How Cold Should Low Pressure Line Be - 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 07-02-2012, 07:29 AM   #1
Member
 
Join Date: May 2008
Location: Near Philly
Posts: 2,051
Rewards Points: 1,022
Default

how cold should low pressure line be


I was weeding near my York condenser unit (YCJF42S41S1, not a heat pump) and felt the low pressure line (unit was running at the time). It wasn't very cold and no condensation (quite humid lately). House is keeping cool (set to 77* during day) in 98* weather but I'm wondering if freon charge might be off?
Condenser YP9C080C16MP with Aspen coil and thermal expansion valve.
Does the TXV "compensate" for off-pressure charge?

Advertisement

bob22 is offline   Reply With Quote
Old 07-02-2012, 07:48 AM   #2
Member
 
biggles's Avatar
 
Join Date: Jan 2008
Location: Long Island
Posts: 3,630
Rewards Points: 2,000
Default

how cold should low pressure line be


beer can cold...as long as that liquid line is filled from 3-4 rows up out on the condenser that is the state that the TXV looks for to operate(if you have it might be cap tubes).if the liquid level(charge) is low that liquid seal where the LL starts coming out of the condenser is changed seeing flashing and gas burps into the TXV....somewhat like a garden hose spray.so as the liquid is metered out into the evap the pressure drops as so does the temperature to give you 40F.typical evap is 18F drop on return air vs supply air taken at the air handler,with 10F rise on the air into and out of the condenser.sounds like it needs a tweek with questionable charges effecting the unit run time(longer) trying to make setpoint

Advertisement

biggles is offline   Reply With Quote
Old 07-03-2012, 01:17 PM   #3
Member
 
Join Date: May 2008
Location: Near Philly
Posts: 2,051
Rewards Points: 1,022
Default

how cold should low pressure line be


I measured temp at a register close to the unit, 63*. Temp inside house set for 77* so I assume intake air would be close to that.
Do I have to measure within the duct work leading just out of the unit or is a register 10' away ok?
bob22 is offline   Reply With Quote
Old 07-03-2012, 01:43 PM   #4
Member
 
biggles's Avatar
 
Join Date: Jan 2008
Location: Long Island
Posts: 3,630
Rewards Points: 2,000
Default

how cold should low pressure line be


right on top of the A coil plenium box and at the filter on the return if you want to get that 18
biggles is offline   Reply With Quote
Old 07-03-2012, 02:12 PM   #5
Member
 
Join Date: May 2008
Location: Near Philly
Posts: 2,051
Rewards Points: 1,022
Default

how cold should low pressure line be


Thanks; I see what holse I can find to poke in a thermometer.
bob22 is offline   Reply With Quote
Old 07-03-2012, 08:18 PM   #6
Member
 
biggles's Avatar
 
Join Date: Jan 2008
Location: Long Island
Posts: 3,630
Rewards Points: 2,000
Default

how cold should low pressure line be


nail and a hammer just above that A coil into the duct work
biggles is offline   Reply With Quote
Old 07-04-2012, 05:52 AM   #7
An old Tradesmen
 
Join Date: Oct 2008
Location: PA
Posts: 26,421
Rewards Points: 4,488
Default

how cold should low pressure line be


Quote:
Originally Posted by biggles View Post
nail and a hammer just above that A coil into the duct work
Make sure your above the A coil.
beenthere is offline   Reply With Quote
Old 07-04-2012, 11:46 AM   #8
retired elect/hvac/plumb
 
plummen's Avatar
 
Join Date: Jan 2010
Location: south east of omaha/The island of misfit contractors
Posts: 2,916
Rewards Points: 2,010
Default

how cold should low pressure line be


Quote:
Originally Posted by beenthere View Post
Make sure your above the A coil.

Advertisement

__________________
"facts" have no relevance to this discusion
Posting from a concrete bunker under a non descript barn
plummen is offline   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
Replaced cold cartridge, now hot and cold both have low pressure. zing Plumbing 5 05-28-2012 09:57 PM
Part2-Rumbling pipes and leaking pressure relief valve Homerepairguy Plumbing 9 04-24-2012 04:49 AM
cold water pressure low in new faucet tndale Plumbing 1 03-16-2011 03:15 PM
High pressure in water line atlfiveo Plumbing 5 02-06-2007 10:04 PM
Help with low pressure cold water upstairs lewissv Plumbing 5 01-26-2007 09:05 AM




Top of Page | View New Posts