Air-Handling Equipment

{0 Comments}

Air-handling equipment is available as packaged equipment in many configurations using any desired method of cooling, heating, humidification, filtration, etc. In large systems (over 25 m3/s), airhandling equipment is usually custom-designed and fabricated to suit a particular application. Air handlers may be either centrally located or decentralized. Central Mechanical Equipment Rooms (MER). Usually the type […]

Read More…

Air Handling Unit

{0 Comments}

Air Handling Unit

The basic secondary system is an all-air, single-zone, air-conditioning system consisting of an air-handling unit and an air distribution system. The air-handling unit may be designed to supply a constant air volume or a variable air volume for low-, medium-, or high-velocity air distribution. Normally, the equipment is located outside the conditioned area in a […]

Read More…

Temperature Versus Air Quantity

{0 Comments}

Designers have considerable flexibility in selecting the supply air temperature and corresponding air quantity within the limitations of the procedures for determining heating and cooling loads. ASHRAE Standard 55 also addresses the effect of these variables on comfort. In establishing the supply air temperature, the initial cost of lower airflow and low air temperature (smaller […]

Read More…

Space Heating

{0 Comments}

Although steam is an acceptable medium for central system preheat or reheat coils, low-temperature hot water provides a simple and more uniform means of perimeter and general space heating. Individual automatic control of each terminal provides the ideal space comfort. A control system that varies the water temperature inversely with the change in outdoor temperature […]

Read More…

Zoning – Exterior

{0 Comments}

Exterior zones are affected by varying weather conditions wind, temperature, and sun and, depending on the geographic area and season, may require both heating and cooling at different times. While the engineer has many options in choosing a system, the system must respond to these variations. The considerable flexibility to meet such variations enables the […]

Read More…

All-Air System

{0 Comments}

An ALL-AIR SYSTEM provides complete sensible and latent cooling, preheating, and humidification capacity in the air supplied by the system. No additional cooling or humidification is required at the zone, except in the case of certain industrial systems. Heating may be accomplished by the same airstream, either in the central system or at a particular […]

Read More…

AIRFLOW MEASUREMENT IN A FAN COIL WITH ELECTRIC HEAT

{0 Comments}

AIRFLOW MEASUREMENT IN A FAN COIL WITH ELECTRIC HEAT

Purpose – This procedure describes how to calculate the quantity of airflow in cubic feet per minute (CFM) being delivered by a fan coil containing electric heating elements. Having the correct quantity of airflow is important in order to maintain heating comfort in the conditioned space and for efficient and safe equipment operation. Airflow measurements […]

Read More…

COOLING SYSTEM PROPER AIRFLOW RANGE

{0 Comments}

COOLING SYSTEM PROPER AIRFLOW RANGE

Purpose — This procedure describes how to determine if airflow across the evaporator in a cooling system is adequate. For proper operation of a cooling system, the blower should be moving from 400 to 450 CFM of air across the evaporator coil for each ton of cooling capacity. For example, on a 2-ton cooling unit, […]

Read More…

TEMPERATURE RISE MEASUREMENT IN A FOSSIL-FUEL FURNACE

{0 Comments}

TEMPERATURE RISE MEASUREMENT IN A FOSSIL-FUEL FURNACE

Purpose – This procedure describes how to measure the temperature rise in fossil-fuel furnaces. Temperature rise is the difference between the return air temperature entering the furnace, and the supply air temperature leaving the furnace. The amount of temperature rise gives an indication of whether adequate air is flowing across the furnace heat exchangers. However, […]

Read More…