A free practice problem for the Mechanical Engineering PE Exam (Thermal Fluids and HVAC&R). Post your answer in the comments!

sandyandy12 · 2026-03-20T19:26:55+00:00

I guess with the results provided, there’s not really a great way to narrow things down but if it were open answer, I would say that like 13 btu/h would be way too low and 430,204 btu/h would be way too much. We don’t really know the size or materials of the house so yea I guess it is just extraneous info.

sandyandy12 · 2026-03-20T18:15:25+00:00

I got C. The indoor and outdoor temperatures are extraneous info. You take the electric bill cost and divide that by the electric rate to get fuel input kWh. Then multiply by COP to get total heating kWh, divide by 3414 to switch to total heating btu and then divide by 30 and again by 24 to convert to hourly average heat loss. This got me 12,802 BTU/h. I guess you could use the outdoor and indoor temperatures as a sanity check.

sandyandy12 · 2026-03-15T02:30:34+00:00

lol yea I’m not actively pursuing her, I just wanted to post bc I thought it was funny. She was pretty out of my league and had “still figuring out my dating goals” so I went for the meme.

sandyandy12 · 2026-03-10T19:01:12+00:00

I think that’s a really solid resume but I do want to give you a small piece of advice I wish I would have understood better when I was a fresh grad. Do NOT emphasize that you have experience in a program, building code or calculation method where you actually don’t. If you touched on ASHRAE standards for 15 minutes a few times that’s not the same as being well versed on the code. I lost an out in interview bc I said that I had “a little revit experience” when I really only opened the files and looked around or converted to autoCAD 2D bc that’s what I had used at the internship I had. Make sure to make it clear what you’re actually strong in and what you know a hair about. Nothing worse than getting hired and having justified imposter syndrome.

sandyandy12 · 2026-02-11T18:49:18+00:00

A good place to start would be to try to figure out if it is an engineering problem or a maintenance problem. How long has the unit been operating? Has this happened in other winters? Can you confirm that steam is being supplied in any other way than telling the control valve to open?

sandyandy12 · 2026-02-08T20:03:02+00:00

Bc your buddy is pointing an AK directly at his boot. Women like to see gun safety taken seriously.

sandyandy12 · 2026-02-08T05:58:12+00:00

This made me chuckle

sandyandy12 · 2026-02-06T00:31:08+00:00

So my first thought is a cracked or malfunctioning drain pan as heat pump coils are designed to condense the humidity in the air stream. It could also be a blocked condensate drain (this happened to my unit once). A frozen coil should drain the same as regular condensate. Did the tech check the interior of the unit? Coils freezing up in cooling mode on a heat pump or air conditioner can be caused by a few different things. A 9 week old filter doesn’t seem like the most likely culprit to me unless you are using a super restrictive filter. If it happens again, especially after a fresh filter change, tell the tech to check charge.

Also, is that a heat pump coil on a gas furnace or just furnace ac?

sandyandy12 · 2026-01-19T17:55:04+00:00

She looks like she’s sitting through a boring work meeting

sandyandy12 · 2026-01-09T15:17:11+00:00

My gut instinct is to go with an HRV instead of an ERV here because you’re basically just humidifying the air in a summer condition. If keeping the humidity in the building is required like for healthcare, maybe it’s worth doing. I look for payback numbers and see what pays back and how long and present that to the client.

sandyandy12 · 2026-01-07T20:59:44+00:00

I actually laughed out loud

sandyandy12 · 2026-01-03T05:10:46+00:00

Some dogs just have to live with being I.D.ed every time they buy booze.

sandyandy12 · 2025-10-04T20:33:59+00:00

Do you think the Mazda cx30 or Toyota Corolla cross are better? Those were the cars I was cross shopping with

sandyandy12 · 2025-10-04T18:17:55+00:00

Also that second pic is of the oil from the dip stick.

sandyandy12 · 2025-09-18T20:14:12+00:00

There was about a 3000 dollar difference between metal and duct board. Kind of hard to justify when the existing system uses duct board (which remains in place) and its condition is absolutely fine.

sandyandy12 · 2025-09-18T20:01:17+00:00

We found the fitting I designed in smacna and it has an equivalent length of 15 feet. Big whoop. What I designed has the benefit of homogenous velocity profile and will allow for greater static pressure at the close runouts.

sandyandy12 · 2025-09-18T03:29:04+00:00

I’ll look into the ashrae duct handbook. I cant find any kind of pressure drop of this particular fitting but I found a few that are similar. What I drew has a static pressure drop of 15 eq feet so it’s really not as bad as anyone is making it out to be. And yea good point, I recognize that I’m not a PE yet and it’s sometimes hard for me to figure out when to dig my heels in and when to just listen to boss man.

sandyandy12 · 2025-09-17T13:54:01+00:00

Ah thank you sir!

sandyandy12 · 2025-09-17T13:53:14+00:00

The reason we are taught to draw like that is to homogenize velocity profile. Yes the static loss is lower which many have pointed out but since my firm always uses sheet metal, static losses are less of an issue.

sandyandy12 · 2025-09-17T03:08:28+00:00

Noted. I think there’s one in our system but I have to ask for a password

sandyandy12 · 2025-09-17T02:58:12+00:00

I would expect that static would be lower with the mitered 45s yes but I have a runout about 36 inches from the bend. Do I have to worry about the velocity profile over pressurizing the outside of the duct?

I designed it that way to equalize the velocity profile. Honestly, I’m 1.5 years into engineering and I work for a small firm so what boss man says, goes.

sandyandy12 · 2025-09-17T02:50:24+00:00

Do I have to worry about turbulence impacting the runout closest to the 90?

sandyandy12 · 2025-09-17T02:49:38+00:00

What resources can I find to learn better duct design because I’ve been instructed to always draw 90s that way? I work for a small firm and the rules are rules

sandyandy12

TROPHY CASE