No Heat From Furnace? Do This Before Calling an HVAC Company

no heat in house

When it's the dead of winter and there's no heat from your furnace, you might think it's freak-out time. Your first impulse is probably to call an HVAC company and request that they come out ASAP. The reality, however, is that many furnace issues can be resolved with some simple troubleshooting.

Many aren't actually "furnace issues" at all. And yes, there are some you can fix yourself.

Here's what to do when you've got no heat from your furnace

Stay calm. Take a deep breath. Go through this checklist and see if you can make the heat come back on without calling for service.

1. Check your thermostat settings

Make sure you've set the temperature to a level above the current room temperature. If you want your home to be 70 degrees but the thermostat is only set to 66 degrees, that might be why you feel cold.

You should also verify that the system switch is set to "heat" or "auto." You'll usually want the fan set to "auto" as well so that the system only circulates air while the furnace is heating.

Oh, and if the thermostat isn't coming on at all, you might just need to change the batteries.

2. Check your air filter

Sometimes, your furnace won't heat your home properly but there's still some warm air coming out of the supply registers. Take a look at your air filter. Is it really dirty?

An extremely dirty air filter blocks airflow and can inhibit system performance. Clean or replace the filter and see if things improve. If the system actually locked out due to a dirty air filter (it happens!) you may also need to cut the power to the unit, wait a minute, and then turn it back on to reset it.

3. Check all your air registers

Have you been moving furniture around? Have you got a lot of boxes sitting around? Do you have a wily 4-year-old who breaks things?

We're asking because sometimes people put things on top of their air registers, which effectively closes the register and prevents air from circulating. Other times, they or their kids close the registers without really understanding the implications.

By air registers, we're talking about the louvered holes in your floor or ceiling where the warm air comes out. You might know them as "vents." Whatever you call them, just make sure they aren't blocked!

4. Take a look at your breaker box

You might have just overloaded the circuit. If one of your breakers is visibly tripped, switch it back on. Your furnace might start up straightaway!

Keep in mind that the circuit for your HVAC system should be on a dedicated breaker. If you overloaded the circuit because of some activity unrelated to furnace operation, your furnace might not have its own breaker. Contact your HVAC company as soon as possible so that a professional can assess why other other items are on that circuit — and whether some adjustments are needed.

5. Check the power disconnect switch

Next to your furnace, there's a switch that turns the system on and off. Sometimes, it gets bumped. Maybe you or your plumber was in the crawlspace making a repair and you flipped the switch by mistake. Who knows? Sometimes, it just gets turned off.

If yours is off, flip it back on. Problem solved.

6. Is the gas control valve open?

It might not be. When the valve isn't open, the furnace can't get any gas. You can call a professional if you're not comfortable working with gas-related system components, but opening a valve is just a matter of… opening the valve.

Keep in mind that your gas valve might be closed for a reason! It doesn't just close by itself. In other words, think about whether someone working at your house might have had cause to close it. On the other hand, if you can verify that your kid turned it off for no reason, it's probably ok to open it back up.

7. Check your pilot light

If you've got a really old furnace, you might have to manually light the pilot light to get your furnace to turn on. You may have just forgotten to light it this year, or maybe it's your first year in a new house with an old HVAC system. Lighting the pilot light isn't hard, but your furnace won't operate without one!

No heat from your heat pump? Here's what to do

For heat pump systems, a lot of the above advice applies. While you can safely ignore any gas or flame-related guidance, you still need to check your thermostat settings, air filter, breaker box, and air registers. The potential problems are the same as with gas furnaces.

The one additional thing you might need to do is check the outdoor power disconnect switch. Heat pump systems have one at each part of the system, the indoor unit and the outdoor unit. Instead of just checking the indoor one, check both.

Did you do all these things and you still have a problem?

There are lots of reasons why your heat might not turn on. When your furnace or heat pump still won't work after troubleshooting with the above checklist, you need to call an HVAC professional.

It's impossible to say what the problem is without evaluating your system. Possible issues range from a cracked heat exchanger to blown inducer draft motor or, in the case of heat pumps, a refrigerant leak. An HVAC pro will be able to diagnose the problem and point you toward the best solution.

No heat in your Atlanta home? We can help!

If you covered the above checklist and still don't have heat, give us a call! We'll be out to find the problem as soon as possible, so you can start feeling cozy again.