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Installing a powered attic ventilator in your home is generally not recommended due to a variety of drawbacks, but if you do insist on having one, there are several steps your technician should take to maximize the appliance’s effectiveness.
Seal Air Leaks Between the Attic and the House
Before having a powered attic ventilator (PAV) installed in your roof, you should have an indoor air quality expert try to mitigate the amount of air leakage from inside your house to the attic. Your technician should seal any ductwork in your attic with mastic, and he or she should make sure that any wall cavities used as returns are airtight, such as by sealing the gap between the boots and sheetrock.
Your technician should then look for several features in your attic: open chases for ducts and plumbing stacks; open balloon-framed wall cavities; dropped ceilings over bathtubs, closets, cabinets and hallways; and open floor joists under knee walls. The technician should use expanding urethane sealant and foam sheathing board to seal each of those items off.
The air conditioning or roofing technician should then use sheet metal and high-temperature sealant around chimneys, and then should weatherstrip the pull-down stairs or attic hatch. Finally, he or she should replace repressed light fixtures with airtight alternatives.
Go over this checklist with your technician and make sure each item is address before the PAV is finally installed in the roof.
Optimize Intake Ventilation
A running PAV will require a sizeable amount of intake ventilation. The first and simplest step in boosting ventilation is to make sure existing vents aren’t blocked by insulation, new siding or soffit material, or by dust, pollen and bugs accumulated on the screening of all entry points. Indoor air quality experts recommend replacing any insect screening with hardware cloth (1/4-inch metal screening), which only keeps out rodents. Replacing insect screening is advised because it quickly clogs up when a PAV is in use, making the vent useless. If more intake ventilation is needed into the attic, have the technician install as many soffit vents under the eaves of your roof as necessary.
If your technician finds it untenable to install any new intake vents, he or she should consider setting up a PAV on one end of the attic to blow air toward a PAV of equal capacity on the other end, which will push the air out into the sky above. If this option is viable, the technician just has to make sure no insulation is being blown off the attic floor.
Hook up the PAV to a Thermostat
For starters, the PAV you want installed in your attic should not be too large for the job. As with air conditioning units, bigger is not always better. The smaller PAV you have installed, the less conditioned air it could unintentionally suck out from inside the home, which is the main reason indoor air quality experts caution against PAVs in the first place.
If you still want a PAV for your home in the Rancho Cucamonga, CA foothills area, have a McLay Services technician install it high in the attic, and ask to have us set up the unit with thermostatic control; that way, the PAV’s fan will only turn on when the attic has eclipsed a temperature of your choosing, rather than running continuously. If your attic has a furnace, a McLay technician will install an interlock that shuts off the PAV when the heating unit needs to run. Also, note that a PAV should not be installed if there is a gas or oil water heater in the attic, as the PAV could cause such a unit to backdraft.
Maintain Insect Screening and Intake Vents
If your attic’s intake vents get plugged up with insulation or siding, the PAV will start drawing more cool air from inside your house. Don’t let that happen! Whether you kept your insect screening or switched to hardware cloth, you need to have it inspected and vacuumed regularly, as you should do with the PAV’s insect screening. Additionally, most PAV motors need to be oiled once a year.
Why Choose a PAV for Your Home
Since the main concern about powered attic ventilators is the amount of air leakage in an attic floor often found in a home, if you mitigate those leaks, you may find a PAV a very sensible option, particularly if you work in your attic often or keep items up there that you’d like not to get charred. Also, if you choose one of the newer solar-powered models, you’ll weed out the energy costs of running a PAV, which is another major concern about the ventilation units.
In choosing to alter your roof to make room for a PAV, make sure you have good reasons for upgrading, and have a McLay heating and cooling technician address take the steps mentioned above before the unit gets installed. Your McLay technician can find the best spot for a PAV in your roof, and will also determine if it’s the best course of action for your attic. If it’s not, we can recommend other options to improve the ventilation in your attic. Our whole home performance assessment will give you ideas on how to maximize airflow and heating and cooling efficiency from top to bottom in your residence.
Call McLay Services for Ideas and Help on Improving Ventilation in Your Attic:
You have probably driven by a home or a small commercial building and seen fan blades spinning out of an opening of the roof, looking like hot air is being released to the skies. While, yes, the appliance is designed to release hot air out of the building, it doesn’t always lower air conditioning costs. In many cases, the air conditioner has to work overtime because of how the electronic attic appliance functions.
It may seem counter-intuitive, but when it comes to a house, powered attic ventilators (PAVs) – which are designed to pull hot air out of an attic – raise home cooling costs, in many situations. The makeup of a home and the physics of how air moves both work against the intended benefits of a PAV.
Air Leaks in the Attic Floor
A powered attic ventilator wouldn’t be problematic if a home’s attic floor were completely airtight, but that’s not feasible in virtually every house. The tops of interior partition walls often harbor a number of small openings, and other air leaks come from ceiling features such as recessed can lights and attic hatches. Insulation cannot seal the leaks in an attic floor; instead, insulation acts as a filter for air that passes through it.
How Air Moves in the Attic
When a PAV pulls hot air out of an attic, something needs to fill that space. The air pressure needs to stay relatively constant throughout the building space. So what happens? Air gets pulled from outdoors and indoors to fill the void. That’s right: indoors too. So if your AC and has cooled down and dehumidified the air inside your home, if the PAV is turned on, some of that cool air could be lost through the leaks in the attic floor.
PAVs Increase the Air Exchange Rate in an Attic
Indoor air quality researchers have found that PAVs hardly work any better than having passive ventilation from the roof to the outside world. PAVs rapidly increase the air exchange rate in an attic in comparison to passive ventilation, but that’s not necessarily a positive attribute. In short, the PAV is making the air move more quickly than it needs to. If the home has a very high number of attic floor air leaks and the PAV is turned on, the PAV will remove the hot air from the attic; however, it will also pull the cool air that the AC unit created right into the attic as well. In turn, this causes the AC to turn back on in order to reach the desired temperature. This may result in higher cooling costs.
Cool Air Can Escape Through the Attic due to a Running PAV
Even in newer homes, it is common to find more than 1 square foot of combined air leaks in the attic floor. Imagine if it’s summer and air inside the home has been cooled to 75 degrees. If the PAV is turned on, some of that 75-degree air is getting pulled into the attic, and let’s say 95-degree outside air is being drawn into the living space to replace it. That means the air conditioner now has to work long and hard to cool the outside air down 20 degrees and then dehumidify it. This process is adding dollars on to your monthly utility bill. When you then consider it costs a little bit of money to run your PAV in the first place, not to mention the added work it places on an AC, you have to question why a PAV was installed in the first place.
The above scenario is a best-case situation. Many homes, especially older ones, have well more than a combined 1 square foot of air leaks. If a PAV is running, the air conditioner will seemingly have to run endlessly to make up the difference in temperatures between air leaving through the attic and air entering the home. The AC may lag behind on the dehumidification part of the process, and the air inside the house will be left feeling clammy and unhealthy.
Alternatives to PAVs for Improved Indoor Air Quality
McLay Services has several options that we consider more effective for saving energy and improving indoor air quality than a powered attic ventilator, including:
- Passive continuous ridge and soffit venting
- Added insulation
- Duct Sealing
- Duct wrapping
- Thermal bypass repair
- Radiant barriers
All of the above options don’t consume any electricity, which right away is an improvement on PAVs. If you have a PAV installed in your roof in the Rancho Cucamonga area, call McLay Services to have an air conditioning technician disconnect the appliance and remove its motor and fan. The unit will then function as passive ventilation, which is more effective than having it turned on and siphoning some of the cool air from inside your home. See more about our indoor air quality services.
For Help on Installing or Uninstalling a PAV or to Improve Ventilation in Your Attic, Call McLay Services:
Many people look forward to the summer months all year long because they are filled with barbecues, get–togethers, time by the beach or pool, and many other exciting outdoor activities. However, the summer cooling costs often turn out to be a significant burden for most people; in fact, the cooling costs may account for up to 50% of the total energy consumption in the average home. Americans spend billions of dollars each year to keep their houses cool with air conditioners. However, following some simple house cooling tips can save people hundreds of dollars each year on utility bills.
The recent heat wave that swept across certain parts of the United States dredged up questions about how best to beat the sweltering heat of summer. Efficient home cooling saves energy and money and improves the whole family’s quality of life.
Simple Cooling Tips for Your Home
· One of the basic tips to stay cool in summer is to keep the sun out. The hot summer heat can pass through an uncovered window as if there is nothing there. One should simply cover the windows facing the sun with drapes, shades, or blinds.
· Sometimes, reducing the indoor temperature may be as simple as switching off the lighting, appliances and electrical devices, all common sources of internal heat gain. In fact, this is one of the simplest summer cooling tips. In addition, switching off such devices will reflect positively on one’s wallet.
· A ceiling fan is a great investment for a home when it comes to beating the summer heat. A ceiling fan can make a room feel cooler by up to 7 degrees, and even the most power–hungry fan costs significantly less to run than a typical air conditioning system.
· The condition of the air conditioning unit’s filter can affect not only the quality of indoor air, but also the efficiency of the system as a whole. Heating and cooling experts recommend replacing the filter at least four times a year.
· Another method of increasing the efficiency of the air conditioning system is by keeping the outdoor unit cooler by planting shrubs and trees that allow airflow, but still provide shade. Shading the outdoor unit can raise the system’s performance by up to 10 percent.
The condition of the air conditioning system is crucial; therefore, one should schedule a maintenance inspection before the summer heat arrives.