Temperature Rise - HVAC - DIY Chatroom Home Improvement Forum


Go Back   DIY Chatroom Home Improvement Forum > Home Improvement > HVAC

CLICK HERE AND JOIN OUR COMMUNITY TODAY...IT'S FREE!

Reply
 
Thread Tools Display Modes
Old 03-15-2009, 04:52 PM   #1
Member
 
Join Date: Jan 2009
Location: NC
Posts: 146
Rewards Points: 75
Default

Temperature Rise


Goodman 5 Ton Heat Pump with Variable Speed Airhandler

Outdoor Temp = 46
Supply Air Temp = 103
Return Air Temp = 70
-----------------------
Temperature Rise = 33

Is this temperature rise to high or ok in relation to CFM setting? The temperatures were taken with the heat strips off and thermostat set to 72. The airhandler is currently set at 1530 CFM.

Advertisement


Last edited by mjbxx; 03-15-2009 at 11:33 PM. Reason: CFM should be 1530
mjbxx is offline   Reply With Quote
Old 03-15-2009, 04:59 PM   #2
An old Tradesmen
 
Join Date: Oct 2008
Location: PA
Posts: 26,520
Rewards Points: 4,682
Default

Temperature Rise


Too high period.

Indicates too low of an air flow for the unit.

Advertisement

beenthere is online now   Reply With Quote
Old 03-15-2009, 05:15 PM   #3
Member
 
Join Date: Jan 2009
Location: NC
Posts: 146
Rewards Points: 75
Default

Temperature Rise


Got it. Should I just increase the CFM setting to correct? And what should the temperature rise be?
mjbxx is offline   Reply With Quote
Old 03-15-2009, 05:21 PM   #4
GC/Master Plumber/Mech
 
Join Date: Feb 2009
Location: Hays, KS
Posts: 1,472
Rewards Points: 504
Default

Temperature Rise


You may have a setting of 1680 but is this your actual CFM

To calculate CFM follow this

CFM = (Volts X Amps X 3.413) divided by ( Temp rise X 1.08)


Your system may be under charged. I would have it checked. Keep in mind the only true ways to check a charge in a heat pump are

1. Checking super heat and sum cooling in a/c mode on a warm/hot day
2. Weighing the freon in on a cold day.

It is best to check charge in the summer just before going into winter.

Also your second stage heat can be set up for stages to come on in the fall/winter. As the tempout side drop the effenicy of the heat pump drops as well.

On the days where it is cold it is not as simple as adjusting blower speed to get more heat. There are other factors as duct work as well.

Is this a new install, replacement or an appliance that you have had for a while.

What made you check temp rise?

Last edited by Plumber101; 03-15-2009 at 05:23 PM.
Plumber101 is offline   Reply With Quote
Old 03-15-2009, 05:24 PM   #5
An old Tradesmen
 
Join Date: Oct 2008
Location: PA
Posts: 26,520
Rewards Points: 4,682
Default

Temperature Rise


27

You shouldn't be 33 until 55 or better outside.

You should have 1850 or better CFM.

Goodman generally want 400 CFM per ton in heating mode.

Last edited by beenthere; 03-15-2009 at 05:26 PM.
beenthere is online now   Reply With Quote
Old 03-15-2009, 05:33 PM   #6
Member
 
Join Date: Jan 2009
Location: NC
Posts: 146
Rewards Points: 75
Default

Temperature Rise


If what you are saying is true, then why does Goodman allow for a 15% reduction of the trim adjust setting which lowers CFM to 1530 from 1800?

Last edited by mjbxx; 03-15-2009 at 11:36 PM. Reason: Reduction should be 15% lowering CFM to 1530
mjbxx is offline   Reply With Quote
Old 03-15-2009, 05:56 PM   #7
An old Tradesmen
 
Join Date: Oct 2008
Location: PA
Posts: 26,520
Rewards Points: 4,682
Default

Temperature Rise


For comfort.

It lowers the efficiency, but gets you a warmer discharge temp.

They, like most manufacturers, don't tell you that part.

They also don't tell you that it increases the amount of time it takes to defrost the coil.
beenthere is online now   Reply With Quote
Old 03-15-2009, 11:05 PM   #8
Member
 
Join Date: Jan 2009
Location: NC
Posts: 146
Rewards Points: 75
Default

Temperature Rise


OK. Should I just place the system back to 1800 CFM? I have to say that since I lowered the CFM on the system, the house has been much more comfortable and in fact, the system does not seem to run as long as the previous setting. I suppose if our next electric bill rises, I'll know it is not as efficient.
mjbxx is offline   Reply With Quote
Old 03-15-2009, 11:21 PM   #9
An old Tradesmen
 
Join Date: Oct 2008
Location: PA
Posts: 26,520
Rewards Points: 4,682
Default

Temperature Rise


Set it to where it makes you comfortable.
beenthere is online now   Reply With Quote
Old 03-15-2009, 11:40 PM   #10
Member
 
hvaclover's Avatar
 
Join Date: Oct 2008
Location: Suburbs of Detroit Mi
Posts: 3,704
Rewards Points: 2,000
Default

Temperature Rise


Quote:
Originally Posted by beenthere View Post
For comfort.

It lowers the efficiency, but gets you a warmer discharge temp.

They, like most manufacturers, don't tell you that part.

They also don't tell you that it increases the amount of time it takes to defrost the coil.
I didn't know that
__________________
Just slow, not stupid.
hvaclover is offline   Reply With Quote
Old 03-16-2009, 05:25 AM   #11
An old Tradesmen
 
Join Date: Oct 2008
Location: PA
Posts: 26,520
Rewards Points: 4,682
Default

Temperature Rise


Your actually removing less heat from the discharge gas.

With the lower indoor air flow, it doesn't supply as much heat to the outdoor coil to thaw it.

Advertisement

beenthere is online now   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Condensation on fiberglass window frame creamaster General DIY Discussions 11 01-05-2012 08:42 PM
how to stop condensation on windows? cake General DIY Discussions 7 11-22-2008 01:12 AM
Sweating windows big daddy-o General DIY Discussions 15 01-06-2008 03:41 PM
Temperature Differance Over Coil rjordan392 HVAC 9 08-11-2007 06:34 PM




Top of Page | View New Posts