How an engineer thinks about solving a simple problem

Illustration for article titled How an engineer thinks about solving a simple problem

Everything had just been unloaded from the uhaul into my apartment and I was exhausted. I had started my day in Pooler GA where I woke up early to return my rental car, pick up a uhaul, have it loaded then drive to Greenville SC. All I wanted was a nice hot shower in my new apartment.

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I hung up the shower curtain and proceeded to turn on the water to warm it up. This is when I came across the first problem. Before we delve into that, we need to talk about mass balances.

Illustration for article titled How an engineer thinks about solving a simple problem
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Normally, under steady state conditions, in a shower you should be removing water at the rate you’re introducing it into the system; therefore, in should equal out. In my case, in didn’t equal out; there was an accumulation term. There was standing water in my tub while I was showering, not good.

When I opened my mail box for the first time, I noticed two names on the card telling the postman who lived there. One name was male and the other was female. I can probably assume that at least one of them, if not both, had long hair. The hair from one of the former residents was creating my accumulation term.

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Before we talk about fixing my accumulation problem, we need to talk about the second problem I noticed, there was hardly any water coming out of shower head. There was hardly any pressure at all. It was was abysmal. I would need to investigate more to see what the issue was.

After my shower I used my sink in the bathroom where I realized there was adequate pressure; probably meaning that the supply to the shower head wasn’t the issue. The was confirmed when I took off the shower head and turned the shower on and there was, once again, adequate supply. Looks like I had found the source of my lack of water, there was a restriction in the shower head.

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Now before I can think about introducing more water into the system, I have to solve my accumulation problem. This was done by submitting a maintenance request; this is one thing I like about apartment life, I don’t have to do maintenance work. The day after I submitted my maintenance request, I come how to a note left on my counter saying the maintenance staff had removed hair from my dream; my accumulation problem had been solved. This was confirmed by turning on the water on and watching in amazement as my drain actually drained. Perfect, now I could look into my supply problem.

Since I had narrowed my supply problem to my shower head, it was time to throw some money at the problem. I went to home depot and bought a new shower head. Upon arriving home, I installed the new shower head. When I turned on the shower, I was not pleased. While flow had been improved, it was still not to my satisfaction. Alright what am I going to do now?

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Well, might as well take the shower head that came with the apartment apart. This is when I see a nice flow restriction in the shower head. It’s a little piece of plastic deliberately put there to restrict flow. Perfect, I grab a screw driver and pop it out. After reassembling the shower head, sans restriction, I reinstall the shower head. This time I turn the shower on and am happy with the results; I finally have good pressure. In fact it’s almost too much, which we’ll talk about in a moment.

Before we address the too much pressure issue, we need to talk about the next problem I ran into. Now that I had greatly increased the rate at the shower head, I had also greatly increased the rate at which I was using the hot water supply. I was now running out of hot water in the middle of the shower.

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I have a tank water heater, which has a finite capacity. I couldn’t change the volume of hot water that I started with; however, I could change the rate at which I used the hot water. Basically, if I made the water hotter to begin with, I would need less of it to get it to the right temperature. We could go over the energy balance, or we could just agree that heat is a manifestation of energy and that if I want to a smaller volume of water to make something the same temperature, it has to be hotter to begin with. So where does this leave us?

I would need to turn up the temperature on the water heater. Problem is that it’s behind a locked door, to which I do not have a key for. Again, this problem was solved with an email to the maintenance department. To my surprise, they actually came and turned up the temperature. I figured they might not because the water can actually scald you now, and there might be some liability issues, but nope they came and turned up the temperature.

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Great, now three issues had been solved and I had a nice comfortable shower.

I lived with the shower like this for a couple weeks before I decided to redress my shower head. I did this by taking apart the shower head I had bought. It also had a flow restricter in it. Now, I didn’t want to remove it because with it removed, it was too much water. This is when I realized that if I could remove part of it, I could increase the flow to what I wanted. So, I got my drill out and picked a bit that looked like it would give me a nice flow and put a hole in the middle of restrictor. I then reassembled the shower head and installed it.

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Now while it was giving my the flow I wanted, it was also leaking from the threads. The original shower head was just screwed on and figured that would also work with the shower head I worked, but apparently the fit wasn’t sealing. Once again, time to throw money at the problem. I went to home depot and got a roll of PTFE tape. Taped up the threads and put the shower head on.

Now I finally had a shower with a working drain, an adequate supply of hot water, and shower head to supply it at the pressure I wanted. Perfect.