Troubleshooting Heat Pumps Review

This article is a troubleshooting heat pumps guide of the most
popular models in North America for residential use, and from the
manufacturers; AO Smith, Bradford White, Rheem, State, Kenmore,
Reliance, American and other. The article deals with the main causes of
the heat pump failure, symptoms, error codes and
recommendations for an easy and safe repair.

It will be assumed that the heat pump was properly installed -
per codes and manufacturer’s instructions. This includes properly
selected room for the unit, electrical and water connections in place,
installed air filter and condensate lines and tank filled with water.

The first step in diagnosis the problem and troubleshooting is
to simply disconnect the unit for some time ( the time depends on the
model), resume the power and determine if the error code is still
present or not. If, after the resumed power, the error code is still
ON, read further, and find the instructions on how to repair the unit.

In order to fix the problem fast and correctly it is good to
know what the main parts of the heat pumps are and what’s consider as
the normal operation.

For example; normal operating temperature of the heat pump is
between 32 F and 150 F. All the heat pumps are equipped with the
electric fan and the compressor, so it is normal to hear some noise,
but not the abnormal sound. Some noise can also be heard during the
metal part contraction (cooling) and expansion (heating).

For any problem related to the heat
pump, recommendation is to call the technician, but if you are
planning to troubleshoot, here are the most common problems with the
instructions:

• The surrounding air gets colder

• Water dripping

• No hot water / not enough supply of hot water to the
  shower/faucets

• Water is too hot

• Noise

• TPR valve - noise and dripping

• Rotten egg odor

• Discolored water

• A problem with the compressor

• High operating costs

The surround air is getting cooler

Solution:

When the heat pump operates, the room air gets cooler… and
that is normal. For the correct and efficient operation, the
installation room should have a recommended size, proper clearances
around the unit and vented correctly, so enough air is coming in and
through the heat pump. The heat pump uses the warm air for water
heating, while it releases the air which is colder than the
surrounding. One of the ways to provide more air for normal operation
is to install the louvered door, so air can get in from the adjacent
room.

Water dripping

Solution:

If the water is dripping down the outside of the water heater,
the water connections should be inspected for any loose joints or the
heater’s condensate drain as it might be dirty and clogged. For
example, if the water leaks around the elements (gasket or threads)
re-seal or replace the gasket. The best solution for these problems is
the regular maintenance and unit cleaning. During the water heater
installation, a suitable drain pan is installed under the unit, to
catch condensation or water leak, and from there piped to the
appropriate drain. Since the leaking water can damage the property it
is recommended to install the automatic leak detector with the shutoff
device.

The most frequent complaints are “no hot water” and “not
enough hot water”.

Solution:

This is what needs to be checked and fixed:

The temperature of water on the thermostat might be set too
low - increase if it is needed. The unit is in a Vacation mode - turn
it off. In some heating modes, if the temperature is above the maximum
or below the minimum recommended, the heat pump won’t operate. If the
water heater hasn't been used for two weeks or more, hydrogen gas can
accumulate inside the tank - which is very flammable. Before running
any of the electrical devices, open the hot water tap for several
minutes.

Check the air filter and if it is dirty, clean or replace the
filter.

When the demand for hot water is high, heat pump cannot
recover fast enough so waiting for the full or partial recovery is the
only option. Sometimes it is needed to change the heating mode due to
the higher demand and therefore make the pump more efficient. If the
water heater runs out of hot water too quick, for example when having
guests, when kids get older and they take shower more often (the demand
increases) than the issue is with the undersized water heater.

Check for the sediment or mineral build-up in heater’s tank or
heating elements - the limescale reduces the heat transfer from the
heat source to water. Draining and flushing is usually the best option.
Water softeners are good as prevention.

As the unit operates efficiently only in the suggested air
temperature range, so when the air gets colder, the unit cannot heat
the water to the desired temperature.

The incoming water is way too cold.

During the winter time, the hot water loses the heat rapidly
through the water pipes, so the proper pipe insulation is required. The
same problem is if the pipe length is too long.

If the unit doesn't work, check the power, fuse, circuit
breaker and TCO (manual reset limit) or ECO - requires resetting. Check
also for the non-functioning temperature sensor - perform the
resistance test and replace it if defective. Replace the heating
element if burned out.

If the mixing valve is installed, check is there
malfunctioning. Also make sure water connections are not reversed -
incoming cold water gets into the hot water pipe and outgoing hot gets
in the cold side.

Water is too hot

Symptoms and solution:

The thermostat might be set to high or not snug against the
tank. A broken thermostat or shorted heating element can also result in
extremely high water temperature. If the electronic control is
malfunctioning - the best is to call the technician. In order to
prevent hot water scald, it is recommended to install thermostatic
mixing valve at each faucet.

Noise

Solution:

As said before, some noise from fan and compressor is normal,
but if there is a rumbling noise than the problem is with the mineral
or sediment build-up on the heating elements. The elements have to be
cleaned or replaced. The noises such as the crackling, gurgling or
popping are usually related to scale or lime buildup while the pounding
noise can be reduced by installing the water hammer arrestor.

Temperature and pressure relief valve makes a popping sound
and is dripping

Solution:

The TPR valve is a safety element that should open only if
there is an excessive pressure build-up within the closed heating
system. It might also be leaking if the debris is stacked inside the
valve. During the normal operation the valve should not leak. The
thermal expansion is kept under control with the installed thermal
expansion tank. In order to limit the water pressure inside the house
plumbing, it is beneficial to install the pressure reducing valve -
PRV. It should be installed on the cold water supply line to keep the
pressure in the range from 50 and 60 psi.

Hot water has a bad smell - smell of a rotten egg

Solution:

Due to the high content of sulfate in water supplies (usually
from well) and its reaction with the anode rod (especially magnesium
type), hot water might have rotten egg odor. One of the solutions is to
replace the anode with the type that is less prone to this reaction
(aluminum) or chlorinate the heater thoroughly.

Discolored water

Solution:

If milky water is seen, the aerated faucets should be
installed to eliminate the buildup gases inside the heating system.

Checking the anode rod regularly or switching to powered anode
can also prevent corrosion (that makes water look muddy or brown), as
the metal tank is always protected with the effective element, which
doesn't deteriorates over time.

The compressor is not operating

Solution:

Replace the broken compressor or check is there a refrigerant
leak. In a case of the AO Smith heat pump, check the run capacitor and
look for any damages on the housing. Measure the resistance - if it is
indefinite the element has to be replaced.

High operating costs

Solution:

The first things that need to be checked are the set
temperature - which might be high, inefficient heating mode and dirty
air filter. Also, if the temperature of the surrounding air is not in
the recommending range, the compressor might have trouble operating
properly.

The above problems are problems that are found on most of the
heat pumps for the residential use… there are many more off course. Due
to the advanced electronics followed by the diagnostic system and small
display screen implemented in almost every new unit, the error codes
are what appear when the problem occurs - making diagnostics easy.

For example, American heat pump uses the error codes such as
E20, E21… Bradford White and GE heat pumps use the error codes such as
F1, F2… F15, followed by the beeping sound - and each code means
something; faulty heating element, dirty air filter, compressor or air
failure, sensor malfunctioning …

Every user manual contains the troubleshooting heat pumps
guide with the list of the most common diagnostic codes.