Ventilation Systems

VENTILATION SYSTEMS Good ventilation is important because it helps to protect your health and your home. Good ventilation is as critical to your comfort and safety as a reliable heating system, a smoke alarm, or a dry basement.

YOUR HEALTH • Your health- Good ventilation protects you, your family, and your guests from unpleasant odours, irritating pollutants, and potentially dangerous gases like carbon monoxide and radon. Well planned ventilation also prevents the growth of mold and mildew, which can cause or aggravate allergic reactions and lung problems such as asthma

YOUR HOME Good ventilation protects your home from damage by eliminating excess moisture from the air. Too much moisture rots window sills and attic eaves, peels paint, and invites insect infestation. Damp insulation in walls and ceilings means lost heat, higher fuel bills, and destructive mold growth. Carpeting, wallpaper, electronic equipment, and furniture all can be damaged by excess moisture.

Point Exhaust

Point Exhaust • Good – Minimizes moisture problems. • Bad – Heat loss, negative pressure infiltration, raydon gas and dirt are sucked up form the basement.

Central Supply • Good – Fresh air is brought into the house. No makeup air is required. • Bad- Positive pressure, causes exfiltration and moisture can be forced to the insulation.

CENTRAL EXHAUST • Good – One fan to maintain, one exterior penetration. • Bad – Negative air pressure.

How a Heat Recovery Ventilator Works • Heat recovery ventilation systems allow R-2000 homes to maintain high indoor air quality without excessive additional energy costs. • As shown in the diagram below, a heat recovery ventilator (HRV) consists of two separate airhandling systems – one collects and exhausts stale indoor air; the other draws in outdoor air and distributes it throughout the home.

HEAT RECOVERY • At the core of an HRV is the heat transfer module. Both the exhaust and outdoor air streams pass through the module, and the heat from the exhaust air is used to pre-heat the outdoor air stream. Only the heat is transferred; the two air streams remain physically separate. Typically, an HRV is able to recover 70 to 80 percent of the heat from the exhaust air and transfer it to the incoming air. This dramatically reduces the energy needed to heat outdoor air to a comfortable temperature.

• Air Exchange • The HRV system installed in an R-2000 home can change all the air in the house over a threehour period. Most HRVs are also equipped with automatic humidity sensors that increase the ventilation rate when needed - for instance, when you use the shower. Exhaust air is normally collected from the kitchen and bathroom areas, where most moisture and odours are created.

HEAT RECOVERY VENTILATOR • Good – Balanced system even distribution of fresh air. • Bad – Constant energy draw and expensive maintenance cost.

MIXED AIR TEMPERATURE • Example #1 • A furnace has 1,100 CFM of return air at 65° F. If there are 120 CFM of outside air at 3° F. mixing with the return air. What is the M.A.T.? • MAT= (CFM x OAT) + (CFM x RAT) Total CFM

• MAT= (120 x 3) + (1,100 x 65) 1,220 MAT = 360 + 71,500 1,120 MAT = 58.9°F.

MAT EXAMPLE #2 • A rooftop unit has 2,350 CFM of return air at 70°F. There are 705 CFM of outside air at 8°F. mixing with the return air what is the MAT? • MAT= (CFM x OAT) + (CFM x RAT) Total CFM

• MAT= (705 x 8) + (2,350 x 70) 3,055 MAT= 5,640 + 164,500 3,055 MAT = 55.69°F

MAT EXAMPLE #3 • A unit has 1,300 CFM of return air at 75°F. There are 140 CFM of outside air at 95°F. mixing with the return air. What is the MAT? • MAT= (CFM x OAT) + (CFM x RAT) Total CFM

• MAT= (140 x 95) + (1,300 x 75) 1,440 MAT= 1330 + 97500 1,440 MAT= 76.94°F

EXAMPLES TO TRY CFM

OAT

CFM

RAT

120

3

1100

65

705

8

2350

70

140

95

1300

75

200

15

1500

65

180

5

2000

60

500

25

3000

50

TOTAL CFM

MAT