Presentation is loading. Please wait.

Presentation is loading. Please wait.

This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison 100% Outside Air and Dehumidification.

Similar presentations


Presentation on theme: "This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison 100% Outside Air and Dehumidification."— Presentation transcript:

1 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison 100% Outside Air and Dehumidification Management

2 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison 100% Outside Air - What is it ? Referred to as “Make-up Air” –Unit operates continually during occupied mode –Replaces exhausted air –No mixture with return air –Totally changing load Summer design (High temperature and high humidity) Winter design (Cold temperature)

3 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison Why 100% Outside Air? Ventilation standards indicating recommended air changes for a variety of space usages and occupancy have been established by ASHRAE. The ventilation requirements for a given structure or space are based either on desired number of air changes or the number of occupants. The amount of outside air fresh air required for each change per hour equals the amount of inside air that must be removed from the space during the same time span. CFM= Area of space / Minutes of air changes

4 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison Ventilation Requirements (continued) College classroom 8 air changes20-30 cfm/person Hospitals9-17 air changes40-50 cfm/person Kitchens10-20 air changes cfm/person Schools 8-12 air changes cfm/person Theaters 5-10 air changes cfm/person Factory Buildings air changes cfm/person

5 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison Return Air Ducts –Typically will not affect space conditions – May not require Reheat – Control is not as critical Direct to Space –Usually applied to large areas (Auditoriums, Kitchens, Corridors) – More precise control is necessary – Reheat is required for control Applications of Make-Up Air

6 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison 100% Outside Air “Supply Air Properties” Unit discharge air properties –Main purpose – positively impact building humidity Lowest dew point possible –Ideally close to room (neutral) conditions Typically between degrees Not to overcool or overheat space –Below 70% RH per ASHRAE standards

7 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison Dew Point Comparison Reheating to Neutral Air DRY BULB TEMPERATURE - °F 70°F72°F75°F DEW POINTRELATIVE HUMIDITY – RH % 45°F °F °F °F °F

8 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison Air Control Leaving Air Control –Hot Gas Reheat Cycling Control Modulating Control Room Control –Hot Gas Reheat Cycling in conjunction with a reheat thermostat Modulating in conjunction with a reheat sensor

9 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison 100 % Outside Air - Room Reheat Control Reheat Control - room thermostat in series with discharge thermostat (neutral or cold air) T T

10 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison Compressors Usage Single Compressor -- Single Circuit –Used when low dew point in required –Dehumidifies all the air all of the time Dual Circuits – Single Compress each circuit –Used when leaving air conditions are not critical –Air will bypass lag circuit and then mix with lead circuit Dual Circuits – Two compressors (Tandem) each circuit) –Lag compressor cycles based on suction pressure. –Four (4) stage operation –Large Tonnage

11 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison “Refrigeration” Control Hot Gas Bypass –Modulates to match the evaporator load –Evaporator freeze protection –Suction pressure activated Hot Gas Reheat –Raises leaving air temperature to room neutral conditions –Cycling with discharge air thermostat –Modulating with sensor. Liquid Subcool Coil –Raises leaving air temperature –Subcools liquid –Two (2) degrees of subcool equals one (1) percent increase in evaporator capacity

12 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison Standard Cycling Hot Gas Reheat

13 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison Hot Gas Reheat Plus Sub-Cooling

14 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison Hot Gas Reheat Using Digital Scroll

15 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison 100% Outside Air Example Summer design –1800 cfm –92/75 ambient –Leaving air 55 deg Dew Point 65 deg leaving air temperature Winter design –0 degree ambient –Leaving air (minimum 70 deg)

16 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison 100% Outside Air Summer Design w/Reheat Ambient 92/75 Supply Temp. 55.0/55.0 Leaving Air 79.7/ ton 1800 cfm

17 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison 100% Outside Air Summer Design w/Reheat Plus Ambient 92/75 Supply Temp D.P. Leaving Air 90.5/ ton 1800 cfm Liq. Sub-cool 66.1/59.4

18 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison 100% Outside Air Summer Part Load w/Reheat Ambient 75/75 Supply Temp D.P. Leaving Air 86.1/ ton 1800 cfm

19 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison 100% Outside Air Part Load w/Reheat Plus Ambient 75/75 Supply Temp D.P. Leaving Air 94.0/ ton 1800 cfm Liq. Sub-cool 65.7/58.8

20 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison 100% Outside Air Summer Part Load w/Reheat Ambient 70/70 Supply Temp. 48.8/48.8 Leaving Air 79.5/ ton 1800 cfm

21 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison 100% Outside Air Part Load w/Reheat Plus Ambient 70/70 Supply Temp D.P. Leaving Air 83.1/ ton 1800 cfm Liq. Sub-cool 59.9/54.3

22 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison 100% Outside Air Summer Part Load w/Reheat Ambient 65/65 Supply Temp. 46.8/46.8 Leaving Air 73.7/ ton 1800 cfm

23 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison 100% Outside Air Part Load w/Reheat Plus Ambien t 65/65 Supply Temp D.P. Leaving Air 79.4/ ton 1800 cfm Liq. Sub-cool 55.8/51.5

24 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison 100% Outside Air Summer Part Load w/Reheat Ambient 60/60 Supply Temp. 51.4/51.4 Leaving Air 64.3/ ton 1800cfm

25 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison 100% Outside Air Part Load w/Reheat Plus Ambient 60/60 Supply Temp D.P. Leaving Air 72.6/ ton 1800 cfm Liq. Sub-cool 55.2/52.1

26 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison 100% Outside Air Winter Design Conditions Ambient 0 Leaving Air ton 1800 cfm 175,000 BTUH Furnace

27 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison Recap Do No Harm – Dehumidify to 55 0 Dew Point or less. – Reheat to Room Neutral. – Temper to Room Neutral – Possible humidify when ambient temperatures are below 35 0

28 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison Energy Conservation Wheel Applications Require exhaust air from the building Require defrost in most areas Total Unit EER can exceed 25 on some water source heat pump applications

29 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison Load Reduction Example: Dedicated Outdoor Air Loads based on: 4250 cfm supply and exhaust airflow 48” Energy Conservation Wheel 75F/ 50%RH summer exhaust air 70F / 30%RH winter exhaust Source: (graphic)www.novelaire.com

30 This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison for your attention


Download ppt "This document is intended to assist licensed professionals in the exercise of their professional judgment.  2011 Addison 100% Outside Air and Dehumidification."

Similar presentations


Ads by Google