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: 55

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

Videos

  • Add Videos
  • View All

Latest Activity

Joe Davis liked Wayne Melancon's discussion What's the Most Profitable HVAC Job for Your Company?
1 hour ago
Joe Davis replied to Mary Sinkler's discussion Lighting replacement - 300 watt LED flood light
"Well said Dennis, try a lighting calculation for the space you need."
1 hour ago
Chris Laumer-Giddens's blog post was featured

Rock Wool Insulation for Floor of High Performance Tiny House

ROCK WOOL INSULATION FOR FLOOR OF HIGH PERFORMANCE TINY HOUSEIn August of 2016, we posted a video…See More
5 hours ago
Horace Douglas Hunt, Jr. joined Tom White's group
Thumbnail

Weatherization

Share your concerns and successes as a weatherization professional, or information for this…See More
7 hours ago
Horace Douglas Hunt, Jr. joined Sean Lintow Sr's group
Thumbnail

Best Practices (Residential)

Best Building, Retrofitting, or even Auditing Practices - what are they, what should change, what…See More
7 hours ago
Horace Douglas Hunt, Jr. joined allen p tanner's group
Thumbnail

Energy Auditing Equipment for Sale, Trade or to Purchase

Discuss the pros and cons of the equipment you are interested in prior to purchase. Post equipment…See More
7 hours ago
Dennis Heidner replied to Mary Sinkler's discussion Lighting replacement - 300 watt LED flood light
"Have you looked how much light you need in the backyard and where you need the light?  Often a…"
19 hours ago
Nate Adams liked tedkidd's discussion Home Performance is Failing - let's turn that around?
23 hours ago

Home Energy Pros

Welcome to Home Energy Pros – the unique digital community by and for those who work in the home energy performance arena.

Home Energy Pros was founded by the developers of Home Energy Saver Pro (supported by the U.S. Department of Energy) and brought to you in partnership with Home Energy magazine.  Home Energy Pros is sponsored by the Better Buildings Residential Network. Please honor our Guidelines

© 2017   Created by Lawrence Berkeley National Laboratory.   Powered by

Badges  |  Report an Issue  |  Terms of Service