Comments on: Are We Off Track With Combustion Safety Testing?

By: Bruce

Bruce — Fri, 28 Feb 2014 20:23:23 +0000

A lot of information to be
A lot of information to be sure. thanks to all.

If the CAZ test is too involved, not involved enough just go in and
A: recommend a CO monitor
B: All sealed combustion appliances
C: Electric water heater

Save the angst of the CAZ test and apply the savings to the selected remediation.

By: kyle

kyle — Fri, 28 Feb 2014 14:40:20 +0000

Regarding CO monitors/alarms:
Regarding CO monitors/alarms: where should they be located? Low, near the floor, or high, near the ceiling? Should they be located near a combustion devise, or near bedrooms? Should they be battery-powered or hard-wired or both? If using multiple monitors/alarms, should they be interconnected?

By: Andy Kosick

Andy Kosick — Thu, 27 Feb 2014 09:51:19 +0000

Having just sat through two
Having just sat through two sessions at the RESNET conference with the folks from LBNL (whose work I deeply appreciate) I think the problem is that their conclusions are getting lost in all of their wonderful data. What I gathered is this, do the tests and understand the problems, but stop worrying as much about getting a combustion air inlet to a water heater when it probably won't solve the depressurization issue anyhow and start making sure the range hood gets ducted outside and actually used. In others words lets spend more time addressing the things that are actually causing problems and less time meticulously testing things that are not. We auditors have a limited amount of time with our customers, LBNL wants to make sure we use it to do the most good.

By: Jim Davis

Jim Davis — Tue, 25 Feb 2014 07:27:02 +0000

John, the original comment
John, the original comment above seems to say that but that doesn't matter because it has created a good conversation.

Depressurization testing is necessary but it is not really done correctly, and is misinterpreted as what appliances can withstand. I read lots of useless theories that seem to think things behave in a fixed manner.
Another problem I see is that we say you have a problem. What problem? You failed the depressurization test. How do I fix it? You fix the problem. What problem? The problem that caused the depressurization test to fail. What cause it to fail? The problem. What problem? The problem you need to fix. Fix what? The problem. I could go on forever with this but I think we might get the point.

It might not be you John but I do hear many others make the comment that safety testing is too time consuming and may even cost us work.

By: Michael

Michael — Mon, 24 Feb 2014 17:20:56 +0000

Did everyone forget why the
Did everyone forget why the test was developed in the first place and the massive study that followed? CEE demonstrated the very high number of homes that were back drafting before any energy improvements had been made to the home. We've since documented thousands of homes with combustion spillage and occupants who had potentially related health issues.

We need to take a do no harm approach to homes, and rather than quibble over deaths and levels, focus on removing atmospheric venting and open combustion appliances from our homes.

By: John Krigger

John Krigger — Mon, 24 Feb 2014 07:07:26 +0000

I don't advocate and never
I don't advocate and never have advocated neglecting CO testing. I only question whether worst-case depressurization testing is effective in reducing the risk of CO poisoning. I have stated that opinion many times. I have never advocated neglecting or reducing the importance of CO testing. My last blog post on the importance of effective combustion testing was on 1/5/14. The post recommended simplifying the procedure and relying more on observations and a complete electronic combustion analysis. You can read about what I consider effective combustion safety testing by following this link:

By: Jim Davis

Jim Davis — Mon, 24 Feb 2014 06:55:43 +0000

Allison, comment about
Allison, comment about combustion testing was in reference to John Krigger who has said this more than once and should know better.

The majority of CO poisoning and deaths occur from appliances that aren't venting correctly, not necessarily backdrafting. As said before and I think BPI agreed "Worst case testing is not Worst case".

If CO is spilling into the space so is CO2. CO2 will be in the 10,000ppm range. CO2 displaces O2 rapidly, so if you are spilling, backdrafting etc. COppm will accelerate.

My students find thousands of CO problems every year that go unreported. Worst case depressuriztion is rarely the problem. To the credit of the Home Performance people, they are probably doing more CO testing than HVAC contractors. Our industry still doesn't require it most of the time.

I will be glad some day when checking the pressure of the flue during worst case (as is case) gets implemented. That is the only pressure that is important. Any interference there is unacceptable.

Low level CO detectors were available before the UL2034 was written. But because of the nuisance they caased fire departments and utilties the detectors sold in stores were raised to higher levels to assure people were poisoned before they went off. I just hope the ones that are currently available don't cause the same problem.

By: Jim Maletta

Jim Maletta — Mon, 24 Feb 2014 04:05:48 +0000

I believe there needs to be
I believe there needs to be some improvement in the CAZ limits and the worst case depressurization testing procedures. Over 15+ years of doing these tests in thousands of houses I have repeatedly encountered situations where CAZ limits as per BPI protocols will be exceeded but the gas appliance(s) will pass the worst case test. In doing in-field testing for BPI candidates I have observed multiple test candidates testing the same house on the same day and having multiple sets of test results. There are variables at play here such as wind, humidity levels, and possibly even barometric pressures as weather fronts move through an area which I believe are not adequately accounted for in the test protocols. If it cannot be scientifically replicated then the test is dubitable. I do not advocate throwing out the test, but I do advocate not making the CAZ depressurization limits in themselves an actionable item UNLESS the gas appliances themselves fail to draft adequately. As to the comment about trip hazards, I look at it this way; I am in the house to help my client solve a problem without making more problems in the process, BUT I am not there to save them from every last hazard in the world. My focus is on my particular speciality. That does not include trip hazards. I am enough of a clutz some days to know that none of you cvould save me from myself!

By: Jon Traudt

Jon Traudt — Sat, 22 Feb 2014 22:22:07 +0000

A typical chimney cap, or top
A typical chimney cap, or top, is designed to use the Venturi effect to increase suction and pull the combustion gasses up and out when the wind is blowing. Air pressure in a building is often higher when the wind is blowing because wind typically pushes more air in through the upwind side than it sucks out of the downwind side. Both of these factors help to explain why carbon monoxide poisoning is more common when there is little, or no, wind.

By: Dale Sherman

Dale Sherman — Sat, 22 Feb 2014 19:09:38 +0000

Allison ,
Allison , Thanks for the clarification. Part of my response is probably due to the recent simplification of BPI's BA field testing for WCD CAZ testing.

Dr. Rapp, Thanks for your succinct response. I agree there is more we can do to ensure safe operation of atmospheric combustion appliances, and I applaud LBNL for taking this on.

I submitted a list of CAZ testing strategies to BPI in response to their draft BA standard, yet the end result was a less comprehensive CAZ test protocol.

I think between skilled field personnel and LBNL scientists, CAZ testing can be improved. There is a lot of practical knowledge being applied in the field that does not make it into any literature, but would be helpful to Dr. Rapp and others in improving our testing procedures and improving our solution strategies.

I look forward to the sequel to this blog, and the next chapter of CAZ testing.

Dale