AH - Fan Speed - How to determine

AndrewF · 01-29-2009, 07:32 PM

Now that I have finished the upgrade of the main trunk lines in the basement, I am trying to figure out how to determine what the right fan speed would be for my AH.

It is a fixed speed unit, which means by moving the the wires I can change from slow/med/high.

It is a 5 ton comfortmaker AH matched with a 5 ton Heat Pump. What other info would one need to determine the optimum fan speed?

I have monitoring setup in that I can tell the suction line temp, the liquid line temp, the return (input) air temp and the supply air temp after going through the AH.

JohnH1 · 01-29-2009, 07:52 PM

Do you have the Mfg specs on the AH and HP. A basic 5 ton a/c will need 2000 cfm. If you have the blower curve info on the AH you can check the static pressure then look at what blower spped you are at and cross to the CFM. The best CFM is whatever the MFG says it should be for your condenser AH match up.

JohnH1 · 01-29-2009, 07:53 PM

Only after proper CFM is set up can the A/C be properly charged.

**beenthere** · 01-29-2009, 08:10 PM

Hmmmm.

Why was I thinking you had a Goodman.

hvaclover · 01-29-2009, 08:26 PM

Be nice to the DIYer Been.

hvaclover · 01-29-2009, 08:27 PM

Need to know the house sq ft first.

**beenthere** · 01-29-2009, 08:30 PM

I could have sworn he said he had a Goodman in another thread.

hvaclover · 01-29-2009, 08:34 PM

He did and they were mismatched off the website he bought them from.

AndrewF · 01-29-2009, 08:39 PM

Yes I have a Goodman. Fourth one in the family. (All working great.)
No I did not buy it online. I bought it from a local dealer.
The AH is a 5 ton 12 seer unit
The Goodman is a 5 ton seer unit.

Background info can be found in these posts.

HVAC - Airflow Issue

HVAC - Airflow Issue

HVAC - Airflow Issue

hvaclover · 01-29-2009, 08:39 PM

http://www.metacafe.com/watch/115041..._conditioning/

hvaclover · 01-29-2009, 08:43 PM

Quote:

Originally Posted by AndrewF

Yes I have a Goodman. Fourth one in the family. (All working great.)
No I did not buy it online. I bought it from a local dealer.
The AH is a 5 ton 12 seer unit
The Goodman is a 5 ton seer unit.

Background info can be found in these posts.

HVAC - Airflow Issue

HVAC - Airflow Issue

HVAC - Airflow Issue

My bad.Sorry.

AndrewF · 01-29-2009, 08:45 PM

Quote:

Originally Posted by hvaclover

http://www.metacafe.com/watch/115041..._conditioning/

Sure I can whip up one of those for each room.

Sometimes you do what you have to do to get cool air....dumping some ice in that cooler would give a nice boost too.

AndrewF · 01-29-2009, 08:46 PM

Quote:

Originally Posted by JohnH1

Only after proper CFM is set up can the A/C be properly charged.

That is where I was heading. From all the reading I have done, every HVAC guy I have had out has failed to do what I would think would be the proper way to measure the system.

So I am on a mission to figure it out myself so that it is done right.

hvaclover · 01-29-2009, 09:01 PM

Quote:

Originally Posted by AndrewF

Sure I can whip up one of those for each room.

Sometimes you do what you have to do to get cool air....dumping some ice in that cooler would give a nice boost too.

Your ok Andy.

**beenthere** · 01-29-2009, 09:56 PM

You'll find Comfortmaker uses a different CFM on their heat pumps then what Goodman does.

So, you can't actually ever have proper air flow for it.

ou can download the specs for your Goodman outdoor unit you have, and see if you can match its rated performance.
Goodman includes the temp rise it shold have. But, that swith its rated matched coil.