Category Archives: Duct Leakage

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?

Indoor Air Quality Evaluations

The quality of the Indoor Air of our homes and offices is an important part of our health and comfort.

There is not much sense in putting a lot of good insulation into a building if it is:

  • Not Structurally Sound
  • Not Healthy

What types of things can be done to improve the Indoor Air Quality of any home or property?

  1. The immediate environment of the structure must be kept separate from the inside.
  2. The required fresh air that is needed, in every one of our buildings, should be filtered and otherwise treated for comfort and to remove pollutants.
  3. The pollutants that are created during the normal operation of our building must be eliminated, removed, replaced, diluted or neutralized.
  4. Moisture in any form must be controlled , and then removed avoiding any accumulation.
  5. Any and all accumulations of moisture damage or animal infestation must be cleaned up and damaged building components replaced.
  • A Full Indoor Air Quality evaluation must address all of those concerns.
  • Full interior visual inspection
  • Full exterior visual inspection
  • Testing of the building enclosure to ensure the outside stays outside
    • Infrared Evaluation as part of the above testing
  • Inspection of HVAC Duct Work and systems that move air.
  • Combustion Safety Inspection on open combustion appliances
    • Moisture, Carbon Monoxide, N02, SO2 and others
  • Infrared and other testing for moisture accumulations.
  • Sample Collection of suspended and/or deposited material that are potential pollutants or irritants.
    • Examination and Evaluation by a certified Microbiological Laboratory of these samples.

This evaluation is typically completed in two visits to the home or business. Level I Evaluation and Testing is non-destructive and not invasive.

Level II Evaluation and Testing involves invasive inspections. These may be as simple as drilling a few holes for visual inspection or sampling. It may involve removing obviously damaged building material, that requires replacement, for example wet drywall.

Contact The Energy Guy for further information about an Indoor Air Quality Evaluation.

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

 

 

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.

Those Pesky Directions

How many times have you started into a project and had to stop and redo some steps?  How many times have you finished and then realized that you had extra parts?  So what do we do?

Insulation RulerWe go back and read the directions! The manual!  It is so common there are several acronyms for reading the manual.  Directions written by the manufacturer serve several purposes. Some of the cynics around, including myself, realize there is a bit of self promotion and defense in these instructions.  We should also realize that the manufacturer has probably tried to put a few of these together. He may be sharing his wheel with us, so we don’t have to invent it ourselves.

Most importantly, the manufacturer knows how the piece was engineered. The directions take that knowledge and apply it to how the equipment is set up, used or installed. Equipment changes over time. New features are added, materials change and the way it used to be done, is not a good idea.  So, read the manual.

See the attic rafters above. This is the top of a vaulted ceiling, and the insulator has properly placed an insulation ruler.  In a few weeks, blown insulation will be installed and the tech needs to measure how much. The use of the ruler and blowing the insulation level are two of the biggest helps to installing blown attic insulation.  And Yes! They are in the manual!

The choice of this picture isn’t the insulation ruler, it is the nail grid on the ceiling joists. Machine applied in the truss shop, it is fast easy and effective.  Notice the upper right hand corner of the grid.  That is a sharp edge. Be careful, it will cut things.  Hands, pants, shoe tops. Yes! All of those and don’t ask me how I know that!  My wife makes me carry a first aid kit with lots of bandaids for a reason.Duct 1

The house I finished a rating on yesterday had these nail grids on the floor trusses between the basement and the main floor. It also had the HVAC Ducts run between and through the trusses.  The contractor on this job uses sheet metal supply plenums and take offs. He uses the flex duct to form the return air side of his duct system. Yes!  Flex duct gets torn also. Especially with a nail grid.

Two weeks ago, I tested this home. The duct system was very leaky.  According to the Quality Installation Verification Standard written by the Air Conditioning Contractors of America, it was leaking 100%. Wow!  I’ve tested this contractors work before. He always does better than this.  So I ran the test again. Checked my set up.  No change. So I called him.  Shon came right out.  He looked over the system and immediately saw a couple of problems. Including this section of flex duct.

ZeroNow, two weeks later, his crew has reworked their ducts. I’m back to test it again.  I run the same test and scratch my head.  What leakage –  I can get the readings right. The picture left shows no air flow, on the right side, and a very low pressure difference, on the left side of my manometer.  The procedure is to have the Blower Door depressurized the house. Then you depressurized the duct system with the duct blaster to equalize the pressure.  When the pressure difference comes down to Zero, you read the leakage to the outside of the house.

So I checked my set up and tested again. Still no readings.  So ….   I read the manual.  In this case a Field Guide from the Quality Folks at my RESNET Provider and The Energy Conservatory that makes my equipment. I read it twice.  Then it hit me.  This line: Check the duct pressure. A negative duct pressure indicates leakage to the outside. If the duct pressure measure Zero with the Blower Door running, then the leakage to outside is Zero CFM.

As you can guess, the leaks when I tested two week previous prevented this result. What changed?  The crew had found a small tear in the flex from one of the nail grids. Did you see it in the picture up above?  I can see it because I know it is there.  So I enhanced the image and that one is posted below.  To get around all the reflections of the silver colored coating, I placed a piece of white plastic inside the flex so the hole would show.Duct 2

So reading those pesky directions on a test that I routinely run, gets me the right answer. What about the Heating and Air Contractor.  Shon does good work on his jobs, because he follows the professional guidelines and tests his work.  In this case he knew the test, he knew what it meant and immediately saw how to fix it.  What would have been the result if this basement had been finished out and then he had to remove drywall to fix it?

Why is ZERO duct leakage to the outside important?  I don’t want to pay money to heat or cool the outside. If your ducts leak very much to the outside or don’t distribute the air properly, then you are spending more than you need to.  Installing ducts with no leakage to the outside in a new home is an easy process for the contractor. It give the home owner a much better value.

DuctLeak2 copyYes!  I have found duct leakage behind drywall also.  Here is an infrared image of a finished basement ceiling. The homeowners complaint is there is no air flow into his bedroom and it is cold in the winter and hot in the summer. To get this image I turned the furnace up to about 80° F. It was usually about 73° F.  I stretched out on the basement floor and waiting for the heat from the furnace to leak into the cavity between the main floor and the basement ceiling.  In a couple of minutes I had heat patterns showing.  You can see where the duct is running up and down next to the floor joist. Interesting heat spot to the right next to the other joist. Also across the joist and over to the left joist. So we are seeing the duct and hot spots on each side 16 inches away.  Lots of lost heat not getting into his bedroom.

The home with the infrared picture had the leaks on the supply side of the duct system. The one I tested yesterday had the leaks fixed on the return side. I could not have tested with the infrared in the same way yesterday.

So, on this Independence Day, we celebrate!  We celebrate our freedom to be in a business we love, where we can do some good, and make a difference.  And yes, where we can make a living for our families.  We also celebrate the freedom to know our job, to continue to learn as things change and to utilize our professional standards to keep our customers happy and satisfied.

Have a Safe and Happy 4th of July!

Credits:  Photos, myself.  Insulation Ruler –  Northstar Comfort Systems Install.  Duct system install tested yesterday with no leakage to the outside — Shon Peterman and Midwest Mechanical.  The audit providing the infrared image, my customer Craig. The new home tested yesterday courtesy of Sharon and Wade Wilkinson of GJ Gardner Homes. It is in Fontana.