Bad/Clogged TXV Valve?

Reply

  #1  
Old 10-06-16, 02:20 PM
Member
Thread Starter
Join Date: Aug 2016
Location: USA
Posts: 12
Received 0 Votes on 0 Posts
Bad/Clogged TXV Valve?

So I have been chasing poor cooling for the last 2 years in a brand new home and think I found what is going on but could use some validation before I spend any more time or money. The short story is a 1800 sq ft house with a Trane XV95 variable speed furnace and a XB13 1.5 ton single stage condenser. I could never get the temp below 71 degrees no matter what I did. The RH was always around 55%. The builder has been no help and the HVAC installer tells us my wife cooks too much in the house. I brought in another contractor who upgraded us to a XR17 2 ton unit which helps but 70 degrees and 50% RH is still about the best I can do. The unit will run for long periods so I would think my RH would be lower.

This week, I come across a Trane Tech bulletin from 10/2014 (two months after we bought the house) with an issue of TXV valves being clogged due to debris in the and causing systems to not working correctly. This bulletin included my condenser by both model and serial number. Is it possible that the TXV Valve could be causing such an issue? My last measurement was 70 degrees for return are and 58 degrees for supply. All measurements on the system are OK according to the Tech. My neighbors who built a year later with a similar system can keep the house at 68 without an issue (with a 2 ton unit).

Any thoughts would be helpful. Any I expecting too much?
 
Sponsored Links
  #2  
Old 10-07-16, 08:14 AM
Member
Join Date: Feb 2014
Location: USA
Posts: 2,104
Received 0 Votes on 0 Posts
Has anyone done a load calculation on your house?
 
  #3  
Old 10-08-16, 07:58 AM
Member
Join Date: Aug 2008
Location: Texas, California
Posts: 1,460
Received 0 Votes on 0 Posts
With delta-T at 12 (70-58) you have a problem, whether it is caused by bad TXV or not, you need to call an AC tech to fix it. ( I am sure not all measurements are OK, call a different tech, tell him you want Delta-T at around 16-18)
 
  #4  
Old 10-08-16, 11:26 AM
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,482
Received 25 Votes on 19 Posts
Normally I would state that a plugged/obstructed expansion valve was unlikely but since you have factory documentation of that happening with your particular model I would have to consider it a likely possibility. You need to get a factory authorized technician to do the troubleshooting and be sure to point out the technical bulletin.
 
  #5  
Old 10-09-16, 06:25 AM
Member
Thread Starter
Join Date: Aug 2016
Location: USA
Posts: 12
Received 0 Votes on 0 Posts
Thank you for the replies. The manual J we were provided states we need 1.5 tons. We were the first home built in our sub division and every unit after has been sized to 2 tons. The builder would not upgrade our unit based on the Manual J so we did it ourselves after our one year warranty.

I think part of the issue is the factory certified dealer we brought in is walking into a problem they did not create. He has been trying to isolate the issues one at a time. I did get a call on Friday that they are looking into replacing the TXV valve under the factory warranty. We will see where it goes from here.

I have installed the in duct temperature sensors, on an average, what should I see on the Delta T for the first and second stages?
 
  #6  
Old 10-10-16, 10:47 AM
Member
Join Date: Aug 2008
Location: Texas, California
Posts: 1,460
Received 0 Votes on 0 Posts
16+ delta-T for both stages.
 
  #7  
Old 10-12-16, 09:09 AM
Member
Thread Starter
Join Date: Aug 2016
Location: USA
Posts: 12
Received 0 Votes on 0 Posts
Thanks, I got a call that they are coming out to change the TXV and flush the system per the Trane Service Bulletin. I will see where this goes.
 
  #8  
Old 10-14-16, 05:09 AM
airman.1994's Avatar
Member
Join Date: Dec 2005
Location: VA
Posts: 5,769
Received 4 Votes on 4 Posts
I second heat load! 2 tons sounds low unless your house is built really tight.
 
  #9  
Old 10-17-16, 07:47 AM
Member
Thread Starter
Join Date: Aug 2016
Location: USA
Posts: 12
Received 0 Votes on 0 Posts
So my home is new construction (very tight) and the Manual J I was provided by the builder states we only needed 1.5 tons of cooling. I asked the builder to upgrade me to a 2 stage/2 ton unit but was denied because the "building inspector" would not allow him to install anything over what the Manual J stated. I did not realize the inspectors have that much control and he would not consider a two stage unit. I argued (through the builder) that a two stage would run at roughly 1.5 tons unless there was a significant demand? How about a little extra capacity?

The same exact townhome with the same construction and same N/S orientation cools to 68 with no issues (using a 2 ton condenser- now standard with the currently built homes????).

The new factory certified contractor will be out this week to replace the TXV per the tech note and we will see.

I'm happy to send the Manual J to anyone who is interested. Maybe they missed something? As I found out, the builders HVAC contractor is not factory certified and appears to not be very knowledgeable.
 
Reply

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


Thread Tools
Search this Thread
Display Modes
 
Ask a Question
Question Title:
Description:
Your question will be posted in: