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HVACR416 – Design Principles

HVACR416 – Design Principles

Air ExchangeAir Exchange

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HRV’s(Heat Recovery

Ventilators)

HRV’s(Heat Recovery

Ventilators)

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1. Heat Recovery Ventilators brings in fresh air while expelling stale air.

2. Recommended for colder climates (longer heating season)

3. HRV's air exchange core transfers heat from outgoing household air to the incoming fresh air (pre-heats)

4. Works opposite way in the cooling season

1. Heat Recovery Ventilators brings in fresh air while expelling stale air.

2. Recommended for colder climates (longer heating season)

3. HRV's air exchange core transfers heat from outgoing household air to the incoming fresh air (pre-heats)

4. Works opposite way in the cooling season

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ERV’s(Energy Recovery Ventilators)

ERV’s(Energy Recovery Ventilators)

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1. Brings in fresh air, expels stale air from the home

2. Recommended for warm humid climates (long cooling season)

3. Uses enthalpic "core" to transfer heat and moisture

4. Reduces indoor humidity in the A/C season

5. Maintains comfortable humidity level in the heating season.

1. Brings in fresh air, expels stale air from the home

2. Recommended for warm humid climates (long cooling season)

3. Uses enthalpic "core" to transfer heat and moisture

4. Reduces indoor humidity in the A/C season

5. Maintains comfortable humidity level in the heating season.

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Why use an HRV or ERV?Why use an HRV or ERV?

1. The natural exchange of air between the indoors

and outdoors through air infiltration and exfiltration is

not satisfactory for good moisture control and IAQ

2. Traditional venting methods (opening a window or use of a bath vent fan) do not providing adequate ventilation.

3. A properly designed ventilation system provides moisture control and helps ensure healthy IAQ for the occupant.

1. The natural exchange of air between the indoors

and outdoors through air infiltration and exfiltration is

not satisfactory for good moisture control and IAQ

2. Traditional venting methods (opening a window or use of a bath vent fan) do not providing adequate ventilation.

3. A properly designed ventilation system provides moisture control and helps ensure healthy IAQ for the occupant.

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1. The system uses a fan to maintain a low velocity flow of fresh outdoor air into the house (incoming air stream) while

exhausting out stale indoor air (exhaust air stream)

2. Fresh air is supplied to all levels of the house as stale air is removed

1. The system uses a fan to maintain a low velocity flow of fresh outdoor air into the house (incoming air stream) while

exhausting out stale indoor air (exhaust air stream)

2. Fresh air is supplied to all levels of the house as stale air is removed

How It Works

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Common Questions about HRV’s and ERV’s

Common Questions about HRV’s and ERV’s

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Who needs an HRV/ERV? Who needs an HRV/ERV?

1. Every home needs ventilation to bring in fresh air, to remove stale air, and provide moisture control

2. An HRV/ERV offers convenience, comfort and

durability

3. In new construction connections should be

roughed in if, for budget reasons, an HRV/ERV is not installed during

construction.

1. Every home needs ventilation to bring in fresh air, to remove stale air, and provide moisture control

2. An HRV/ERV offers convenience, comfort and

durability

3. In new construction connections should be

roughed in if, for budget reasons, an HRV/ERV is not installed during

construction.

14How much does it cost? How much does it cost?

1. Costs vary depending on the type and complexity of

the installation

2. Size and features of the HRV/ERV also effect cost

3. For new construction costs run from $1,000 to $2,500 and up

4. Retrofits generally cost more due to difficulty running ductwork to the source points

1. Costs vary depending on the type and complexity of

the installation

2. Size and features of the HRV/ERV also effect cost

3. For new construction costs run from $1,000 to $2,500 and up

4. Retrofits generally cost more due to difficulty running ductwork to the source points

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Do operating costs increase electric, heating or cooling bills? Do operating costs increase electric, heating or cooling bills?

1. An HRV/ERV requires service and electricity to run the fan but provides for heat recovery

2. On average the cost is approximately $42 annually to run an HRV/ERV fan

1. An HRV/ERV requires service and electricity to run the fan but provides for heat recovery

2. On average the cost is approximately $42 annually to run an HRV/ERV fan

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How does the heat and moisture transfer work?How does the heat and moisture transfer work?

1. The incoming fresh air is tempered with a heat or energy recovery core

2. Heat is exchanged through a core made of multiple plates of aluminum or plastic

3. Water vapor is transferred through a rotating wheel with desiccant material or permeable plates

1. The incoming fresh air is tempered with a heat or energy recovery core

2. Heat is exchanged through a core made of multiple plates of aluminum or plastic

3. Water vapor is transferred through a rotating wheel with desiccant material or permeable plates

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Enthalpy WheelEnthalpy Wheel

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1. HRV’s transfer heat from the exhaust air to the incoming air in the heating season and from the incoming air to the exhaust air in the A/C season

2. HRV’s with heat recovery and moisture recovery

transfer heat and moisture from the exhaust air

to the incoming air during the heating season

3. During the A/C season heat and water vapor from the incoming air transfers to the

exhaust air

1. HRV’s transfer heat from the exhaust air to the incoming air in the heating season and from the incoming air to the exhaust air in the A/C season

2. HRV’s with heat recovery and moisture recovery

transfer heat and moisture from the exhaust air

to the incoming air during the heating season

3. During the A/C season heat and water vapor from the incoming air transfers to the

exhaust air

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Heat Exchange PlatesHeat Exchange Plates

20How to size HRV/ERV How to size HRV/ERV

Manufacturers have guidelines for sizing(many states do not have standards at this time).

The following is a Minnesota new home constructionstandard:

The total number of bedrooms with a minimum airflow of 15 CFM/bedroom + 15 CFM and a total

ventilation capacity equal to 0.05 CFM/square foot.

NOTE: Additional ventilation may be required for special

needs such as crafts/hobbies and excessive moisturesituations

Manufacturers have guidelines for sizing(many states do not have standards at this time).

The following is a Minnesota new home constructionstandard:

The total number of bedrooms with a minimum airflow of 15 CFM/bedroom + 15 CFM and a total

ventilation capacity equal to 0.05 CFM/square foot.

NOTE: Additional ventilation may be required for special

needs such as crafts/hobbies and excessive moisturesituations

21How to maintain a system? How to maintain a system?

Typical maintenance can be done by thehomeowner and includes the following: • Clean or replace air filters every 1-3 months.• Clean or unblock outside hoods and screens

every 13 months• Clean the energy recovery core every 6

months • Clean condensate drain and pans every 6

months • Clean(oil if needed) fans every 3-6 months• Annually clean grills and inspect ductwork for

leaks or obstructions• A professional should annually check the

system to verify proper balance

Typical maintenance can be done by thehomeowner and includes the following: • Clean or replace air filters every 1-3 months.• Clean or unblock outside hoods and screens

every 13 months• Clean the energy recovery core every 6

months • Clean condensate drain and pans every 6

months • Clean(oil if needed) fans every 3-6 months• Annually clean grills and inspect ductwork for

leaks or obstructions• A professional should annually check the

system to verify proper balance

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24Enthalpy WheelEnthalpy Wheel

25HRV InstalledHRV Installed

26HRV InstalledHRV Installed

27Honeywell ERVHoneywell ERV

28Commercial UnitsCommercial Units