Welcome to Week 2 Part of HVC 210 & 211

1. Welcome to Week 2 Part of HVC 210 & 211

2. This week includes • Total Comfort • Cooling – Systems and Controls

3. Filtration • In a total comfort system, a provision should be made to filter the air in the living space. • Lint, dust, dirt and other organic materials are removed from the air as they pass through the filtration system or device. • Clean air will enhance the indoor total comfort conditions.

4. Other contaminants are : • V.O.C. (Volatile Organic Compounds) • CO • CO2 • Bacteria • Molds • Dust • Gas Offs

5. ALL FILTERS STARTOFF LIKE THIS…. BUT END UP LOOKING LIKE THIS...

6. AND THE EVAPORATORENDS UP LOOKING LIKE THIS

7. Slab Foam or Fiberglass 15 to 25% Efficiency Pleated Media 85 to 95% Efficiency Activated Charcoal Filter Filters Mechanical • Standard Media, USUALLY MADE FROM S • High Efficient - Space Guard

8. 80 to 95% Efficiency 45 to 65% Efficiency Electro-Static Electronic Filters Electronic • Electro - Stat • Electronic

9. ELECTROSTATIC The Electrostatic filter is a combination of both a mechanical and electronic filter designs. It consists of a fine fibrous weave to catch particles, but also produces an electrostatic charge to attract particles without the use of electricity

10. ELECTRONIC FILTER Is made up of two components. The first is the pre-filter. The second are the Electronic cells Electronic Cells Pre-Filter

11. The AC voltage is converted into DC voltage The particles left are given a positives charge The particles left in the air are picked up by the negatively charged plates. Clean air Dirty Air enters the pre-filter where lint, dog-hair, and large dust is removed. How an electronic filter works

12. More common today is a combination filter. Using a MERV 12 pleated filter, a UV light filter and an activated charcoal filter.

13. Kills 99.9% of all bacteria and viruses.

14. Fresh Air The Introduction of a controlled amount of outdoor air is important to a Total Comfort System

15. Fresh Air Negative Pressure can cause cold air to be “sucked” into the house through leaks around doors, windows and down the chimney. Mild Positive Pressure is good but too much will cause heat to “leak” out through doors, windows and chimney.

16. Fresh Air One way to bring in outdoor air into the system, a vent is placed outside with a control damper. When the furnace turns-on, the damper opens and the outside air in brought into the “return air” duct. Or a MRV can be used.

17. Humidity • Heat that cannot be felt…. • Latent Heat is mostly moisture content… • People,Bathing and Cooking produces Latent load...

18. Humidity Relative Humidity is the amount of moisture in a given quantity of air at a given dry bulb temperature compared to the maximum amount of moisture that same quantity of air can hold at the same dry bulb temperature. In other words, when the relative humidity of air hits 100%, it rains. So relative humidity is the amount of moisture in the between “no moisture” and rain.

19. Humidity In the winter, Low Relative Humidity can cause: Sore Throats Furniture Damage Static Electricity

20. Humidity In the winter, High Relative Humidity can cause: Condensation to occur on windows and walls resulting in mildew and Damage.

21. Humidity Summer High Relative Humidity Properly sized cooling equipment will result in longer cycles, allowing more humidity to be removed. Oversized cooling equipment will result in shorter cycles and higher humidity levels.

22. Comfort Guidelines • In Summer • Higher temps. can be offset by lower humidity. • Air movement helps with high humidity. • In Winter: • Lower temps can be offset by higher humidity. • Air movement is more noticeable.

23. Comfort Guidelines In the winter when the inside, wet bulb temperature is 70 degrees, And the relative humidity is 15 %. The temperature will “feel” 65 degrees.

24. Comfort Guidelines But, if you raise the humidity to 45%, look at the how the temperature “feels” now. to That is a 3 degree increase with no increase in heat.

25. Comfort Guidelines In the summer, if it is 85 degrees and the relative humidity is 80%, it is going to “feel” like it is 97 degrees. If you lower the relative humidity to 45%, look what happens. It now feels 10 degrees Cooler.!

26. Good Humidity Control • In order to produce total comfort, the moisture content of the air must be controlled during the heating and cooling seasons. • During winter months, the furnace will dry out the air and cold moist outdoor air must be brought into the house to raise the relative humidity. • The opposite happens in the summer, the interior of the house is filled with muggy, moisture laden air which must be removed. The air conditioning system removes moisture from the air lowering the relative humidity.

27. Air Movement through the system Supply Air The air enter the air-return grill as warm air. After the air goes thru the evaporator, it is now cold air and move into the distribution or duct work system and back into the house. The air passes through the air-filter. Return Air The air moves thru the blower

28. Disrupted airflow can cause: • Compressor flooding • Drafty rooms • Humidity problems • Mold/Mildew • Sweating ductwork • Electrical problems • Motor wear • Noisy systems • Positive or negative house pressure • Dust • Heat exchanger failure

29. Filter Sizing • Sizing the filter to a lower velocity is always best • The speed of air in a duct system is measured in Feet Per Minute (FPM) • Air-conditioning systems are designed to move 400 CFM per ton

30. A mismatched system is a common problem • Low airflow will make the air colder and remove more moisture; however, if less than 400 CFM per ton is moved across the evaporator coil, the system will have to run longer. Also, the coils can ice up. • High airflow will remove more Sensible Heat; however, if the air is moving across the coil too quickly, moisture removal will be a problem. The home will be cold but clammy