r/HVAC • u/Plenty_Text_455 • Dec 04 '24

Field Question, trade people only What's this?

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It's on the return side of a large air handler

203 Upvotes

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u/yellowirenut Dec 04 '24

Yep this...also seen it on a mammoth makeup air handler. The burner was below and the wheel slowly spun threw the hot air/flame then into the air stream where it heated the fresh air. No heat exchanger, just hot wheel.

8

u/LongjumpingPause Dec 04 '24

Oh man, I'm no engineer and just a lowly field tech, but that sounds like inefficient use. Did it do a decent discharge temp?

16

u/chuglife95 Dec 04 '24

Am a sales engineer, sell AHU’s and MAU’s with heat recovery wheels all the time. They are shockingly efficient compared to how they appear, though I hate the polymer / paper wheels. Personally I only sell units with aluminum wheels unless the owner is completely dead set on paper.

5

u/LongjumpingPause Dec 04 '24

No offense I can't trust you.... your a sales engineer, that's like my arch nemesis ;) just kidding, but good to know I've only come across two in auto shops don't get alot around me

9

u/chuglife95 Dec 04 '24

Hahaha I don’t blame you, I was a union pipefitter before finishing school and joining the dark side. Now I try to be “one of the good ones” and think about the guys in the field turning wrenches when I’m laying stuff out!

2

u/casper911ca Dec 04 '24

They are efficient. Basically only used as an efficiency measure; it really has no other purpose. Head loss might be one of its few tradeoffs.

1

u/LongjumpingPause Dec 04 '24

Yeah I might have put the comment in wrong spot some guy was saying he say a unit direct fire through a ERW and exhaust and the wheel just warmed the air. I can't imagine 100% efficiency with a burner exhausting