Outside fresh air pipe - needed in summer?

[geberly]

I live in Virginia in a house built in 2002. I have a 6" pipe that runs from the outside to my cold air return. I have a propane furnace, but it is not the high efficiency kind that require a separate line into it for combustion.. I can kind of see a reason to have this in the winter time, but in the summer is it really necessary? Also, my 6" pipe is located about 2 feet from my outside AC unit. When I was having my routine maintenance done, the AC guy commented on the horrible location saying it would be pulling in even hotter air with that location. I would love to seal it up during the AC season, if possible.

Speaking of return, how do they check to see if the return ducts are pulling air adequately? I know nothing about HVAC systems, but it seems to me the last intake location in my house is not doing much.

[<kjpro]

What did your service guy say?

What&#39;s your reasoning for having it in the winter?

[geberly]

What did your service guy say? The service guy said that was a crazy location to have an air intake pipe.

My reason for having it in the winter? Here is my uneducated guess: In a newer house, it is going to be (hopefully) sealed pretty well. With the furnace using combustion, it seems plausible that grabbing air from the outside would help supply any extra air for that and would stop any drafting around the house.

[<kjpro]

I read that, I meant as far as closing it off.

Pretty good... now sitting at my computer, I&#39;d say close it off in the Summer. But this doesn&#39;t allow for a fresh air intake that could lead to indoor air quality issues.

[Jeffrey Lebowski]

Safety issue not comfort.

Respectfully disagree, and venture that almost certainly would be against code...

See.....what if he gets run over by a garbage truck during the summer ?

===

Suggest a motorized 120vac self opening damper with 24vac relay coil between W and C--source line voltage so as to always close the damper unless W is energised

If you want to get real fancy then additionally install a timer....

[daytona°]

Also it is there for ANY exhaust needing air intake. For example...bathroom exhaust fans, microwave exhaust fan, clothes dryer (either gas or electric) ...anything in the tightly sealed, newly constructed house that needs air make up to work.

[<kjpro]

It&#39;s not really a safety issue... the equipment room should still have the required combustion air intake.

Your suggestion is nice, however, IMC doesn&#39;t require make-up air in a residence.

[Abby Normal]

Well, from my experience in a humid climate, if you could put a damper in that intake, it could help lower the humidity in your home.

For it to work, you are going to have to have the furnace fan in the "Auto Mode" so that it just runs when the compressor runs.

What will happen is that whenever the AC runs, some fresh air will get drawn in directly to the AC system. The heat and humidity of this air goes right to your cooling coil, and you end up pressurizing your home with dry air. Dry air will try to leave your house rather than warm humid air infiltrate into your house.

You would adjust the damper and open it up enough so that when the AC was running, you could just notice cool air leaving from a door that was cracked open.

If your house leaks like swiss cheese it will not work, but if it is reasonably tight it could work great.

You cannot run your fan all the time, otherwise you will be pumping humidity into your house when the compressor is off.

[Jeffrey Lebowski]

Not sure why it was done ( with timer and damper as described above ) at my brothers place then.

[<kjpro]

It might very well be a local code.

[daytona°]

Hey guy.....where are you. We give all these recommendations, at least you can come back and acknowledge one of them

[geothermaljones]

IMC requires combustion air for commercial systems. Some residential codes may require it as well. I use them everywhere, unless an ERV/HRV is installed. Here in MN. I&#39;ve seen lots of them drop down the wall into a 5 Gal. bucket or looped back up to act as a P-trap & stop cold winter air from flooding in. Direct into the return works as well, but if it faces north or west, runs the risk of winter winds blowing into the return, etc... Dampering is a possibility, but a gas dryer, stove, or water heater will need the combustion air year round. If all of the units are on full fire, the fart fans & kitchen hood are running, you can backflow the flue gasses & make the whole family sick... We had a case here last fall of a home owner that installed his own boiler, bought direct from local wholesaler. Cops pulled him over thinking he was drunk, took him in for tests & released him... He went back home & woke up sick with a family member dead of CO... Sparky needs a license to wire a panel, but gas lines are anybody&#39;s business?

goodluck geothermaljones st.paul,mn.

[<kjpro]

He replied to me once.

I guess he didn&#39;t want to talk to the rest of you Bozo&#39;s! :-)

[Abby Normal]

Combustion Air

Ventilation Air

Make Up Air

Three related but separate issues. Should not rely on one system to do more than one of those tasks. In some places a fresh air duct to the return would not be deemed as providing combustion air.

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[<kjpro]

Especially when the combustion air is to be ducted into the equipment room.

[geothermaljones]

True... Make-up air is usually required to be induced in to the space via blower. Combustion should be ducted, & ventilation air is commonly allowed via infiltration, residentially speaking, unless there&#39;s an inordinate amount of exhaust, in which case MUA is required. Take a look at the MN pressurization schedule for all three. Unfortunately not all officials require them for permitting, & fewer still know exactly what they&#39;re for. I&#39;ve seen the shortcuts used, best definite as "liars figure & figures lie" They end up in the file & act as a CYA for the permitters if something ever happens.

That said, I will again say I wouldn&#39;t block it off if gas appliances of any type are in use... Especially conventional B-vent natural drafters that could easily backflow if a dryer or a couple bath fans are in operation...

goodluck geothermaljones st.paul,mn.

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