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Utility Curtailment is a power company program used to address peak power demand, an aging and insufficient electrical grid, and the power generation mix available in your area. At this point, it is not mandatory, and you receive $20 to $40 / year for agreeing to participate.
Utility Curtailment allows the power company to interrupt the operation of your A/C or H.P. for up to 10 hours during the summer months. Connecting to a single-stage piece of equipment is easy; they install a box on the side of the house that cuts the low voltage at the compressor contactor.
Utility Curtailment is more complicated when it involves communicating equipment. There are two ways they can do this; through an electrical box near the outdoor unit or through the internet connection to your Evolution System Control.
Typical Utility Curtailment low voltage
Communicating circuit board wiring:
Older 2 Stage = R & Y2
Newer 2 Stage = UTIL & Y2
5 Stage = UTIL1 & UTIL2
Variable Stage = UTIL & 24V
The electrical box method uses a normally closed dry contact that connects to your A/C or H.P. The power company can send a signal through the power lines that tells their box to open the dry contact and disable the equipment. Look in your A/C or H.P. Installation Manual to find the correct screw terminals to use, wire the low voltage, then set up this feature on the thermostat. On a Connex System Control, go to the Installation and Service menu and select Setup; scroll down to Utility Curtailment, where you will see three options: Disabled means the feature is turned off and will not influence the equipment. Turn off means shutting down the A/C or H.P. when the power company sends the command to their box. Low Stage means the A/C or H.P. will run at reduced capacity when the power company sends the command to their box.
Don’t assume that the utility company knows how to wire into a communicating unit.
The utility may wire their dry contact in series with the compressor contactor coil, as they are used to doing with non-communicating equipment, which could damage the ECM condenser fan motor.
The utility may wire their dry contact in series with a communication wire, which will interrupt communication when they send the signal to turn off the equipment. The customer will receive a message on their phone, email, and thermostat saying that the A/C or H.P. has lost communication. The customer will schedule a service call with your company, and by the time you get there, everything will be working fine. You will be left scratching your head, wondering why you have a communication error in history.
When wired correctly and set up properly on your thermostat, your customer will receive a message on their phone, email, and thermostat letting them know that the utility company has interrupted the power to the equipment.
Utility Curtailment through the Internet does not use a dry contact or wires from a utility box to turn off the A/C or H.P. The Internet method is not widely used yet but is available on your Connex System Control and some other thermostats. The local utility will let your customer know if they have a program in their area. Typically, a representative from the local utility will come to the home and get the customer signed up for Demand Response or Price Response Wi-Fi utility events and set up the thermostat for them. HVAC Service Technicians are not usually involved with setting up Wi-Fi utility events in the Connex System Control or other thermostats. Wi-Fi utility events are controlled by going to Installation and Service, then scrolling down to Utility Event Setup, and following the prompts on the screens.
Utility Curtailment and Utility Event Setup are not the same thing, so be careful to use the correct one.
Contact the B-Y customer assurance team with any questions on Utility Curtailment.