I got this email from a QA program manager. Looking for feedback. Thanks

 

 

I have a question for you I'm hoping you can shed some light on.

How are we supposed to proceed with getting combustion and worst case depressurization numbers from an area that is inaccessible?

I just ran into this situation over at customer's home with a tankless water heater on his second floor.
The only option to get a flue gas sample is to set up an extension ladder in an alley which doesn't have clearances that are proper for an extension ladder.

Look forward to hearing how you would proceed on this.

Views: 24

Replies to This Discussion

 

You should be able to access the room where the water heater itself is located.  Otherwise if it is in some kind of sealed off space, then it probably doesn't meet code requirements.  So you should be able to do a worst case depressurization test on the CAZ.  Although since it is sealed combustion, it is probably not a big deal. 

 

I think a lot of programs will waive requirements to get a CO reading on the flue gases if the appliance is condensing and/or sealed combustion, and the flue vents out the roof and is not easily accessible. 

 

I'd agree w/ the previous post. When going for a worst case test, you only need to measure presssure difference in the CAZ WRT outside. I'm figuring you can get into the CAZ. If required, Measuring exhaust gas for CO and efficiency on a sealed appliance is done from the outside according to most, though several well known pro's will drill the PVC pipe and sample from there, then seal the pipe with fire rated caulk.   
Thanks folks. The culprit here is an older tankless that is not sealed combustion.

If the tankless water heater is not sealed combustion, then it could be either power vented (one PVC pipe), induced draft (inducer motor and metal pipe), or natural draft (with draft hood).  I am not comfortable drilling a PVC pipe to measure CO, but some will drill it and seal it with silicone caulk.  A metal pipe for an induced draft appliance can be drilled and plugged with a metal plug or taped with metal tape.  If it is natural draft, you can measure the CO by putting the probe down in the heat exchanger from the draft hood.

This is what we do:  The Standards are clear:  No air sealing, dense packing more than 15% of the shell area, duct sealing outside the thermal envelope, if you cannot complete the or combustion testing protocol.  So, if we cannot test all the appliances that might be affected by modified house pressures due to air sealing, than we don't recommend air sealing.  More accurately, we explain the issues on the work order and customer report.  If we get full access to the entire building, so we can create worst case conditions in all CAZ's, and we can test to the Standards, then we include air sealing on the work order (if apporpriate).   Also... yes, we've climbed ladders to take samples from flue gasses... but of course we prefer to drill and fill where allowed!

RSS

Home Energy Pros

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

Latest Activity

Profile IconSharon DeRidder, Jason Hiep, Chris Chmiel and 4 more joined Home Energy Pros
29 minutes ago
John Watson Ley replied to Luis Hernandez's discussion Distribution Efficiency and heating safety factor in TREAT in the group TREAT Software
"Luis, Good Evening, John of NY Construction Pros here. I don't think you need to worry about…"
12 hours ago
Mike Kandel added a discussion to the group Building Performance Institute (BPI)
Thumbnail

BPI Introduces IDL Certification for Duct and Envelope Tightness Testing Verification

Expand your knowledge, expertise and opportunity with BPI's BRAND NEW Infiltration and Duct Leakage…See More
16 hours ago
Mike Kandel posted a discussion

BPI Introduces IDL Certification for Duct and Envelope Tightness Testing Verification

Expand your knowledge, expertise and opportunity with BPI's BRAND NEW Infiltration and Duct Leakage…See More
16 hours ago
Kurt Shafer replied to Kurt Shafer's discussion Where can I find the best radiant barrier to install under my roof?
"Tom, I would like to see that article. Where is it? And what kind of radiant barrier could cost so…"
19 hours ago
Hal Skinner replied to Kurt Shafer's discussion Where can I find the best radiant barrier to install under my roof?
""On a RESNET discussion some insulation experts agreed that insulation will not prevent hot…"
20 hours ago
Tom White's video was featured
23 hours ago
Adam Swain's blog post was featured

Top Worst Crawl Space Insulation Ideas

With winter right around the corner, many of us start looking at various ways to reduce heat loss…See More
yesterday

© 2014   Created by Lawrence Berkeley National Laboratory.

Badges  |  Report an Issue  |  Terms of Service