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Discussion Starter · #1 ·
Wanted to reroute my make-up air duct to get it out of the way....same connection and ducts just moving it over a beam.

Took apart the cold air return end ...looked and felt down the duct and there was zero air flow.

Went up to the wall where it went up into the floor joist area and started feeling around. Got my hand in an open end of the duct there too. Pulled it down and it wasn't connected to anything....just kinda buried up against the wall in the floor joist cavity.

This house was built in 2004...and I'm the 3rd or 4th owner and no one had caught this.

So I guess since this has been operating for 15 years without makeup air I'm just gonna get rid of the duct.

The high efficiency furnace has outside air intake for combustion....does this makeup air really need to be there?

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I apologize for laughing, but some of the things builders do because they are cheap and lazy just amaze me.

Correct approach would be to determine the fresh air needs for your house. Note, fresh air is different than combustion air which it sounds like your furnace is built to take care of.

Building code requirements vary by location and when adopted. At one point homes were required to add fresh air by some formula whether they needed it or not. Where your house stood is unknown but I suspect the guidance is more reasonable now than then.

A proper amount of fresh air is good and healthy even if it uses a few dollars to condition it. Adding fresh air is one of the unintended consequences of building energy efficient air tight homes.

Do some reading about how much fresh air is desirable and come back here if you want more help.

Bud
Retired energy professional
 

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Discussion Starter · #3 ·
Yeah it blew my mind when I pulled it down. Would it really have been that difficult in the initial home build to have it go outside???

I realize the fresh air is beneficial....and I realize the house has been going on 16 years without the duct. Just wondering on opinions here. I have no idea what it would cost, probably not too much to core a hole through the brick and add the proper cover/screen.

What you you all do? I'm in Michigan if that matters.
 

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One of the changes they made, don't ask me when, was to ignore natural air leakage (no credit) and just impose a requirement on all homes based upon size and number of occupants. In your case, if you were to have the house tested to determine the natural air leakage (the credit) and then calculate the amount of additional air needed to meet that number you would be good. Basically that is the old way of meeting air quality and I like it better.

The other aspect of providing a fresh air path is to prevent the house from pulling outside air in through unwanted places, bringing dirt and moisture with it and in most cases depositing those inside your walls. Dirty insulation is a common indicator of an
unwanted air leak.

Another option might be to check and see if MI offers any free energy evaluations. If so and it includes a blower door test they could tell you how tight your home is and how much fresh air is needed. Somewhere in the future indoor air quality will end up on an inspection list requiring such a test. Might be a few extra decades with fuel prices tanking the way they are. But an option.

A canary in the mine observation would be, are you seeing any condensation on your windows? If not, then the house is finding its own source of outside air.

Bud
 

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Discussion Starter · #5 ·
I used to... But last year I disconnected the humidistat from the return near the furnace and wired it up to the ecobee.

I let that control the humidity and it varies it now based on outdoor and indoor temp and humidity.

Haven't seen any moisture this winter on the windows.

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Since you aren't having condensation issues you are probably just fine.

I would also recommend you pick up a couple of inexpensive humidity and temperature meters, RH varies with temp so you need both numbers to make any comparisons. Include outside numbers as well.

As mentioned indoor air quality is becoming a hot topic when considering a new home and codes are upgrading to ensure new construction and resales are meeting demand. No citations.

Bud
 

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balanced ventilation (not what OP was talking about) has the added benefit of not pulling more radon into the house than "natural" ventilation will.
 
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