Load Lock out System

[td1236]

Customer has a battery back up system with a smart controller. The smart controller locks out certain non critical loads in the event of a power outage, via control wire and relay. The voltage from this control wire is 24 volts.

The customer would like 2 heat pumps used for his pool to be locked out when the power goes out. The heat pumps are controlled through a control wire that comes from a 5 volt control board to the heat pump.

Is it possible to interrupt heat pump control wire with a relay?

 

[LarryFine]

Didn't I just answer this question?

 

[qcroanoke]

Customer has a battery back up system with a smart controller. The smart controller locks out certain non critical loads in the event of a power outage, via control wire and relay. The voltage from this control wire is 24 volts.

The customer would like 2 heat pumps used for his pool to be locked out when the power goes out. The heat pumps are controlled through a control wire that comes from a 5 volt control board to the heat pump.

Is it possible to interrupt heat pump control wire with a relay?

Yes. Just break "R" of the secondary on the control xfmr in the heat pump through N/C contacts of a relay powered by the 24 vac. you are talking about

 

[td1236]

Yes. Just break "R" of the secondary on the control xfmr in the heat pump through N/C contacts of a relay powered by the 24 vac. you are talking about

What does "R" refer to?

 

[qcroanoke]

What does "R" refer to?

The "hot" side of the secondary of the control xfmr.
Usually on schematics it shown as R and the other side is C.
I havent looked at a HVAC control schematic in a long time so I may be wrong on what they call it now.

 

[LarryFine]

What does "R" refer to?

HVAC thermostat wiring colors:
R = red = 24v
W = white = heat
G = green= fan
Y = yellow = A/C
Etc.