Space Heaters

Space heaters are often used when the main heating system is inadequate, or when it would be too costly to operate or install central heating. Space heaters can also be useful to supplement adequate central heating in certain instances, such as heating one room that will be primarily occupied while lowering the thermostat on the central system so that heat is not wasted in unoccupied rooms. In some cases, it is possible to lower total heating costs by up to 10%, as well as reduce CO2 emissions by up to 800 pounds, by using space heaters in this manner.

Different Types of Space Heaters

Understanding some of the differences between the types of space heaters and how they work can be helpful when deciding what the most efficient and effective options are for a given situation. Below are descriptions of some of the main types of space heaters available:

coil-based convection space heaters: This type of heater uses a fan to push air into a room that has been heated internally by passing through hot metal coils. These space heaters utilize a safety mesh in order to ensure that nothing in the room will come into contact with the internal heating elements.
ceramic-element space heaters: This type is generally considered safer to operate than a coil-based unit. Since the ceramic core is larger than heating coils, these units can operate at a lower temperature while providing an equivalent amount of heat that spreads over a farther area. This type of heater is also able to maintain a higher temperature for a longer period of time compared to a coil-based unit, which makes it more efficient.
oil-filled radiators: These space heaters are highly efficient and operate silently because they do not use a fan. Instead, they use fluid contained in a permanently sealed radiator apparatus, which does not ever need to be refilled. The oil is heated within the unit, and the heat from the oil then radiates into the room. Once heated, the oil will continue to gradually release warmth into the room even when the internal heating element is turned off.
halogen lamp space heaters: Energy-efficient halogen bulbs are used in these types of space heaters to provide instant warmth at the touch of a button. They are made safe by employing safety grilles and cool cabinets, and can be especially appropriate in areas where small children or pets are of concern.
Estimating the Cost of Operation of space heaters

The operational costs of space heaters depend on the type of heater in use, as well as the room it is being used to heat. “Kilowatts x Rate x Time = Cost” is a useful formula, in general, to determine how much a heater will cost to run. Here is how the formual breaks down:

kilowatts: the setting of the heater. Divide watts by 1,000 to get kilowatts per hour;
rate: the cost of electricity per kilowatt-hour, which can be determined for an area by contacting the local utility company; and
time: the amount of time the heater is in use.

For example, a 1,500-watt space heater running for 10 hours at a rate of $0.10 per kilowatt-hour will cost $1.50. Using the formula:

Kilowatts x Rate x Time = Cost,

the usage can be figured as:

(1,500w ÷ 1,000) x $0.10 kWh x 10 hours = $1.50.

Safety With Space Heaters

Since space heaters can generate extreme temperatures at the surface, they have the potential to be dangerous and even cause injury. Although they are safe when operated correctly, it is estimated that 25,000 residential fires and 300 deaths are associated with the use of space heaters every year. When using portable space heaters, following these safety precautions, as well as any guidelines recommended by the manufacturer of the unit, can lessen the risk of accident or injury.

Use only the type of fuel or energy intended for use with the specific device. The use of gasoline in a kerosene heater, for example, would be very dangerous.

Never attempt to repair or replace parts in a heater yourself. This should always be handled by a qualified service center, since the results of repairing a malfunctioning unit could be dangerous.
Use of extension cords for the power supply should be avoided. A cord marked 14 or 12 AWG can be used if absolutely necessary.
Do not use space heaters in wet or moist areas, such as in a bathroom.
Always keep heaters level and on the floor. If a heater has been placed on furniture and it falls off, or if a table it has been placed on collapses, the damage to the unit could result in a fire or shock hazard. Some units contain a tip-over switch which automatically shuts the power off if the unit is knocked over, but even these should be situated in such a way that they will not be at risk of falling over.
If the surface of the unit has a high operating temperature, there should be a guard around the heating element to keep people, pets and combustibles a safe distance away from it.
The unit should have an indicator light to signal when it is plugged in or turned on.
Be sure to install the correct size unit for the space to be heated. Too large or small of a unit may actually decrease energy efficiency, or could cause pollutants.

Other Factors to Consider When Using Space Heaters

When considering the use of a space heater, especially for the purpose of improved energy efficiency, there are several final factors to consider. Space heaters will only impact energy efficiency in a positive way if they allow for the home’s main thermostats to be turned down. If a space heater is used simply in addition to central heat without lowering the central thermostat, it will only add to energy bills.

Here are some other things to take into consideration when deciding whether a space heater will be right for a given situation, and which type of space heater will work best.

What area of the building will the heater be used in? Be sure to select an appropriate unit for the area, and carefully consider whether this area will really benefit from use of a portable heater to begin with. For example, heating a room that is generally too cold but not often used anyway would simply suck energy without much return on savings.
Space heaters that include a thermostat are more efficient than models that do not.
If the unit doesn’t have a thermostat, utilize the different settings on it for maximum efficiency. Once a heater has adequately heated a room at full power, turn the setting lower to maintain current levels, rather than adding more heat to an already warmed room.
Select a heater with appropriate safety features for the application. For example, a heater that achieves extremely hot surface temperatures may not be a good choice in an area where small children are present.
The surface temperature of space heaters can also be an issue in areas where combustibles might be found in close proximity to the unit.
Some units that use a fan can be noisy, which may be an issue in certain circumstances, and should be taken into account during the selection process.

Space heaters can be effective energy-savers under the right circumstances, and different types of units will perform better in different situations.

Knowing a bit about acceptable applications, as well as the properties of different designs, can be helpful in deciding if space heaters are a good choice for a home.

About Thermostats

Thermostats and Climate Control

Thermostats are devices designed to climate control of the heating and cooling systemsin a building so that air temperature remains comfortable.

Most inspectors are not required to verify, inspect or determine a thermostats calibration, heat anticipation, automatic setbacks, timers, programs or clocks. It is wise, however, for inspectors to understand a thermostats operation and solutions to common defects.

Thermostats can be manually controlled or set to activate automatically based on timers or room temperature readings. Most thermostats contain two meters:

the “set” temperature that the thermostat is asking for, and the actual temperature. On traditional dial-type thermostats, the user can increase the set temperature by rotating the dial clockwise, and lower it by rotating it counter-clockwise. Newer programmable thermostats usually will have digital displays, which can be used to adjust automated heating and cooling schedules.

A Thermostats Location

In order to avoid false or “ghost” readings, which will cause unnecessary furnace or air-conditioner cycling, thermostats must be installed so that it correctly reads the room temperature. The following locations may cause thermostats to give false readings:

near a heat source, such as a fireplace, hot water pipes, bright lights, direct sunlight, electrical appliances that produce heat;
in a drafty hallway, or near a window or exterior door that is opened often; and
on an outside wall. Outside walls are too affected by outside temperatures, which may make the thermostat “think” the air in the house is warmer or cooler than it really is.

Problems and Solutions with Thermostats

erratic operation or fluctuating temperature. This is often caused by poor pin connections between the thermostat and the backplate when the backplate is flexed against an uneven wall. To allow the backplate to flatten out, loosen the screws that attach the backplate to the wall, then snap the thermostat back onto the backplate.
thermostats that don’t respond to changes in room temperature. This can happen when there is air passing over the temperature sensor from a hole in the wall behind the thermostat, through which wires enter from the air-handling unit. To rectify this, insulate the hole behind the thermostat with insulation, spray foam, or any other insulating material.
temperature that is inaccurate. A convenient way to test the temperature sensor is to tape a thermometer to the wall next to the thermostat and wait 15 minutes. A faulty thermometer needs to be recalibrated. Instructions for recalibration vary by manufacturer.
loss of power. This may be caused by the following two situations:
If the air handler powers the thermostat, check the circuit breaker meant for the air handler and make sure it has not tripped causing climate control issues.
If batteries power the thermostat like a programmable thermostat, make sure they are lithium, not alkaline. Alkaline batteries will die rapidly or cause erratic thermostat operation.

Maintenance and Other Tips on Thermostats

Give the thermostat’s interior a light dusting with a small, soft paintbrush. Canned air can also be used to blow off dust. Twist the screws to remove the cover. Be sure to clean the contacts, which are small metal plates within the unit. The wires coming from the transformer attach to the contacts. Do not touch any of the interior parts of a programmable thermostat with fingers.
If the base is loose, re-tighten the screws. Check the wires coming from the transformer. If any corrosion is present, remove the wire from the contact and clean it. Use a wire stripper to remove the surrounding insulation, cut back the wire, and reconnect it.
Make sure the terminal screws are tight.
For wireless thermostats, make sure the model number of the thermostat matches the model number of the receiver. If the model numbers do not match, the stat and receiver will not be compatible.
Make sure that your thermostat has been set to the proper position for the season for proper climate control:
cooling or heating. The air conditioner will not run with the switch set to “heating” and, conversely, the heating system won’t run if the thermostat has been set to “cooling.”
Thermostats that contain a mercury switch must remain perfectly level or they may not control the temperature setting.

Thermostats and Energy Savings

Many people believe that furnaces work harder than normal to warm an area back up to a comfortable temperature, which will counteract energy savings gained from turning the thermostat down. This belief is a misconception that has been disproved by years of studies and research. Fuel is saved between the time the temperature is stabilized at the lower level and the next time heat is needed, while the fuel required to re-heat the space is roughly equal to the fuel saved while the building drops to a lower temperature.
According to the U.S. Department of Energy, consumers can save 10% on their utility bills by setting their thermostat back 10° to 15° for eight hours. This energy savings can be accomplished easily with a programmable thermostat.
Be careful not to set the thermostat so low in the winter that pipes freeze, or so low during the summer which may allow humidity-spawned mold to grow.

Thermostats are used to ensure the comfort of building occupants through the proper control of the heating and cooling cycles while improving energy savings. A Programmable thermostat can help achieve the greatest energy savings climate control.

Heat Pump Defrost Cycle FYI

Heat Pump Defrost Cycle

Heat pump inspection, identification and understanding this type of heating system.

To inspect and identify a particular heating system, understand its heating method, and identify any material defects observed, we should be able to understand the following:

the heating system;
its heating method;
its type or identification;
how the heating system operates;
how to maintain it; and
the common problems that may be found.

We must be able to thoroughly examine a heating system, understand how a particular heating system operates, and analyze and draw conclusions as to its apparent condition.

We will cover some fundamentals of a particular heating system called a heat pump using non-invasive, visual-only inspection techniques. We will also discuss its defrost cycle.

How a Heat Pump Operates

When a heat pump is operating in the heating mode or heat cycle, the outdoor air is relatively cool and the outdoor coil acts as an evaporator. Under certain conditions of temperature and relative humidity, frost might form on the surface of the outdoor coil. The layer of frost will interfere with the operation of the heat pump by making the pump work harder and, therefore, inefficiently. The frost must be removed. A heat pump has a cycle called a defrost cycle, which removes the frost from the outdoor coil.

A heat pump unit will defrost regularly when frost conditions occur. The defrost cycle should be long enough to melt the ice, and short enough to be energy-efficient.

In the defrost cycle, the heat pump is automatically operated in reverse, for a moment, in the cooling cycle. This action temporarily warms up the outdoor coil and melts the frost from the coil. In this defrost cycle, the outdoor fan is prevented from turning on when the heat pump switches over, and the temperature rise of the outdoor coil is accelerated and increased.

The heat pump will operate in the defrost cycle until the outdoor coil temperature reaches around 57° F. The time it takes to melt and remove accumulated frost from an outdoor coil will vary, depending on the amount of frost and the internal timing device of the system.

Interior Heating Element

During this defrost cycle with older heat pumps, the indoor unit might be operating with the fan blowing cool air. To prevent cool air from being produced and distributed inside the house, an electric heating element can be installed and engaged at the same time as the defrost cycle. In defrost mode, this heating element will automatically turn on, or the interior blower fan will turn off. The heating component is wired up to the second stage of a two-stage thermostat.

The Typical Heat Pump Defrost Cycle

The components that make up the defrost cycle system includes a thermostat, timer and a relay. There is a special thermostat or sensor of the defrost cycle system, often referred to as the frost thermostat. It is located on the bottom of the outdoor coil where it can detect the temperature of the coil.

When the outdoor coil temperature drops to around 32° F, the thermostat closes the circuit and makes the system respond. This causes an internal timer to start. Many heat pumps have a generic timer that energizes the defrost relays at certain intervals of time. Some generic timers will energize the defrost cycle every 30, 60 and 90 minutes.

The defrost relays turn on the compressor, switch the reversing valve of the heat pump, turn on the interior electric heating element, and stop the fan at the outdoor coil from spinning. The unit is now in the defrost cycle.

The unit remains in the defrost cycle (or cooling cycle) until the thermostat on the bottom of the outdoor coil senses that the outdoor coil temperature has reached about 57° F. At that temperature, the outdoor coil should be free of frost. The frost thermostat opens the circuit, stops the timer, then the defrost cycle stops, the internal heater turns off, the valve reverses, and the unit returns to the heating cycle. A typical defrost cycle might run from 30 seconds to a few minutes. The defrost cycles should repeat regularly at timed intervals. An inspector should not observe a rapid cycling of the defrost operation.

In summary, certain conditions can force a heat pump into a defrost cycle (or cooling cycle) where the fan in the outdoor coil is stopped, the indoor fan is stopped or electric heat is turned on, the frost melts and is removed from the outdoor coils. When the frost thermostat is satisfied or a certain pre-set time period elapses, the outdoor fan comes back on, and the heat pump goes back into the heating cycle.

One problem of many older heat pump systems is that the unit will operate in the defrost cycle regardless of whether ice is present. On these systems, if it’s cold outside, the defrost cycle might turn on when it is not needed.

If the defrost cycle is not functioning properly, the outdoor coil will appear like a big block of ice, making the unit non-functional. Damage could result if the heat pump operates without a functional, normal-operating defrost cycle.

Causes of Frost on a Heat Pump

There are many reasons why we might find frost and ice stuck on an outdoor coil of a heat pump that is not properly defrosting. The cause of the frost and ice problem may include:

a bad reversing valve;
a damaged outdoor coil;
a wiring problem;
a bad thermostat;
a leak in the refrigerant;
a dirty outdoor coil covered with grass, dirt, debris and/or pet hair;
a fan that won’t turn on;
a fan installed backwards with the blades running in the wrong direction;
a motor operating in the incorrect direction; and/or
a replacement fan motor spinning at a very low rpm.

Diagnosing apparent problems with the defrost cycle of a heat pump can be tough but hopefully this information can help.

There are three cycles of a heat pump: heating, cooling and defrost cycles. We learned about the defrost cycle of a heat pump.

Heat Pump FYI

Home Inspection FYI

Providing Help, Knowledge and Other Useful Information To Home Owners Everywhere

Tag Archives: thermostat