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Heating

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Heating is something that every electrician will have to deal with. Electricity is needed to power almost every form of heating or cooling units available today. The connections, terminations, or disconnects will need to be addressed by a qualified electrician - which means you'll have to familiarize yourself with most units.

If you're finding in your job travels that unqualified personnel are making the connections to heating units, and you don't think that's such a bad idea...think again. If the panel that the unqualified worker is adding units to - is already overloaded - he's endangering the clients. We've seen some people grab a receptacle circuit because it was convenient to "finish" a job, then this leaves the client to deal with constant overload tripping, or in some situations...fire.

Some heating and cooling units require a substantial amount of power. There are also several additions (Delta) to the 2006 CEC that require different loads, connections, wire sizes, designated circuits, and lengths that need to be calculated for a safe installation. Some people don't realize the harm they're doing when they connect a seemingly simple unit to a house. The truth is is that the work they're doing is "guesswork" that could eventually cost people their life. House fires happen every single day. People lose their lives, every single day.



Characteristics of Heat

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Energy. Heat is a form of energy that travels or transfers from hot areas to cold.

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Temperature. (Like voltage or water pressure) Temperature is thermal pressure.

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Heat. (Like kw per hour, or gallons of water) Heat is a quantity of energy.

- Heat always travels from hot to cold at a rate proportional to the (Temperature Difference - TD) and inversely proportional to the normal insulation.



How Heat Transfers

- The Transfer. Heat may be transferred to one place to another by means of;

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Conduction. Heat transfers from one molecule to another.

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Convection. Heat movement due to density differences.

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Radiant Absorption. Radiation is energy in the form of waves and can move through anything.




Production and Measurement

Heat Production. Is the change of one form of energy to another. Also called potential energy.

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BTU. British Thermal Unit. The amount of energy needed to raise the temperature of one pound of water to 1 degree fahrenheit, or 1.8 degrees celcius. BTU to Watts conversion multiple by 3.41. Watts to BTU conversion divide by 3.41. This is a per hour conversion.

- Calorie. The unit of heat equal to the amount of heat required to raise the temperature of one kilogram of water by 1 degree celcius.




Electric Heating

There are two types of electric heat;
Central
Unitary


The advantages of electric heat are
Clean
Efficient
Space Saving
Easy to install
No odor
and it's versatile


Unitary/Central Overview

Advantages
Disadvantages
Unitary
-Seperate units with own control
-Lots of breakers used.
-Cost of installation
-Power outage - all heat is lost.
-Close off portions of heating area
-In event of break down, one heater is out - vs all heat.
Central.
-Versatile
-Break down, all heat is lost
Forced Air/Duct
-Smaller
-The need of duct work.
-No fuel storage
-Adaptable to other systems




Calculating Heat Output

A kilowatt or KW, is 1000 watts. This is used for per hour calculations. For instance, if you had a 3600 Watt Heater, you could state that it uses 3.6 KW per hour of power usage.
Volts multiplied by Amps give you Watts. If your home is wired for 120 Volts, and you know the equipment is (for an example) 8.8 Amps, you can calculate the Watt output. In this case...
120 V x 8.8 A = 1056 Watts


Breaker Sizing for Heating (62-114 CEC)

Look at the above section in your CEC codebook. Continuous vs non continuous. If you are sizing a breaker for primary heating purposes the CEC states that you must size the breaker for continuous usage. The easy way to calculate this load is to multiply your heating Amps by 1.25 to get the correct breaker size.


Thermostats

There are two types of thermostats
Line Voltage
Low Voltage
From these two types, there are bi-metal, solid state, and hydraulic thermostats.

Line Voltage thermostats are either wall mounted, or built in to the unit itself. The built in thermostats are only acceptable in vestibules, kitchens, bathrooms, service or storage areas, and garages. These are not meant as a primary source of heat, and are only considered a secondary source.
The wall mounted thermostats are either single pole, or double pole. The double pole thermostat gives itself away by having an actual "off" position. The single pole does not, therefore the unit will turn on when the thermostat reaches the lowest setting. Most are 5 degrees celcius. This kind of unit would be good in summer homes needing a low amount of heat for plumbing pipes in the winter while you're away.

Low Voltage thermostats are safer to work with. They have small resistance heaters (anticipators) allowing faster cycles and quick response.



Mechanical Lag

Is the term for temperature change, that the sensing element must sense before it actuates the switching device on the thermostat.