Category Archives: Mechanical Systems

What you need to know about correct ventilation and installing duct work

Q: My home has condensate on the windows. I want to put in a new bathroom fan, but I need to know the correct way to vent a bathroom exhaust fan and the correct size of motor the fan should have.

The airflow through a bathroom fan is measured in cubic feet per minute (CFM).

A bathroom needs a minimum of 50 CFM intermittently or 20 CFM continuously. Fans are labeled with a CFM rating, but the duct work you attach to the fan will affect its flow rate.

If you run ducting in long, 30-foot runs and/or lots of 90 degree turns, you will need to double the fan capacity to 100 CFM. Ducts for a bath fan exhaust can be run with plastic, such as ABS or PVC, or metal, such as 29gauge warm air snap seam.

Ducting made of smooth materials will let more air flow than the flexible slinky-style duct materials, which are only appropriate for very short lengths, approximately 5 feet.

Another use is for the connection between the fan and the ducting, in order to reduce vibration.

If the ductwork passes through the attic, or any unconditioned space, it will need to be sealed and insulated to prevent heat loss.

There are several local companies that can assess your situation and install the right system or sell the appropriate hardware if you want to do the job yourself.

If, after installing and using your fan, you continue to see condensation on your windows, you may want to consider a more substantial ventilation system for your home. Today, most building codes require some form of mechanical ventilation.

This can range from an appropriately sized exhaust fan operating with fresh air inlets installed in the living spaces to a Heat Recovery Ventilation System (HRV).

Regardless of which type of system is used, it must be sized and installed to meet the needs of the home it will be serving.

Heat ventilators and snow on the roof: How to handle both of them

Q: I have an HRV (heat recovery ventilator). I have been told it needs to be balanced.

What does that mean and how do I do it?

 

This is the darkest, coldest period of the year when people spend the most time indoors, so having a properly functioning ventilation system is particularly important. A heat recovery ventilator (HRV) must be balanced and tuned so that it delivers as much air as it exhausts. Because the resistance to air flow varies with different lengths and types of ductwork used in the system, an unbalanced system may deliver too much or too little air, and operate inefficiently. Balancing an HRV involves measuring and adjusting the airflows through the unit, and it should be done by a professional with the proper metering equipment. A sticker should be placed on the HRV noting when it has been serviced.

A homeowner can still perform a basic inspection.

This includes cleaning the filters in the unit, and making sure that the intake and exhaust grilles on the outside of the home are clear of snow and debris. In the rooms, the supply and exhaust grills should also be examined to be sure they are open, clean and moving air without obstruction.

Q: I have a roof with a very steep pitch. I’m worried about snow sliding off my roof and damaging my gutters. What can be done about this?

Because of November’s icy rains, unprotected gutters may be more vulnerable than usual this year, particularly those made of plastic which may not be able to handle the additional weight.

Unfortunately, it may be neither safe nor even physically possible to deal with the problem now. Next summer, when the roof is clear of snow, there are several things you can do to prevent snow from damaging gutters. If the roof is metal, then snow stops are often cheap insurance and will not only protect the gutters, but any people or property that could be struck by melting snow in the spring. Vulnerable areas such as chimneys and entryways can also be protected by a cricket, which creates a berm that will divert sliding snow to either side.

If you plan to buy new gutters, then professionally installed seamless gutter systems are worth a look.

Metal gutters are typically made on-site in long sections using a forming machine. They are attached through the fascia with long fasteners and are, in general, much stronger than standard gutters.

Since the snow will likely stick to the roofs in Fairbanks with greater tenacity this year, keep an eye on those areas that could be vulnerable to falling snow when things start to thaw — it may be wise to put up some temporary signs to warn passersby.

Nissan Will Sell 500,000 Electric Cars a Year by 2013, Says Chief

From The New York Times,  Tuesday, November 16, 2010:

On the eve of the market debut of the Nissan Leaf electric carCarlos Ghosn, chief executive of the Renault-Nissan alliance, said the only constraint on sales for the next three years will be how many battery packs the factories could churn out.

Deliveries of the Leaf are scheduled to start next month. Mr. Ghosn, speaking to reporters in Washington on Monday afternoon, did not say just how many he expected to sell in the first three years. He said, however, that the Leaf would hit 500,000 units a year in three years. Mass production, he explained, would lower costs enough to make the car a sales success without subsidies sooner than once expected. He said he once thought that number was a million cars a year, but now believed it was from 500,000 to 1 million.

“We’re going to have to put some efforts into selling the car, but the kind of spontaneous demand is going to be driving the sales for the next three years,” Mr. Ghosn said. “There is such a curiosity about the car and attention to the car.”

He predicted that 10 percent of the world car market would be electric vehicles by 2020. “There is no doubt in the minds of anyone in the industry that this is going to be a big factor in the industry,” he said.

Continue reading: Nissan Will Sell 500,000 Electric Cars a Year by 2013, Says Chief

Air exchangers work but study up on them

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By CCHRC StaffQ: I understand it is important to get fresh air into my house, but exchanging air in my home means the warm air is going out and cold air is coming in. I pay quite a bit to heat my home and reheat all that air coming in. Can air exchangers help to solve this problem?There are several types of air exchangers on the market, but not all of them capture heat from the outgoing stale air.Q: When should I start plugging in my vehicle?

The “Ask a Builder” series is dedicated to answering some of the many questions Fairbanks residents have about building, energy and the many other parts of home life.

Commercially available exterior wall vents combined with a fan designed to operated all the time will provide fresh air for a home.

These devices are the least expensive, but provide no heat recovery feature.

A heat recovery ventilator (HRV) is a more expensive device that has a heat exchanger inside, where the air flowing out of the home passes by the air flowing into the home, without mixing the two. As the warm air moves out, it transfers some of its heat to the cold air moving in.

The heat recovered by this process is in the 60 to 75 percent range, which is significant because any amount of heat that is recovered represents air that the homeowner does not have to pay to reheat.

As the cost of fuel increases, this savings will be more significant.

An energy recovery ventilator recovers heat and moisture as well. Unfortunately, these systems cannot be used in the Fairbanks area because extremely cold air will freeze the device.

Many Interior Alaska residents are retrofitting their homes now.

Adding insulation and tightening a house makes ensuring you have good indoor air quality more important than ever. Insulating a home will conserve heat and adding an air-exchanging device will clean the air.

But only an air exchanger with a heat recovery option will do both.

Be sure to consult with a licensed professional to help design and or install any ventilation system.

Many of us will start plugging in our vehicle right away when it gets cold but plugging in will have an unfortunate affect on our electric bill.

The Alaska Department of Environmental Conservation provides the rule of thumb: plug in for at least a couple hours before starting the vehicle when it is 20°F or colder.

At that temperature, you can get by plugging in for less time, and as it gets colder you need to plug in for progressively longer.

If you find you need to leave your car plugged in substantially longer than these guidelines before it starts smoothly, then you car may need maintenance.

Alaska HomeWise articles promote home awareness for the Cold Climate Housing Research Center (CCHRC). If you have a question, e-mail us at akhomewise@cchrc.org.You can also call the CCHRC at (907) 457-3454.

In-ground heat pumps require some expertise

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By CCHRC Staff

The “Ask a Builder” series is dedicated to answering some of the many questions Fairbanks residents have about building, energy and the many other parts of home life.

Q: Recently I read the News-Miner story about the heat pump being installed at Weller Elementary School. Are there different ways to install this type of system and is this something I can do myself?

Ground source heat pumps operate in a way similar to how a refrigerator transfers heat out of an insulated box to the surrounding air of your kitchen. In this case, the heat pump absorbs heat from the ground and transfers it to a home. The heat exchange mechanism between the ground and the heat pump is typically a series of liquid-filled tubes.

There are different methods to get the heat out of the ground each of which require different installation needs.

One system is the shallow horizontal trench, which is being used at Weller Elementary.

In this configuration, the tubes are made into overlapping loops and placed approximately 10 feet in the ground. For people who live in areas of shallow ground water, it is beneficial to get the loop below the ground water table. This requires a large area, so this type of system is probably not feasible in a downtown lot, but would work well on a southsloping hillside with a lot of land available.

Another option to consider is drilling multiple wells.

These would be similar to drilling a drinking water well for a home, except that only the heat in the water is being extracted, not the groundwater itself. It is likely that more than one well would be needed to heat a house.

The third option is to sink the ground loops deep into a body of water such as a pond or lake, provided that the water body is sufficiently large to accommodate the heat demand. Contact the Alaska Department of Environmental Conservation before beginning this type of project.

All of these options are for a “closed-loop” system, where freeze-protected fluid is circulated in a closed system of piping. There are also “open-loop” systems that draw ground water directly and then inject the water back into the ground.

In most cases these are not appropriate for use in Interior Alaska.

In terms of a do-it-yourself project (and Alaskans are pretty handy) a heat pump involves digging a deep well or large trench, which will probably require hiring a driller or excavator. The equipment that makes up a heat pump is technical. Hiring someone who has been certified by the manufacturer or by the International Ground Source Heat Pump Association to install these systems is recommended.

Contact local heat pump distributors to get more information on installation.

Alaska HomeWise articles promote home awareness for the Cold Climate Housing Research Center (CCHRC). If you have a question, e-mail us at akhomewise@cchrc.org.You can also call the CCHRC at (907) 457-3454.

Time to get all decked out

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By CCHRC Staff

The “Ask a Builder” series is dedicated to answering some of the many questions Fairbanks residents have about building, energy and the many other parts of home life.

Q: What are my options for eco-friendly decking?

In today’s market, the selection of decking materials is vast and can be overwhelming.

Other than wood or treated wood — which have been traditional materials for years — there now exists a wide variety of composites which may contain a combination of synthetic materials.

Composite decking is typically comprised of some type of plastic or vinyl, and in addition, some brands also will also use ingredients derived from wood products. When it comes to treated woods, the chemicals used in the treatment process have gotten more eco-friendly than the chromium copper arsenate (CCA) which dominated the industry for many years. Be aware that the new treatments tend to be more corrosive to metal fasteners, so today’s treated woods may require a specific type of treated connector in order to insure that the deck will hold together safely in the long term.

Composite decking may contain recycled plastic and/or recycled wood fragments. Some brands may even be composed almost entirely of reclaimed products. Common recycled ingredients include old pallets, mill waste, plastic shopping bags, bottles, and other discarded plastics. One of the primary advantages of composite decking is it requires little or no maintenance. Not all composites can span the same distances between joists as wood decking, and so may require additional framing for support.

Most local lumber yards will carry both wood and composite decking. A good resource which compares decking and other products is the website www.healthybuilding.net.

The site has lots of information on a number of different building materials.

Q: I have a heat recovery ventilator in my crawlspace, and it’s starting to make funny noises, what should I do?

HRV systems require routine maintenance, and if the maintenance schedule is ignored it can severely impact performance.

For regular maintenance, examine the filters, outside hoods and screens for cleaning or replacement every one to three months. Filters can become clogged with organic debris including insects, pollen or dust and grass, especially if the fresh air intake is close to the ground.

Most of these filters are washable.

The exchanger core also needs regular maintenance. It should be inspected approximately every six months and cleaned as necessary. The core can be vacuumed or washed with soap and water depending on the situation, so refer to the owner’s manual for specifics. Also, be sure to examine the condensate drain, and if needed, clean it at the same time. The lines can be tested by slowly pouring water into the drains to check for obstructions.

The HRV drains should have a trap or a loop containing water, which will prevent the unit from drawing in air through the line.

Testing the lines is important because the HRV is sometimes tied into a septic line for drainage, or is located in a crawl space with other plumbing. Consequently, if there is a problem with the drain, the HRV system may suffer the ill effects.

Also, fans need to be checked every three to six months. Many fans are designed to function without lubrication, but some HRV fans require it, especially the older models.

Another important point is to make sure the HRV is “balanced.” That means it should be taking in roughly as much air as it is exhausting so as not to create pressure problems in the house. If you are not sure that the system has ever been professionally balanced, this is definitely a step worth taking to insure the system is operating properly.

Most manuals will contain information regarding maintenance specific to that particular brand and model of HRV. If you have lost yours, typically there are only a few different brands in Fairbanks and those manuals are usually available online.

Alaska HomeWise articles promote home awareness for the Cold Climate Housing Research Center (CCHRC). If you have a question, e-mail us at akhomewise@cchrc.org.You can also call the CCHRC at (907) 457-3454.

Replacing your windows, all panes at a time

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By CCHRC Staff

The “Ask a Builder” series is dedicated to answering questions Fairbanks residents have about building, energy and the many other parts of home life.

Q: What is the relationship between boilers and combustion air?

Any appliance that expels air must have its own air supply or one appliance could be drawing air through another. When a boiler expels gas out its flue, an equal amount of make-up air must be brought in. Similarly, any appliance that sends air out of the house needs to be supplied with intake air. If an appliance is not supplied with intake air, it may pull the air it needs down through the boiler’s chimney, thus “backdrafting” the boiler and pushing combustion gasses into your home.

For example, in a “tight” home (one with sound insulation and well-sealed doors and windows), where a wood stove and a boiler both draw air, the boiler may get its air supply by backdrafting the wood stove. However, if you have provided adequate air supplies for both appliances, both should operate with no problems.

Q: If one of the panes in my double or triplepane window breaks, can I get the pane replaced, or do I need to replace the whole window?

When one of the panes in a double or triple pane window breaks, all of the glass layers must be removed and replaced.

Taking apart a window also involves removing several parts such as the “stop” which holds the glass in place, the jamb liner, and other components.

Typically the frame and any associated trim can remain untouched. Virtually all factory- built vinyl, fiberglass, and wood windows have provisions for removing the glass.

If the window can open, simply disconnect the opening portion from the frame and take it to a glass shop.

Repairing a “fixed” or “picture” window can be more complicated. Wood windows may use screws and be relatively easy to replace, however removing the glass from vinyl or fiberglass units is less obvious. In many cases, this involves a “snap in” type window stop located either on the inside or the outside of the window, separate from the main portion of the frame.

Generally, this type of repair is best left to professionals, since removing the stops can be difficult and can result in more broken glass.

Sometimes the window stop will be adhered to the frame with two-sided glazing tape or adhesive caulking.

The replacement glass not only needs to be the proper length and width, but also the proper thickness and space between the panes. If a glass shop replaces the glass, they will provide a guarantee, which in itself is worth piece of mind.

Alaska HomeWise articles promote home awareness for the Cold Climate Housing Research Center (CCHRC). If you have a question, e-mail us at akhomewise@cchrc.org.You can also call the CCHRC at (907) 457-3454.

Your ventilation system is key to indoor quality

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By CCHRC Staff

The “Ask a Builder” series is dedicated to answering some of the many questions Fairbanks residents have about building, energy and the many other parts of home life.

Q: I had an energy rating performed on my home, and it said my house does not have enough ventilation air for acceptable indoor air quality. What does that mean and what are my options?

As part of the energy rating, the rater conducts a blower door test to depressurize the house. This test uses a large, calibrated fan to determine how much air is leaking in and out of the house. If this leakage rate falls below a certain range, the energy report will contain a cautionary statement warning the homeowner that the home is too “tight.” This may result in poor indoor air quality unless the building has mechanical ventilation. All homes must be able supply a specific number of air exchanges per hour in order to meet state and national standards for air quality. The required volume of fresh air is determined using a calculation that factors in house size and number of occupants. A tight home can suffer from a variety of ailments, such as moisture build-up and mold growth. Not all air quality issues are this obvious, however. For example, if combustion appliances such as propane ovens aren’t operating properly, or if car exhaust is drawn into the house from an attached garage, then low levels of carbon monoxide can linger in the living quarters for extended periods. These levels are often too low to register on a carbon monoxide detector, but over time can have a negative effect on occupant health. Air quality issues can also arise from off-gassing of building products such as new carpets and solvent-based finishes.

Animal dander, dust mites and chemicals released by household cleaners can also contribute to poor air quality.

Today, most building codes require some form of mechanical ventilation.

This can range from an appropriately-sized exhaust fan operating in conjunction with fresh air inlets installed in the living spaces to a Heat Recovery Ventilation System (HRV).

Regardless of which type of system is used, it must be sized and installed to meet the needs of the home it will be serving.

A healthy, efficient house must perform a balancing act between cost and indoor air quality. This means that the ventilation system has to supply enough fresh air to meet occupant needs, while at the same time minimizing the energy penalties associated with over ventilating.

Q: Who determines building code and how is it changed?

At this point, the most predominant residential code used in the United States is produced by the International Code Council (ICC), although some municipalities opt to use codes from other sources.

The ICC produces the International Residential Code (IRC) which is updated every three years. The city of Fairbanks building officials uses the 2006 IRC book, but will soon be adopting 2009 codes.

Because this is a national code, it does not perfectly meet the needs of every individual region, so it is up to the local jurisdiction to establish appropriate exceptions. For each code cycle, our local Building Code Review and Appeals Commission makes amendments to the IRC in order to adapt it to Fairbanks. This commission is comprised of contractors, engineers, architects, and local code officials. As an example, the Commission has increased the snow load requirements to better reflect conditions in Fairbanks. All the amendments are available at the building department and online on the city of Fairbanks website at www.ci.fairbanks.ak.us/index.php. Outside the city of Fairbanks, no code is enforced unless the lending agency requires it. However, building codes exists to insure that a minimum standard of occupant health and safety is met. It is worth noting that if a house is not built to meet local codes it can be difficult to sell.

Alaska HomeWise articles promote home awareness for the Cold Climate Housing Research Center (CCHRC). If you have a question, e-mail us at akhomewise@cchrc.org.You can also call the CCHRC at (907) 457-3454.

Wash, rinse, dethaw … repeat?

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By CCHRC Staff

The “Ask a Builder” series is dedicated to answering some of the many questions Fairbanks residents have about building, energy and the many other parts of home life.

Q: I am going to dig up my foundation this summer so I can put on outside foam insulation.

Do I need to clean off my foundation in any way?

How far down should I dig? How long will the ground be frozen?

If the foundation has not been waterproofed or the product that is installed needs some touching up, then clean the area thoroughly. In the case of cement block or cast-in-place concrete, cleaning will probably involve hosing off the foundation, letting it dry, waterproofing it, then adding the insulation. For waterproofing, apply a peel-and-stick membrane or a waterproof foundation coating. Be sure to follow the application instructions carefully. These membranes work well for both new construction and retrofits, but the concrete must be clean first. If your foundation already has good waterproofing, then dig away the dirt, brush off the foundation and place the foam tight against the wall. In terms of how far down you should dig, remember that heat always goes to cold. Where you have a temperature difference inside to outside, you are going to have heat loss. The bigger the temperature difference, the more aggressively the heat will try to escape. The frostline in Fairbanks goes down roughly 4 feet on average.

Some winters, that frostline goes much deeper. Below the frostline, there is an average soil temperature of 32 to 40 degrees. A good practice is to apply rigid foam insulation that is approved for direct burial, all the way down to the footings.

Fairbanks building code requires three inches of thickness for foam below grade (below the soil).

Good resources for finding out when the ground has thawed would be the local excavation and septic companies. They work in locations throughout the area and may be able to help you predict the thawing time for your location. June is usually a good month in which to begin excavation, though if you are on the north side of a hill, in a heavily shaded area, or have wet soils, your ground may behave differently.

Q: Where can I go if I want more information on ground source heat pumps?

There is information on our website (www.cchrc.org) including heat pump resellers in Fairbanks. Also the Department of Energy has a website dedicated to energy efficiency and renewable energy (www.energysavers.

gov.) The site has general information about how heat pumps work and the considerations in installing a system. The Permafrost Technology Foundation website (www.permafrost.org) has several technical reports on the use of ground source heat pumps in permafrostladen soils. As ground source heat pumps grow in popularity, we are seeing more being built in the Fairbanks area. CCHRC is beginning research projects that will look at the effectiveness of ground source heat pumps in our region and should have some preliminary information on our website by next spring.

Alaska HomeWise articles promote home awareness for the Cold Climate Housing Research Center (CCHRC). If you have a question, e-mail us at akhomewise@cchrc.org.You can also call the CCHRC at (907) 457-3454.

Get in the know about plugging in your car

By CCHRC Staff home life.

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Q: Is there anything I need to be cautious about when plugging in
my automobile?Q: I’ve seen that there are now roof shingles that are solar panels.While a wide range of solar technologies work in Alaska and other cold climates, photovoltaic roof shingles are still too new and untested for cold regions. The basic concept of solar shingles is excellent because the space is usually wasted and basic support structure is already in place. But remember, things perform differently in our extreme climate. If the shingles are glued on, you have to check how that glue performs in cold temperatures. When it comes to solar technology, there are some general rules to be aware of. Anything that applies to solar means you have to have a good exposure to the sun, preferable facing south.Q: What is a heat recovery ventilator and what does it do?

The “Ask a Builder” series is dedicated to answering some of the many questions Fairbanks residents have about building, energy and the many other parts of

For starters, there are the basics of electrical safety: when you are plugging in anything, you do not want to make direct contact with the circuit because of the risk of electric shock. Besides that, a lot of Fairbanks car fires can be attributed to improperly maintained vehicles. Oil leaks, fuel leaks or other heating elements can be ignited by a small spark. Because winterizing cars in Fairbanks includes installing electrical heating devices, people need to be more cautious about leaks because of the risk of fire.

So if you have leaks, get them checked out and perform any other standard car maintenance.

 

Could those work in Alaska?

 

The shingles are going to be covered with snow, so how will that factor into their

East or west might work too, depending on how your roof is built and the pitch of the roof. Consider all the options before choosing a system.

 

A Heat Recovery Ventilator, or HRV, is designed to bring fresh air into your home. The “tighter” your home is (fewer leaks in insulation, doors and windows), the more essential an HRV is to the safety of the occupants. The other important part of an HRV, heat recovery, means it captures as much of the heat that is leaving the building as possible. You have already heated the air in the house.

To bring fresh air in, you are going to have to expel stale air, but that air has heat in it that you do not want to waste. So the HRV acts as a heat exchanger. As cold fresh air moves in, the warm stale air moves out. When the two air flows pass by each other, the heat from the warm, stale air is transferred to the cold, fresh air through a heat exchanger. These devices will help keep your home warmer in the winter, while saving you energy and money because you do not have to reheat the air coming into your home quite as much.

Alaska HomeWise articles promote home awareness for the Cold Climate Housing Research Center (CCHRC). If you have a question, e-mail us at akhomewise@cchrc.org. You can also call the CCHRC at (907) 457-3454.