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: 53

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

Twitter

Latest Activity

Alfie Davis posted a blog post
2 hours ago
Profile IconAlfonso Scott, Susan Benford, HomeWiz and 2 more joined Home Energy Pros
14 hours ago
Hannah Wood added a discussion to the group Building Performance Institute (BPI)
Thumbnail

Healthy Home Evaluator (HHE) certification + recorded webinar

Thanks to those of you who joined BPI's webinar on the Healthy Home Evaluator certification…See More
14 hours ago
Michelle Usher posted a blog post

Addison Homes Wins Pinnacle Award for Best Achievement in Energy Efficiency

Addison Homes was amongst the home building industry’s best and brightest honored with a 2016…See More
15 hours ago
Eric Kjelshus replied to Beverly Lerch's discussion Fireplace drafts
"A brick chimney will take some 70,000 BTU's to heat up to draft on a fireplace.   A…"
yesterday
Ed Voytovich replied to Beverly Lerch's discussion Fireplace drafts
"Our solution was to install a Lopi Answer wood burning insert that vents directly through a metal…"
yesterday
Jim Gunshinan's blog post was featured

A Healthy Home and a Healthy Bottom Line

There has been a lot of interest of late in the weatherization and broader home performance…See More
Monday
Jonathan Beers commented on Home Energy Magazine's blog post Natural Gas is Becoming Less Attractive
"The carbon intensity of electricity use (lbs. of CO2/MWh) varies a lot from region to region. For…"
Monday

© 2016   Created by Lawrence Berkeley National Laboratory.   Powered by

Badges  |  Report an Issue  |  Terms of Service