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peterv 12-06-2008 07:37 PM

new Infinity system shows static pressure at 0.09
From what I have been reading this seems too low, correct? It is an Infinity 80 Gas Furnace model 58cva. I also have a humidifier and ERV Ventilator (both Aprilaire) attached. I closed these unit off and ESP jumped to ~ .12.
My ductwork was never changed. Only hardware. I also have a ERV Ventilator and a Humidifier mounted directly off the duct from furnace. Closing their feeds raises pressure to ~.12.
Reason I am searching is that some rooms get little air flow and, hence, not much heat.
Despite the installers having made improvements I remain concerned. Any thoughts?

yuri 12-06-2008 07:55 PM

That unit has a variable speed ECM motor from what I saw on the Carrier website. I would imagine the static pressure to be at least .3-.4 "WC. Either the motor is not getting up to speed or you have ductwork the furnace is not compatible with. Lennox uses the same motors and my tech guy was telling us that if the ductwork is too small the motor can hunt and have a hard time finding the proper speed. Post some pics of the furnace and ductwork and we may have a better idea of what you have going on there. I balance some of my units with a velometer and that gives you a reading of the velocity/flow which static pressure doesn't do easily. I have this one:$part=PORTAL.USA.SimpleContentDesk&$event=show-from-menu&categoryid=6106408

peterv 12-06-2008 08:37 PM

Thanks. I will see if I can take and (hopefully) upload a photo. I jus now checked my Dehumidifier ductwork (forgot to mention that item!) It is mounted to receive air just after the furnace. The duct going into it is hot and when I opened the unit (as if to take out the filter) I feel alot of warm air moving in it, Bet that is where my air is going. I wondered about the install.

beenthere 12-06-2008 11:30 PM

Is that the ESP in first or second stage.

Posting duct sizes along with pics helps.

Marvin Gardens 12-07-2008 11:53 AM

There is a continuing below the surface discussions about air velocity. This is a classic example of why I prefer a higher velocity than others in the business.

The solution would be to put in smaller ducts into the rooms. This will increase the pressure and therefore increase velocity.

I redid my home this summer with a new 95+ furnace and reducted the whole place. Now I have very even heat/cool year round. Before some rooms were cold from ducts that were too small, others were cold from ducts that were too big (as in your case).

I can feel the air movement but it is not uncomfortable. The air in the room is stirred up enough to make it even in every corner.

I also have my vents up high on the wall and aim then at the opposite wall floor so they are not obstructed by furniture. They are also on the inside walls and aim at the windows which is where the heat/cold is most noticeable.

beenthere 12-07-2008 12:22 PM

About all he needs is some balancing dampers, to balance the system.
His static will come up then.

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