Hi There;

I have a huge house to do soon, and the only heating source is radiant. My job is to compare surface temperatures of the regular vs. bermed perimeter walls, and check for insulation voids. There will be no blower door test, as the owner is concerned about pulling in mold (he's bermed in on the west side, near a seep, and last year had mold in his ductwork).

To get a good Delta-T here in Northern California, seems I should go in two hours before the warmest part of the day, turn on the radiant heaters and let them go for 2 hours, then shut them off and wait about a half hour before shooting. Over that period, the outdoor temp will have dropped only 6F.

Does this sound like a reasonable plan for getting at least a 10F Delta-T?

Thanks!

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Lorna Fear
(650) 520 4869
San Francisco Bay Area
Visual Cue Thermal Imaging
http://www.infraredmagic.com

The standards call for a stable 18F temperature difference (delta-T) between the interior and exterior WALL SURFACES. Clearly good work can, in many instances, be done with less delta-T than this. Exactly how much is required for the framing and insulation and air leakage to show up depends on several factors including the wall construction details, how long things have been at steady-state, exactly how the heat (in your case) is applied and the camera being used. 

I'm not sure what kind of radiant heat they have (hydronic floor or electric ceiling) but  suspect you will have good results after a couple hours of it being on. You may need to turn it off and wait another 30-60 minutes, depending on which type, to even out any non-uniform heating. I would also think it might be better in the COOLEST part of the day/night and would aim for doing this early in the morning rather than the hot afternoon. Certainly on the areas that are bermed you should get good results as the "exterior" will be very stable at ground temperatures. You may also not get it right the first time!

Since air leakage is always an issue in buildings—I've yet to see a perfect one!—consider pressurizing the building and using a combination of thermography on the exterior (not always perfect but still useful) and a smoke pencil on the interior which works very nicely. Often less of a temperature difference is required to locate air leakage but use the blower door only after you've done your conduction inspection.

What about moisture? With berms it is something I'd be on the outlook for. Good luck. Let us know how it  all turns out. 

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Thermally Yours,

John
ASNT NDT Level III #48166
The Snell Group
www.thesnellgroup.com
www.thermalsolutions.org
800-636-9820

I struggle with Delta T. I am in San Diego so the whole city is one big conditioned space at most times of the year.

I have found that the heat will escape so quickly out of uninsulated walls coupled with inadequate roof insulation and a leaky envelope which are common in my area: if I wait a half hour for stabilization I have lost my delta.

I will image as soon as the heat turns off and get images of the same areas over the right after heat and stabilization period and compare the images. I find that often my best images are right after the heat has turned off. There are ghosts that are not worth chasing thus imaging the same area twice

Outside Imaging can be difficult due to the lot sizes in my area. It is tough to get far enough away at times. That and my dew point is fast and hard. It arrives soon after sunset and stays the whole night through often.

Space heaters have worked in a room by room basis to accelerate the existing heat.

I would agree with a Blower door pressure test. I use the smoke pencil for customers that have the same concerns as yours. I would almost insist on it as the tool has capabilities the camera does not.

Glen

Hers Rater, Level I training, Energy Auditor San Diego California

http://www.rede3.com

Glen, glad to hear you are having some success. I know your situations are very challenging. I've had some good luck "painting" the wall with a quartz work light too. No need to heat the whole room but just an area on the wall. The %$(*& are HOT to handle and it is not always easy to get a uniform heating but using them can really make a difference for limited areas. 

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Thermally Yours,

John
ASNT NDT Level III #48166
The Snell Group
www.thesnellgroup.com
www.thermalsolutions.org
800-636-9820

You might want to also check out a water based fog machine for the pressurize application.  It works really well in ducts as well, where IR cannot always get to, and where low E targets are prominent. 

Do your research as to what the smoke pen you are about to purchase is actually made of (not all of them use the following technology).  One common chemical used in these things is titanium chloride.  It is a corrosive, harmful and possibly fatal if ingested, irrites the eyes and skin, toxic by inhalation and inhalation may cause lung damage (what happened to IAQ in energy auditing?).  And that is just the good stuff.  It can react violently with water.  It normally comes in a vial that is then packed with some sort of cotton (or similiar) wrap.  It is broken on the inside of the device like a light stick.  In a humid environment that cotton wrap could potentially become a storage device for moisture, 2 + 2 = pop!

JJ 

If the only sourse of heat is radiant- then I assume the ductwork is only for cooling?

If this is the case then is the mold from condensation in the duct work ,that may not be insulated? Is the unit ac only ? is the fan on or auto?

need more info on the unit- there is an easier way if I knew the mechanical system layout.

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John Cannamela
ASNT II Vibration/ Level II Thermographer
HVAC Journeyman
Owner ISC Building Diagnostics
http://www.infraredsurvey.com www.iscbuildingdiagnostics.com
jc@iscbuildingdiagnostics.com

Hi everybody;

Thanks for your input. Would post some images, but didn't see a quick way to do that. I did my work late at night and got good Delta-Ts. Thanks, John.

The site is a steep and narrow, wooded canyon.This house is about 4,500sf, built down from the crest, facing North and you can walk under two of the three levels -- but the area isn't open enough to allow adequate air circulation. Instead of sitting on stilts, the house sits on a cinder block wall built up against the hill.

Regarding smoke pencils, they aren't stocked anywhere nearby, as far as I can determine. They seem to be available only online. I started to try using incense, but thought the odor might stick around and offend the homeowner.

The HVAC ductwork had been under the house, running along the hillside. It seems to have been removed. All the registers and returns are now covered over with plastic and painter's tape.

Heat is provided by close to two dozen portable radiant heaters, many of them bearing the name of a well-known home performance contractor whose specialty is sealing crawlspaces. I turned them off an hour before capturing images.

The walls looked pretty good, which is typical for high-end construction in this area. Still a few old double-hung windows down in the wine cellar. Lots of displaced and degraded insulation. And that cold, damp hillside will pull away all the heat you can give it. 

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Lorna Fear
(650) 520 4869
San Francisco Bay Area
Visual Cue Thermal Imaging
http://www.infraredmagic.com

When inspecting my residential units I scan all electrical panels that I can put a load on and struggle some times getting a good delta T when the panels are outside at the meter or in a garage with the ambient below 30 degrees. Unless I can apply 50 amps or more to the panel there is just not much visible. Here is a couple of shots from a garage panel yesterday with the outside ambient around 30 degrees

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CMORE Thermorgraphy Level II
http://www.oklahomathermalinfraredimaging.com/
http://www.freedomexpressinspections.com/
Commercial Inspections Thermal Imaging, Mechanical, Structural, Oklahoma, Kansas, Missouri, Arkansas,Texas

A close up of the Main breaker

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CMORE Thermorgraphy Level II
http://www.oklahomathermalinfraredimaging.com/
http://www.freedomexpressinspections.com/
Commercial Inspections Thermal Imaging, Mechanical, Structural, Oklahoma, Kansas, Missouri, Arkansas,Texas

I don't look at residential panels for this reason. There is too much liability to make any recommendations on house panels because it is too difficult to get a load on them.

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Jeremy Kays Reliability Technician
Level II IR, MCA / UE Level I, In Compliance with the ASNT guidelines
X-Ray Eyes
xrayeyesjl@hotmail.com
www.xrayeyesonline.com

Between the A/C unit electric cook top/oven and sometimes a water heater I can usually acquire a decent load. Especially on a oven with as much use as it gets I find a tremendous amount of loose lugs/connections that would other wise not be detected during a standard visual inspection. I get a lot of referral work because of this. I personally don't worry about liability it goes with the job

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CMORE Thermorgraphy Level II
http://www.oklahomathermalinfraredimaging.com/
http://www.freedomexpressinspections.com/
Commercial Inspections Thermal Imaging, Mechanical, Structural, Oklahoma, Kansas, Missouri, Arkansas,Texas