Some cold weather thermoscans

[peakbagger]

I got up to early to feed the boiler, with minus 21 degrees F outdoor and gusting winds, even my 30 year old house heat demand exceeds 500 gallons of hot storage. I was up so I figured a good time to take some shots with my Flir Thermal Camera as the bigger temperature difference between the outdoors and indoors lead to better resolution. The house was at 62 degrees on the T stat located on an interior wall.

The display is pretty simple,the upper left is the temperature of the target in the center of the screen. The bar on the right automatically adjusts to the highest and lowest temperature in the room and assigns colors. The coldest temp is the lower right the highest temp is the upper right. This bar will change for every shot.

First shot is outer wall that I had redone at one point. Its 2 x6 framing with closed cell foam sprayed in the cavity on the exterior wall and then the balance is insulated with slightly compressed 6" fiberglass with a 1/2" sheet of isoboard foil faced foam on the interior covered with 1/2" sheetrock. Interesting thing to note is the drywall nailheads are still conducting heat despite the foam but the studs are not visible. Also note the wall outlet, its the coldest spot despite my attempting to insulate it well when I redid the wall. The big lesson is I need to air seal the exterior plywood walls which were not sealed. The house is farily tight with stack effect from the boiler and the house in general so air is being pulled in through the cracks in the outside and finding their way in through the outlets.

Next one is a window in the same wall, its a fixed casement type window with a double cellular shade that has splined side tracks on the sides but not on the bottom. The shift in color from bottom to top is classic convective flow, the shade is 3 or 4 inches from the outside window, so heat rises from the bottom of the inside of the shade then rolls to the inside of the window glass where the air cools and drops down then loops back up again spilling some cold air to the room out the bottom. The blue spot to the upper right is my minisplit (see next one)

This one covers a lot of points. The minisplit is not running but the minisplit tubing is acting to conduct cold air into the room. I did the install and the hole through the wall is insulated around the tubing so my guess is its just being conducted in through the tubing. Note the corners, the house is conventionally framed 30 years ago, wood conducts heat far better than fiberglass or the cold so areas like the top of walls and corners of the house are going to be colder. The exterior wall to the right of the corner is the original house, fiberglass insulated 2x6, no foam. You will note the stud line is obvious. The impact of the minisplit tubing is also very apparent.

And now my "walk of shame", the front door had a rotted sill due to poor flashing at the factory and the door frame was rotted out. Its a custom size and I needed something, so I hacked in standard door and temporary filler. Work and Covid happened, and I did not get around to ordering a new front door. It does have a tight outside glass storm door for the door portion but the side light does not. Definitely on the "to do " list this spring since I am now retired and the supply chain is bit more functional. Note to the left of the door, is looks like a lot of framing cold spots. The window opening to the left is a large triple angle bay window with double hung windows. I have a double cellular blind with side tracks covering the entire opening. it really cuts down on drafts. I am considering doing the same retrofit, remove drywall, than flash and batt the cavities then cover with 1/2" isoboard foam before drywall.

Looks like its time for bathroom ceiling renovation. The exhaust fan was replaced with an "energy efficient" Panasonic unit several years ago but they reused to vent to the outdoors under the sealed soffit. There is backflap at the fan but cold air from outside runs inside the ceiling to the fan case. There is also a triple corner in the back over a bathtub. I wonder if there is also a potential for compromised insulation from moisture from the bathtub. I have considered removing the tub and replacing it with a large shower and that would allow access to the rear walls.

Of all my windows on the finished first floor, only one does not have cellular blinds and its over my kitchen sink. Its prone to splashing and these blinds are not readily cleanable. The other thing to note is there is a can light over the sink. The builder had built a false panel over the cupboards and continued it across between the cabinets but its obvious that cold air is either leaking into this area or there are insulation issues.

As I mentioned the house is modular built in factory in two lower finished sections and lifted in place with crane. Therefore the framing is pretty beefy along with "gluing" the drywall in the ceilings to the ceiling joists with closed cell foam. Modern super energy efficient homes are being framed up with far less wall framing especially on the gable ends. This requires more design than a typical framed home where a framing crew works off plan with wall opening dimensions and they use standard framing techniques. This goes quick but the end result is more heat loss through the wall.

The house despite its flaws is far tighter than most houses in the area despite being 30 years old. The towns in the area do not typically inspect residential homes and require the applicant to self-certify the design, the net result is contractors and homeowners ignore the state residential energy codes. I use 3.5 to 4 cords to heat it in a Zone 6 area with a Mini split for shoulder season. Since I cut and split my own wood of my own property, it would be hard to justify a full energy retrofit on an economic basis. I do need to deal with siding on two sides of the house that needs to be replaced so that means I could air seal those walls with lots of zip tape and then install continuous builders wrap prior to installing the new siding. If I wanted to go extreme, I would extend out the window jambs and then install a couple of inches of vapor permeable wood or similar insulation board on the exterior of the house. That would solve a lot of the corner and stud issues. I am borderline on air changes as it is so I would probably also install and ERV to bring in controlled fresh air and drop the pressure difference between the outside and inside.

Then again. I could build a new house and use all the things I have learned to build one far more efficient.

BTW, this is higher resolution camera than a typical one but even lower resolution units like the ones that plug in cell phones, give useful info. Home Depot rents them by the hour or the day and I expect if someone is looking for the biggest bang for the buck, this is good method once they have taken care of the obvious air leaks which are best located using a blower door during an energy audit.

 

[KDubU]

This is brilliant! I can’t believe I have not thought of getting a thermal camera and then truly knowing the issues with this house. Your door does look like it’s a problem child but we all have spots like that in our homes.

Now to lookup the price of a Flir Thermal Camera!

Edited to say I just read your HD comment. I did not know they rent these. Good idea.

 

[peakbagger]

Its better than a X ray. I needed one with a bit more resolution for work but the lower resolution units work pretty well. The FLIR images tend to be bit clearer as they superimpose a video image on top of thermal image.

 

[semipro]

I have an older dedicated FLIR imager. I think I'd go this way now though.

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[peakbagger]

BTW, the Flir and the Seek cell phone plug in units show up on Amazon Warehouse quite often with some savings.

 

[Poindexter]

This is great info, appreciate your honesty.

I have some questions.

For minisplits, how long can the tubing in the wall be?

I wonder how soon the NEC will stop mandating electrical receptacles on exterior walls.

Are you planning to get some exterior pics when it warm enough to be out there safely?

 

[EbS-P]

Nothing too surprising. I guess that’s good. Here is my biggest surprise and I’m not sure how to address it.

The sub floor is 1 by laid on the diagonal. It’s got a 1/4-1/8” gap between planks. When I insulate the rim joists each gap need filled. Many are smaller than canned foam applicator tip. Found another bug leak note to self tell hvac contractor to seal up all ductwork penetrations really well.

I have the FLIR one phone attachment. Is decent for the price. The resolution and contrast are not as good as what the OP posted. This is what mine look like.

 

[peakbagger]

Typically, minisplits are set up for some predetermined length of tubing as the volume of the refrigerant has to be adjusted for tubing length. There is some flexibility but at some point, the volume needs adjustment. I think the minimum length is really practical, it is the distance from the connections on the side of the unit to inside minisplit unit. I would not recommend that for a typical framed structure, as even with vibration pads there could be sound transmission from the outdoor unit. Getting the unit down lower closer to the bottom of the wall reduces that vibration but its got to be balanced with keeping the outdoor unit above snow depth. Unless someone is in an area with little of now snow, I do not recommend mounting them on the ground, but I see a lot of commerical installs done that way that implies that they are only using them for cooling as they are full of snow in the winter. I also see a fair share of commercial installs line up with the drip line off the roof.

Yes, I do plan to do some external scanning but I think getting the internal scans are more important from a dewpoint consideration. Mold only forms when warm air hits a surface below dewpoint. Heating with wood my house is dry but a bathroom is exception. I take short showers and dont think I have ever used the bathtub in 30 years so expect that humidity getting into the walls is not a major issue but someone with a large family with folks who like long hot showers, it could be a bigger issue. In general, the heat loss patterns from the outside of a building tend to be diffused by the outer layers of the envelope which means the actual source would be obscured. Finding that exhaust fan and duct issue would probably not show up from the outside. Same with the outlets. Practically I would rather deal with the cold spots on the interior as that is comfort issue for more than a heat loss to the outdoor.

I think the exercise is illustrative of using the conventional carpentry and finish approach compared to the recomended energy efficient/Passive home approach. There is more up front design and detailing with either and less dependence on field decisions. There is also third party continuous inspection. With a super tight envelope, small air leaks can lead to air infiltration and potential dewpoint issues. My house was built in a "factory" in controlled conditions 30 years ago by a higher end firm (featured on This Old House a few times), yet it is obvious that compromises were made. Trades like electricians, plumbers and HVAC are infamous for ruining envelopes, unless someone is chasing them around with caulking and other sealing products, they are big contributor to not being able to meet a tight blower door test. That is not to say its bad construction as least its built to code. In my area of mostly rural small towns, residential is not inspected and the local contractor employees tend to be self taught. There is big market for second homes and the higher end profitable contractors (usually LLCs) are real good at building good looking homes but they scrimp on the hidden details as no one is looking. I know of more than a few great looking homes in the area that have significant flaws in their envelopes, I dont need a thermal camera, I can see the pattern of snow melting on the roof and the significant icicles. There is brand new home which should have built to NH energy code just down the road from me. I go by post snow storm and I can see different snow depths where heat is leaking out through the roof. No way does it meet the required minimum state code https://www.puc.nh.gov/EnergyCodes/Ecforms.pdf , but with no local inspection, certificate of occupancies or third party inspection, the home owner is clueless that their energy bills are going to be much higher than it needs to be for the life of the building.

 

[peakbagger]

Nothing too surprising. I guess that’s good. Here is my biggest surprise and I’m not sure how to address it.

The sub floor is 1 by laid on the diagonal. It’s got a 1/4-1/8” gap between planks. When I insulate the rim joists each gap need filled. Many are smaller than canned foam applicator tip. Found another bug leak note to self tell hvac contractor to seal up all ductwork penetrations really well.

I have the FLIR one phone attachment. Is decent for the price. The resolution and contrast are not as good as what the OP posted. This is what mine look like.

View attachment 309205

Do not get me wrong, the plug in units are perfectly fine with high enough resolution for building construction. I had potential use for higher resolution for work so I got to write it off as an expense. Once out of the commodity grade chip category, the chips are grades post manufacture (similiar to computer processors, the ones that test out good get sold for one speed while the ones that do not test out as well are sold for a lower speed. Folks have figured that out, the place I bought mine had an almost identical model with the same resolution for considerably less cost, they had hacked the software and were running it over its rated resolution. Definitely not under factory warranty and they included a caution to never upgrade the software. For business use not a great decision but for home use probably a good one.

 

[woodgeek]

I borrowed a FLIR from work last year, and did this from the outside on a windless winter morning before dawn.

My whole house looked dark (the windows a little warmer) and the foundation and basement block walls were all lit up like a XMas tree.

I was hoping to find holes/gaps in the framing insulation, but saw none. I already knew my basement was an outside source of coolth.

 

[peakbagger]

The trick with the software is that it looks for the highest and lowest temp and calibrates itself accordingly. If there is large heat loss in the rangfinder it can overwhelm smaller heating losses. There is a way on mine to ignore the auto ranging function which can help with that if I remember to use it. My guess is your block walls are such a big heat loss that the small stuff just does not appear.

 

[woodgeek]

The trick with the software is that it looks for the highest and lowest temp and calibrates itself accordingly. If there is large heat loss in the rangfinder it can overwhelm smaller heating losses. There is a way on mine to ignore the auto ranging function which can help with that if I remember to use it. My guess is your block walls are such a big heat loss that the small stuff just does not appear.

Very true. The framed exterior was within range, just very uniform (I could faintly see the studs on the outside). I think if I estimated the ouside air film R-value at 0.5 or something, the skin temps made sense with an R-10 wall. The same approximation on the block walls was R-3. All very reasonable.