6(A) and 440.6(B)talk about sizing the OCDP and que wiring and it get blurry the concepts of rating and ampacity.

 

[ING23]

You calculate the higher of gas heat versus cooling. Gas heat will be minimal electricity and uses the same air blower that cooling uses (evaporator fan). So ignore the heat.

The outside cooling has a compressor and an condenser fan. There may be an electronics load too. In the real world, they give you an MCA rating you use to size the wires and a max fuse/breaker to size the overcurrent device. If that isn't provided, it is compressor RLA * 1.25 + the condenser fan RLA.

The furnace should also have an MCA nameplate because most furnaces have electronics and power for the 24V for controls. But again, if a test question you use fan FLA * 1.25 if nothing else is given.

LRA is locked rotor amps, this is usually used to make sure the supply transformer and/or generator can supply that current to get the motor started.

Thanks for your reply. following your directions and my label [ LRA * 1.25 + FLA ] * 240 = HVAC VA ? or [ LRA * 1.25 + FLA ] * 230 = HVAC VA?

 

[suemarkp]

Not LRA, What choices do you have on the label? RLA, FLA, MCA, ???