Category Archives: Air Conditioning

Why The Way your AC is installed Matters! Part I

Screen Shot 2016-06-24 at 8.49.56 AMThe Air Conditioning Contractors of America (ACCA) publishes ANSI Standards for HVAC Contractors to follow. These professional standards are well known in the Home Performance Industry and the HVAC Contractors.  I found a link on their website this morning to a study showing the problems caused with problems that can easily occur if the Industry Professional Standards are not followed.

I covered a study from California about these types of faults recently. This one was completed by NIST.  The National Institute of Standards and Technology, a part of the US Department of Commerce.

CookA quick review of the reports shows many technical details and mathematical formulae.  That forms the back ground for comparisons with other studies.  However, they did write in some plain English for the rest of us. Here is one of their findings, about the performance of heat pumps.

A Heat Pump provides both heat and air conditioning. It is efficient because it moves heat.  In the summer, it moves heat from inside to outside, just like an ac unit.  The same technology and principals. In the winter they move heat from outside to inside. Yes, there is heat outside at cold temperatures.

Think about your refrigerator. When it gets up to around 40° F inside, the unit turns on and finds the heat in that 40° temperature and moves it out of the refrigerator to keep your food cool and fresh. If you watch your temperatures outside, you know more heating is done at 40° and above than at 20°.

This findings for a heat pump cooling your home apply to geothermal heat pumps, regular heat pumps and to air conditioners. They are all working on the same principals.

The first fault they report on is having the wrong size unit.

Changing the size of the heat pump for a given house – either undersizing or oversizing – impacts the heat pump performance in several ways:

  • Cycling losses increase as the unit gets larger; the unit runs for shorter periods and the degraded performance at startup has more impact (parameters used in simulations are: time constant = 45 seconds, or CD ~ 0.15).
  • In the cooling mode, the shorter run periods impact the moisture removal capability (i.e., ability to control indoor humidity levels) because operational steady-state conditions are an even smaller portion of the runtime fraction.
  • In the cooling mode, continuous fan operation with compressor cycling greatly increases moisture evaporation from the cooling coil. However, this impact is minimal with auto fan control (indoor fan time ‘on’ and ‘off’ the same as that of the compressor), since only a small amount of evaporation occurs with the assumed 4 % airflow during the off-cycle with the indoor fan off. If the air conditioner controls include an off-cycle fan delay – that keeps the fan on for 30-90 seconds after the compressor stops – then the impact of off-cycle evaporation is in between these two extremes (Shirey et al., 2006). The results in this study assumed auto fan operation with no fan delay.
  • Heat pump sizing also affects the level of duct losses.

A improperly sized unit will run for shorter periods, and will turn on and off more often. That is just like driving your car around downtown Wichita. Lots of stop lights. Compare you gas mileage to highway driving at a steady speed of 55 mph or higher.

OK, I know efficiency isn’t as important as being comfortable. So the next item is the comfort side.  Running you AC like your car in Down Town, doesn’t remove the humidity as well. Your house temperature is cool, but the humidity is high and you turn down the thermostat again to get rid of the humidity. Pretty soon you are cold, and yet you are not comfortable because you feel the high humidity.  Then you go out and buy a de-humidifier.

The third item is also a comfort issue. That is the advice of many HVAC technicians to set your AC fan to run continuously. When the AC shuts off and the fan keeps running, the humidity the AC just removed from your house is put back in. Oops!

DadBabyESFinally the report mentions duct losses. They are important in a home that has no basement. In those homes ducts can be located in the attic or the crawl space, or both. If you have one of those houses, I would be glad to address that one in the comments. So leave a comment if your are interested.

How do you get a right sized AC unit?   Your HVAC contractor can run a series of calculation found in the professional standard from ACCA Manual J.  It is a Load Calculation.  For cooling it considers the insulation in your home, the windows and size of the home and other details. It can be done on a paper worksheet or a spreadsheet. Both are free from ACCA. Most contractors have a software program to run these Load Calculations.

Load calculations for cooling, are a balancing act. The homeowner wants a home that is cool in the summer and in Wichita, they want the humidity controlled.  Without a lot of formulae or detail, how do, the rest of us, understand a cooling Load Calculation?

My advice is to look at the out door design conditions that must be factored into the calculation.  For cooling, ACCA Manual J has 6 outdoor conditions.

  • Two relate to location. Cooling in Atlanta, is different from Wichita and is different from Denver.
  • One is the outside temperature. The choice is a temperature that covers all but 1% of the hours in a year that require cooling for that location.
  • There are four design conditions that relate to Relative Humidity.

This obviously requires a balance. If your contractor varies from these conditions, it still must balance.  You may or may not like the balance, if one item is changed without consideration of the others.

What should you as a consumer do?

Insist that professional standards be used.

Require that all the items of the standard be measured and reported.

For Air Conditioning the standards require measurements of:

  • Air Flow Actual compared to manufacturer’s requirements. (+/- 15%)
  • Air Flow Static Pressure (ESP)  Actual within the manufacturer’s acceptable range
    • AND
  • No more than 25% or 0.10 IWC over the design pressure for the duct system.
  • Refrigerant Charge Verification
    • Superheat method:  Within +/- 5% of manufacturers superheat value.
    • Sub cooling method: Within =/- 3% of the manufacturers subcooling value.
  • Measured line voltage and low voltage circuits for voltage and amperage. These values shall be within the manufacturer’s requirements.

If you have good air flow in some rooms and not enough air flow in other rooms, your home has an air balancing problem. Have your system checked and balanced. This is known as test and balance or TAB. I have done test and balance work. Generally, the air flows should be within 20% of the design or application requirements.

Hey! It’s Hot Out There! — A conversation with@KWCHDeedee

Interview

 

 

DeeDee from Channel 12 KWCH called Friday morning looking for someone to talk about holding the line on cooling costs as the summer heats up.  We met Friday afternoon at a home in NW Wichita. This 4 year old home was larger than most in the Wichita area. 1800 SF on the main floor with a full basement. The Heating and Air is provided with a ‘Geothermal’ Heat Pump.  This system uses the 55 degree water under ground to provide heating, air conditioning and during these oppressive heat days in July, 2016 – de-humidification.

When I got there, the HVAC techs were there working on the system. It had shut off. The temperature in the home was 80° F and the relative humidity inside was in the lower 50% range. They reported the system was now running and during my time with DeeDee we felt and saw the system working. After a couple of hours, the temperature had dropped to 78°F and the relative humidity was down to 48%. The outside conditions at 2:30 pm, while I was there were a temperature of 98° F and a relative humidity of 45%.  Remember that humidity is relative, thus a higher temperature has the capacity to hold more moisture.  At 8:30 am Friday morning the outside temperature was 81° F and the relative humidity was 75%. Much higher than the inside RH at the same temperature when I arrived.

Not Comfortable

Not Comfortable

I think everyone was glad that the air conditioning had been restored.

DeeDee wanted some quick, easy to do, items for any one to help hold the electric bill down during the hot days of summer.  So we went around the home and we looked at some simple, low cost, easy to implement changes that could be made. These would work in you home as a home owner or in a rental home or apartment. We also looked at several improvements that should be considered.

Where does our energy get spent? Here is a graphic that was in my training text.
HHPie

The variations in percentages are due to differing house sizes, energy costs and types, and lifestyle choices.

Under the quick and easy category, people usually look at lights, electronics, and the thermostat.  Each of these requires the person in the home to do something. Turning out the lights, or turning the TV off, or setting the thermostat higher in the summer.  All of them save energy and thus lower your bill.

I classify all of these and others under the heading of Conservation. Then there are those that fall under the heading of Efficiency. These are things like adding insulation to your home, replacing your weatherstripping on doors/windows, or replacing a furnace / ac unit that is over 15 years old.

The difference: Conservation is changing how people work! Efficiency is changing how things work!  Both are important.

A quick summary of the summer conservation items would be:

  • Turn things, like lights and electronics, off when you aren’t using them.
  • Turn the temperature in the house up and turn a fan on.  Ceiling fans are great. If you need some ideas on ceiling fans, I wrote about them.
  • Reduce or eliminate excessive heat sources in the home. Turning off lights is great. Changing an incandescent to a CFL or LED saves energy and reduces the heat put into the home.
  • Another Heat Source is the Water Heater.  Turn it down to 120 degrees. Most people take a shower at 105° F. A 50 gallon tank with a medium flow shower head will provide 1 person with a shower of more than 30 minutes, with a typical mid efficiency recovery time.
  • Cooking inside produces heat and moisture.  Use a kitchen exhaust fan to remove both of those. They make your AC work longer.
  • Use the fan in your bath room to remove the heat and humidity when you shower.
    • if your fans noise level bothers you, replace them with a quiet fan. In Wichita the bath fans are selected and furnished by the electrician. The code requires 50 CFM to be removed from the bathroom.  Since electrician’s are trained in volts and amps, our common practice, means the person selecting your bath fan will bring the least expensive one. You might consider telling your builder on a new home, to have the HVAC contractor bring a quiet fan that will actually remove 50 CFM.
  • Move tasks that generate heat, such as baking a cake or washing and drying clothes to cooler parts of the day. In the morning or after nine at night are good times.
  • Use a clothes line to dry clothes, instead of the dryer.  In the summer do not dry them inside. That will just increase the humidity and make your AC work more.
  • At least one area electric utility has a demand charge for using electricity in the hot day times of the summer.  It is not Westar Energy. If you use another electric Utility, check your bill inserts, check their website, call customer service, and know when not to use electricity. A demand charge is an extra charge for usage during a specific time. Instead of 15 cents, you could be paying several dollars per unit.

Turning electronics off, such as your TV or computer, also involves the various accessories.  Computers have a printer, and sometimes other items that are plugged in. Along side your TV is a cable box, a DVD player, and other plugged in accessories. using a smart strip will help. A smart strip is a power strip that is controlled by the main device in the group.  So you plug your computer into the primary, and the printer, the monitor and other accessories into the other plug ins.  Now when you turn the computer off, the smart strip shuts the accessories off.  The same with the TV, or a game center.

The longer term changes you make to your home, cost more, and can have a larger impact.  These are the efficiency items.

  • Buy Energy Star certified appliances when you replace your refrigerator, washer and other appliances.
  • If your refrigerator or deep freeze is over 12 years old, I would strongly recommend that you look at replacing it.  The technology is changing fast and competition is holding prices down. Those made in the last 2 years use considerably less electricity then older models.

The largest portion of your energy use from the Pie Chart (above) is heating and cooling your home. The chart shows 45 – 55% of your energy use for this.

The simplest, and easiest to work on, would be the insulation in the attic. Others would include replacing less efficient equipment, considering the use of an exterior solar shade, or other improvement. After the work is done, you can sit back and enjoy your home.

Exterior Shade is a great thing, sometimes easy to do. Trees placed with shade considerations are great. Sometimes the builder can build some shading features into the home.  A wider eve for example. 30 inches instead of the standard 24.  Then the gutter, all work to extend the shade. The link below is to an Infrared image of shade from some builder included features.

Follow Up Thought for Friday’s Summer Cooling Tips.

We did take a look in the attic.  I found an attic that could use some attention. Some levels were in the 14 inch range, some were in the 10 inch range. One place had obvious density problems.  Insulation should be installed consistently level, certainly not lumpy. The fibrous insulation, fiberglass, cellulose, or rock wool, must be installed to the density specified by the manufacturer.  If not, you are not getting what your paid for.

attic

This is the attic from the KWCH video camera. I am reaching into a hole in the insulation and I can see the ceiling at the bottom of the hole.

I found no insulation card in the attic.  I can tell it is fiberglass and it is white. In the past two weeks, I’ve seen 5 different types of white fiberglass insulation.  If you install Johns-Manville Fiberglass, the three products I’ve seen in the past two weeks require 20 inches, another 16 inches and another 11.25 inches of thickness.  These depths would provide an R-49 level of insulation. This has been the requirement for attic insulation in our climate zone.  Since there is no legal requirement for insulation in South Central Kansas, most new homes are insulated to R-30 or less.

Call IR

This was the Infrared Image you saw in DeeDee’s video. I have reproduced it here with the visual light picture to help understand what it is showing.

I would like to thank DeeDee and Betty and Jack Call for their hospitality and seeing their home. I offered the Call’s a no charge Utility Usage Analysis for their hospitality. I will go back with that when I get the gas and electric usage from the utility companies.  Jack expressed some interest in adding some insulation to his attic so I will get some quotes for them to consider.

You can view the story DeeDee wrote and the video shown on the 6:00 news at the KWCH website.

Quality Installation and Maintenance of HVAC Equipment

The news this month has multiple stories about Heating and Air Companies being very busy with units not cooling or not cooling enough.Screen Shot 2016-06-24 at 8.49.56 AM Driving around town, I see most of these contractors have a sign out front looking for help. The wait time is up to two weeks.  In the 7 homes I’ve been in this week.  One had no working AC, one home was on it’s last legs, and two other homeowners were very concerned. For the 1st time in 7 years, I’m getting calls from my website asking if I can fix their AC unit.

This morning I found a report on HVAC Problems, Problem Identification and Repair.  I have scanned this 27 page report and these are the things that jumped out.

Background:  California has some of the toughest energy requirements for buildings, both new and remodeling of existing buildings. These is a direct result of the problems they had 15 years ago, with not enough electricity.  They resulted to black outs, (Utilitys were allowed to shut off electricity to various geographic areas).  and brown outs, (Utilities were allowed to provide only part of the electricity needed to a geographic area).  Both are not good.

These energy codes are generally referred to as Title 24.  A large part of the work in California the last few years has been testing and measuring how well the requirements are being met.  This report is just one small piece of that process.

Title 24 refers to the problems, their identification and repair as “Fault Detection and Diagnosis” or “FDD”

Screen Shot 2016-06-24 at 8.51.18 AM

The Report was working on the answers to these questions

  • Is FDD worth the investment, and what is the savings potential?
  • How effective are available FDD methods and what do they cost to implement?
  • What training is needed for effective FDD and is it being provided?
  • Are codes and standards working?
  • What are the major gaps and how can they be addressed?

This particular session and reporting was limited to:

 

  • System Types–new and existing residential only
    • Air conditioners
    • Heat pumps
    • Furnaces and air handlers
  • Fault Types
    • Low airflow
    • Refrigerant system charge, restrictions, and contaminants
    • Mechanical and electrical faults and faulty installation
  • Repair vs. Replacement Issues
    • Cost-effectiveness of FDD
    • Replacement refrigerants for R-22
  • Human Factors
    • Training and quality of maintenance
    • Homeowner knowledge and expectations.

The reporting included tests applied with standard AHRI methods. The tests were designed to determine the impacts on efficiency and capacity of a variety of conditions, including:

  • Airflow of 250 cfm/ton reduced energy efficiency ratio (EER) by 12% and has the potential to produce a false overcharge diagnostic due to freezing of the coil (the asterisk denotes an unofficial EER)
  • Liquid line restrictions (e.g. due to clogged filter-dryer or metering devices) reduced EER by 30% to 36% for non-TXV and TXV systems respectively
  • Only 0.3% Nitrogen in the refrigerant reduced the EER  by 18% with no TXV and 12% for the TXV-equipped system

Discussion pointed out that California Title 24 charge verification methods, which only measure superheat (for non-TXV) and sub-cooling (for TXV) systems, and ACCA Standard 4, for which only 3% of the procedures are related to energy performance. Also covered were  how improperly maintained vacuum pumps, test instrument error, and poor service practices such as use of rules of thumb contribute to the introduction of non-condensables, improper charge, and other faults.

John Proctor, PE presented a case for making improvements to California’s Title 24 standards, John worked with a team to inspect a large number of recently built homes to identify HVAC installation and performance issues. He began his presentation by defining an “incremental effectiveness ratio” that divides benefits of maintenance by the incremental cost to diagnose, repair, and ensure quality, which is fundamental to the question of the value of HVAC service. He proceeded to show a series of graphs from his experience and other studies that illustrate the deviations from the ideal for airflow, charge, duct leakage and efficiency, and non-condensables, as well as the incidence of occurrence of these defects.

For example, his graphs show:

  • 50% reduction in airflow reduces EER by 25%.
  • A refrigerant charge that is 70% of the recommended charge reduces EER by about 55%.
  • Leaving Nitrogen in the line set and coil at 20 psig before charging with refrigerant reduces the sensible EER by about 45%.
  • From his 2003 survey, more than 60% of the houses checked failed on refrigerant charge, airflow, and duct leakage, and more than 95% failed overall.

Many of these issues result from a lack of training and a lack of follow up by supervisors.

They had some specific things that could be done by builders, HVAC Contractors and home owners to ensure these items do not get missed.

I will read the report in more detail and have further comments.

You may read the entire report.

Improving Air Conditioning Effectiveness?

I just noticed a post about improving AC performance. They had a short YouTube Video showing water being sprayed on the condenser coil.

 

 

I’ve seen regular sprinklers used also.  Typically, I see older compressors being treated this way.  I also notice something going on inside. Typically the loads are not calculated correctly or something has changed inside.  The other piece could be extremely high outdoor temperatures.  I’ve seen this in homes, and businesses.

This is a restaurant,  my long distance guess is a load issue.  Was this originally built as a restaurant? Are the exhaust systems and economizers working and actually turned on?

This simple table will keep your home cool

Table 1 Jean-Sébastien Lagrange and Raphaël Ménard with their Zero Energy Furniture Climatic Table.

Consisting simply of a surface and legs, the table is one piece of furniture that has remained largely the same for thousands of years. But now, a French design duo has come up with a way to turn the humble table into a means of climate control that doesn’t use any electricity. Paris-based industrial designer Jean-Sébastien Lagrange teamed up with French engineer Raphaël Ménard to create the Zero Energy Furniture table, also known as the ZEF Climatic Table. The ZEF table looks like any other with a sleek design of a solid plank oak top and angled legs — but it could hold the secret to cutting energy costs by as much as 60%.

 

Table 2A close up of the ZEF table, which could cut energy needs by as much as 60%.

 

“We wanted to see if it was possible to address climate and energy issues on a furniture scale,” Lagrange told WIRED.

Beneath the oak table are a series of phase-changing materials (PCMs) placed between the wood and anodized aluminium bottom. The materials soften when the surrounding room reaches around 71 degrees, absorbing the excess heat, and then harden once the temperature dips back below 71 degrees, releasing the trapped heat with the help of the aluminium and causing a noticeable change in the room’s temperature.

Table SpongeThat means the table is essentially working like a “thermal sponge,” as Lagrange and Ménard put it, sucking up excess heat and then releasing it once the room becomes cool enough.

According to the inventors, the table has the potential to reduce heating needs by as much as 60% and cooling demands by as much as 30%, which could save a lot of money as well as energy.

It’s a feat of engineering that makes the most sense in homes that don’t have climate control.

In climates where the temperature can drastically swing from hot to cold in short spans of time, the ZEF Climatic Table is most useful. For example, if a room heats up on a sunny day and then the temperature drops at night, the ZEF table would make the climate in that room more consistent.

The ZEF table works best in rooms that undergo significant temperature changes frequently.

The Full Article on Business Insider Australia


 

This article is reprinted in part from the above digital source. It was originally from Wired and was brought to my attention by ASHRAE. Phase Change Materials have many applications in heating and cooling. One phase change material everyone uses is water.  At 32°F it changes from solid to liquid or liquid to solid. Of interest to energy efficiency are materials that act in this way around 70°F.

Indoor Air Quality – Guideline Revision Public Comments Requested

imagesATLANTA – Public input is being sought into a proposed revision of ASHRAE’s residential indoor air quality guideline.

ASHRAE Guideline 24-2008, Ventilation and Indoor Air Quality in Low-Rise Residential Buildings, is the companion guideline to ANSI/ASHRAE Standard 62.2-2007, Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings.  Guideline 24 provides information on achieving good IAQ that goes beyond the requirements contained in Standard 62.2 by providing explanatory and educational material not included in the code-intended standard.

Read Entire Article

 

Who Is Building an Igloo in Wichita?

It all started on Twitter. @AIAWichita @moongodess316 and I had some fun over building an Igloo.

Igloo1

I saw this Tweet and immediately thought of a quote from Dr. Joseph Lstiburek: “The Igloo was the First Passive House.” Joe is an engineer by training and has been working with buildings, insulation and energy use for over 30 years. His Building Science Corporation, based in Massachusetts, conducts research and is one of the best sources of verified information on building energy efficiency in buildings.

So I tweeted back.

Igloo2

What is the difference between a Passive House and a regular house? What is the buzz all about?

Strawbale

When you build a home you can use lots of insulation to reduce the amount of electricity and gas to heat and cool the home.

GSHP Diagram

You can use a lot of high tech equipment to reduce the amount of electricity and gas to heat and cool the home. You can also do both.

PHIUSThe Passive House was developed in Germany, so you see it referred to at times as Passiv Haus.

We know that insulation works and that more insulation works better. As the cost of electric and gas goes up, it makes financial sense to add insulation to a home or business. In 2000, the local cost of Electricity was 8 – 9 cents, the recommended level of attic insulation was R-30. Today the cost of electricity is 12 – 13 cents and the recommended level of insulation is R-49.  Both have increased about 1/3 in 1 years. We also know that air movement, cold drafts, makes people uncomfortable and causes insulation to not work as effectively.

Round Metal TubeThe sources of air entering a home are usually related to corners. Since we like living in buildings that have square corners there are a lot of them in a home. Windows do not usually cause air leakage. How they are installed can cause air leakage. The age or the quality of the window does not seem to matter when installation mistakes occur.

PHIThe primary requirements for a passive ouse certification are based on Energy Usage and creating a structure that needs very little energy for heating and cooling. These standards are effectively summarized with these two limits.

  • Total primary energy (source energy for electricity, etc.) consumption (primary energy for heating, hot water and electricity) must not be more than 120 kWh/m² per year (37900 btu/ft² per year)
  • The building must not leak more air than 0.6 times the house volume per hour (n50 ≤ 0.6 / hour) at 50 Pa (N/m²) as tested by a blower door.

In our Twitter Conversation, Angee McBustee tweeted a question about how is building a igloo in Wichita. Then I responded with the offer to run the blower door test. As you can see from the primary requirements the Blower Door result is very important to a passive house.

Igloo4

How good is a Blower Door Test of 0.6, as required by Passive House? Energy Star New Homes require a Blower Door Test of 5.0 or less. New homes in Wichita routinely test around 4.0. In the blower door testing, lower is better.

For standard construction, I have tested several homes at 1.0. There is one home that I have tested with a lower result. A custom home in Butler County is under construction. They had me do a Blower Door test after it was sheathed. No insulation, no drywall. The test result was 0.62. We were able to find several leaks using biometrics and the infrared camera. That was last September. I returned in December to test it a 2nd time, the results were so low, that I didn’t have the right test equipment to measure the result. I would estimate it to be in the 0.30 range. I now have the equipment to test a home like that.

In February, I have been accepted for training and certification as a Passive House Rater/Verifier. Christine is building the home in Butler County, I want to thank her for the push to obtain this certification.

In the Twitter Conversation, AIA Wichita came back and said they were posting an information tweet.

Thanks to Angee and AIA Wichita for a nice idea for a Blog Post.

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 1c: How Dry is Dry

rainIn Part 1a, we have looked at how your builder builds your home to keep water from the outside from damaging your home.  He used materials to shed the water and he lapped them over each other, from the roof peak and the shingles all the way down to the ground. And then directed the water away from the house, using gutters and sloping the landscape away from the house. Easy, quick and it looks nice.

In Part 1b, we looked at how your builder builds your home on the inside to keep water where you want it, and provide easy clean up when it does get out of the pipes, the sink, tub or shower.

BucketYou can think of this as bulk water.  You can see it, this is water that is usually measured in quarts or gallons, and it is responsible for 50 – 60 % of the water damage that occurs over time. The exact percentage depends on the source doing the figuring.  So why is there a Part 1c?   There is one remaining source of moisture in most homes.  Water Vapor.  Hard to see it, hard to measure it.  The damage water vapor causes is usually found to be very extensive.

If you have a roof leak, it usually ends up inside and you find it while it is relatively small. When it is fixed the damage is limited and fairly easy to fix.  Leaks from plumbing and over flowing sinks and tubs, is usually caught very fast. The surface is easy to clean up and many times contains the water.  Damage from these sources doesn’t really occur unless the water continues over time to get there.  It stays wet and is not allowed to dry out.

Flood type events are not really of concern here. When they happen, the homeowner is aware, his insurance may cover repairs and there are lots of contractors that will do the work. Generally, they have little to do with how the house was built.

teapotWater vapor is present in varying amounts in every home.  What is the relative humidity in the home?  40% – 25% – 65%?  That is water vapor in the air. We add to that from breathing, cooking, and hygiene activities, like showers and running hot water for various purposes.

How do we control this water vapor?

Spot ventilation.  This may be as simple as opening a window next to the stove where the pasta is boiling, or the tea pot is ready to pour. It may be using an exhaust fan over the stove to actually remove the water vapor from cooking out of the house. Same in the shower.

acWhen the heat and humidity arrive around here, in the summer, it is air-conditioning season. Most air conditioners will lower the temperature of the air and remove some of the humidity at the same time.  Somedays they do a great job, somedays the ac unit really has to work and it.  Occasionally, you will find a unit that makes the room fairly cold, and you just feel clammy.  Like you just walked in from 100° outside and you are wet all over. The trouble is, it doesn’t go away.  You keep feeling cold and clammy.

That is the first way that water vapor causes a problem with our homes, it makes us uncomfortable.

How does the water vapor move into the walls and attic to cause problems like the liquid or bulk water we looked at?  It has two ways to move.  Air Movement and Vapor Diffusion.

Vapor Diffusion involves moving a vapor, in this case water.  It involves temperature and pressure.  It also involves Math, lots of fancy math.  I know some math teachers that can run these numbers, and a couple of physicists here in Kansas.  I’m sure the characters on TV’s ‘Big Bang Theory’ could run the numbers.

Adding MachineThe good news is, we don’t have to run the numbers.  If you take a room in your home with the humidity at 40% and 70° –  you will find less than a gallon of actual water.  By the time all the numbers are done, the answer is:  Yes – Vapor Diffusion put some of that water vapor into the wall.  And we can test that the 7% moisture content of the drywall, studs and other parts of the wall, is now 7.5 or 8%.  Not much change.   If you have read much on this blog, you know I lower my blood pressure by turning wood, into bowls.  Anything less than 12% moisture content in wood is considered dry.

If the builder bought kiln dried lumber, and kept the rain off it, while the house was built, the wood is probably 8 – 9 % moisture content when the home is finished.  Kiln dried lumber is typically 6 – 8 %.  Moving from an enclosed type shed to the job site, wood will pick up a little moisture.

What about air movement and water vapor?  That is the one to take care of.  Uncontrolled air movement takes the water vapor right along with it. When that vapor comes in contact with a surface that is below the current dew point, it will condense and the liquid wets the material.  We know that energy savings is easy to obtain with air sealing.  So fixing the air leaks is good for stopping the water vapor from making our house wet also.   How much?  This graphic from the guys at Building Science Corporation shows how much.

Air_Vapor

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

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.