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BillyHvac, Journeyman HVAC Tech
Category: HVAC
Satisfied Customers: 22515
Experience:  Endorsed for unlimited heating, cooling, oil burners, boilers, refrigeration, hydronics
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We are installing a 60,000 furnace and interested in having

Customer Question

We are installing a 60,000 furnace and interested in having 100% fresh air come in to the household instead of using the standard recycling or minimal air exchange suggested in traditional HVAC systems. Is this possible? If so, what would we need to do differently to accomplish this and what are the pros/cons to this?
Our house is approximately 1100 SQ FT and is in Washington state.
Submitted: 8 months ago.
Category: HVAC
Expert:  Rick replied 8 months ago.

Welcome to Just Answer, my name is ***** ***** I will do my best to help you with your issue. If my initial response doesn’t answer your question then let me know and we can continue our conversation.

Most 90%+ furnaces have their own air intake. If that's not what you have you can bring in outside air via (ducted?) vent(s) to the outside, which is the prefered/cheaper/easier method. Or you can install a Fan in a Can combution air intake fan.

Customer: replied 8 months ago.
Our furnace does have it's own intake where air could be brought from outside instead of recycling but I don't see this being done. I was wondering if there are reasons for this so I can determine if this is feasible. I have studied this briefly over the internet because we don't have the cash to hire a professional installer. My questions are: Would this damage the furnace and what accommodations in ducting/ventilation do I need to make to successfully complete this project?
Expert:  Rick replied 8 months ago.

You follow the installation instructions for piping the air intake (to the outdoors) as well as the exhaust.

Expert:  Rick replied 8 months ago.

Do you have more questions?

Expert:  Rick replied 8 months ago.

In case my previous answers weren't clear if you don't want to take combution air from inside the house then piping the air intake to the outdoors is the only option.

Customer: replied 8 months ago.
correct, we want 100% fresh air coming into the house. This question was really about how to work the exhaust ducting so there's not a positive pressure and only stale air is exhausted.
Expert:  Rick replied 8 months ago.

Either I don't follow what you're trying to do or you have a misunderstanding about how these systems work. You seem to be talking about an air to air heat exchanger not a furnace. Your furnace (with the air intake piped to the outside) pulls in fresh air from out side and the exhaust vent piping dumps the exhaust, from burning the fuel the furnace uses, outdoors.

Customer: replied 8 months ago.
We are trying to utilize the furnace for heating & fresh air without purchasing an exchanger. The combustion chamber has it's own vents we are venting through the roof that are separate from the return and supply lines I'm referring to above.
Expert:  Rick replied 8 months ago.

You can't use the furnace for heat and fesh air. The supply and return ductowrk is not designed and cannot be use for pulling in fresh air.

Expert:  BillyHvac replied 8 months ago.


My name is Billy.

Please tell me the temperature and humidity range of the region you live in.

And also keep in mind by NOT recirculating air, the humidity cannot drop during ac. It is the constant recirculation that enables the ac to bring down humidity.

And on the Heat side the furnace is rated to only "raise temp" by a set amount. Say a furnace is rated for 40 degree temp rise......if the air temp outside is 10 degrees, the air coming out of furnace will be 50 degrees.

On ac the "delta T" or temp difference is usually around 15 degree. So if 90 degree outside the air blowing out of register would be 75.

Likewise the humidity removal as mentioned....the ac can only remove so much humidity so if you ran in 90 degree weather with 50% humidity you would still be supplying 75 degree 45% humidity.

With your region info of temp and humidity I can tell you what to expect....


Customer: replied 8 months ago.
We are in Washington state. The last tech mentioned this isn't possible...
Expert:  BillyHvac replied 8 months ago.

Ok, I had just seen the question was still open.

If you are all set just rate service to move off the active list.

If you need info please let us know.