The HVAC Air Handler Freeze Stat is a low temperature limit control and it is used mainly in commercial systems in the duct work on economizers or in air handlers just before any coil especially water coils. It is a safety and protection control to prevent extremely cold air from reaching the hot water or chilled water coils inside the air handler where the air enters from the economizer. Under ideal control set up if the freeze stat trips the economizer dampers close and the blower fan stops. This prevents coils from freezing. A frozen coil can bust open and will need to be replaced if it freezes thus the purpose of the freeze stat in HVAC air handler applications which utilize economizers for free cooling. Air Handler Freeze Stat
As the cost of energy rises engineers are looking for ways to improve and increase energy efficiency. Aside from HVAC equipment with higher energy efficiency rates, improving structures for less heat loss and heat gain, and building automation systems giving the equipment precision control for better efficiency of the equipment, there are other ways to increase energy efficiency inside buildings. One of the ways to increase energy efficiency inside buildings is to add energy recovery wheels to the economizer systems. A US Department of Energy study concluded energy recovery wheels can save over 15% of the energy used in commercial HVAC applications.
This is a hot water economizer and is a big preheater for domestic hot water use. This boiler plant serves a large community for heating and domestic hot water use. Domestic hot water is used for showers, washing dishes, laundry, ect, ect, ect…. The cold water supply from the city is routed through the economizer to be pre-heated before it goes through a heat exchangerand then the hot water storage tank. This system saves money because it uses the exhaust gases from the boiler to pre-heat the city water supply which is normally 50 degrees Fahrenheit. The exhaust gases from the boiler would otherwise be vented to the atmosphere and would be considered wasted heat. Continue reading “Hot Water Boiler Economizer PreHeater” »
These return air dampers serve a large air handler on a roof top. This return air damper ends up in a mixing box inside the air handler where the return air from the building mixes with the outside air from the economizer. This air handler has a desiccant wheel so it has a built in energy recovery systemso any relief air goes through the energy recovery wheel on one side of the wheel while the outside air goes through the energy recovery wheel on the other side. The wheel absorbs energy on one side and releases it on the other maintaining an optimal level of preconditioned air for introduction to the mixing box where it mixes with the return air. This allows the economizer to be open and used even when outside air conditions are not ideal for using the air outside. Continue reading “Air Handler Return Air Dampers” »
This damper actuator controls a free cooling damper for an economizer. It is part of an economizer damper system which allows free outside air cooling when the outside air temperature and humidity are ideal. In the Fall and the Spring when the outside air temperatures are mild it is unnecessary to run the air conditioning system to cool the building if the system is set up for free cooling. The air conditioning system has duct work running to the outside. When the control system program calls for free cooling the outside air damper opens and the system draws in cool air from the outside. Another damper directs the return air, which originates inside the spaces of the building, to the outside. This brings cool conditioned air into the building while exhausting the warmer air to the outside. Another action that the control program initiates is the lock out of the air conditioner or mechanical cooling. Continue reading “HVAC Damper Actuator – Economizer – Free Cooling” »
High Performance HVAC: High Performance Air Conditioning and Heating Economizer Systems – Free Cooling or Free Air Conditioning
I’m looking for residential high performance system that uses air intake damper or a multistage (multizone) heating and cooling system similar to what I found at Economizer Systems and HVAC Control ?
Any suggestions? Answer……………
In the old days we called it opening a window or turning on a fan or both. Commercial HVAC systems use the mechanical code for introducing fresh air into the structure and the requirements in the mechanical code vary from building type to building type. There are rudimentary economizer systems which are used for commercial HVAC systems to comply with code requirements but in my experience these systems do not work very well and are simply on the units to meet minimum mechanical code requirements for commercial fresh air code. Depending on the type of building and space in the building and its use depends on the mechanical code requirements for so many changes of air per hour. For example: A movie theater with a maximum occupancy of 150 people will require 15 CFM’s per person of outside air to satisfy the mechanical code. In the old days before solid state sensors and controls an adjustable panel or damper on the air handling unit would be opened a certain percent to the outside air depending on the required amount of fresh outside air needed to meet the fresh outside air requirement in the mechanical code. Continue reading “Free Cooling and Air Conditioning” »