Need help with a 15tom R22 system - Commercial HVAC Forum - HVACSite

Need help with a 15tom R22 system

 
Thread Tools Display Modes
Old 07-12-2016, 01:26 PM   #1
Junior Member
 
Yoyoman05's Avatar
 
Trade: Hvac certified
Join Date: Jul 2016
Posts: 1
Default

Need help with a 15tom R22 system


Hi..this system is called a pca (precondition educated air) it for cooling a passenger boarding bridge at an airport..it's a 30ton unit which is made from 2 separate 15ton units.. the primary side is working perfectly R22 press is 58.9/213.8 at around 70deg ambient..the secondary side had a bad leak at the txv..we replaced the txv and ensured it didn't leak anymore..the system comes with a predetermined 20lbs of R22..so after vacuum we put 20lbs in...right away the evaporated coil started to freeze and readings were 41.2/225 evaporated temp-18.3 cond temp-109.6...I figured it was still low on refrigerant and added a few lbs but nothing changed with my pressures and temp..note that coming off the discharge side there is a hot gas bypass valve going to the evaporated coil..any ideas what I should look at next
. Any help would be appreciated..thank you

Yoyoman05 is offline  
Warning: The topics covered on this site include activities in which there exists the potential for serious injury or death. HVACSite.com DOES NOT guarantee the accuracy or completeness of any information contained on this site. Always use proper safety precaution and reference reliable outside sources before attempting any construction or remodeling task!

Old 08-11-2016, 06:48 AM   #2
Member
 
airtrackinc's Avatar
 
Trade: airtrackinc
Join Date: Feb 2014
Location: Mississauga
Posts: 76
Default

Re: Need help with a 15tom R22 system


check your air filter. If it’s dirty, replace it with a new filter and turn your air conditioner back on after your coil has thawed out.
airtrackinc is offline  
Old 09-26-2016, 07:57 AM   #3
Junior Member
 
ShepherdEHC's Avatar
 
Trade: HVAC Contractor
Join Date: Feb 2016
Location: NYC
Posts: 19
Default

Re: Need help with a 15tom R22 system


Idk if this will help but, Anytime I change anything on any system I check 95% or the time Change the filter dryer also. looks alil like theres a small restriction in the system. Make sure solenoid is opening all the way. Or if you know how too isolate low sides n check
ShepherdEHC is offline  
Old 10-20-2016, 12:13 PM   #4
Junior Member
 
pintofstout's Avatar
 
Trade: Service tech
Join Date: Oct 2016
Posts: 6
Default

Re: Need help with a 15tom R22 system


Is the other side hot gassing? If so pull the solenoid, put a screwdriver in it obviously, and see where the pressures settle. Probably the same, it's probably not gassing much, but that should give you a good model.

The discharge air temp should be a big indicator of what's going on. If it's extremely cold then it would lean toward low air flow, if fairly warm starved coil.

If superheat is normal then the txv is doing its job but if it's high that doesn't necessarily mean that it isn't. If it's being denied a column of liquid because of a plugged drier, it may be maxed out. Need to determine if it's getting a solid column.

What's controlling that hot gas? Staging? Usually a system with hot gas won't allow suction to get so low.

225 seems like a pretty high head for a system with no load. This one looks like the supply fans not even on, there's definitely no load. Fan cycler keeping it that high? If not it must be PACKED with 22.

Are you SURE the supply fan is dragging air across that coil?



Sent from my iPhone using Tapatalk

Last edited by pintofstout; 10-20-2016 at 12:20 PM.
pintofstout is offline  


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
Looking for digital work orders system. jj1222 HVAC Tools and Equipment 2 05-31-2019 11:42 PM
Learn How to Troubleshoot an Air conditioning System zabaady Residential HVAC Forum 4 03-26-2016 10:43 PM
What should be the target superheat and subcooling for my system? 8829BusExp Residential HVAC Forum 1 12-21-2015 09:14 PM
RTU Refrigeration Problem evergreen General HVAC Discussion 4 10-11-2015 08:40 AM

Join Now... It's Fast and FREE!

I am a professional contractor
I am a DIY Homeowner
Drywall Talk is for
PROFESSIONAL CONTRACTORS ONLY!

At DrywallTalk.com we cater exlusivly to professional contractors who make their living as a contractor. Knowing that many homeowners and DIYers are looking for a community to call home, we've created www.DIYChatroom.com DIY Chatroom is full of helpful advices and perfect for DIY homeowners.

Redirecing in 10 seconds
No Thanks
terms of service

Already Have an Account?

 

SEO by vBSEO 3.6.1