Why Does Nest Thermostat Say Delayed & How To Fix It


A common issue most people who own the Nest Thermostat experience is a message displaying Delay at the bottom. This is a power issue and can be fixed through your wiring particularly the Common (C) wire.

The Nest thermostat comes with rechargeable lithium-ion batteries, the way it works is Nest recharges its self every time you run your heating and cooling system.

But what happens if you don’t turn on your heating or cooling system often?

The Nest will consume energy from your furnace through your heating wire. This is fine for some systems but other systems may react differently and cause various issues. The best solution to this problem to simply install a C wire.

How To Solve The Delay Issue

The delay message occurs because of a power issue & this can be fixed by simply adding a C wire.

The Nest Thermostat runs on a rechargeable lithium-ion battery which recharges its self through your HVAC system’s wiring. If your system does not have C wiring the thermostat charges its self when you run your heating or cooling system. What happens is the thermostat consumes some of the power from your heating or cooling to recharge its self. Although if you don’t use your heating or cooling system often Nest will consume power from your HVAC system on its own, which may cause problems for some users.

By simply adding a C wire the Nest simply charges it’s self from the C wire current & maintain power easily & efficiently.

Take a look at the diagram:

The W1 wire refers to the heating loop, The Y1 is the cooling loop, RH refers to power, and the G refers to the fan control. and the C (Common wire) simply acts as a power supply.

How To Fix The Delay Issue Step By Step

What Does The C Wire do? (Common Wire)

The common wire’s main purpose is to deliver constant power to your thermostat. This doesn’t control the heating or cooling whatsoever.

Nest thermostats don’t usually need a C wire & the reason being is Nest Thermostats are designed to use minimal power, less than1 kWh a month.

But there are occasions where you would want to use a C wire, Nests compatibility checker will also let you know whether or not your thermostat needs a C wire.

Typical Issues That Can Be Solved With a C Wire

According to Nest these are common issues that can be resolved by adding a C wire:

  • The thermostat displays a “Delayed” message on the screen (For example: Delayed for: 3:20).
  • Strange noises coming from your thermostat (Due to thermostat turning off and on at a fast pace).
  • Your heating or cooling system will not turn off.
  • Heating constantly turns on & of in short intervals.
  • System fan turns on & off
  • The system fan not turning on or always running

Don’t Have a C Wire?

If you lack a c wire you have a couple of options first is the Diy method. one of the easiest Diy solutions to this is to get a Venstar adapter. The Venstar adapter helps you add an additional wire quite easily.

The Next option is to get a thermostat that doesn’t require a C wire the best ones on the market that don’t require a C wire is an Ecobee thermostat. The Ecobee provides its own Power Extender Kit that you can set up in your furnace quite easily.

The last option is to simply hire a professional to add a C wire for you. Setting up a C wire might be a daunting task and if you don’t feel confident it’s best to just hire professional help sometimes.

Final Thoughts

Although the c wire is not usually required when installing a Nest thermostat it’s usually a better option to just install it to avoid any future problems. The Nest thermostat relies on recharging its battery by consuming some of the power used to heat or cool your home. This may cause issues with your system and therefore cause your thermostat to be on delay mode. The C wire’s job is just to provide your thermostat with power it doesn’t do anything else at all, this will ensure your thermostat is getting the power it needs without burning out or causing problems to your system.

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