insulation & ventilation

SUPPLY VENTILATION SYSTEMS how does it operate?

- Supply ventilation systems use a fan to pressurize your home, forcing outside air into the building while air leaks out of the building through holes in the shell, bath, and range fan ducts, and intentional vents (if any exist). - A typical supply ventilation system has a fan and duct system that introduces fresh air into usually one -- but preferably several -- rooms that residents occupy most (e.g., bedrooms, living room). This system may include adjustable window or wall vents in other rooms.

Energy Recovery & Heat Recovery Ventilators pros& cons

pros: Reduce heating and cooling costs Available as both small wall- or window-mounted models or central ventilation systems Cost-effective in climates with extreme winters or summers and high fuel costs. Cons:Can cost more to install than other ventilation systems May not be cost-effective in mild climates May be difficult to find contractors with experience and expertise to install these systems Require freeze and frost protection in cold climates Require more maintenance than other ventilation systems.

pros and cons of supply ventilation

pros: Relatively inexpensive and simple to install Allow better control than exhaust systems Minimize pollutants from outside living space Prevent backdrafting of combustion gases from fireplaces and appliances Allow filtering of pollen and dust in outdoor air Allow dehumidification of outdoor air Work well in hot or mixed climates. cons: Can cause moisture problems in cold climates Will not temper or remove moisture from incoming air Can increase heating and cooling costs May require mixing of outdoor and indoor air to avoid drafts in cold weather. Supply ventilation systems work best in hot or mixed climates. Because they pressurize the house, these systems have the potential to cause moisture problems in cold climates. In winter, the supply ventilation system causes warm interior air to leak through random openings in the exterior wall and ceiling. If the interior air is humid enough, moisture may condense in the attic or cold outer parts of the exterior wall, resulting in mold, mildew, and decay.

BALANCED VENTILATION SYSTEMS operation

- Balanced ventilation systems, if properly designed and installed, neither pressurize nor depressurize your home. Rather, they introduce and exhaust approximately equal quantities of fresh outside air and polluted inside air. - A balanced ventilation system usually has two fans and two duct systems. Fresh air supply and exhaust vents can be installed in every room, but a typical balanced ventilation system is designed to supply fresh air to bedrooms and living rooms where occupants spend the most time. It also exhausts air from rooms where moisture and pollutants are most often generated (kitchen, bathrooms, and perhaps the laundry room). - Some designs use a single-point exhaust. Because they directly supply outside air, balanced systems allow the use of filters to remove dust and pollen from outside air before introducing it into the house. - Balanced ventilation systems are appropriate for all climates. Because they require two duct and fan systems, however, balanced ventilation systems are usually more expensive to install and operate than supply or exhaust systems.

defects of clothes dryers

- Duct to large or to small- inches unless manufacture - terminates inside closed space instead of exterior attics & crawlspaces) - disconnected duct before the exterior termination hood- fire hazard, moisture damage - Duct terminates w/in 3 ft from a door, window, mechanical air intake, or crawl space ventilation opening- this may allow the dryer exhaust to return into house - duct terminates w/in 3 ft of condenser- moist dry air can damage condenser - duct cannot terminate into a bucket- these indoor lint trap buckets are not an approved method of exhausting a clothes dryer - excessive lint build up behind termination hood- a screen will trap lint and block opening ( no screen allowed, defect) - exterior damper stuck open or shut- dampers are often blocked by the wall covering or screen at terminal - transition duct penetrates floor, wall or ceiling- fire hazard or duct is damaged

HVAC Ducts should be wrapped with insulation with an R-value of...and with a.... ..... retarder facing on the ...... side?

- The ductwork should be wrapped with insulation that has a minimum R-value of 6, with a vapor diffusion retarder facing on the outer (exterior) side - It should be overlapped and sealed with fiberglass tape where sections of the insulation meet.

Bathroom fan defects

- fan is exhausted into crawlspaces, attics or soffit and not to exterior - duct cannot be connected to other systems ( plumbing vent or clothes dryer exhaust) - damper absent at termination hood or blocked - noisy fan - water staining by duct caused by condensation

Whole house fan defects

- fan not operational using normal controls - louvers damaged or not operate - fan drive belt loose, worn - winter cover not available or damaged - attic ventilation openings blocked or not sufficient enough

Kitchen exhaust defects

- flexible duct material used: kitchen exhaust ducts may not be constructed with flexible corrugated material. will trap grease and cause fire - The duct is not Air Tight: common installation technique is to blow the fan exhaust into the cabinet space above the hood or microwave w/out connecting the fan to the duct; this allows grease in the exhaust air to collect in the wood cabinet and can result in grease fire - Screen protection is absent- blocks rodents , exterior openings should be protected by a screen, louver or a grill or an exterior damper - duct or exterior terminal is too small- restrict air flow, exhaust will not function properly and grease could collect in the duct - grease filters absent or blocked; fan wont function properly without these filters

Bathroom Exhaust 1) when is an exhaust fan not required in a bathroom? 2) current best practice of exhaust fans in bathrooms? 3) how to report exhaust fans that are not to exterior in older homes? 4) sz and material used for ducts?

- local exhaust fan is not required if mechanical ventilation is used or natural w/ window provided. - current best practice is to install exhaust fan in bathrooms including those w/operable windows . Failure to follow best practice is not an efficiency but moisture damage is a defect without a exhaust fan. ( fan speed 50 cu ft a minute) - exhaust to exterior, not attic or crawlspace. some report older homes that do no go to exterior and some recommend upgrade - duct sz per manufacture. IRC effectively eliminates the use of 3 inch diameter flexible duct. Typical duct material is flexible coil 3-4 inch diameter

gas dryers located in closest need how much make up air ventilation?

- opening 100 sq inches - openings may be in the door or as an opening in a wall - good idea in general for any laundry room

Transition duct for clothes dryer exhaust duct: describe

- the transition duct is the flexible duct between the clothes dryer and the duct - not more than 8ft - may not run through walls, ceiling, floors or be concealed - materials: metallic material - cut as short as possible and not crimped or constricted - blockage causes reduced air flow, dryer works harder and more lint into exhaust - out of scope

condensing clothes dryers describe:

- they condense the moisture from the dryer exhaust and discharge it into the plumbing discharge vent - these appliances do not need an external exhaust duct - uncommon appliances

Whole house fans description: 1) Sz and location of installment of whole house fan? 2) operation of traditional whole house fan operation? 3) Newer style of a whole house fan operation? 4) What does a whole house fan do for occupants for comfort?

1) - sz 24 to 36 fan installed in the ceiling usually centrally located in home ( hallways). 2)When a tradional whole house fan is activated, lovers in ceiling open and fan draws air in from open windows through the house and exhaust the air into the attic. 3) The fan exhaust the inside air through an opening in the roof or gable wall and connects the fan using ducts to an opening in the ceiling. 4) Both fan styles, make occupants feel cooler because of evaporation of moisture from their skin caused by air movement.

Local Exhaust systems for Clothes Dryer Exhaust: Requirements: 1) What is the developed length? 2) Developed length a duct should not exceed & why? 3) what does the developed length not include? 4) When is it acceptable for the developed length to be longer?

1) Developed length means the straight length of the duct plus additional length to account for the reduction of air flow caused by fittings that change duct direction. ( add 5ft for most 90 degree bend fittings and 2 1/2 ft for most 45 degree bend fittings. ( refer to irc for developed length) 2) 35 ft 3) the transition duct 4)it is acceptable for the duct developed for the duct developed length to exceed 35 ft if per manufacture permit, many do this.

ENERGY RECOVERY VENTILATION SYSTEMS Operation

1) Energy recovery ventilation systems provide a controlled way of ventilating a home while minimizing energy loss. They reduce the costs of heating ventilated air in the winter by transferring heat from the warm inside exhaust air to the fresh (but cold) outside supply air. In the summer, the inside air cools the warmer supply air to reduce cooling costs 2) Because an energy-recovery ventilator transfers some of the moisture from the exhaust air to the usually less humid incoming winter air, the humidity of the house air stays more constant. This also keeps the heat exchanger core warmer, minimizing problems with freezing. 3) In the summer, an energy-recovery ventilator may help to control humidity in the house by transferring some of the water vapor in the incoming air to the theoretically drier air that's leaving the house. If you use an air conditioner, an energy-recovery ventilator generally offers better humidity control than a heat-recovery system. However, there's some controversy about using ventilation systems at all during humid, but not overly hot, summer weather. Some experts suggest that it is better to turn the system off in very humid weather to keep indoor humidity levels low. You can also set up the system so that it only runs when the air conditioning system is running, or use pre-cooling coils. 4) Most energy recovery ventilation systems can recover about 70% to 80% of the energy in the exiting air and deliver that energy to the incoming air. However, they are most cost-effective in climates with extreme winters or summers, and where fuel costs are high. In mild climates, the cost of the additional electricity consumed by the system fans may exceed the energy savings from not having to condition the supply air. 5) Energy recovery ventilation systems usually cost more to install than other ventilation systems. In general, simplicity is key to a cost-effective installation. To save on installation costs, many systems share existing ductwork. Complex systems are not only more expensive to install, but they are generally more maintenance intensive and often consume more electric power. For most houses, attempting to recover all of the energy in the exhaust air will probably not be worth the additional cost. Also, these types of ventilation systems are still not very common. Only some HVAC contractors have enough technical expertise and experience to install them. 6) In general, you want to have a supply and return duct for each bedroom and for each common living area. Duct runs should be as short and straight as possible. The correct size duct is necessary to minimize pressure drops in the system and thus improve performance. Insulate ducts located in unheated spaces, and seal all joints with duct mastic (never ordinary duct tape). Also, energy recovery ventilation systems operated in cold climates must have devices to help prevent freezing and frost formation. Very cold supply air can cause frost formation in the heat exchanger, which can damage it. Frost buildup also reduces ventilation effectiveness. 7) Energy recovery ventilation systems require more maintenance than other ventilation systems. They need to be cleaned regularly to prevent deterioration of ventilation rates and heat recovery and to prevent mold and bacteria on heat exchanger surfaces.

There are four types of whole-house ventilation systems:

1) Exhaust ventilation systems force inside air out of a home. Spot ventilation is a form of exhaust ventilation. 2) Supply ventilation systems force outside air into the home. 3) Balanced ventilation systems force equal quantities of air into and out of the home. 4) Energy-recovery ventilation systems transfer heat from incoming or outgoing air to minimize energy loss. (This type of ventilation system is covered in the next slide.)

Kitchen exhaust 1 & 2) two types of exhaust fans, describe each? 3) kitchen exhaust Duct installment ways & materials & requirements? 4) under slab exhaust requirements? 5) duct sz and length per manufacture. round ducts? rectangular ducts? damper installment

1) Hood or microwave oven with an exhaust fan installed above cook top. These exhaust fans can usually be installed as an externally exhausted fans w/an exhaust duct or as a recirculating fan 2) Less common is the downdraft in which a fan and duct are installed under the cook top. Downdraft exhausts are often used with the cook top located in an island 3) Kitchen exhaust ducts installed above ground constructed using single wall metal w/a smooth interior. galvanized steel most common ( stainless steel and copper used also) 4) may be installed under concrete slab useing schedule 40 PVC 5) round ducts- 6 inches rectangular ducts- 31/4x10 inches - back draft damper installed - damper may be installed in termination hood or at the fan

Three Ways to Ventilate A home can be ventilated in the following three ways:

1) Natural ventilation is uncontrolled air movement into a home through cracks, small holes and vents, such as through windows and doors. This method cannot be relied upon for tightly sealed and many new-construction homes. 2) Whole-house ventilation is controlled air movement using one or more fans and duct systems. 3) Spot ventilation is controlled air movement using localized exhaust fans to quickly remove pollutants and moisture at their source. It is typically used in conjunction with one of the other strategies. Spot ventilation can be used to improve the effectiveness of natural ventilation. However, if both spot and natural ventilation together don't meet the home's ventilation needs, then the homeowner should consider a whole-house ventilation strategy

Ventilation by HVAC Connected Outside Air Duct: 1) Describe 2) Describe possible problems with this method?

1) The HVAC connected air duct method is inexpensive to install and can provide the recommended ventilation air. This method is common in some markets. An automatic damper that closes when the system is not active should be installed in the duct system 2) 1st problem is that this method is unbalanced, meaning that more air may enter the house through the outside air duct than leaves the house through other openings. The air entering the house through the outside air duct may increase the pressure in the house forcing air out of the house. This can create mold and moisture problems by the air collecting in the wall cavities - another problem is homeowners pay to heat the outside air - another problem is that cold outside air can cause water to condense in the HVAC system and create mold problems. Mostly occurs in cold climates with condensation - this method relies on occupants to use the local exhaust system to remove pollutants which often overlooked - not ideal for ventilation

Local Exhaust systems Requirements: Intro part 2: 1) Some requirements apply to all air intake and exhaust systems except for what appliance? why? 2) Where should a screen be installed (allowed) on appliances to vent exhaust air? why? 3) Sz of screen openings on outdoor air intake and exhaust opening? 4) Where should a damper be installed? (required) 5) Where should you install an accessible air filter? ( not required)

1) clothes dryer exhaust ( no screen allowed) because it will block lint causing potential fire hazard ( defect) 2) Install a screen on the outdoor air intake and exhaust openings to restrict vermin entry. 3) between 1/4th & 1/2 inch 4) In the air intake and exhaust system that automatically closes when system is not operating 5) In the HVAC connected air intake system to remove some of the dust in the outside air (pollutants )

Local Exhaust systems for Clothes Dryer Exhaust: 1) clothes dryer exhaust duct sz & material used? 2) why does duct sz matter? 3) how should duct sections be connected? ( fastening requirements and sz, support for duct sections)

1) duct min 4 inch diameter & min 28 gauge smooth wall metal ( usually galvanized steel)( PVC duct encased in concrete may be allowed in some jurisdictions) 2) duct sz matters to air flow, to small may not allow efficient air flow for dryer to function properly. A larger duct diameter may not allow the air flow at a sufficient velocity to carry the lint through the duct 3) smaller end fits into larger end in direction of air flow. Sections mechanically fastened using pop rivets or sheet metal screws not longer than 1/8th inch. duct supported every 12 ft ( 4 ft for gas clothes dryers)

3 duct configerations for installing HRVS & ERVS in a home 1) fully ducted configuration? 2) partially ducted configuration ? 3) simplified configuration ?

1) fully ducted configuration uses exhaust ducts connected to grills in bathrooms, kitchen and laundry to remove pollutants and uses supply ducts to provide outside ventilation to the air to living areas. This system operates independently from the HVAC system and is the only suitable configuration for homes without ducted heating or cooling. The fully ducted configuration relies on the HRV or ERV internal fans to remove pollutants and circulate ventilation air 2) Partially ducted configuration uses exhaust ducts connected to grills and bathrooms, kitchen, and utility rooms to remove pollutants and provides outside ventilation air to living areas through HVAC return Ducts. 3) the simplified configuration draws some pollutants from the HVAC return duct, and provides outside ventilation air through the HVAC return duct by connecting the outside ventilation air further downstream from where the exhaust air ducts connect to the return duct. The simplified configuration relies on the local exhaust fans to remove the pollutants and on the HVAC system fan to circulate outside ventilation the air. The HVAC system fan must be set to run continiously or the fan must be linked to the HRV or ERV controls set to run on a time basis.

Describe the two types of energy-recovery systems: Difference between the two:

1) heat-recovery ventilators (HRV) and energy-recovery (or enthalpy-recovery) ventilators (ERV). Both types include a heat exchanger, one or more fans to push air through the machine, and controls. There are some small wall- or window-mounted models, but the majority are central, whole-house ventilation systems with their own duct system or shared ductwork. 2) The main difference between a heat-recovery and an energy-recovery ventilator is the way the heat exchanger works. With an energy-recovery ventilator, the heat exchanger transfers a certain amount of water vapor along with heat energy, while a heat-recovery ventilator only transfers heat.

Local exhaust systems Intro: 1) Local exhaust systems include? ( what areas of home) 2) These systems are often called vents (bathroom or kitchen vents) preferred name is exhaust, why?

1) kitchen, bathrooms, laundry rooms and clothes dryers. 2) because it better describes the function of these systems and it distinguishes them from other systems, such as appliances and plumbing vents

Whole house fans 1) How to mitigate the problem of letting large amounts of conditioned air escape into the attic during the winter? 2) Fans that rely on exhausting the air into the attic should have sufficient attic ventilation openings to allow the air to escape and not be forced back into the house through openings between the attic and house. What is the ratio of net free ventilation for an attic for this cause?

1) problem corrected by building an insulated box that is placed around the fan during winter. 2) A ratio of 1 sq ft net free ventilation opening per 750 cubic ft per min of fan air flow is common recommendation

1) During heating seasons , HRVs & ERVs systems do what? 2) during cooling season, HRVs & ERVs system do what?

1) they absorb some of the heat from the exhaust air leaving the home and transfer it to the ventilation air entering the home. 2) they absorb heat from the ventilation air entering the home and transfer to the exhaust air leaving the home. This reduces the energy efficiency penalty when the unconditioned supply air is brought into the home

Mechanical & ventilation systems INTRO: 1) Current standards allow intermittent or continuous ventilation when whole house mechanical ventilation is required. What is usually required with new homes being tightly sealed? 2) an outside air duct to the HVAC return. outside air is drawn by the return suction when the system is running. 3) local exhaust system, such as bathrooms and the kitchen 4) HRV or ERV

1) whole house ventilation required when? 2) Intermittent mechanical ventilation may involve connecting... 3) For the intermittent system what provides pollutant removal in the system? 4) Continuous or intermittent mechanical ventilation may be provided by a whole house ventilation system such as?

Difference between HRV & ERV ?

Difference between an HRV and an ERV is that HRVs transfer only heat between the incoming supply and outgoing exhaust air, while ERVs transfer heat and some moisture. Absorbing some of the moisture from incoming supply air reduces the Latent load on the air conditioning system, which improves air conditioning efficiency and reduces air conditioning costs

Whole house fans 1) describe two situations when a whole house fan is not recommended?

First problem - Fan should not be used when a combustion appliances draws combustion air from inside the home. This applies mostly to gas water heaters and gas clothes dryers because furnaces and other heating appliances are usually not running at same time as the fan. Second problem - A fan should not be used when the attic has possible asbestos containing substance such as vermiculite insulation, or toxic substances. Why- because material could be blown back into house

Ventilation by HRVs & ERVs describe function compared to connected duct method?

HRVs & ERVs may provide ventilation by operating continuously or intermittently. They rely less on occupants intervention to provide the reccomended amount of ventilation air and to remove pollutants than compared to the HVAC connected duct method; however HRV and ERV rely on occupants to clean the systems and replace filters

Whole House fans pros/ cons

Pros: - reduces need to run A/C / making it cost effective by using small amounts of electricity used by A/C unit - most cost effective in cooler and dry climates where an A/C is used less Cons: - less effective in warm/humid climates and in hot climates ( draws more moisture in these areas into house) - traditional fans make loud noises - allow large amounts of conditioned air to escape into the attic during winter

Exhaust ventilation systems pros? cons? How does exhaust ventilation work? components of an exhaust system?

Pros: Relatively inexpensive and simple to install Work well in cold climates. Cons: Can draw pollutants into living space Not appropriate for hot humid climates Rely in part on random air leakage Can increase heating and cooling costs May require mixing of outdoor and indoor air to avoid drafts in cold weather Can cause backdrafting in combustion appliances. Exhaust ventilation systems work by depressurizing your home. The system exhausts air from the house while make-up air infiltrates through leaks in the building shell and through intentional, passive vents. -Exhaust ventilation systems are most appropriate for cold climates. In climates with warm humid summers, depressurization can draw moist air into building wall cavities, where it may condense and cause moisture damage.

One concern with exhaust ventilation systems is that -- along with fresh air -- they may draw in pollutants, including:

Radon and molds from a crawlspace Dust from an attic Fumes from an attached garage Flue gases from a fireplace or fossil-fuel-fired water heater and furnace. These pollutants are a particular concern when bath fans, range fans, and clothes dryers (which also depressurize the home while they operate) are run when an exhaust ventilation system is also operating.

spot ventilation

Spot ventilation exhaust fans installed in the bathroom and operated continuously represent an exhaust ventilation system in its simplest form. One concern with exhaust ventilation systems is that they may draw pollutants, along with fresh air, into the house. For example, in addition to drawing in fresh outdoor air, they may draw in the following: - radon and mold spores from a crawlspace; dust from an attic; - vapors from an attached garage; and - flue gases from a fireplace or fossil-fuel-fired water heater and furnace. - This can be of special concern when bathroom fans, range fans, and clothes dryers -- which also depressurize the home while they operate -- are run while an exhaust ventilation system is also operating. - Exhaust ventilation systems can also contribute to higher heating and cooling costs compared with energy-recovery ventilation systems because exhaust systems do not temper or remove moisture from the make-up air before it enters the house.

difference between supply and exhaust ventilation

Supply ventilation systems allow better control of the air that enters the house than exhaust ventilation systems do. By pressurizing the house, supply ventilation systems minimize outdoor pollutants in the living space and prevent backdrafting of combustion gases from fireplaces and appliances. Supply ventilation also allows outdoor air introduced into the house to be filtered to remove pollen and dust or dehumidified to provide humidity control Like exhaust ventilation systems, supply ventilation systems do not temper or remove moisture from the make-up air before it enters the house. Thus, they may contribute to higher heating and cooling costs compared with energy recovery ventilation systems. Because air is introduced into the house at discrete locations, outdoor air may need to be mixed with indoor air before delivery to avoid cold air drafts in the winter. An in-line duct heater is another option, but increases operating costs.

exhaust ventilation consists of?

consists of a single fan connected to a centrally located, single exhaust point in the house. A better design is to connect the fan to ducts from several rooms, preferably rooms where pollutants are generated, such as bathrooms. Adjustable, passive vents through windows or walls can be installed in other rooms to introduce fresh air rather than rely on leaks in the building envelope. Passive vents may, however, require larger pressure differences than those induced by the ventilation fan to work properly.

pros and cons of a balanced ventilation system

pros: Appropriate for all climates cons: Can cost more to install and operate than exhaust or supply systems Will not temper or remove moisture from incoming air Can increase heating and cooling costs. - Like both supply and exhaust systems, balanced ventilation systems do not temper or remove moisture from the make-up air before it enters the house. Therefore, they may contribute to higher heating and cooling costs, unlike energy recovery ventilation systems. Also, like supply ventilation systems, outdoor air may need to be mixed with indoor air before delivery to avoid cold air drafts in the winter.