Category Archives: New Homes

World’s first 3D-printed apartment building constructed in China

A Chinese company has successfully 3D printed a five-storey apartment building and a 1,100 square metre (11,840 sf) villa from a special print material.

3D Printed BuildingWhile architectural firms compete with their designs for 3D-printed dwellings, one company in China has quietly been setting about getting the job done. In March of last year, company WinSun claimed to have printed 10 houses in 24 hours, using a proprietary 3D printer that uses a mixture of ground construction and industrial waste, such as glass and tailings, around a base of quick-drying cement mixed with a special hardening agent.

Now, WinSun has further demonstrated the efficacy of its technology — with a five-storey apartment building and a 1,100 square metre (11,840 square foot) villa, complete with decorative elements inside and out, on display at Suzhou Industrial Park.

Read More for C Net

What Counts? Product A or Product B

Blower Door Testing & Weather Resistant Barrier

Tyvek TopThe practice of covering sheathing with asphalt impregnated papers has given way to the use of synthetic fabrics, known as house wrap; or spray on coatings. There are factory applied coatings on some brands of sheathing and some types of coatings are field applied. Along with the discussions of fiberglass / cellulose in the insulating of homes, there has been plenty of discussion about the merits of one form or another of WRBs.

As with any step in the building process, I believe it is less about the product and more about the people. Products that are hard to install will be less successful then others. Installers that are not properly trained; work that is not verified in some manner can defeat the proper performance of the best products.

WRBWhat does the WRB do for a home. First it provides a drainage plane behind the siding to divert rain and other weather related moisture from wetting the sheathing. Second, when all manufacturers install instructions are followed it can act as an air barrier, reducing infiltration. For the house wrap type fabrics, this means properly lapped, using capped fasteners, and then taped. Finding house wrap installed according to manufacturer’s install directions is rare.

When all three of these directions are not followed, not only are the potential qualities of an air barrier not present, the potential for water to run behind an uncapped fastener, or an incorrectly lapped joint, which is also untaped. Repeated wetting of the sheathing over time, will eventually result in rot and the accompanying problems.

Country HollowA local Wichita Home Builder, G.J. Gardner has just finished two homes based on the same floor plan. These homes went through the independent verification process involved in obtaining a HERS Rating. These homes utilized the same sub-contractors and types of insulation. The only difference in construction was the use of a job site applied spray on WRB, in place of a house wrap type fabric.

One part of this verification process is a Blower Door Test. This test simulates the effects of a 20 mph wind on all sides of the home at the same time. Blower Door testing has been completed on homes since the late 1970’s. Energy efficiency programs and building codes have consistently recognized the value of a Blower Door test on each home.

BlowerDoorThe value of doing a Blower Door test on each home is primarily to check the work of all subs has not compromised the Builder’s plan for an energy efficient home. Many existing homes, have a test rate of 7 – 12 or higher rates of air exchange during the test. The 2012 code requirement is 3 on this scale, and lower is better.

The use of 4×8 sheet goods for sheathing and other simple, and inexpensive techniques have brought the infiltration rates down. This reduces the cases of cold drafty homes, and significantly lowering the energy use of a home.

The Blower Door test can verify the quality of work involved with installing the WRB, specifically the degree of sealing of the outside of the sheathing. In the case of the two homes involved in this comparison, there was a change of 20% in the measured infiltration rates of the two homes.

In completing the Blower Door tests, we used the ANSI / RESNET published standard of a Multi-point test. These results were entered into a software package provided by the maker of the blower door, The Energy Conservatory, Below is a comparison screen between the two Blower Door Tests.

Tectite 2 Bldg Comp Data

I would like to thank Wade Wilkinson, with GJ Gardner of Wichita; his subcontractors and their technicians for building quality energy efficient homes. I enjoy being able to verify the quality of their work.

If you would like to see this home, it is currently in the Fall 2014, WABA Parade of Homes.  It is located in the Country Hollow Development.  Between Kellogg and Harry on 127th and East to Glen Hills Court, on the corner.  Find out also about the HERS Index earned by this home. It will save you operating costs on your Energy Bills.

Passive House Work in Wichita

In the last two weeks, two national groups that certify construction for Passive House Standards conducted their annual conferences.  PHIUS was held in Portland, OR; and PHI was held in Maine. Locally, I have completed the first of 3 planned Blower Door tests for a passive concept home under construction; discussed the planned construction with another builder to start later this year; and discussed passive building concepts with another builder planning his first homes next year.

PassivhausDarmstadtKranichstein-300The Passive House concept started in Germany, with construction starting in 1990 on several homes. In German, it is Passiv Haus,  PHI for Passiv Haus Institute.  The standards followed by this concept require an attention to detail in design and construction of the thermal enclosure.  Historically referred to as the envelope, the thermal enclosure involves the exterior bottom, sides and top of the structure.

  • Higher than commonly used levels of insulating material,
  • windows meeting specific standards and very
  • Effective work on air sealing
  • Attention to the Solar Orientation of the home to maximize the use of solar heat in the winter

PHIThis results in an extremely low energy bill.  How low? In the Wichita area, this would translate to an $88 – $110 annual natural gas bill, instead of $500 – $900 bills that I routinely see on Home Energy Audits.

The passive term comes from the idea of using insulation and construction techniques to create a significant energy savings instead of relying on fancy machinery to create that savings. Dr. Wolfgang Feist of Dahrmstat, Germany founded the Passiv Haus Institut in 1996.

Smith HouseThe passive house concept arrived in the US in 2003.  Katrin Klingenberg, a licensed architect in Germany, She built a home meeting these standards, 2 hours south of Chicago.

 

Most countries have a local organization that trains and certifies homes and commercial buildings to the Passive Standard. Yes, passive concepts apply to buildings other than homes. These groups train people to apply and measure the standards. They also review the reports on specific buildings and accept or deny actual certification for a specific building.

PHIUSIn the US, this organization has been known as PHIUS.  Passive House Institute, US. Ms Klingenberg has been the leading light of this group, which was founded in 2007.  There are some things in each country that differ from the original German model of Passiv Haus.

The experience of the professionals working with PHIUS in the US has resulted in some changes to how the concept is applied in the US. For example, the metric units used in the German (and most others in the world) have been translated to the Imperial units used in the US. The collaborative nature of US business groups has been essential to moving the passive concept from being used by a relative few to becoming a market force in the US.

Because these adaptations by PHIUS to the US market, were not acceptable to the original PHI, a divide between the approaches has occurred in the US.  It is mostly technical, and both groups agree the concept is still primary.  Effective building resulting in low energy use.

Some claims have been made that these concepts are two expensive for the US market. The original Passive House in Illinois was built at a 2003 cost of $94/ sf.  That is very favorable with current US construction costs. Since additional people are using the concept and the resulting products that manufacturers are producing, the mass production will bring some drop in costs.

If you wish to read more about the two national conferences for both the PHI and the PHIUS organizations that just finished, you may use these articles.

The 9th annual North American Passive House Conference (PHIUS)

Report from the Passive House Conference in Maine

I will keep you updated on activity in this area about Passive House building activity, as it progresses.  Three projects is a great start.  I’m glad that builders are willing to try new concepts and that home buyers are willing to step up and buy these homes.

In the introduction of this post, I mentioned a house under construction with the Passive House concept. I conducted the first of 3 Blower Door Tests last week.  This test was after the framing and exterior sheathing was completed.  Insulation, plumbing, electrical and trades had not started.  The second test will be in a few weeks after these trades have done their initial work and put holes in the enclosure.  Electric wires, plumbing, HVAC and other necessary conveniences of our lives will be installed in passive concept homes. The third test will be done at the end of construction.

The PHI/PHIUS standard for Air Infiltration as measured by the Blower Door Test is 0.60 –  The current 2012 recommended code requirement for this is 3.0 — Wichita/Sedgwick County does not have an energy code in place, but the Kansas City area does. They enforce a 5.0 standard.  Typical homes built from 1980 and prior are in a range of 10 – 38 from my testing.

The goal of the builder on this passive concept home was to reach 1.5 on this first test. Then using the Infrared Camera to find areas to caulk, and fixing the penetrations mentioned above, have the next test come in lower.

Blower Door62This test, actually came in at 0.62 —  almost the standard.  Much better than the expected 1.5 .   While the blower door was running, the Infrared found some places that could be fixed.  Dan, the carpenter, was right there with a caulking gun.  We also found some leakage with biometrics. A back of your hand that is wet, will show you extremely small amounts of air movement.  Most builders like to use expanding foam to seal the actual window to the rough opening.  We found some of these foamed openings were still leaking. Again the caulking gun was a good answer.

 

A Healthy Home Part 4 – Free of Combustion By-Products

This post is written as a conversation between a homeowner and myself as it could have occurred during a Home Energy Audit. It is actually the gathering together of several conversations on different audits over the past few years.

smoky fires

 

A Healthy Home is Free of Combustion By-Products

Homeowner: Oh!  You mean no Carbon Monoxide!  I have a  Carbon Monoxide Detector.  It has had some false alarms, but it has never found a problem.

The Energy Guy: OK!  Carbon Monoxide (CO) is one by product of combustion.  There are others.

Homeowner:   So, you mean the house must be all electric?

The Energy Guy: No, not necessarily.  An all electric home, might have a fire place, and an attached garage. Both are sources of CO and other byproducts of combustion. A healthy home will deal with all of these in some fashion.

Homeowner: What other things are you talking about besides CO?

rustDHWThe Energy Guy: The one I see the most of is moisture.  Many of the flue pipes I’ve seen have rusted from the moisture.  If you have a gas hot water heater, look at the top.  Is the top rusting, what about the flue pipe or the draft diverter? Moisture from open combustion appliances also increases the humidity in the home and adds unneeded work to your air conditioning unit, increasing the bill.

There are others, such as Nitrogen  Dioxide, and Sulphur Dioxide, and various particles of all sorts.

Homeowner:  So, those are like Carbon Dioxide?  Something that is just there?

The Energy Guy:  Yes!  They are just there, with two concerns.  First the Lung Association points out the health effects of Sulphur Dioxide include:

  • Wheezing, shortness of breath and chest tightness and other problems, especially during exercise or physical activity.
  • Continued exposure at high levels increases respiratory symptoms and reduces the ability of the lungs to function.
  • Short exposures to peak levels of SO2 in the air can make it difficult for people with asthma to breathe when they are active outdoors.

Health effects of Nitrogen dioxide include:

  • Increased inflammation of the airways
  • Worsened cough and wheezing
  • Reduced lung function
  • Increased asthma attacks
  • Greater likelihood of emergency department and hospital admissions
  • Increased susceptibility to respiratory infection, such as influenza

Homeowner: I’m pretty healthy, but you said ‘First!’

The Energy Guy:  The second is moisture. Moisture could be a high humidity situation, or moisture from the combustion that produced these dioxides and if you inhale some of them, or moisture in your nose and lungs. Here are the basic chemical equations for those interested.

Sulphur Dioxide plus Water ends up as Sulphuric Acid [SO2 + H20 ===> H2SO3 (sulphurous acid) SO3 + H20 ===> H2SO4 (sulphuric acid)]

acid_storageNitrogen Dioxide plus Water ends up as Nitric Acid [NO2 + H2O ===> HNO3 + NO]

Homeowner: But acid eats things up!

The Energy Guy:  Yes, it does. These acids start the rust process, I mentioned earlier. The other place you can look for rust is to look at the flue on the roof of some homes. If the coating is attacked by the acids, then rust occurs.

So How do I keep this stuff out of my home and away from my family?

co detectorThe Energy Guy:  First install some Carbon Monoxide Detectors.  If your furnace and water heater are in the basement, you need one down there.  You also need one near bedrooms.

Homeowner: OK!  I’ll get that one that works with my Nest!

The Energy Guy:  That will work for one.   The Nest Protect is like most CO detectors, it will alarm at the higher amounts of CO as required by the Underwriters Laboratory requirements.   These start at 70ppm of CO for an hour. Professional organizations such as ASHRAE and NIOSH list 35ppm as the level for technicians and others to stop work, turn off equipment and evacuate the building. A low level detector is important.

Low Level CO detectors do not meet the UL requirement because they alarm at lower levels, typically 20ppm.    15-20ppm CO levels have been found to impair judgement in people exposed for short periods of time.  The UL testing does not allow a CO detector to pass if it alarms below 30 ppm. Low level CO exposure can result in headaches and general malaise.  If you are exposed to low levels over a period of months or years the effect is unknown at this time.

Homeowner:  OK!  So I’ll get a low level detector also.  What else can I do.

The Energy Guy:  Do some careful air sealing between the garage and the house. You can add exhaust ventilation to your garage as recommended in the International Residential Code. Open the door before you start the car, and then immediately back out. More information about CO and the garage. Air sealing here and a simple closer on the door to the garage will help keep CO and other pollutants from the garage out of the house.

Inside the house, you can buy smart when you replace your water heater or furnace.  Buy sealed combustion units.  These are generally more efficient units, so they will save you some on your bill each month.

95Water Heaters can be sealed combustion, such as the demand models or a power vented unit. Either of these units can be identified with the use of PVC exhaust flue, instead of the metal flue needed by traditional units. They do not need the metal, because the exhaust is a lower temperature. This has a side effect of increased efficiency. The image to the right is the flue of at sealed combustion furnace.

Finally, think about your wood burning fireplace or your gas oven.  These also create the same problems.  Here a low level CO detector would be very valuable. Following the fireplace manufacturers instructions in keeping the glass door shut and having it checked regularly are important.  For a gas range, especially with a gas oven, install an exhaust fan that vents to the outside.

 

Some of this information came from the Maine Indoor Air Quality Council

Some of this information came from the American Lung Association

A Healthy Home — The first of this series

A Healthy Home Part 3 — Well Ventilated

Fresh AirA Healthy Home is well ventilated.  Everyone knows fresh air is important. This should be easy.  Well ventilated in more than just bringing in fresh air. The concepts are certainly easy, the details on the other hand take some thought and planning.  A new home ventilation strategy is fairly straight forward to design and implement. An existing home needs the input from the occupants and good analysis to address the problems. An effective ventilation strategy should address these issues in either new or existing homes.

  • Remove humidity, odors,, or significant problems from specific areas.
  • Remove stale, musty or other objectionable air.
  • Allow the occupants to choose fresh air sources that can be filtered or treated in other ways
  • Allow the occupants to choose to open windows when outside weather is appropriate
  • Allow the occupants to operate a system that can provide the amount of fresh air, to the appropriate places, in adequate amounts when needed
  • Provide fresh air when the outside air creates potential problems, such as Ragweed season or when other allergens are active
  • Provide air movement within the home, without the use of the expensive blower on the furnace or heat pump.
  • Allow minimal use of heating or cooling equipment during the shoulder seasons, when temperature changes are minimal, while keeping the home comfortable.

Billings QuoteHow much fresh air is needed?  Going back to the 1890’s, the number has been pegged at 30 CFM (cubic feet per minute) per person. This number was validated in a number of different studies and with the public health authorities in larger cities, dealing with large apartment buildings and recurring respiratory diseases.  I was pointed to the quote at the left by Allison Bailles. he located the original book on Google Books, page 20.

Beginning in the 1930s, research into changes in building techniques began to show the optimal number was closer to 15 CFM per person.  Some of the changes in construction included the increased use of forced air heating, moving from balloon framing to platform framing, increasing square footage, and the use of insulation in walls and attics. The formula changes from time to time and everyone has an opinion on details. The common point remains, fresh air is needed in every house.

Part of the Ventilation is removing air with a problem. Where is that?  Humidity is found in rooms that use hot water and basements.  Showers, tubs and cooking are the large sources of humidity.  The smells from food preparation and cooking can be very mouthwatering.  When the meal is finished and the refrigerator is full, the lingering smells become odors.  The answer is some spot ventilation in these areas. If your basement has a humidity problem, you can tackle that with a fitted sump pump cover to contain the humidity, and work to eliminate any water seepage.

vent fanSpot ventilation is a window that opens and an exhaust fan. The size of these fans is part of the formula that is specific to each home. The features of the fan are common to all homes.  It must be quiet. Builder grade fans are noisy. Noise in fans is measured in ‘Sones’. The Sone is a linear measurement of noise, compared to the decibels used by OSHA and others which is an exponential measurement.  Linear is better for quiet sounds, and decibels is better for loud noises. Fans should be less than 3 sones, and preferably less than 1 sone.  Reasonably priced fans are available that rate a 0.3 sones. A 1 sone fan is very quiet.

UnknownFans are certified for air flow and noise levels by the Home Ventilation Institute. HVI certification is very common and includes both the Sone rating and CFM rating.  When installing a fan, you must consider the duct losses that will occur in meeting the required air flow.   The rates for bathroom air flow  are 50 CFM, and 100 CFM for a kitchen.  Do not expect to buy a 50 CFM fan for a bathroom and connect it to 6 or 8 feet of duct work, and obtain 50 CFM.  I have measured 30 CFM routinely in these set ups.

Most people understand that various parts of their body are just a part of the whole.  If you start some type of therapy, there may be a side effect. Physical Therapy starts and you end up with some sore muscles, aha!  Side Effect!  Start a therapy for cancer and your hair may fall out, aha! Side Effect!  Your home works the same way.  Each part is just part of the whole. Change something, aha! What is the side effect?

House-System-imgAll of the items in the list above are part of the whole. For an existing home, some specifics of that house may indicate concentration on one or another of those areas.  A home built in the 1920’s will benefit from a different approach then a house built in the 1980’s.

A new home should have the ventilation system that meets the general points above.  The natural ventilation provided when windows and doors are opened, or the mechanical ventilation system that allows filtered and perhaps treated fresh air brought in from specific places and in specific amounts, allow the occupants to make the system work as they need.

 

This post is part of a Series on A Healthy Home

 

 

A Healthy House Part 1b: How Dry is Dry

In the first installment of A Healthy House, we looked at water issues.  Specifically, water from the outside of the home.  Most of this type of water is directly from what the weather refers to as ‘precipitation’, or rain and snow.  Even the ground water we looked at were related to rain and snow.  There are other types of water issues.

pipe_leakFirst would be a plumbing problem.   You can have a leak in a water pipe, or a sewer line.  I know, sewer lines generally do no leak, they slow down, or plug up and then back up.  Either way there is water in the house, and someone is cleaning it up.

Many plumbing leaks like this or sewer problems are an ongoing maintenance issue. Not much can be done during construction.

Situations like the drain line, getting stepped on and thus the floor drain is the highest spot in the floor is a construction issue.  It takes all the trades to help finish the building correctly. The plumber may have done it right, only to have someone else step on the line.

A nail accidentally driven next to a supply pipe, may cause a problem later. If you have copper, 2 dissimilar metals touching will eventually cause a leak.  A nail next to a plastic line that moves, can also create a leak. You may find great work in a home and good, conscientious, plumbers, drywall installers, electricians and others. Sometimes these defects are hidden, like the tip of the nail inside a wall. So maintenance becomes an ongoing effort.

daltile-Bath-Accessories01Thoughtful design can help.  Specifying hard surfaces for areas within a few feet of tubs, showers, toilets, sinks and laundry facilities is important. Most leaks, spills and accidents will occur in these areas. An easy to clean surface that doesn’t hold the moisture is essential.  Carpet has it’s place, just not near water. Some floor coverings such as linoleum or cork type flooring may also not be appropriate for these areas. (Image to the right is courtesy of DalTile.)

 

Hard SurfaceAppropriately located floor drains can help.  Use of appropriate materials in the floor structure is a good thing. Most homes in this area have a basement, meaning a wooden subfloor is under and of these facilities on the main or upper floors.  The proper type of sub floor in these areas is crucial to keeping the home dry. It is also helpful in drying, when the floor does get wet and not encouraging mold growth, as many types of common building materials.

This post is part of a series of posts on A Healthy Home.

A Healthy Home Part 1a: How Dry is Dry? –

rain

Water in a house, Good Thing, Bad Thing?  Some places like the sink you expect to find water. Other places like the floor, water is a problem. Builders work hard to build a home so water says where it belongs.

RoofLook at the way the roof is installed!  The shingles are layered from bottom to top. They are also lapped over each layer. So water, will drain down the roof and off.  If water gets up under a shingle, the roofing crew has done some other things like roofing felt, metal valleys and flashing to do the job.

Look at the water run off the overhang in the top picture.  When it rains most of the water hits the roof, the overhang changes how much strikes the wall. Matt Risinger, a home builder in Austin, TX, tweeted this graphic recently.

Overhang

Do you think Matt builds homes with short overhangs?

SidingThe layers on the roof are repeated for the same purpose for other areas of the house. They work the same way. Some are installed the same way, some are installed differently. Other areas of your home have a different experience with water.

Tyvek TopThe outer layer of a wall, the siding, like the shingles, are lapped. The next layer behind the lapped siding is usually known as house wrap. That’s the white covering you see on many new homes, before the siding is installed. Technically, the term for this is ‘Weather Resistant Barrier’ or WRB. Just as the roofing felt helps keep water outside on the roof, the WRB helps keep water outside on walls.

Just as the roofing felt, shingles, and siding are lapped; house wrap should also be lapped, each new layer draining onto the top of the layer below. The directions call for a 6 inch lap, and then tape. The tape is used on house wrap and not roofing felt, because it is a different material, cap nails should be used.

IMG_7672How does the home buyer know the house wrap is right? It passed a code inspection, didn’t it?  This image shows damaged house wrap. Is it taped and lapped correctly? Are the fasteners used according to the manufacturer’s directions.

Do these problems mean that house wrap is bad.  Certainly not!  House wrap is a great product when installed correctly.  It will do the job it is designed to do; act as a Weather Resistant Barrier. It will then, direct water back outside and not allow it into the wall.

DetailWindows and doors need an opening in the wall. These openings must be detailed correctly or water will enter. These details involve flashings, and tapes. How the window is made, with nailing flanges, with foldable nailing flanges or field installed nailing flanges must be considered. Here we see a tape used to seal the nailing flange to the house wrap.

Is house wrap the only type of WRB used?  No!  It is the most widely used in this area. The others will be covered in a future post.

Now if the roof and the wall properly shed water, and they guide any water that gets inside back out, we get to the ground. At this point the water should be directed away from the house.  Gutters and down spouts do a great job when the ground slopes away. Recommended slopes are 1/4 inch per foot for hard surfaces like concrete, and 1/2 inch per foot for other surfaces. Local codes may require more, or a builder preference may result in a larger grade.

damp_proofingThe basement or foundation walls should be damp-proofed on the outside. This is the black spray applied to the concrete. A tile drain system is installed around the exterior of the foundation and tied into a sump to be pumped out of the home.

 

If these or other equivalent measures are built into a new home, the builder is doing the job right. They are all in the building code. The issue is not what material, the issue is quality of workmanship.

This post is part of a series of posts on A Healthy Home.

 

 

 

A Healthy Home

Healthy HomeBuilding a new home, gives the homebuyer an opportunity to build in all the things they want. The floor plan, bedroom arrangement, windows are all important.

Also right up there is a house that is healthy. Everywhere you look, someone is pitching, this is healthy for you.  We have lots of buzz words for healthy.  Organic, whole grain, anti-oxidant, reduced fat, low sugar, wellness, all-natural are but a few. How do you make a house into a healthy home?  It starts with design and a few simple objectives.   Ideally, a healthy home is:

  • Dry
  • Clean
  • Well Ventilated
  • Combustion by-product free
  • Pest Free
  • Chemical Care
  • Comfortable
  • Safe

read beforeIt seems fairly simple.  We want a roof over our head to keep the elements out.  Hot or cold, rain or snow, we don’t want them in our home.  The dry home starts with a well constructed roof.  That keeps the weather related water like rain or snow out. Then the walls, and the foundation.

Clean may be obvious, or not. Well Ventilated and Combustion by-product free, along with pest free, no toxic chemicals, comfortable and safe seem also to be obvious.  There is a saying about the Devil being in the details.  It is certainly that way in building a home. So a few details on these topics that make up a Healthy Home are important.

I will be posting a series based on the Healthy Home. We will take a look at each of the points listed above and what they mean to the home owner.

Part Ia   How Dry is Dry       Bulk Water from Precipitation

Part 1b  How Dry is Dry       Bulk Water From other Sources

Part 1c  How Dry is Dry       Water Vapor

Part II    The Home Starts Out Clean

Part 3    Well Ventilated

Part 4     Free of Combustion Byproducts

Part 5     Pest Free

Part 6     Chemical Care

Using One HVAC System for Two Areas

My first audit was triggered by the homeowner concerned that the upstairs was several degrees warmer than downstairs. Since we all have experienced Hot Air  goes up, it makes some sense.  In this case the difference was 15° F at 8:00 am, rising to 20° F by noon that August morning.  Yes, it was hot.

4 square craftsmanThere are a number of ways to help this out, for existing homes. Which one is best depends on the specific home, the existing setup and the homeowner.  For new homes, it usually falls to the HVAC guys to work out.

In a new 2 story home, it is common to see two HVAC units.  One in the basement for most of the home and one in the attic for the second floor.  Some builders, concerned with cost, or space considerations, will try a Zoned System.  You can also find Zoned Systems in single story homes, with the master suite on one zone and the rest of the home on another zone.

furnace bypass zoneTypically, the set up uses a bypass and several dampers to control the air.  The wisdom of this approach is that changing the air flow through the unit costs a lot of $$$$.

In the video below, John Proctor, goes through the measurements and calculations of using or not using a bypass and dampers to figure out exactly what is happening.  His conclusion:  The Bypass Damper set up costs 22% – 32% more.

This video is primarily written for HVAC contractors and others interested in the details and workings of air conditioning.  If all the numbers make your eyes glaze over, that is OK.  All you want is comfort, a Bypass dampened system may do that at a cost. It may have the cost and not do that.  So if you are considering a Zoned HVAC system,  tell your contractor —  ‘No Bypass Dampers’!  And refer them to this post.

What Happens After You Finish Your Part of the house, and Then The House Is Finished?

images-2Modern home building takes a lot of people. Concrete, Carpentry, Heating and Air, Paint, Drywall, Insulation, Electrical, Plumbing and many others. These professionals work on the house at various times. Usually there is a sequence, the foundation is done before the framing, the roof is done before inside work gets very far. Toward the end, it can get somewhat hectic. Everyone is trying to finish. The deadline is looming. Painters, trim carpentry, flooring, plumbing, final electrical installations are all happening.

One of the last things is the final work on the Heating and Air Conditioning system. This cannot happen until after the electrician is finished, and if you have a gas furnace, the plumbing must be there. Some of the work by the HVAC contractor was completed before the drywall went up. The duct work was installed and the inside unit of the system was probably put in place and hooked up to the duct work.

If the home is built on a 120 – 150 day schedule, the initial work, rough-in, on the duct system would happen about 1/3 of the way. Then about 2/3 of the waywall_duct, the Heating and Air techs are back to install the thermostat, the outside unit, hook up the electric and finish the job.

Last week, I went out to complete a rating on a new home. I had completed some testing on the duct system at rough-in. I used a Duct Blaster unit and testing the duct system for Total Leakage. I got a great number. There is a professional standard, issued ACCA (Air Conditioning Contractors of America) for this test. It is based on the size of the amount of air flow pushed through the system by the fan; in this case it would have been about 1,200 cubic feet per minute.

The standard is 10% of system air flow or in this case 120 CFM. In a previous blog post, I discussed a test where the system leaked over 100% of system air flow. This is an important test, because it can be compared to the test done at rough in.ACCA_5

The rough in test for Total Duct Leakage came in at 4.8% of system air flow. This is a very good number and typical for this HVAC contractor. Now at final, the total leakage was 16%. Wow! What happened?

I cleaned up and left the house about 6:00 for the weekend. Sleeping on the ‘What Happened?’ seemed like a great idea. I did just that.

Tuesday, I went back to take another look. I would conduct some additional testing to see if the leak(s) could be isolated. I started by removing the grills that fan the air out through each room. That would be easy and fast. So, the first few looked pretty good. It was going fast, I kept going and half way through I found one that showed some problems. At the end 1/3 of these grills had a significant problem.

Duct BootAs you can see the vent in the wall, had the drywall cut too large for the duct. The openings ranged from a quarter inch to over an inch wide, all around the opening. The air instead of 100% leaving the duct system into the room, was being pushed back into the wall. The idea of the duct system is to put the hot or cooled/dehumidified air into the room where the people are. A grill can do a great job of sending the air into various parts of the room. A good grill for one place may be absolutely the wrong grill for another place. Grill manufacturers refer to this as ‘Throw’. If you have the wrong throw on your grill, you aren’t getting much comfort from your system.

The infrared image, below, shows the outside of a wall in the winter (It was 20° F that morning). The hot area below the window is from the grill directing the heat up the wall, not out into the room. I found this condition on an audit last winter and made two alternate recommendations for the home owner. The cost was less than $20.00 for either one. The problem was fixed the same day by the homeowner.exterior_wall

Back to fixing the leaks! I filled the cracks and gaps in the poorly cut openings, replaced the grills and then set up to re-test the duct system. The leakage was back to the original number.

This shows the value of testing your work. We work with Quality Control Systems in our everyday work life. As consumers we depend on the quality of the products we buy. We see how companies respond when they are faced with a quality issue. A number years ago a lot of Tylenol was recalled. A few bottles had been tampered with, not really the manufacturer’s fault. They recalled anyway and their customers were well served. In the past few years, several auto manufacturers have had some problems with their cars, and they did not promptly recall the cars to fix the problem.

qcApplying good quality control lets the customers and the management of a company know the level of quality. The company can make drugs, cars, or install your heating and air system. In this case the quality work done by the Heating and Air techs was changed by another person working on the job. Good quality control found the problem. The fix took only a few minutes. Now the home buyer will not experience the discomfort from a badly installed duct system. I will not get a call in a few years because the home owner is not comfortable. The heating and air techs will not have a lot of call backs.

My thanks today goes to the crew at Cooks Heating and Air in Wichita. They did the quality work and deserve the credit. I am lucky to be able to work with people like this.