CONTROLS IN HVAC AND ITS IMPORTANCE.

A  HVAC control system applies regulation to a heating and/or air conditioning system. Usually a sensing device is used to compare the actual state (e.g., temperature) with a target state. Then the control system draws a conclusion what action has to be taken (e.g., start the blower, open the control valve etc).

The capacity of the HVAC system is typically designed for the extreme conditions. Most operation is part load/off design as variables such as solar loads, occupancy, ambient temperatures, equipment & lighting loads etc keep on changing throughout the day. Deviation from design shall result in drastic swings or imbalance since design capacity is greater than the actual load in most operating scenarios. Without control system, the system will become unstable and would overheat or overcool spaces.

What Parameters are controlled?

A proper environment is described with four variables: temperature, humidity, pressure and ventilation.

Direct digital control (DDC Panels) : is the automated control of a condition or process by a digital device (computer). Central controllers and most terminal unit controllers are programmable, meaning the direct digital control program code may be customized for the intended use. The program features include time schedules, set points, controllers, logic, timers, trend logs, and alarms. The unit controllers typically have analog and digital inputs, that allow measurement of the variable (temperature, humidity, or pressure) and analog and digital outputs for control of the medium (hot/cold water and/or steam etc). Digital outputs are typically relay contacts used to start and stop equipment, and analog outputs are typically voltage or current signals to control the movement of the medium (air/water/steam) control devices. Usually abbreviated as "DDC".

These systems controlled by a central computer are called BMS (Building Management systems) which are normally complex & comparatively costly to be installed moreover these also need to be programmed.Also,it is difficult in pulling cables & wires in a fully operational buildings.

Hence, for projects with lower or no budgets for these costly BMS systems or operational building we recommend these special type of Energy saving Thermostat which can be programmed as per your time schedule. These thermostats can be programmed for daily, weekly, monthly & yearly schedules for running the equipment.

Once the programming/scheduling on the thermostat is done you can also calculate the payback in terms of actual Dollars saved & your energy saved in terms if KWH/BTU at actually & hence your monthly ,annually savings against that.

Should you require any further queries you are are always welcome to get in touch,by leaving your comments or contacting me on my email.

Await my further post for Energy savings on Chilled water Pumps.

SAVE ENERGY SAVE MOTHER EARTH