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Outdoor temperature sensor could be used if your system is designed to utilize the outside air for the cooling operation. This device will allow you to decide to increase the amount of the fresh air which injected to your system or not depend on the reading of the outdoor condition. this will lead to reduce the cooling operation by condensing unit or by chield water. but you need to take care of2 things:
1- Exhaust system should be linked into your control system. (% of Exfaust Air + %of Exfiltration = %Fresh air + %of Return Air).
2- Outdoor condition is not Temperature only it includes also the relative Humidity also.
The sensor should be fitted at the Fresh Air Duct of AHU. The Analog Input to the DDC will get compare the fresh air set point and PID loop will control the modulation of fresh air Damper, Return Air damper respectively, it will lead the VFD of AHU motor will control hence the energy of amps get saved. Also dehumidification taking place if the out side temperature crossed the return air temperature, the cooling valve actuator and duct heater gets modulating to give space temperature at normal affordable condition. here the water pumps also be get controlled by VFD, so complete parts and electrical energy get saved by exact operation.
We can use the outdoor temperature value to disable or enable indoor HVAC system, to open or close blinds...
By real time control of devices like mixing valves or frequency regulators of air conditioning systems.
In New England, USA, we have4 months mild temperatures. During mild temperatures, such asF toF, we provide chilled water by waterside economizer through a3-way valve. 3-way valve directs the water flow from the cooling tower to the economizer, and not to the chiller, and chiller stays off due to no water flow.
Once the temperature rises above the threshold,3-way valve directs the water flow to the chiller and cooling is provided through the chiller during hot summer months.
It optimizes the use of-ton chiller, reduces unnecessary start/stops, increases the life by reducing the wear n tear, and reduces operational cost.
The outdoor temperature sensor can be use to control the amount of fresh air to be taken inside and highly needed for an intelligent building automation system
A lot of scenarios can be done using the Outside temp sensor
outdoor temperature sensors are essential part in saving energy in buildings. If we know that outdoor temperature is2-3 degree lesser compared to return air temp in the conditioned area. we could use Heat recovery wheels to extract that temp difference into fresh air and save energy.
for example, soon after the rain the temperatures drop in the atmosphere. during this time we could if we know temperatures outside are cooler, allow air to pass to conditioned areas with lesser cooling.
outdoor temperatur sensor might be used when need to control humidity inside the room by injecting fresh air to room.
Outdoor temperature sensor mounted on outside air duct will give you environmental temperture value, by this you can decide whether to operate your AHU in Summer/Winter mode. In summer mode you will utilize 70% of return air in order to save energy for cooling by just cooling return air . In winter mode it utilizes the already cooled air from outside to cool the building.
