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First condo inspection


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Did first condo today and was just wondering if anybody could give me info on the best way calculate whether or not there is enough combustion air for an hvac unit in a utility closet.

In this one case it was 75,000 btu mid efficiency installed in a five by six space.

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No louvers in the door for ventilation? 50 cuft/kBtu/hr I think is the reference.

Often times, there will be a combustion air intake duct running up to the roof, along the flue, to bring fresh air into the utility closet. Sometimes it's hard to spot if you're not looking for it - it might just terminate behind other ductwork.

Chicago, I'm reading what I just wrote, and I explained it pretty poorly. If you aren't familiar with the set-up I'm talking about, say so. Maybe someone else can explain it better. Bad brain-to-fingers connection today.

Congrats on getting the gig. Hope it was otherwise painless.

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Call People's Gas, and get "Construction Guide for Gas Usage in Chicago". It has everything you need to know about furnace installation in Chicago.

The city abdicated on responsibility for gas codes; the gas company took the NFGC, essentially adopted it in total, changed the formatting and numbering layout, and renamed it the Peoples Gas thing. It's a really nice book, and I think they still give them away for free.

What you want is on pages 11 and 13.

You have to determine if it is a confined or unconfined space.

There are calculation examples on page 42-43.

The gas company wants to see not just a single combustion air intake for confined spaces; they want 2 openings, one high on the wall and one low, so the room can develop a convective air flow to facilitate air movement.

Practically speaking, louvered doors satisfy all requirements for combustion air; I can imagine a few instances where they might not, but if it's all louvers, I think you're OK.

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Hi Kurt I was informed that louver doors were actualy only calculated as twenty-five percent efficient when closed of course.

So anyway I just wanted to see if this might cause problems in such a tight space.

Hi Frank , that is what I was looking for as HVAC might be my weakest area ,just need to find that golden site with lots of pictures for my primitive mind Thanks for the help to both.

Back to my report,and what a time for writers block.

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The pdf is most of the book I'm talking about; there's a few more tables in the book, but that's about it.

Louvers can be inadequate in a few situations, but if the entire door is louvered, it should still provide adequate air even calculated @ 25%. Don't need a lot of vents; just need a couple square feet @ most for the "average" condo furnace.

And, every condo, and I'm talking tens of thousands, has the louvered door thing. I did calculations on dozens of them, then stopped, because the louvered door always provided combustion air well in excess of the required amount.

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