How a Programmable Thermostats Works | HVAC Control

How a Programmable Thermostats Works - Programmable thermostats can save you more than ten percent on your homes utility bills. For that reason a programmable can pay for itself within a few years depending on the type and expense of the type you purchase. I always lean towards Honeywell thermostats simply because I’ve seen their reliability in the field and sometimes ease of use. Among others, you can expect good quality from Honeywell thermostat products. The new, hi-tech style currently out on the market is the Honeywell touch-screen thermostat.
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VAV Box Types Fan Powered and Shut Off

VAV Box Types Fan Powered and Shut Off VAV Boxes - When attempting to name the different types of VAV boxes we find there are different names given to VAV boxes by different people and we find that no one is on the same page when VAV boxes are definitively defined.

We have fan-powered VAV and non-fan-powered VAV’s and we have series and parallel VAV’s and we have VAV boxes with a hot deck and a cold deck that mixes and one of the last projects I worked on some of the VAV’s were referred to as shut-off vavs. Variable Air Volume Boxes (VAV Boxes) regulates airflow into zones using a primary air source from a VAV air handler.

VAV Box Types Fan Powered and Shut Off

  • Cool only single ducted series
  • Fan-powered single duct series with reheat
  • Fan-powered single ducted parallel with reheat - uses plenum air before using reheat for energy efficiency

Aside from the control aspect of VAV boxes, pneumatic, electric, electronic, or DDC, there are many different variations to VAV Boxes and we will attempt to define each type of VAV including offering a diagram of each type and matching it with a specific application. VAV boxes are simply an assembly of a damper, damper controls, and sometimes reheat such as electric heat strips or a hot water coil. VAV boxes get their primary air source from a central VAV air handler and then distribute air throughout a specific zone the VAV box controls.

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Outside Air Temperature-Humidity Sensor | HVAC Control

Outside Air Temperature-Humidity Sensor Outside Air Temperature-Humidity Sensor  - The outside air temperature sensor uses a thermistor to read the outside temperature. This sensor also senses humidity using a humidity transducer. The temperature and humidity readings are collected by a direct digital control system and used in a program. Aside from using this information for user interfaces, the information is also used in a control program to open and close an outside air damper.  (more…)

Duct Temperature Sensor

Duct Temperature Sensor - Thermistor Temperature Sensing DeviceDuct Temperature Sensor - The duct static temperature sensor measures air temperature in the ductwork. The solid-state temperature sensing devices are commonly used in HVAC applications that are controlled by direct digital control or a modern building automation system. At the base of the box is a probe that sticks into the air stream of the ductwork. As the air passes over it, the probe changes resistance. (more…)