Excellent for HVAC trouble spots
591294
I've been using the HVAC Load+ iPhone app to enter a detailed list for the block load to figure out the heating and cooling.  Walls, ceilings, windows, internal gain, etc.  But this calculation is always a little bit theoretical.  Now with this Fluke FLK-VT104 I can actually see the regions contributing to heating or cooling losses from across the room!

I posted a couple saved images to the customer photos section.  Here you can actually see where the attic beams are in an uninsulated attic.  These beams provide a tiny bit of insulation so the ceiling directly below the beams appear as blue-purple lines on the VT104.  I wonder if I could use this as a ceiling stud-finder!  This is great in case there are any gaps in the insulation, this tool will find the insulation gaps (easiest to find on the very hot or cold days).

Don't just leave this on the default settings.  Play around with some of the menu settings because you can get dramatically different views using the color palette and image blending %.  Some settings that you can adjust that affect the measurement include the emissivity of the materials and the background temperature.

The included CD contains the SmartView software to download captured images from the micro SD card.  Don't install the CD but rather download the latest version from the Fluke website (Support / Software Downloads) so that you get the very latest version of the SmartView application.  This allows you to change the color palette and blending (and other image manipulation) after the image capture so you don't have to worry about getting these settings perfect in the field.

The first thing to do after you open the box and fully charge the device - update the firmware on the Fluke website (Support / Software Downloads), since the device ships with an older firmware.  This is a simple download that you copy onto the micro SD card and then the VT104 will prompt you to update when it powers on.  The firmware contains various improvements to the device features.

I highly recommend the VT104 for pinpointing actual heating and cooling loss locations rather than relying on theoretical data or guesswork.
3798182
My main HVAC filters are located at the air handlers so I cut these to fit on the air intake grills to stop my ducts from getting dirty.  I replace them once a month.  They are easy to cut and fit and have kept the ducts clean for years.  The evidence of their trapping ability is visible every time I replace them.  Adding them does not seem to have diminished the air flow any and the service techs who service my unit have endorsed them.
2631246
This was very easy to use and it worked quite well. I had no issues flushing out the a/c system I had to fix. With a good solvent (also by FJC), a lot of gunk came out of the system and left me with a good, clean system to install the new compressor and other parts to.
497458
Had a utility room with a heat build-up problem. Plugged this in and added a fan. Now when the room gets hot the fan blows. It really helps keep the heat down. The fan is pointing up a small area into the attic.
3835855
Bought this to put over my AC condensers which my HVAC contractor let me put on the south side of my home like an idiot.  It's a sturdy sail, works well, and allows the updraft from the condensers to pass through so they are much cooler now than before.  Only wish I'd been able to install something a little larger to give them more protection throughout the day.
195588
This product is great for anyone that has trouble heating/cooling their home due to the location of the thermostat.  With this product the thermostat can be placed anywhere in the home.  Product was as described.  Arrived on time.  Great price.  I had it professionally installed because I have no idea how to even begin doing the installation.
4750113
It has worked flawlessly.  It solved the problem on my furnace.  It was easy to diagnose.  Be Careful - they are very fragile.
60595
This works great.  I installed it from start to finish about six months ago without HVAC professional assistance (There's a fantastic instructional video on YouTube, not specific to this model).  This unit is heating and cooling a 400 square foot shop I built.  It gets pretty hot in Texas, but on a 110 degree day it lowered the temp down to 62(the lowest setting and just a test) and didn't continuously run.  The heat pump seems to work perfectly too. Although temps haven't gone much below 30 yet, it has easily increased the temp to 80 ( again, a test).  It has lived up to my expectations.  I will add though, my shop is 2 x 6 construction with R19 in the walls and R30 in the ceiling and low-e windows.  It lost a star because the remote is the only way to control it. There are no on board controls.  It's about twice the price of a similar window unit, but a much cleaner look.  It only needs a 3in. hole, which is hidden once the inside portion is hung.  I see that this isn't available now, but all the units are VERY similar and probably made in the same location.  One more thing about that video, I ignored the hanging of the outside unit on the exterior wall and mounted it on a small concrete pad.

UPDATE:  (October 8, 2014) Worked great for three years continuously until fan started making noise then died.  Replaced fan motor with no luck for me.  The local HVAC company was lucky enough to charge me $170 to confirm it's broken and would cost more to repair than replace.  I've gone without one for a while now. So, I'll be looking for a new system with a different brand name.  My personal warranty is never buy a failing brand more than once.
3072481
I installed these in my up stairs rooms that were poorly heated/ac and it made a big difference. It also helps to close off or reduce air volume on other vents where you have rooms you don't use as much.
725175
I am using this with my well house to ensure the pipes do not freeze.  Easy, quick solution to ensure my trouble light is still on inside my well house without lifting the heavy concrete cover.  Very inexpensive and peace of mind when I look at the monitor to see my pipes are still above 32 Degrees.  Extremely pleased with the product.
1773874
I installed 2 of these in my crawl space a few months ago.  I can tell a big difference in the humidity levels in my house already.  Our air conditioner would keep the temp at 74 as set, but it didn't run long enough to really get the humidity level in the house to a comfortable zone.  I know the titans are dragging a lot of water out of the crawl space air since the condensation pipe outside is always dripping water.  My crawl space is that, a crawl space and it was at times a challenge to manure these things into place around all the ductwork we have down there.  I'm really glad these were as small as they are as a larger unit would not have fit.  I was worried about the electric bill with them running a lot, but I was pleasantly surprised at how modarate the increase was (only about $15 and I'm running 2).  So far I am very pleased with this product and I look forward to many years of service and increased comfort.
4747832
This kit was the perfect DIY solution to a problem I had been living with for over three years.  My local repair shop had quoted over $1,000 to repair the HVAC blend door in my truck and I completed the repair myself in three hours for less than $50.  A great product that I would highly recommend.
559173
We live in a very humid area.  Recently, we replaced the HVAC but it freezes up due to the extreme humidity despite the company's tweaks to stop it.  We have ceiling and floor fans running in each room of our small rancher.  Plastic is in layers in the crawl space.  Bleach kills mold but this is the dampest our house has been in over 50 years.  With the help of a new portable 70 pint dehumidifier and 4 hygrometers to see where the worst problem spots are, the humidity level has been reduced to 55% and temperature to 78 degrees, a far cry from 90% and 85 degrees.  This gadget is in the kitchen and is comparable to the others I bought.  All 4 I have are within 1% and 1 degree of each other.  That to me was amazing because I wasn't expecting them to work this well considering the low price.
3343872
We had an overheating issue with our 06 Pontiac Torrent.  My husband checked the thermostat, water pump, fuses, relays etc., and finally found that the problem was caused by the fan connector switches.  Neither fan was working properly.  One of the connectors was making a loose connection, while the other was bad.  Like others have described, the one that was bad was burnt/melted.  After replacing the non-functional part, the AC is now working like it's supposed to and we are no longer having the overheating issue.  So thankful Amazon carried this part and at HALF THE PRICE of the local parts store!!
2142994
I have used an older version of this Lascar USB logger since 2008. It is awesome for diagnosing problems with heat pump systems. You can use 2 at the same time and track outddor temp vs duct temperature at the closest heat duct from the air handler.

 If your heat pump is failing, you can see when the duct temps are low, and when the electric auxiliary heat turns on. Normally you would NOT know if your electric auxiliary is on, raising your utility bill!! I caught my heat pump failing. The installers did an absolutely miserable job with the line set, and their soldered (NOT BRAZED) connections had failed in a few spots, allowing the heat pump refrigerant and compressor oil to escape over a couple years. It was NOT diagnosed by the installers, and I had to get data loggers to prove that the electric heat was supplementing the heat pump when it should NOT.

 They fixed the leaks but the damage was done. The compressor failed a few years later. I had to have the line set replaced and the compressor replaced, they were already out of business.  If I had thought or knew what to do BEFORE having the problems it could have been caught much sooner and saved me $3000 in repairs AND $$$$ in excess heating/cooling costs.
3907865
I bought this precision pocket 7 in one screwdriver to work on Hvac thermostats, and air handler thermostat wire connections. works great for me.
4142452
I bought this product to solve a tough problem in an old house.  The thermostat that controlled the upstairs heat was located on the first floor.  I did not want to pay to have wires run upstairs etc etc. so this seemed a good solution.  I read about the complications of installing and the need for the "C" or "Common Wire" which my existing thermostat did not have.  When I got the unit, I realized that is just a 24 volt circuit to power the send and receive unit.  The furnace control circuitry runs on 24 volt and I was able to easily locate where to connect the unit's C wire.  It took 10 minutes to figure out. (You want to put the send/receive unit down by the furnace. It's too big on the wall.) Product works beautifully. The thermostat itself and it's program-ability are fantastic.  All the internet control stuff is a plus.  I highly recommend this product.