Common Gas Furnace Problems
Thermostat Problems
The
first thing to check is the battery. Most digital thermostats have a
battery indicator on the display. If you see an icon in the display
asking for a battery, follow the manufacturer's instructions and replace
the battery with an appropriate size.
If you see no display at
all, check the power to the furnace. This particular thermostat has a
sealed battery in it, and it isn't replaceable.
If you've checked
the battery, you've checked the power supply, and your thermostat is
still not operating properly, it's likely that you're going to have
to replace your thermostat. It's important to know how your
thermostat works when it's normal. If
you're familiar with the proper operation of your equipment, then it's
going to be easier if you notice something acting unusual and you
can call an HVAC Technition for a proper diagnosis.
Electronic Ignition Furnace Problems
To
determine what type of ignition system you have, open the front of the
furnace and turn up your furnace. Observe what happens in the burner
area. If there's a very small flame that starts first, and then ignites
all of the main burners, that's an intermittent pilot type of ignition.
If the ignition happens and the main burners come on immediately, then
that's a direct ignition.
Once you figure out which type of
ignition system you have, if you see it operating in a way that's not
correct, it's best to call a service technician as soon as
possible. It's important that you are aware of how the system is
supposed to operate when everything is normal. So that way when things
do change, you can be aware of it and call for service before it becomes
a bigger problem. It's going to help maintain the equipment, keep it
lasting longer, and also reduce energy costs.
Furnace Is Noisy
Squeaks,
rattles, and rumbles are some of the things that we hear from furnaces.
In the case of a squeak, it can be related to a motor failing or just
making noise. Rumbling and rattling can be caused by an out of balance
blower wheel caused by debris, age, or just being dirty. Early gas
furnaces used a motor with a belt to drive the wheel. That's the blower
that moves the air into the house. All modern furnaces use a direct
drive blower that's permanently lubricated. It doesn't require any
lubrication or maintenance.
Squeaks and squeals can also
happen from air leaks. There can be a leak in the duct work or around
the furnace somewhere that's allowing a small amount of air to leak in
or out causing a whistling or squeaking sound. If you suspect that a
high-pitched squealing or whistling noise could be coming from the air
flow, what you can do is check some of the gaps or joints where the
sheet metal is connected. Those are the likely sources where that can
happen and it can be simply sealed up with tape or a piece of putty. Sometimes as little as a door being
out of alignment can cause a squeal or a squeak and you can just move it
a little bit or just make sure it's firmly placed where it should be.
So
when you look at the burners on a furnace, you can kind of judge the
condition. If you see any kind of dust, lint or other kind of dirt in
the furnace, that could be clogging one of the burners and causing
excess noise in a furnace. In that case, it's important to get a
professional out to do a proper cleaning on the furnace for you. Knowing
a little bit about your system and being educated about it is the best
way to stay on top of it and avoid breakdowns. A lot of times when
homeowners hear the system operating in an unusual way, they can have us
come out and take care of it before it becomes a bigger issue.
Furnace Blower Doesn't Turn Off
The
first thing to check is the fan switch on the thermostat. "Auto" means
that the fan should only be running to try to heat or cool the home to
try to match the thermostat setting. If you see the thermostat fan
switch set to "on," or "low," "medium," or "high," then you're going to
have continuous fan operation.
The next thing to look at is your filter. If you find a clogged filter, it may have caused damage
to the limit switch. What the limit switch does is it senses the
temperature inside the furnace. If it sees a temperature that's too
high, then it shuts off the fire as a safety and only will allow it to
come back on once it's cooled. If the filter has been
clogged too long, then it may have damaged that switch to the point
where it needs to be replaced. In this case, the furnace high limit is a
small button type device that's got two wires connected to it. Every
furnace is a little bit different. Some of them have more than one
limit, and some of the limits look very different. If that limit switch
is failed, it's very important to find the source of why it failed and
not just replace the switch.
It's a very important safety issue.
Furnace Cycles On and Off Too Frequently
If
you notice the frequency of the heat cycles becoming too short, that's
an indication of a problem with your system. The first thing you want to
check is the fan switch on the thermostat. In this case, it's up here
in the display and it says "auto." Now, "auto" means that the fan should
only be running to try to heat or cool the home to try to match the
thermostat setting. If you see the thermostat fan switch set to "on," or
in this case "low," "medium," or "high," then you're going to have
continuous fan operation.
If your filter has been in the furnace
for a long time and its gotten very clogged, it can cause the furnace to
what we call cycle on limit. That means that instead of heating
continuously, the flames turn on and off because the unit is overheating
due to that clogged filter.
The important thing with filters is
watching the air flow direction. There's always an arrow that tells us
which way the air should flow through the furnace. On most furnaces,
people have drawn arrows that tells you which way the air flow direction
should be.
Furnace Does Not Produce Enough Heat
One
of the most common sources of this kind of problem is a clogged filter.
It's very important that you check your filters regularly and change
them frequently for good furnace operation and best efficiency. The
second possibility is that the furnace was not sized properly, meaning
that it doesn't have enough capacity to keep the home warm. It's
important that a heating and air company size the equipment for the
capacity needed to keep your home warm. Another possibility, though it's
pretty rare, could be that your burners could be clogged to the point
where it's not allowing the furnace to create enough heat and meet its
full capacity.
Furnace Does Not Heat
Some possible
causes of that are: thermostat not adjusted properly, the power going to
the furnace could be shut off, the gas going to the furnace could be
shut off, or the pilot light could be out. A couple things to check with
the thermostat: The first thing to remember is that everybody's
thermostat is going to be different. In this case, when the red light is
on, that means that it's in heat mode, so it's ready to heat the house.
The next thing to check is to make sure the set point is higher than
the room temperature. So if we raise that set point above the room
temperature, that's going to turn the heat on.
Furnace Pilot is Out
Some
of common sources of a lost pilot light are a failed thermocouple, a
strong draft, or a clogged orifice to the gas supply to the pilot
light. A thermocouple is a device on a standing pilot system that proves
the flame to the gas valve and allows gas to keep flowing as long as
there's a flame sensed. It's probably best if you have a professional
check it out, clean it and verify that it's working properly. Now, the
thing to keep in mind is most modern furnaces don't use a standing pilot
light anymore.
