No Heat! What Now? A Basic Step by Step Checklist


It’s evening and you just came home. The house is cooler than normal so you check your thermostat and it appears to be “heating”. Thirty minutes later you realize the house isn’t getting any warmer. Panic Mode! It’s going to freeze tonight! Who can I call for help? Hopefully you know a great company that’s available,  even after hours. Before you panic there are some things you may be able to check on your own that could save you time and money.

The following is a basic list of things you can check when your HVAC Forced Air System goes down. For some, these steps may seem very basic, but every year our technicians make service calls that involve nothing more than performing some of these simple steps .

       First…are you having a power outage? Or what occurs more commonly… was the furnace shut off accidentally? (In a crisis we sometimes overlook the basics.)   If not,  check that power is getting to the furnace. Look for a switch on or near the equipment.

  •     GAS FURNACE: This typically looks like a light switch. Make sure this is on by turning the switch off, and on again.
  •     ELECTRIC FURNACE: Sometimes there is a disconnect switch next to the furnace. Usually these switches are on the furnace itself and can be seen without taking the furnace doors off. They usually look like a breaker switch. These should be turned off and on again to ensure they’re actually in the on position.

If the switch is on and there’s still no power, or there’s not a power switch near the furnace, check the power at the breaker panel. The furnace typically has a dedicated circuit and its own breaker. Switch the breaker to the off position and back on again.

 If this is a tenant situation double-check that they have power to the whole house. Ask if there is a lock on the gas meter. (No one likes to pay their HVAC contractor to tell them there is a power outage or they need to call their utility)

        TIP: Whenever resetting your furnace or turning the power off and back on, first make sure the thermostat is not calling for heat or cooling. Once the furnace is on, set the thermostat for normal operation. If you remove the furnace doors … turn the power off first.

         Next …check your Filter.Even if the furnace starts after turning the breaker or switch back on, you could experience another furnace failure if the filter is clogged.  Before checking your filter, turn the power off to your equipment at the breaker. If your filter was clogged it’s very likely your equipment was overheating. It’s recommended that a professional look at the equipment to verify it’s safe, the safety limits are working, and the heat exchanger has no carbon monoxide leaks.

       TIP: If you have to remove the furnace doors to access your filters, make sure the doors are completely reattached when you’re done. A loose door will prevent the furnace from starting.

       Check for air flow restrictions. Restrictions can include any heating register or return air grill that might be blocked.

  •    Closing too many heating registers can actually restrict air flow and cause the furnace to overheat and fail on a safety limit.
  •    Blocking the return air grill can also cause a major air flow restriction.  This is usually a larger grill. There is at least one in every home on a forced air furnace.

 Blockages commonly include a new area rug or carpet runner, a desk or shelf pushed against a wall blocking the return air grill, an extra filter in the return air grill, or supply register filters in every supply register.

       TIP: If a furnace has been working with a blockage of any kind (including a clogged filter) that has caused the equipment to fail for safety reasons, it is best to call in a professional HVAC technician to inspect the furnace for safety.

        Check your Thermostat. First make sure it is in the correct mode; Heating or Cooling. (some will actually have an “off” mode). Also double check the settings to ensure the temperature is above room  temperature to call for heat (or for cooling, below room temperature). If your fan is always running even when it is not heating or cooling, double check the fan setting on the thermostat. To run the fan only when the equipment is heating or cooling set the fan to “Auto”. Any other setting typically means the fan will run non-stop.

        Be Prepared. When heating equipment fails it often goes undiscovered until the most inopportune time. Know who to call in an emergency. Find an HVAC contractor you can trust, that’s available evenings and weekends.

 It’s a great idea to have a second heat source readily available. If it is a fireplace, make sure the annual pre-season inspection is done so you know it’s safe and operational. For electric heaters, confirm they are in safe working order. This simple step can save you hundreds of dollars and allow you to temporarily get by until you’re able to call an HVAC technician to your home.

 Carbon Monoxide Alarms should be properly installed throughout any home with fuel burning appliances.

 HVAC systems need regular annual maintenance by a professional HVAC contractor. This is not the time for a DIY project. The liability is too great. When it comes to the safety of your family or tenant, the value of hiring a professional HVAC technician greatly outweighs the costs. 

The next time you or your tenant come home to a cool house when it should be warm, follow the basics and you just might be able to avoid a needless service call. Keep in mind, that when dealing with gas and electricity,  safety should be the number one concern.  When in doubt, don’t put your safety at risk. Ask a HVAC Contractor you can trust for help. Stay warm!

 Bruce Davis Jr.

General Manager

Day & Nite Plumbing & Heating, Inc.

 Bruce is a second generation plumber and HVAC technician. He earned his Commercial Plumbing License and later became N.A.T.E. Certified and E.P.A. Refrigerant Certified for HVAC service and repair for commercial and residential HVAC appliances. Bruce has years of experience as an HVAC Technician, Boiler Technician, and Plumber. He is now General Manager for the company he has been with his entire career and oversees the Plumbing, Heating, and Air Conditioning business for Day & Nite Plumbing & Heating, Inc.


2 Responses to “No Heat! What Now? A Basic Step by Step Checklist”

  1. Great tips mentioned above. I hope I can do this and not panic right away when the heater won’t work, hehe

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