How to choose a portable air-conditioner

Bcoool offers a top quality range of portable air conditioning units, evaporating coolers, humidifiers and fans to help you keep your office environment cool and comfortable during the hot summer months.  These units also aid the suffers of hay fever by removing pollen particles from the air.

To get the most out of your portable air conditioning, you’ll need to consider the size of the unit that will best suit your needs.  To work out the maximum cooling capacity for the room where the air conditioner will be just following the simple calculations shown below.

Calculate the right-sized air conditioner for your needs

The cooling capacity of room air conditioners is measured in British thermal units per hour abbreviated as Btu/h.  Start by multiplying the width of the room by the length of the room.  You can make a quick selection of an air conditioner by looking at the measurements below.

Calculating your air conditioning requirements considering all factors that affect the temperature of the room for a more accurate guide

Heat Load

The amount of heat depends on a number of factors, by taking into account those that apply in your circumstances and adding them together a more accurate measure of the total heat can be calculated.

Factors include:

The floor area of the room
The size and position of windows, and whether they have blinds or shades
The number of room occupants (if any)
The heat generated by equipment
The heat generated by lighting

You first need to determine whether your windows are north or south facing.  If north facing windows produce more heat than south facing ones.  If your room has no windows, you can ignore this part of the calculation.

South Window BTU = South Facing window Length (m) x Width (m) x 870

North Window BTU = North facing windows Length (m) x Width (m) x 165

If there are no blinds on the windows multiply the result(s) by 1.5.

 - Finally add together all the BTUs for all the windows. 

Occupants

The heat output for occupants is 400 BTU per person.

Equipment

Clearly most heat in a room is generated by the equipment.  This is trickier to calculate than you might think.  The wattage on equipment is the maximum power consumption rating; the actual power consumed may be less.  However, it is probably better to overestimate rather than underestimate it.

Equipment BTU = Total wattage for all equipment x 3.5.

Lighting

Lighting BTU = Total wattage for all lighting x 4.25

Total cooling required

Finally add all the BTU’s together.

Room area BTU + Windows BTU + Total Occupants BTU + Equipment BTU + Lighting BTU.
This is the amount of cooling required so you need one or more air conditioning units to handle that amount of heat.  Disclaimer:  These calculations are a rough estimate only.  Complete accuracy cannot be guaranteed.

How portable air conditioners work

An air conditioner contains an evaporator, a compressor a condenser and a fan.  They are enclosed by a refrigerant system that contains a pipe that has refrigerant gas pumped around it. 

                The indoor unit contains the evaporator where the refrigerant evaporates.  This happens because the refrigerant has a very low boiling point of -40.8ºC at atmospheric pressure.

                To cause the evaporation to happen there needs to be slight rise in temperature which is supplied by the warm air from the room.

                The compressor reduces the pressure in the evaporator by drawing the evaporated refrigerant vapour out.  The vapour is then compressed into the condenser.  The temperature and pressure of the vapour rise as it is compressed into the condenser.  The vapour is then cooled down to the temperature of the refrigerant inside the condenser and subsequently the vapour turns into liquid.  This liquid is passed back to the evaporator where the warm air from the room causes it to evaporate once more. 

                The fan has two purposes.  The first is to draw warm air into the air conditioner from the room outside.  The second is to blow cold air out of the air conditioner into the room once the refrigerant has absorbed all the heat.  For this reason the condenser where all the heat ends up once the refrigerant has evaporated needs to be kept cool with either air or water. 

                Some air conditioners contain a screen which catches particles from the atmosphere as they are drawn into the air conditioner by the fan.  These particles include pollen which is great for people suffering from hay fever and also mould, dust and smoke.