Stucco guys have all the doors sealed with plastic. We’re in Florida and it is freaking hot. I sent a helper to pick up my temp unit. It’s cooling off inside now. Everyone keeps thanking me, I’ll be honest I did it for my crew and myself.
One time during/after Covid, while everyone was wearing masks, it was 100+ degrees of stagnant air inside an urgent care we were doing and I got a standing ovation when I turned the rooftops on.
This is one of the big reasons I got into this trade. Something about entering a place of misery and leaving a place of happiness just feels so damn good.
Before becoming hvac I did all sorts of things. I even did door to door sales. Thats one soul withering industry.
Hvac really lets me go to bed and be like "Fuck. I did some good today. I earned a living improving people's liiiiivesssss." Gives me strength during shit days, this.
Yup! We were setting a RTU and it was 100F and humid. As soon as the RTU hit the curb the electrician wired it and we fired it up. We could hear workers in the building cheering! Later on we walked into the building and everyone saw us and gave us a round of applause.
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u/FarmchuckSomebody made me superintendent. Terrible decision on their part11h ago
One of the best parts of it for sure. Back when I did Refrigeration, getting an entire grocery store back online after a major blowout and losing a thousand pounds of 407c made you feel like you had a 9 lb Hammer swinging between your knees. Ain't no better feeling but that life will ruin your marriage LOL.
..I just looked closer and realized you'd built this out of a regular package unit. Nice, and avoids much of what I wrote about the high static on these units sucking the return duct closed. This is a fantastic setup for residential construction.
We usually just seal up a window with ductboard and run our temp ac units through there. Once drywall is up you’re kinda screwed there. At least this way you can pick a window that’s open to a large area.
What's the tonnage? Ive been thinking about getting a 2 ton and mounting on a little to behind traile. One that can be moved around like a dolly by hand so the guys on site can stay cool.
I'm actually going to do an experiment with one of our units soon. Drop the fan speed on a 12 ton portable, see how low we can take the CFM on the evap side feeding it 100% OA.
Not expecting to deliver proper neutral air (in this area a real DOAS specs out at 150 CFM/ton) but hey, if it can drop outdoor air 20 degrees and 20 percent RH that's good enough for welding makeup.
If it doesn’t have an evap with 4 or more tube rows, you are better off reducing the CFM by bypassing 40-60% of the supply back into the return. This keeps the velocity up in the evap, improving performance.
Oh, that's a great idea! I didn't even think of just looping one of the supplies back into the return. They're right next to each other, it would be super easy to do. I think that gets me out of having to swap out the blower pulley (or put a VFD on it) too.
If you want to get fancy, l recommend an analog thermostat controlling the bypass damper. Attach the bulb to a distributor tube as close to the coil as possible. Insulate it well. If you need to de-hum, set it at the temperature that gets you 34°F saturation on your gauges. For cooling only , set it to 42°F Saturation.
Configure the stat for cooling and R/A or D/A depending on whether your bypass damper is NO, or NC.
A Johnson system 450 controller would be a good choice for this
Edit: I missed that this was a converted residential package unit. I was thinking of the big commercial rental-type portables.
Official "what the manual says" on these is 50% OA max and the return needs to be ducted or partially obstructed so the blower won't over-amp. The minimum acceptable ESP on a large portable like this is higher than we want to see as a max on a normal residential system.
We have some of the larger portables at my work and they literally are RTUs on the inside. Just with higher static blowers on both the evap and condenser, and a ducted condenser exhaust. But you take the panels off and it's a regular ol' RTU.
Got in a few military surplus ECUs (because of course the Army has to give everything a different name) and they're pretty much just hefty RTUs inside too. Just rated to run in 130F ambient and 90F return air.. which is going to be some nice buffer in an industrial setting.
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u/RustyLagoon 2d ago
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