Journey with Confidence RV GPS App RV Trip Planner RV LIFE Campground Reviews RV Maintenance Take a Speed Test Free 7 Day Trial ×
RV Trip Planning Discussions

Go Back   iRV2 Forums > THE OWNER'S CORNER FORUMS > Newmar Owner's Forum
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
 
Thread Tools Search this Thread Display Modes
 
Old 08-29-2017, 01:14 PM   #1
Registered User
 
Newmar Owners Club
Appalachian Campers
Freightliner Owners Club
Join Date: Feb 2017
Location: Midlothian, VA
Posts: 4,774
Thermistor accuracy

In figuring out my RV, obviously setting the temp to whatever ends up being comfortable, I'm surprised how innaccurate the thermistor is and Dometic controller. I have my front A/C set to 71 to feel comfortable, at home I set to 77. I have a temp stick that reports temps over wifi so I can monitor while away for my dog and I bought a thermometer for sanity to visualize what it reads to glance at it. Then I bought an IR sensor and a car thermometer to check values at the vents in the ceiling.

Here are a few pics showing off inaccurate it is. The Dometic indoor temp appears to be on average 4-6 degrees off of actual. I'm fortunate too in that Newmar learned putting thermistors on external walls was a bad idea, mine are on interior walls thankfully so I'm not dealing with outside influences.
Attached Thumbnails
Click image for larger version

Name:	IMG_3931.png
Views:	173
Size:	1.81 MB
ID:	174810   Click image for larger version

Name:	IMG_3933.png
Views:	172
Size:	1.75 MB
ID:	174811  

NealC is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 08-29-2017, 04:00 PM   #2
Senior Member
 
reubenray's Avatar




 
Join Date: Feb 2012
Location: Bella Vista, Arkansas
Posts: 5,386
My setup is the front A/C is not being controlled by the optional sensor. It is controlled by the thermostat in the CCC. I have not been able to find out if the optional sensor is wired correctly or not. I get a lot of sun on the wall where the CCC is at and it is about 7 degrees different from where the optional sensor is. I am using a wireless temperature sensor to check these. To help a little I removed the CCC and put a piece of strofoam insulation between it and the wall.

If it is cool where you are at now the CCC is picking up the temperature through the wall.
__________________
Raymond, Dee Dee and Sophie (Yorkie)
2023 Chevrolet 2500HD LT 4X4
2024 Grand Design Reflection 296RDTS
reubenray is offline   Reply With Quote
Old 08-29-2017, 04:02 PM   #3
Registered User
 
Newmar Owners Club
Appalachian Campers
Freightliner Owners Club
Join Date: Feb 2017
Location: Midlothian, VA
Posts: 4,774
Quote:
Originally Posted by reubenray View Post
My setup is the front A/C is not being controlled by the optional sensor. It is controlled by the thermostat in the CCC. I have not been able to find out if the optional sensor is wired correctly or not. I get a lot of sun on the wall where the CCC is at and it is about 7 degrees different from where the optional sensor is. I am using a wireless temperature sensor to check these. To help a little I removed the CCC and put a piece of strofoam insulation between it and the wall.

If it is cool where you are at now the CCC is picking up the temperature through the wall.
What is a CCC?
NealC is offline   Reply With Quote
Old 08-29-2017, 05:18 PM   #4
Senior Member
 
bruceisla's Avatar
 
Join Date: Oct 2012
Location: Foley AL
Posts: 7,138
Quote:
Originally Posted by NealC View Post
What is a CCC?
Comfort Control Center .... aka thermostat
__________________
2005 Newmar Essex 4502, 2013 Caddy SRX
1997 HR Endeavor 37, CAT, 1996 Geo Tracker
bruceisla is offline   Reply With Quote
Old 08-29-2017, 05:20 PM   #5
Senior Member
 
bruceisla's Avatar
 
Join Date: Oct 2012
Location: Foley AL
Posts: 7,138
My sensors are within a degree of my IR gun when using the "inside temp" on the CCC2 (comfort Control Center version 2).

And, when set to Auto, the A/Cs cycle right around the temperature of my standalone thermometers. For instance, as I turn and look at a tabletop thermometer, it says 77 (which is a verified 1 degree high).... my front A/C is set at 75 and is cycling. Outside temp has been 92 ish all day but around 90 right now.

No complaints here. Seems to be fairly accurate.

BTW, as you suggest, if your IR gun is accurate, and you are focused near the sensor, your CCC2 "inside temp" and gun should match. Have you confirmed gun accuracy?
__________________
2005 Newmar Essex 4502, 2013 Caddy SRX
1997 HR Endeavor 37, CAT, 1996 Geo Tracker
bruceisla is offline   Reply With Quote
Old 08-29-2017, 05:34 PM   #6
Registered User
 
Newmar Owners Club
Appalachian Campers
Freightliner Owners Club
Join Date: Feb 2017
Location: Midlothian, VA
Posts: 4,774
I just shot the temp at the Dometic controller which is set to 72, the wall temp there is 80'ish. I then shot back at the thermistor and it's 73. It seems to have stabilized which is odd.
NealC is offline   Reply With Quote
Old 08-29-2017, 05:46 PM   #7
Senior Member
 
bruceisla's Avatar
 
Join Date: Oct 2012
Location: Foley AL
Posts: 7,138
Quote:
Originally Posted by NealC View Post
I just shot the temp at the Dometic controller which is set to 72, the wall temp there is 80'ish. I then shot back at the thermistor and it's 73. It seems to have stabilized which is odd.
You need to lay off the sauce for awhile Seriously now, my guess would be the gun slipped off target and shot past the sensor. In my case, I can't see what I'm doing anymore ....
__________________
2005 Newmar Essex 4502, 2013 Caddy SRX
1997 HR Endeavor 37, CAT, 1996 Geo Tracker
bruceisla is offline   Reply With Quote
Old 08-30-2017, 05:34 AM   #8
Senior Member
 
reubenray's Avatar




 
Join Date: Feb 2012
Location: Bella Vista, Arkansas
Posts: 5,386
Do either one of you have the AGS option? There is a box in the compartment right before the one with the pegboard that is part of the AGS system. There is a slot for a optional internal option cable to plug into. I am thinking maybe the main/front A/C optional sensor is plugged into this instead of the CCC itself.
__________________
Raymond, Dee Dee and Sophie (Yorkie)
2023 Chevrolet 2500HD LT 4X4
2024 Grand Design Reflection 296RDTS
reubenray is offline   Reply With Quote
Old 08-30-2017, 06:00 AM   #9
Senior Member
 
bruceisla's Avatar
 
Join Date: Oct 2012
Location: Foley AL
Posts: 7,138
ing
Quote:
Originally Posted by reubenray View Post
Do either one of you have the AGS option? There is a box in the compartment right before the one with the pegboard that is part of the AGS system. There is a slot for a optional internal option cable to plug into. I am thinking maybe the main/front A/C optional sensor is plugged into this instead of the CCC itself.
Not really following you ... Dometic temp sensors go to the roof and are plugged into the zone control units at each A/C. The CCC2 receives it's temperature info via the communication cable along with all the other command responses. The sensors are a bit sensitive to heat radiating from the wall but that causes the sensor to read a few degrees high relative to actual room temperature. That, in turn, causes the A/C to run longer because it is trying to reach set point. In other words, the room becomes colder than set point. This is also why the Dometic CCC should not use the internal thermistor for Zone 1 if the thermostat is enclosed in a hot cabinet.

In my case, all thermistors are relocated (away from the wall) using a 3 1/2 inch square (1/2 inch thick) wood rosette matched to the cabinet color.

__________________
2005 Newmar Essex 4502, 2013 Caddy SRX
1997 HR Endeavor 37, CAT, 1996 Geo Tracker
bruceisla is offline   Reply With Quote
Old 08-30-2017, 06:57 AM   #10
Senior Member
 
reubenray's Avatar




 
Join Date: Feb 2012
Location: Bella Vista, Arkansas
Posts: 5,386
My two thermistors are located on interior walls where the sun cannot shine on them. My CCC location gets direct sun for 4 to 5 hours. The front a/c is being controlled by the CCC's internal thermostat not the optional thermistor. While trying to find out where the wiring for the thermistor goes to I came across the AGS box in the compartment. If the rain from Harvey will let up I will take a picture of this box. There is a printout of the connections that shows where the optional internal thermistor is to be plugged into.
__________________
Raymond, Dee Dee and Sophie (Yorkie)
2023 Chevrolet 2500HD LT 4X4
2024 Grand Design Reflection 296RDTS
reubenray is offline   Reply With Quote
Old 08-30-2017, 07:20 AM   #11
Senior Member
 
bruceisla's Avatar
 
Join Date: Oct 2012
Location: Foley AL
Posts: 7,138
Quote:
Originally Posted by reubenray View Post
My two thermistors are located on interior walls where the sun cannot shine on them. My CCC location gets direct sun for 4 to 5 hours. The front a/c is being controlled by the CCC's internal thermostat not the optional thermistor. While trying to find out where the wiring for the thermistor goes to I came across the AGS box in the compartment. If the rain from Harvey will let up I will take a picture of this box. There is a printout of the connections that shows where the optional internal thermistor is to be plugged into.
Assuming you have Dometic A/C, the sensor plugs into the control board on the A/C unit. It's a skinny white pair. Goes from the A/C down the wall directly to the sensor. Difficult to add after the RV is built. You "could" add one from the top, drop it into the return (warm) duct, find it from below at a vent, and then do as you please. In older RVs the sensor was frequently just left in the return vent near incoming air. Typically the sensor was a little on the warm side from air at ceiling level but better than being in a hot location.
__________________
2005 Newmar Essex 4502, 2013 Caddy SRX
1997 HR Endeavor 37, CAT, 1996 Geo Tracker
bruceisla is offline   Reply With Quote
Old 08-30-2017, 07:29 AM   #12
Senior Member
 
Join Date: Dec 2004
Location: Edmond, Oklahoma
Posts: 414
Our thermistor for zone 1 was way off, also, sometimes as much as 10 degrees. I discovered another thermistor behind my pegboard bay, and that's where it wasthe reading! That thermostat came from the roof, and was supposed to be connected to the zone 1. Once connected, temps stay within a coupleof degrees.
__________________
2017 DSDP 4054 Spartan Chassis
BattChief is offline   Reply With Quote
Old 08-30-2017, 07:44 AM   #13
Senior Member
 
reubenray's Avatar




 
Join Date: Feb 2012
Location: Bella Vista, Arkansas
Posts: 5,386
Whenever it quits raining I will check the control board at the a/c unit.
__________________
Raymond, Dee Dee and Sophie (Yorkie)
2023 Chevrolet 2500HD LT 4X4
2024 Grand Design Reflection 296RDTS
reubenray is offline   Reply With Quote
Old 08-30-2017, 05:59 PM   #14
Registered User
 
Newmar Owners Club
Appalachian Campers
Freightliner Owners Club
Join Date: Feb 2017
Location: Midlothian, VA
Posts: 4,774
Quote:
Originally Posted by reubenray View Post
My two thermistors are located on interior walls where the sun cannot shine on them. My CCC location gets direct sun for 4 to 5 hours. The front a/c is being controlled by the CCC's internal thermostat not the optional thermistor. While trying to find out where the wiring for the thermistor goes to I came across the AGS box in the compartment. If the rain from Harvey will let up I will take a picture of this box. There is a printout of the connections that shows where the optional internal thermistor is to be plugged into.
I'm far from any expert here but the AGS connection is a sensor that determines if your A/C (CCC) is on or off. If you have A/C on and you lose shore power and your AGS is set to enable this sensor the gen will kick on so that the A/C continues to run. I use this and learned of it from C.Martin when he helped me with my config with the ME-ARC50 and ME-BMK mods. So AFAIK that's the AGS connection to the CCC which is a failover for shore power loss and need for climate control.
NealC is offline   Reply With Quote
Reply



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
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
Thermistor problem pappaono National RV Owner's Forum 6 10-29-2011 09:18 AM
Norcold thermistor on wrong fin??? azloafer RV Systems & Appliances 19 03-23-2011 07:35 PM
Norcold 600 Series Thermistor replacement Lorene and John RV Systems & Appliances 8 03-24-2010 05:33 PM
exposing HVAC thermistor?? footdoc Newmar Owner's Forum 8 08-15-2009 03:48 PM
Norcold Thermistor Higher or Lower? ronboc RV Systems & Appliances 3 05-02-2007 05:18 PM

» Featured Campgrounds

Reviews provided by


All times are GMT -6. The time now is 02:27 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.