HVAC (Heating, Ventilation and Air Conditioning) equipment needs a control system to regulate the operation of 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).
AGS Monitoring System for HVAC monitor humidity, flow rates, indoor temperature, outdoor temperature, differential pressures, and equipment status. Campbell Scientific systems can activate and control proportioning valves, boilers, heat-exchange units, pumps, blowers, and air handlers. Our data loggers can use various types of input, and can output data and alarms via most communication methods.
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, setpoints, 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 transport medium (hot/cold water and/or steam). Digital inputs are typically (dry) contacts from a control device, and analog inputs are typically a voltage or current measurement from a variable (temperature, humidity, velocity, or pressure) sensing device. 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 such as valves, dampers, and motors.
Some of the more common problems that retro commissioning studies uncover include :
Unscheduled/additional HVAC runtime
Poor control strategies and programming errors
Stuck dampers causing excess outside air intake
Valve leakage leading to uncontrolled supply-air temperatures
Outright equipment failure
By utilizing data loggers to diagnose these problems, proper operation can be restored and, in many cases, improved relative to the original operating strategy.
Continuous Monitoring
Typical IAQ investigation and examination consists of taking single-point measurements of pollutant levels. This monitoring method is unreliable, as the pollutant levels are subject to hourly, daily, and seasonal fluctuations
Continuous monitoring instruments for IAQ eliminate the problems associated with single-point measurements. Multiple IAQ parameters can be monitored continuously in real-time. This enables simple, effective, and flexible management of air quality. The instruments are able to collect a complete and accurate record of IAQ, presenting the data required for effective air quality management within the building.
These instruments can continuously detect and measure many of the factors that contribute to a building’s indoor air environment, such as temperature, humidity, and numerous toxic gases and compounds, including:
Carbon dioxide (CO2);
Carbon Monoxide (CO);
Nitrogen dioxide (NO2);
Sulphur dioxide (SO2);
Ozone;
Ammonia (NH3);
TVOCs;
Methane;
Formaldehyde;
Glutaraldehyde.
Health Effects
Health effects from indoor air pollutants may be experienced soon after exposure. The immediate ones are usually short-term and treatable, including:
Eyes, skin, nose, and throat irritation;
Upper respiratory congestion;
Headaches;
Dizziness;
Fatigue.
Long-term exposure to low levels of certain pollutants could have an effect on an individual’s health in future years. According to the U.S. Environmental Protection Agency (EPA)/Office of Air and Radiation (OAR), these can be severely debilitating or become fatal illnesses, including some respiratory diseases, heart disease, and cancer. Exposure to high pollutant levels — such as carbon monoxide (CO) — can result in immediate death.
