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No Heat? What Should You Do?

January 15, 2015

Something is not working quite right.  All you know is that it’s cold and your heat does not seem to be working as it should.    Listed below are some common issues, their common causes, and tips on how you may be able to fix the problem yourself, before contacting a service technician for repair.  This can save you time and money.

1.   Filter-related Issues

  • Dirty filters are the most common cause of heating (and cooling!) problems because they restrict airflow.  When the filter is clogged and the system can’t “breathe,” the heat exchanger will overheat and shut off too quickly, and your house won’t warm up. It also causes the blower to run hard and for long periods of time, with little heat coming out, and could shorten its lifespan.  Dirty filters also cause soot buildup in the system, reduces your system’s efficiency (thus costing you more money to operate), and shortens its life.  This is an easy solution: replace all filters. Be sure to check for the correct size (they are sold by size, not manufacturer).  Get the highest-rated ones you can afford to get the best indoor air quality and performance.  Important tip:  When you replace the filters, make sure the arrows on the filter are pointing towards the furnace (away from you).  Never try to skimp by vacuuming and re-using filters.
  • Listen for a whistling sound.  This is a sign that the system is not getting enough air, due to a clogged filter or obstructed airflow.  If you’ve already changed the filters and still hear the whistle, then there may be an obstruction elsewhere in the system. Check to make sure all the registers are open and unblocked.

2.   Thermostat-related Issues  

  • If the display on your thermostat is blank, it could be there is no power to the thermostat.  A tripped circuit breaker or fuse could be the problem, possibly caused by a power outage, power surge, lightning strike, or storm. Reset the tripped circuit breaker or replace the fuse. Make sure all the wires going to the thermostat are connected and not loose.  Useful tip: If you’ve lost your owner’s manual for your thermostat, most major-brand manuals can be found on the web-just go to the manufacturer’s web site.
  • Check that the thermostat is in heat mode. If it’s a programmable thermostat, switch it to manual control and set it for 5 degrees above the room temperature, and wait to see if the heat cycles on.   For programmable thermostats, check that it is set to the correct day and time (am or pm).
  • If your thermostat is battery-powered, or relies on battery for backup power in case of a power outage, it could be that the battery needs replacing.  If you have a programmable thermostat, and had a recent power outage, it could be that without a functioning battery backup, all of your settings have been wiped out by the power outage and the thermostat reverted to its default program.
  • If your thermostat has a switch to control the furnace fan, switch the fan “On” (as opposed to “Auto” or “Off”).  If you do not hear the fan coming on, go to one of the supply registers and see if you can feel any air coming out. If the fan is not running, there may be no power to the furnace.  If the fan runs, but the air coming out is cold, you have a problem with the furnace (or heat pump) itself.

3.   Electrical-related Issues

  • Check to see if the circuit breaker or fuse controlling the heating system is tripped or blown.  If a breaker has been tripped it will be in a position that is between ON and OFF. Reset the breaker by turning it all the way OFF, then back ON. If your home has fuses, check to see if the fuse for the furnace is blown. If so, replace it with the same size and type of fuse. Do not increase the size of the fuse. Important Tip:  If a breaker keeps tripping or a fuse keeps blowing, contact a qualified service technician to inspect your system to determine why you are having problems.
  • Check to see if the switch located near the heating unit is switched on.  This often looks similar to a light switch and easy to mistakenly turn off.  (In one house, the switch was mounted upside down, so the unit was actually “on” when the switch was in the “down” position!).  Useful tip: Most thermostats get their power from the same electrical circuit that feeds the HVAC system.  So, if your thermostat is not responding, turning on the switch by the HVAC may be the solution!

4.    Furnace-related Issues

  • Check to see if the pilot lot has gone out (if your furnace has non-electric ignition).  The solution is to relight the pilot light.  If you are unsure how to this, contact your gas service provider.  If the pilot will not light or stay lit, call a service technician.
  • Most furnaces today have electronic ignition switches rather than a pilot light.  If that gets stuck, try switching the furnace off, wait a minute, then switch it back on. If your furnace has a reset switch, press it. After another minute, you should hear the furnace fire up.
  • Make sure the gas is turned on.  Trace the gas line back from the furnace to the meter, and if there is a handle that’s perpendicular to the gas pipe, turn it so it’s parallel. There should be no obstructions or kinks in the gas line. Also, if you have other gas appliances and they are all working, then you know the gas line is on and not obstructed.
  • Some furnaces have emergency cut-off switches that are activated when a door or service panel is removed. If the furnace door is not closed properly (such as after a filter cleaning, or accidentally bumped open), the cut-off switch will prevent the furnace from coming on.  Check to make sure all access doors are properly closed and secured.
  • Make sure the exhaust line or flue is clear.  I’m not talking about the chimney flue in your fireplace, but the part of your furnace that exhausts to the outside, usually through a metal duct.  Sometimes birds, drawn by the warmth, build nests in it.  To clean it, you’ll need to turn off the furnace first.
  • High-efficiency furnaces can drain off several gallons of water a day during the heating season. If the drain lines become restricted by sediment or mold growth, the furnace will shut down. If the drain line is in unconditioned space, and the water in the line freezes, that, too, will cause the system to shut down.  Check the drain hose, and if it looks dirty, remove it and clean it with a mixture of 25% bleach + 75% water, and after flushing it for several minutes, replace the hose.

5.   Heat Pump-related Issues 

  • Check to see if the outdoor unit is covered in ice. It is normal for the coils to frost-over, especially if there is lots of moisture in the air (mist, rain, or sleet).  Your heat pump has a defrost cycle that normally melts this frost.  However, if the ice on the coils is extremely thick, never seems to melt, and only seems to get worse with time, then there could be a problem with the defrost cycle.  Try switching the system to “Emergency Heat” at the thermostat. Wait until the sun melts the ice off, then try turning the system back to “Heat.”  If you do not hear the heat come on, or if you hear loud noises, turn the system back to “Emergency Heat” (thereby shutting off the outdoor unit) and call for service.
  • When outdoor temperatures stay below about 35 degrees, it is normal for the backup or auxiliary heat light (usually a blue or green light) to come on. The colder the temperatures, the longer this light will stay on. But if the light comes on and stays on, even when outdoor temperatures rise above 35-40 degrees, then there is a problem with your outdoor unit and you’ll need to call for service.
  • Clean away leaves and debris around the outside unit that could be restricting the airflow.  Be sure the outside unit is not covered if you are trying to use it!

Never fear.  If none of these fixes your problem, we’re always here to help!