Care and Operation of a Heat Pump
O’Neill Cooling & Heating
913 8th Avenue North
Myrtle Beach, SC 29577
PHONE: 843-385-2220
www.oneillcoolingheating.com
OPERATION:
WINTER: Set System Switch to HEAT or AUTO. Set the temperature lever to the desired
temperature. Set the Fan Switch to AUTO, this prevents the drafty sensation you get from
continuous fan (Indoor Blower) operation.
DO NOT SET BACK THE THERMOSTAT AT NIGHT! If you do, when you turn it back up,
you will do most of the temperature recovery with strip heat. This is much more expensive than
just leaving the heat pump compressor run all night. Strip heat operation costs two to three times
as much as compressor operation. You want to use strip heat as little as possible. If it is very cold
outside, then heat recovery will be very slow as well.
SPRING AND FALL: Set the System Switch to AUTO, if that is available. Otherwise set it
to HEAT or COOL as needed. Set the temperature as desired for comfort. Do not set the cooling
temperature below 68 degrees for more than a few hours, as that may freeze the indoor coil. Set
the fan switch to AUTO.
SUMMER: Set the System Switch to COOL or AUTO, set the temperature lever as desired
for comfort. Set the Fan Switch to AUTO. Do not set the cooling temperature below 68 degrees for
more than a few hours, as that may freeze the indoor coil.
NOTE: When it is extremely humid outside, make sure that the Fan Switch is set
to AUTO, as the system dehumidifies better that way.
INDOOR BLOWER OPERATION: Do NOT set the fan switch to ON when the system is
operating in the heating season, as that can make the house feel drafty. In the cooling season,
continuous fan operation can make the humidity indoors higher. That is because when the
compressor shuts off, any water (condensate), remaining on the coil or in the bottom of the drain
pan will re-evaporate into the air. This will increase the indoor humidity that was just removed
from the air by running the heat pump. With high humidity the air feels clammy and
uncomfortable. You must then set the thermostat lower to make the house comfortable, which
increases your electric bill.
If your system switch is set to OFF, then it is OK to set the fan switch to ON. This will give
you a gentle breeze throughout the house, then that will make you feel cooler in mild weather.
Note: If you open your windows while the fan is running, your air filter will get dirty much faster.
GENERAL INFORMATION: Any time that you turn the system off or change the
temperature setting, wait 3 minutes before turning it back on or changing the temperature setting
back. This is because it is not a good idea for the compressor to short cycle. The compressor should
be off at least 3 minutes before it is turned back on. It should run at least three minutes before it is
turned off, for proper bearing lubrication. Short cycling can shorten the life of the compressor. If
you must play with the thermostat, have O’Neill Cooling & Heating add a time delay relay to the
outdoor unit to protect the compressor.
Note that most digital thermostats have a 5 minute time delay built in. Any time
you turn a system off using a digital thermostat, there is likely to be a 5 minute wait
before the system will come back on. Sometimes the delay can be as long as 10 minutes!
Many heat pumps also have time delay circuits to prevent short cycling.
Most digital thermostats also have an additional 5 minute delay before they allow
the strip heat to come on. Some also have minimum run timers. That means that if you
turn the system on, it will run at least 3 to 5 minutes before it shuts off again.
Don’t block the outdoor coil. Keep bushes and other plantings trimmed well away from the
unit. There should be one foot on all sides of the unit to provide the airflow needed for proper heat
transfer. The service access panels should have three feet of clearance for working on the unit.
Building walls or fences around the outdoor unit should be avoided as well for the same reasons.
Make sure the dryer vent does not blow on the outdoor coil. Lint buildup on the coil has the same
effect as blocking the coil with a wall or dense shrub. Do not bury the outdoor unit in leaves, pine
straw or grass clippings. The dead vegetation blocks the bottom of the coil and can accelerate coil
corrosion at the bottom. Reduced outdoor unit airflow reduces the system efficiency and capacity.
It also increases electric bills and shortens the life of the equipment.
Do not put TVs, appliances or lights near the house thermostat. Any heat producing
appliance near the thermostat will make the system run more in the cooling season or run less in
the heating season. This is because the thermostat will sense warmer temperatures than are
actually present. The result is that the house will be too cold most of the time.
Keep your air filter clean! Proper airflow is essential for the most efficient heat pump
operation. Proper airflow also extends the life of your equipment. A dirty air filter can reduce
airflow significantly. This can freeze the indoor coil in the cooling season. It can trip the highpressure switch in the heating season. It can shorten the life of the compressor. It can also increase
your power bill! Check your air filter at least monthly. Change or clean it when it gets dirty. Dirty
air filters can also increase return side duct leakage, sucking mold, dust and dirt into the indoor
unit from the crawlspace or attic. Don’t block the filter grille.
Do not close registers in rooms that are not used. This decreases overall system air flow and
reduces both the capacity and efficiency of your system. Low air flow can also decrease the life of
your compressor.
SPECIAL NOTE: Be careful when using high efficiency air filters, such as pleated or
electrostatic filters. Even when new, they can have more resistance to airflow than VERY DIRTY
standard air filters. It is also important to note that high efficiency air filters get dirty faster than
standard air filters, so they should be cleaned or replaced more often than standard air filters.
Before installing high efficiency air filters, you should have your airflow checked by O’Neill Cooling
& Heating to make sure that airflow is adequate. Turning off supply air registers or blocking
return grilles can cause the same problems as dirty air filters. High efficiency or dirty air filters
can have the same effect on your heat pump as driving your car with a beach blanket over the
radiator in the summer. It will cause your engine (compressor) to overheat. There is one exception
to using high efficiency air filters. Electronic air cleaners that use electricity to charge the filter
plates have a very low resistance to air flow. They still need to be cleaned, typically once per month
to deliver top cleaning performance.
Get your system checked on a regular basis. If you are like most people, you use your car two
to four hours per day, averaged over the year. You have your car in for service every 3,000 miles or
about every 3 months. Your heating and air conditioning system averages 12 hours operation a
day. It needs regular service too. If you didn’t get your car serviced regularly, it wouldn’t hold up
very well. Your heat pump will last longer and perform more efficiently if you look after it. If you
take good care of your heat pump, it will take good care of you.
DEFROST SYSTEM:
A heat pump is a lot like a regular air conditioner, except that it reverses every heating
season to blow cold air outside and warm air inside. Because the outdoor coil is getting colder than
the air outside in the winter, the outdoor coil can freeze in the winter. This is because the outdoor
coil condenses water on it in the winter. Only instead of liquid water running off the coil into a
drain line, the moisture freezes onto the coil. The heat pump still operates efficiently with a light
coating of frost on it. However, eventually the frost becomes a heavy layer of ice and the efficiency
is reduced. This is why heat pumps have a defrost system that regular air conditioners do not
have. Heat pumps have either a timer or differential thermostat to initialize the defrost cycle.
When defrost starts, your heat pump will do some very strange things. This is especially true if you
are used to a different type of heating system, such as gas or oil forced air.
The first thing you will notice when the system goes into defrost is a “Woosh” noise, like the
air being let out of a tire. Then the outdoor fan will stop. After a short while a vapor cloud will
start to rise from the outdoor unit. We have occasionally had customers call the fire department at
this time. But this is normal operation for a heat pump. If the vapor cloud is white, then it is just
water vapor (steam) coming from the hot outdoor coil. Only if the cloud is black is it smoke. (Then
you can panic!) The compressor noise will usually get louder during the defrost cycle than during
normal operation.
What is happening during the defrost cycle is that the reversing valve has switched back to
cooling mode so that the outdoor coil will get hot. The outdoor fan has shut off so that the outdoor
coil gets hot faster because no air is blowing across it. Then the auxiliary strip heat comes on so it
does not blast you with cold air coming out of the supply registers. You will also see water running
off the outdoor coil. This is not a leak, just normal operation.
The defrost cycle normally lasts up to ten minutes. Then the heat pump resumes normal
operation. The outdoor fan will come back on. The white vapor cloud above the unit may get really
huge. The reversing valve will switch back to heating mode with another “Woosh” and the
auxiliary strip heat will go off after a short delay.
EMERGENCY HEAT
Most heat pump thermostats have an Emergency Heat switch on them. On Carrier and Bryant
thermostats, this switch is labeled “Supplemental Heat” or “Sup. Heat”. This switch is used to
disable the outdoor unit if something has gone very wrong with the outdoor unit, such as a broken
fan blade or serious icing problem. What this switch does is to cut the signal to the compressor
contactor and only allow the resistance heat in the indoor unit to operate.
If you have been away for a while, or want to bring the temperature up rapidly, do not use the
Emergency Heat Switch! By shutting off the compressor, you have only reduced the amount of heat
available. You have shut off the cheap heat, the compressor; and allowed only the expensive
resistance heat to operate. This will make it difficult to keep your house warm and it will increase
your heating season electric bill as well.
NOTE: If you turn on the Emergency Heat switch in the cooling season, you will
have no Air Conditioning at all.
HEATING TEMPERATURES:
When it is very cold outside, it is normal for supply air temperatures to feel cool. If it is 15
degrees outside, a heat pump will only increase the air temperature by about 15 degrees. So if the
room temperature is 70 degrees, the supply air temperature will only be about 85 degrees. Since
your body temperature is about 98 degrees, the supply air coming out of the registers will feel cool.
This is normal. However it is still adding heat to your house and is more efficient than strip heat
alone. The heat strips will cycle on automatically as needed to maintain your house temperature.
When it is very cold outside, typically below 32 degrees, it is normal for your heat pump
to run constantly. The strip heat will cycle on and off to maintain the temperature in your house.
TROUBLESHOOTING:
1)
If the system won’t do anything at all:
a)
Make sure no circuit breakers are tripped or off in your breaker panel.
b)
Make sure the electrical disconnects by the indoor & outdoor units are on.
c)
Make sure the emergency drain pan under the indoor unit in the attic is not full
of water. A float switch may have it turned off.
d)
Make sure the thermostat is properly set; someone may have turned it off.
e)
Call O’Neill Cooling & Heating at 385-2220.
2)
If only the indoor unit runs:
a)
Check the circuit breakers in the main breaker panel.
b)
Check the electrical disconnect at the outdoor unit.
c)
Check the float switch under the indoor unit. See #1c above.
d)
Turn the breakers for the outdoor & indoor units off, and then back on. This
can reset lockout circuits. NOTE: If you must do this more than once, there is
something wrong with your system. Call O’Neill Cooling & Heating.
3)
If you smell something burning the first time you use the heat in the fall:
a)
The dust is burning off the strip heater elements. This is normal.
b)
If the smell persists, something is wrong. Call O’Neill Cooling &
Heating.
4)
If water comes through the ceiling when the A/C is running:
a)
The condensate drain is clogged, turn of the A/C so it stops making condensate and
call O’Neill Cooling & Heating.
b)
Your drain pan has a hole in it. Call O’Neill Cooling & Heating.
5)
If water comes out of the roof while the A/C is running:
a)
The water is coming from the emergency drain pan. The main drain line is
clogged or there is a hole in the main drain pan. Call O’Neill Cooling & Heating.
6)
If the outdoor unit is frozen:
a)
In many cases, this is normal. The unit will thaw or defrost normally,
periodically. See the section on defrost on the previous page.
b)
If there are adverse weather conditions (very cold and raining), it may be necessary to
turn the unit off and pour water on the unit to thaw the outdoor coil. You can also use
a garden hose to thaw the coil. Just be sure to turn the unit off so that you don’t take
a cold shower. Thawing the unit like this won’t hurt the outdoor unit; you can’t do
anything the rain doesn’t do.
c)
If you can’t resolve the problem, call O’Neill Cooling & Heating.
7)
If water runs off the outdoor unit during the heating season.
a)
That is normal. During the defrost cycle, the frost turns to water when it melts and
drains off the outdoor coil onto the pad. If the weather outside is too warm for frost to
form, water can still condense on he outdoor coil. This is because the coil must be
colder than the outdoor air in order to extract heat from it. If the coil is colder than
the dew point of the air, moisture will condense on the outdoor coil. This is the same
thing that happens to the indoor coil during the cooling season.
8)
Fire ants can damage your equipment wiring and electrical components. If you
have ant mounds near your outdoor unit, sprinkle AMDRO fire ant killer
around the mounds and your equipment. This is a slow poison that they
carry back to their nest and it kills over several days. Do not use AMDRO
around pets or small children as you could poison them. Ant control is the
responsibility of the equipment owner.