Letters: May/June 2011

A version of this article appears in the May/June 2011 issue of Home Energy Magazine.

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CO Health and Safety

Recently I read your excellent article on combustion safety (“Combustion Appliance Testing: Why, How, When?” Nov/Dec ’10, p. 38). I’m currently working on a health and safety reference document for home performance trainers and was wondering if I could ask you a follow-up question about your article. About halfway through the first page it reads, “Pure Energy’s quality control inspectors find gas leaks or unacceptable levels of CO in about half of the homes in which they perform comprehensive final inspections.” I’m wondering what constitutes “unacceptable levels of CO” in this case. And are you talking specifically about combustion gas CO or ambient levels of CO or either/both? 

Also, if you found that nearly half of homes that “had already been inspected and, ostensibly, remediated” fail, would you have any estimate on the percentage of homes in the general population that contain gas leaks or unacceptable CO levels?    

Chris Stratton
Research Associate
Lawrence Berkeley National Laboratory

Author Tamasin Sterner replies:

Chris, you asked the million-dollar question! Really, two, million-dollar questions: 

• What percentage of homes in the general population have gas leaks?
• What percentage of homes in the general population have unacceptable levels of CO?

I don’t know the answer to either. But having been in over 40,000 homes, I can say that both answers are way too high, and frankly, embarrassing for a country that the answers to both questions considers itself advanced, sophisticated, and caring! What I can tell you is this: 

• These days we find gas leaks in almost all the homes where we check for gas leaks. 
• We find high ambient CO in about 5% of the homes where we check for ambient CO. 
• We find high CO in the undiluted flue gas in about 30% of the homes where we check for flue gas CO.

This is nuts; and very dangerous. And as I said before, embarrassing. I’m speaking at several conferences this year about air quality issues caused by unbalanced house pressures. Now that we are testing so many houses with accurate and calibrated equipment and by highly skilled and caring Pure Energy technicians, we are shocked at how fragile our houses are and how easily they become unbalanced, and we are amazed at how resilient the occupants are in spite of these dangerous and deadly problems!

If I had some funding, I’d have a team perform comprehensive tests in a sample of non-low-income housing stock and get an answer to your questions! Got any ideas on where we could go to get that funding?

Chris Stratton:

Thanks for your response. If you’d please forgive my intrusiveness, but what threshold does your organization currently use to determine 1) if CO in flue gases is too high, and 2) if ambient CO is too high?  

I don’t know if this is beyond your purview, but I’m also wondering about the home performance industry’s take on new laws requiring CO detectors in existing homes. Based on what I’ve read, it sounds like there are still serious quality control problems with most retail CO detectors. Moreover, it seems like the CO concentration alarm threshold for these (UL 2034) detectors is far too high to protect occupants from chronic CO exposure. What’s your sense? Is this an issue that is on home performance contractors’ radar?

Finally, I’d love to see the study you propose. But I don’t know of funding available at the moment. We’re currently collecting envelope air leakage data from auditors nationwide for a benchmarking database. I wonder if we could have a similar kind of data collection push for CO concentrations and gas leaks. Also, sorry if it’s obvious, but why should the homes be non-low-income?     

Tamasin Sterner:

We follow the BPI standards, which can be downloaded from www.bpi.org. If the CO as measured undiluted in the flue gases is 100 ppm or higher, action must be taken to fix the reason for the high CO, and work on the building cannot be started or continued until the CO level drops. Anything more than 25 ppm CO in the flue gases is cause for action. We don’t want to find any CO in the ambient air, but we are required to stop all testing, evacuate the building, and ventilate the space if we measure over 35 ppm in the ambient air.

You hit the nail on the head when it comes to CO detectors. We’ve been talking this up for a long time. For consumer safety, we recommend the CO alarms sold by www.COexperts.com, and we totally support their efforts to educate the public, technicians, and programs about typical CO alarms being woefully inadequate. Again, this is an embarrassing passivity on the part of those who make regulations. Some of the programs we are a part of have smarter and more aware standards than others.

The reason I said “non-low-income” is that most of the homes Pure Energy Coach LLC tests are low-income homes. So we’d love to find out if homes occupied by non-low-income folks are as bad (poorly maintained HVAC; landlords who don’t care; and old atmospheric draft systems that are easily overcome by unbalanced building pressures, including what the neighbor in the next apartment is doing.)

© Emmanuelle Guillou - Fotolia.com

Creating Healthy Manufactured Homes

Our Illinois organization, Mobile Home Owners Association of Illinois (www.mhoai.org), works with HUD to improve the installation and maintenance of manufactured homes, as well as seeking improvements in legislation.

Air quality is an issue that began with a number of heat exchanger failures in Coleman furnaces that the manufacturer said was faulty airflow due to negative-pressure problems. Conversations with government agencies suggest the addition of a 4-inch duct for outside air input. Is there a product solution that would resolve this issue?

There are two major types of home installed in Illinois—those with cold-air return ducts and others using a natural gravity-fed return to a louvered door. Is there an energy recovery ventilator product for these homes?

Phil Schelinski
MHOA
Springfield, Illinois

Executive Editor and Lawrence Berkeley National Laboratory research scientist Iain Walker replies:

There are three separate issues here.

1. Restricted airflow is leading to heat exchanger failure. This can be fixed by using less-restrictive supply and return ducting.
2. The 4-inch outside air duct is for ventilation. These ducts are generally inadequate, because they have insufficient flow when operating and only bring in outside air when the furnace runs and not at other times. It would be hard to get them to meet the national minimum standard for indoor air quality: ASHRAE Standard 62.2. But they can be made to work in some situations.
3. An energy recovery ventilator (ERV) is designed specifically to provide adequate ventilation air by bringing in outdoor air and exhausting indoor air simultaneously. It also exchanges heat between the incoming and outgoing air—thus saving energy for heating (or cooling). It is highly likely to meet ASHRAE 62.2. Some are stand-alone, with their own duct system. Others connect to the furnace ducts to distribute ventilation air—in which case they often operate the furnace blower (whether the furnace is heating or not). Note that an ERV exchanges heat and moisture. A heat recovery ventilator (HRV) exchanges heat only. Which one you pick is determined by whether or not you control indoor humidity—with a dehumidifier in summer or a humidifier in winter. If you do, an ERV may work best. But most of the time, an HRV is a good solution.