Drilling through a flue pipe of a power-vented combustion appliance

Here is a dilemma for a BPI-certified building auditor - should I or shouldn't I drill through a flue pipe of a power-vented combustion appliance? At first it seems obvious - don't. The BPI standards state that clearly. However, in the industry I see a number of people do that anyway. And even one of the best demo videos of combustion safety test performed by a BPI certified guy you can find online shows him drill through it in TWO places, without even a sign of doubt or concern on his face. Also, some government financing programs require you to gather that data that you can't get otherwise (sticking the probe from the outside into the chimney is not an option).

Another question I see coming up is - since there is fan pushing those combustion gases out, wouldn't the pressure in the flue pipe be greater than the CAZ pressure?

Would appreciate your experience on the matter.

▶ Reply to This

Replies to This Discussion

Permalink Reply by Chris Peters on March 11, 2011 at 11:17am

I guess I can't see why one cannot go outside and test at the vent terminal. Then there is no question about drilling PVC vents. I'll sleep better that night knowing that I didn't drill a hole and leave a compromised vent which could have the potential to fail and cause an indoor air quality issue at some point in the future.

▶ Reply

Permalink Reply by Eric Aune on March 14, 2011 at 1:49pm

Blaine & Chris have noted what should have been obvious to anyone considering testing mechanical equipment. Although many states may not require licensing for this procedure one should not attempt without the highest confidence and training. If you are not sure how to go about testing, what are you going to do with the results when they show that adjustments to the burner, gas valve or venting need to be done? I suggest hiring a competent service tech, leave it to the appliance professional.

▶ Reply

Permalink Reply by Chris Peters on March 14, 2011 at 4:03pm

Eric, I am BA, Envelope and Heating BPI Certified. I have quite a bit of experience in HVAC. Some of the adjustments I could make, or I would either refer the homeowner to a HVAC tech or provide a service tech for them if it was a unit that I did not feel competent to repair. In NY where we have a very active Home Performance programs running, this has not been an issue or should it be. There is a great difference between placing a probe in a flue gas stream to measure vs. making repairs and/or adjustments.

To get back to the topic, BPI appears to be against the idea of drilling power vented (CAT IV, PVC vent). The reasons to not drill are the same as why the radon fan is outside the house and the pressurized part of the system is not allowed to go through living space.

▶ Reply

Permalink Reply by marshall minshew on March 14, 2011 at 4:40pm

I agree with you about the confidence and training. I'm unclear on what level of combustion testing you would advocate for the BPI BA or Shell/Envelope person and if the current standards are allowing too much. The scenario you gave (assuming compliance with the current BPI standards) about the testing results is addressed in the BPI standards Adjustments, if required to be part of the work-scope, are required to be performed by a Heating, AC/Heat Pump, or other applicable BPI-certified person or, if performed by a non-BPI-certified applicable specialist, it must be approved by the appropriate BPI-certified specialist. In other words, the BA and Shell guys are required to enlist the services of a more qualified professional.

I think the theme here is what should and what shouldn't the bazillion auditors out there be testing. Everybody is trying to get on the same page about even the requirements of the existing standards. As new standards come out and existing ones (hopefully) evolve, we need as much consensus on the do's and don'ts. Surely we can come up with acceptable boundaries that will be safe and beneficial for all concerned.

As a BA and Shell/Envelope certified person, I don't drill PVC, B-vent, stainless steel or any positive pressure venting system. I am still concerned about potential results of missed testing opportunities and wish there was an approved procedure that would allow the testing. The limitations of many scenarios prohibit some folks from accessing the exterior vent openings; ladder or roof work may be necessary and not possible due to weather or other liability concerns.

I find it hard to believe that resealable test ports are not a requirement for all installations. Wouldn't this be better for everyone?

▶ Reply

Permalink Reply by David Meiland on March 14, 2011 at 7:25pm

As far as I can tell, the intent of the BPI standard is to determine whether or not there is negative CAZ pressure, and whether or not atmospheric draft appliances are burning cleanly. Checking out typical 80% equipment is quite easy and I don't think it creates any issues. If TWO things go wrong--a vent that's being backdrafted, AND a burner that's emitting a high level of CO, you have a possible disaster. With newer sealed combustion equipment the likelihood is very low, but there can still be issues.

▶ Reply

‹ Previous
1
2
Next ›

RSS

Welcome to
Home Energy Pros

Sign Up
or Sign In

Or sign in with:

Home Energy Pros

Home Energy Pros was founded by the developers of Home Energy Saver Pro (sponsored by the U.S. Department of Energy, under the American Recovery and Reinvestment Act) and brought to you in partnership with Home Energy magazine.