Recent content by russ_watters

Fair enough. I've seen dirty coils, but haven't encountered mold. Admittedly my experience is mainly high-end commercial/industrial. No, I was just letting it go: lowering the humidity below 45% or so isn't going to enable raising the temperature for most people because it's already below the...

Note that usually the filter is on the return side of the air handling unit, so the only place particles can get in when the system is running is through the casing (which will be very well sealed) or through the filter housing (which isn't). The supply ductwork is positively pressurized so...

That's the marketing reason but it isn't a good one. There should be nothing growing on an evaporator coil because it should be dry except when the AC is running. Leakage affects efficiency when the system is running, but I'm not seeing how it would be a big issue for air quality. Sure, you...

Not sure of the exact thrust of the question, but it's forced-air over furnace coils(plates). If you're saying that since they are hot they are sterilizing, that's true. But yes, the same system will have an AC coil that sits on top for the summer. A high fraction of residential systems in...

UV light does kill microbes. It doesn't work very well in forced-air HVAC because the air moves too fast for enough exposure. A lot of my clients looked into it during COVID but more fresh air and remote work both worked better to avoid infection. If you're having issues with pet...

I recently read A BOOK about THIS incident where a Luftwaffe pilot escorted a battered B-17 safely across the northern coast of Germany. Interesting perspective on the war (the book was mostly a biography of the German pilot) - he really hated Goering.

As a student you should use whatever software your professors require. I used Matlab in school. And Excel. I still use Excel but haven't used Matlab since college. It's tough to know what you'll use unless you know exactly what field you'll go into.

We have a guide and thread for that: https://www.physicsforums.com/threads/planning-to-buy-a-first-telescope-comments.391086/ Welcome to PF!

Consider a simple case*: you have an object like a ruler, sitting on a desk. You strike one end horizontally, perpendicular to it. What happens? Per the topic of the thread, what hidden assumptions did you make when describing what happens? *I think this has been discussed before.

I'm a mechanical engineer, so I get it: I sometimes find the physicists' view of things to be pedantic. But you need to recognize that you've selected a reference frame and rotation axis that is convenient and obvious from a practical standpoint -- but that doesn't make it special. No matter...

Welcome to PF! It's probably more than a coincidence but no real explanation has been found: https://en.wikipedia.org/wiki/Titius%E2%80%93Bode_law

What you are saying is true for a simple circuit with one source and one load/resistor, but the power line isn't the only thing in in the circuit. The things the power line is feeding needs specific amperage, voltage and therefore power.

They are expensive to operate (they need 24/7 staffing) so they are only financially viable if they serve very large buildings or campuses. And they require a continuous load for the heat*. A couple of my big pharma campus clients have them, but a large apartment building from the '80s decided...

Yeah, it's 9 arcmin wide, nearly a third the size of the full moon in the sky. So we'd be able to see it's if it were brighter.

I like to think of a/the core pursuit in mechanical engineering as a game of "follow the energy". It's very common for your energy to go missing, but you must, must accept as a starting premise that energy is always conserved and if it's missing you just haven't figured out where it went. OP...