Monthly Archives: June 2016

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 Indicators and Measuring Them

The issue of Indoor Air Quality in a home comes up very regularly for a Home Energy Auditor.

People work hard to keep their homes clean and to serve healthy food from their kitchens. We also want to know the air we breathe in our homes is healthy. There are a lot of things out there to spend our money on like, air cleaners, fancy filters, ozone and UV lights to start with.

What types of things cause a home to have un-healthy air?  A recent presentation to the Indoor Air Quality Committee at the EPA used this slide from a researcher at the University of Pittsburg.

Approaches

What I see as important about this list is that these are measurable. A Thermometer and a Humidity meters are commonly found in many homes. Most homes have a CO Detector for Carbon Monoxide and a lot will have a CO2 detector for Carbon Dioxide.  That covers 50 percent of the items in this list.

What is left are things like small particles, Ozone, volatile organic compounds and formaldehyde. Small particles can be a tough one because we are talking really small.  The standard size we look at is 2.5 microns.  A human hair at 50+ microns gives one a size comparison.

The others are gaseous in nature. Much of these gases can come from materials in the home or the the furnishings and are released over time usually referred to as ‘off gassing’.

As a family lives in a home, things change.  You go in and out, opening doors, windows, cooking, living, enjoying your home. How do you keep track of the air in your home? How do you know it is good, or that you may need to do something to fix a problem?

For years homes have had thermometers and humidity meters available.  Now there is a whole new series of measuring instruments to monitor these various indicators. The simple detector technology for Carbon Monoxide has been improved to respond to a range of levels and actually measure the gas. The other gasses have the same technology.

NOTE:  This measurement technology has been available for professionals at a significant price. Now the progress has made the units smaller and more affordable.

My friend Nate Adams has been doing some major work in existing homes. Nate works in the Akron Ohio area.  He has moved his business from an Insulation Contractor to a full service home performance contractor.  Recently, he has been exploring how the energy efficient features he is installing also improve the quality of the air inside those homes.

Nate has written a blog post reviewing some of these newest monitors to provide homeowners with a comparison of the available offerings.

I was challenged to write this post explaining my reaction to Nate’s Review.  My initial reaction was ‘disappointing’.  Nate’s challenge was ‘Why”.  So here is the why.

First:  While the technology for detecting has moved to measuring, it still has a ways to go.  Partly technology and partly continuing to reduce the cost.

Second: There is a very limited offering. Seven Products were reviewed and three more were mentioned, but lacking the data logging feature. I was hoping for a few more.

Third: Each entry reviewed had pros and cons.  I do not feel that any single item is a comprehensive monitoring solution.

Because I chose to wade through my reactions and thoughts, it has been a good exercise for me. Writing down my thoughts and reasons really helped me look at my initial response of disappointment and why my reaction should be more then that.

My second reaction after working through the above is ‘hopeful excitement’.  While we may be disappointed in the number of monitors and the comprehensive coverage;  we should be looking forward to the future developments and monitors that measure more.

The challenge of these developments and the potential they hold are very interesting.  What can we do?  What should we do?  I suggest that realizing the potential is in many ways up to us. Those in contact with the public, the home owners, or renters. We need to advocate for measurement and then taking action based on what the monitors reveal.