Thursday, February 19, 2015

The Windows Ecosystem is now Ad-supported.

The Windows Ecosystem is now Ad-supported. least for anyone outside of a business. And it has gotten much worse than the average boatload of crapware these manufacturers are known for. It is extraordinarily sad how heavily laden with advertising the entire Windows experience has become. Let's say you buy a Windows 8.1 PC today. As it turns out, your Metro start screen is littered with dozen of tiles for third-party services and apps that have paid $$ to the OEM for placement. Removal requires the user to delete all the tiles, and any new user on the machine will have to delete the tiles for themselves as well. It takes going into Powershell to remove these "provisioned apps" on a machine-wide basis.
Now let's move past Metro. You get to the desktop, only to find more shortcuts for third-party stuff. There are multiple programs installed (whose developers have paid $$ for placement) which are "lite" versions or trialware intending to get you to spend $$ to buy the full version.
Perhaps the worst is whatever anti-virus is included. The computer will usually come with a 1, 3, 6, or maybe even 12 month Norton subscription. Which is fine until the subscription runs out, at which point the AV becomes nag-ware trying to get the user to pay $$ to re-up the subscription. The average user doesn't necessarily grasp the importance of this and figures if the program is still there it must be doing SOME good. But it is actually exposing the user to risk. The user is unlikely to know that they can UNINSTALL the AV and use Windows Defender.
It doesn't stop there. The user goes online. Invariably they end up at a site serving ads that trick the user into installing crapware such as false anti-virus programs, media players, you name it. Stuff they don't need. But even worse, these installs also go ahead and install additional crapware in addition to the crapware that the user was tricked into installing.
So the user might choose to go download something reputable like VLC or PDFCreator or even Adobe Flash. Well now they have more crapware because the download site they use for these programs install other stuff by default. Choosing not to install this extra stuff means knowing that the grayed out "Decline" button, or the grayed out "Custom install" option, really is clickable. Or some other weird user interface trick that makes the user think they CAN'T opt-out.
And this, my friends, is why in addition to the normal crapware cleanout I perform on my family and friends PCs, I also uninstall the antivirus, and I install Firefox and Chrome and configure ad-blocking for IE, Firefox, and Chrome. I don't have a problem with ads, but no possible moral obligation to view ads is worth 2-hour crapware/spyware/malware cleanout sessions every other month.
Macs may not come with crapware but they are increasingly getting targeted by online advertisements that lead to Mac malware.
For a long time, Linux enthusiasts have said the best way to clean and repair Windows is to format and install Linux. Given that malware has become a virtually unavoidable structural component of the consumer Windows ecosystem, I finally have to say they are right. It is high time for the techies in people's lives to burn a Linux Mint install disc and use it regularly.

Friday, February 13, 2015

Figuring out CFM and Grille Sizes (including Return Grille) for Central HVAC systems

A HVAC system is sized for the volume of air in your home. If your house is 1200 sqft and the ceilings are 7 ft tall, the air volume is 8400 cubic feet. A properly sized HVAC system will perform at least 6 full air changes per hour, so it would need to move 8400x6=50400 cubic feet of air per hour. 50400/60 minutes then would equal 840 CFM.
(A real HVAC installer would also want to measure leakage to tweak the CFM rate for your specific house construction but that's beyond the scope of this post.)
To find the size of the compressor in tons, divide 840 by 400 (400 CFM per ton), giving 2.1 tons. Always round up, in this case to a standard size 2.5 ton unit.  If you are going to use a heat pump you've already done your heater sizing. (A house with no insulation or poor insulation should be figured at 300 CFM per ton.)
How big to make the return air grill? You don't want so much air rushing past the grill that it is noisy but you don't want a large grill either. The grill should be sized for an air speed of 300-500 FPM, or feet per minute. 400 FPM is the usual target.
We know you'll need to push 840 CFM. We'll divide by 400 FPM giving 2.1 sqft as the necessary filter face size. Convert to inches: 2.1 x 144 = 302.4 sqin. Take the square root of 302.4 = 17.389. So let's look at some standard size filters near 18in:

18x20 = 360sqin
16x20 = 320sqin

A 16x20 return grill would provide the necessary air flow and actually take us a little under 400 FPM.

If you already have an HVAC system you can work the numbers and see how well your system is sized. Also nice to know if you are planning on adding square footage somehow (new floor, finishing the basement, enclosing a porch, etc.) You can check your HVAC guy's recommendations this way.

You'll want to further assure you can get a full 840 CFM by checking the technical documentation for the air handler. You want to find the max external static pressure drop (intake resistance to air) that still allows the air handler to deliver 840 CFM. Then purchase filters that do not exceed that drop. Ideally, purchase the filter with the highest MERV rating that has a pressure drop for your size filter that is below this value. Most filter manufacturers don't provide detailed pressure drop information, unfortunately.

The air handler will also not push the right CFM if the pressure is not balanced throughout the home. This usually happens in a closed room with no air return (very common). All closable interior doors leading to living spaces (office, bedroom, bathroom, den) should be shortened by 1 1/2 inches on the bottom, or have an air vent installed in the door, or a jump vent.