Upgrading thermostat


  #1  
Old 01-24-15, 03:05 PM
B
Member
Thread Starter
Join Date: Jan 2015
Posts: 11
Upvotes: 0
Received 0 Upvotes on 0 Posts
Upgrading thermostat

Went to upgrade my thermostat and ran into some trouble. Check pic attached. There is older looking wires mixed with newer possibly. The layout of the backplate that has the terminals labeled X, Y, 4, 5, does not match its model number on the dial to my knowledge (searched online). The furnace is gas and was replaced around 5 years ago. It has an on/off kill switch installed (not sure if that makes a difference). As you can see, 2 wires to X, 2 wires to 5, 1 wire to 4, none to Y.

So what can I do to move forward ?

Old thermostat model # : T87F 2873
New thermostat model # : RTHL221B1008

Name:  CAM00539.jpg
Views: 408
Size:  25.6 KB
 
  #2  
Old 01-24-15, 03:25 PM
Geochurchi's Avatar
Member
Join Date: Nov 2012
Posts: 5,086
Received 161 Upvotes on 147 Posts
What type of equipment are you controlling,gas,oil,can you ID the wires at the equipment? Some pics of what you have would be helpful.
Geo
 
  #3  
Old 01-24-15, 03:38 PM
B
Member
Thread Starter
Join Date: Jan 2015
Posts: 11
Upvotes: 0
Received 0 Upvotes on 0 Posts
Here are some pics, shows an older looking wire next to a tube of assumed newer wire that run into the on/off switch. They have it set up to have air installed, but just gas heat is currently installed. I'm not sure if they have the wiring set up for air or not, but I'm going to guess no. I can take pics of inside the furnace if you need and whatever else just let me know.

Name:  CAM00545[1].jpg
Views: 346
Size:  28.5 KB

Name:  CAM00541[1].jpg
Views: 353
Size:  16.7 KB

Name:  CAM00543[1].jpg
Views: 329
Size:  14.3 KB

Name:  CAM00544[1].jpg
Views: 330
Size:  31.9 KB
 
  #4  
Old 01-24-15, 04:34 PM
Geochurchi's Avatar
Member
Join Date: Nov 2012
Posts: 5,086
Received 161 Upvotes on 147 Posts
Can you tell at the thermostat if there is just one cable coming through the wall, and are the other wires just jumpers?I would bet there is just one cable there,if you can pull the front cover off that furnace and see where that brown cable goes and take a pic of that, it maybe helpful.
Geo
 
  #5  
Old 01-24-15, 05:34 PM
B
Member
Thread Starter
Join Date: Jan 2015
Posts: 11
Upvotes: 0
Received 0 Upvotes on 0 Posts
The wire that is taped along the tube goes into the furnace looks like it splits into 3. 1 of which grounds to the box, the other 2 connect as shown. With the wires coming in from the switch (black and white) they connect with blue connector ends shown in pics. The black connects to the panel safety switch? and the goes to the circuit. I also followed the wire sets up to the ceiling and the wire set that is taped to the side ends up traveling along up into the wood. The wire set that is in the pipe goes into a box where it gets spliced with I'm assuming the older wires as shown.

Name:  CAM00546.jpg
Views: 352
Size:  25.2 KB
Name:  CAM00561.jpg
Views: 329
Size:  32.6 KB
Name:  CAM00560.jpg
Views: 333
Size:  27.3 KB
Name:  CAM00556.jpg
Views: 294
Size:  23.3 KB
Name:  CAM00555.jpg
Views: 299
Size:  18.6 KB
Name:  CAM00551.jpg
Views: 307
Size:  23.0 KB
Name:  CAM00549.jpg
Views: 352
Size:  22.1 KB
Name:  CAM00548.jpg
Views: 299
Size:  26.1 KB
Name:  CAM00547.jpg
Views: 307
Size:  30.7 KB
Name:  CAM00562.jpg
Views: 306
Size:  28.4 KB
 
  #6  
Old 01-24-15, 05:38 PM
B
Member
Thread Starter
Join Date: Jan 2015
Posts: 11
Upvotes: 0
Received 0 Upvotes on 0 Posts
heres the rest of pics

Name:  CAM00563.jpg
Views: 297
Size:  31.8 KB
Name:  CAM00564.jpg
Views: 296
Size:  44.7 KB
Name:  CAM00565.jpg
Views: 293
Size:  45.5 KB
 
  #7  
Old 01-24-15, 06:02 PM
Geochurchi's Avatar
Member
Join Date: Nov 2012
Posts: 5,086
Received 161 Upvotes on 147 Posts
WOW!the box that has the yellow wire nuts in it should be 120 volts and should have nothing to do with the thermostat.
The 2 wires that are on R &W are the wires you want to go to the thermostat,see if you can trace them and see if they go up through the floor at the Tstat location.
As a side note that box with the yellow wire nuts should be repaired with cable connectors going into that box and the insulation cut back and a proper splice made.
Geo
 
  #8  
Old 01-24-15, 06:30 PM
B
Member
Thread Starter
Join Date: Jan 2015
Posts: 11
Upvotes: 0
Received 0 Upvotes on 0 Posts
Can you point out an example of what the box should look like? Is it unsafe? I'm unfamiliar. Whats confusing is where did the other wires come from in the thermostat? There should be something to control the fan separately right? Or would I have to run a new line for that or? Also, the W and R wires look like they are the skinny wires out of the 5 in thermostat. So what the heck are those other 3 fibery ones?
 
  #9  
Old 01-24-15, 08:39 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 6,526
Received 95 Upvotes on 88 Posts
The junction box needs a couple of romex connectors.

Name:  Romex connector.jpg
Views: 406
Size:  16.5 KB

I don't see any control wires in the j-box.
I don't see a ground wire from the old high voltage wire connected to the ground wire from the new high voltage wire.

If you don't correctly screw on the wire nuts they will melt after you remove and reinstall them.

I would pull new stat wire from the furnace to the stat if you want to be able to run the fan only.

I usually run 6 conductor wire to the stat for future upgrades.
 
  #10  
Old 01-25-15, 04:48 AM
Geochurchi's Avatar
Member
Join Date: Nov 2012
Posts: 5,086
Received 161 Upvotes on 147 Posts
A box like this would make it easier for you,use the same cover,the clamps are built into the box,just push cables into the clamps,strip insulation on cables back a bit ,maybe use a little electrical tape on them to make it easier to push in,connect W to W ,B to B and if there are 2 bare wires there connect them together,although the brown cable may not have a bare,no bare copper should be showing from the other wirenuts,BE SURE TO SHUT THE POWER OFF FIRST!
As for the Tstat,I would agree with Houston and pull new thermostat wire 18-5 or 18-6,especially if you do plan on having AC at some point.
Shop CANTEX 20-cu in Plastic New Work Ceiling Electrical Box at Lowes.com
Geo
 
  #11  
Old 01-25-15, 06:11 AM
B
Member
Thread Starter
Join Date: Jan 2015
Posts: 11
Upvotes: 0
Received 0 Upvotes on 0 Posts
So 18-6 would be 18 gauge with 6 wires? Do they make specific sets for hvac? In order to get them through I am thinking of taping the ends of the new to old at thermostat and pulling through. Might be nailed in somewhere im the wall though. Still wondering about those other 3 wires and what to do about em. Thanks for all the help
 
  #12  
Old 01-25-15, 06:33 AM
Geochurchi's Avatar
Member
Join Date: Nov 2012
Posts: 5,086
Received 161 Upvotes on 147 Posts
You should be able to get the 18-6 at a Big Box store,nothing special just measure your length ,as for taping and pulling in new with the old, probably won't work but you can try.as for the 3 wires you may have to remove the Tstat subbase from the wall and see if they are there, the third wire is likely for the fan control as you mentioned earlier,not really needed unless you want to start the fan to circulate air.
PS. 18-6 is 18 gauge 6 conductor,you were correct
Geo
 
  #13  
Old 01-25-15, 09:39 PM
B
Member
Thread Starter
Join Date: Jan 2015
Posts: 11
Upvotes: 0
Received 0 Upvotes on 0 Posts
So, that ceiling box, I would put the wires in and then connect them together with what? And if there is no ground wire on the old wire, what do I do with the other ground wire from the newer line?
 
  #14  
Old 01-25-15, 09:46 PM
B
Member
Thread Starter
Join Date: Jan 2015
Posts: 11
Upvotes: 0
Received 0 Upvotes on 0 Posts
And what would you guess the other older 3 wires on thermostat are for? If they dont go to anything anymore, why would they have left them connected with the other 2?
 
  #15  
Old 01-26-15, 02:17 PM
B
Member
Thread Starter
Join Date: Jan 2015
Posts: 11
Upvotes: 0
Received 0 Upvotes on 0 Posts
alrighty, I got the a new 8-wire thermostat wire running through to the furnace. So I hook up R, Y, W, G, C(blue) straight to those furnace inputs right?
 
  #16  
Old 01-26-15, 04:29 PM
B
Member
Thread Starter
Join Date: Jan 2015
Posts: 11
Upvotes: 0
Received 0 Upvotes on 0 Posts
Nvm there is no C on this thermostat. I hooked up RWGY and it is working great! Thanks guys, I'll have to tackle that box soon too. I bought the box for it. Still looking into how to do it though.
 
  #17  
Old 01-26-15, 04:50 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 6,526
Received 95 Upvotes on 88 Posts
2 Romex connectors would have been easier.
I actually stock connectors. I do not stock plastic j-boxes.

I avoid hammers except when setting female anchors for 3/8" all thread rod in high rises. There isn't much wood in my work place.

If a ground is not available to the furnace, I usually measure for 120 vac from hot to the plumbing and clamp a wire to the plumbing to connect to the furnace ground.
 
  #18  
Old 01-26-15, 05:13 PM
B
Member
Thread Starter
Join Date: Jan 2015
Posts: 11
Upvotes: 0
Received 0 Upvotes on 0 Posts
I got the ceiling box that was linked. I noticed the furnace fan stays on a minute after I turn off the heat, is that normal? Is there a way to make it just stop when the heat or air is off?
 
  #19  
Old 01-26-15, 09:26 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 6,526
Received 95 Upvotes on 88 Posts
The furnace would trip out on hi limit if it turned off immediately when you turn off the stat.
The fan must run a while to cool down the furnace.
 
  #20  
Old 01-27-15, 10:43 PM
user 10's Avatar
Member
Join Date: Mar 2004
Location: NA
Posts: 1,829
Received 57 Upvotes on 50 Posts
Y is for cooling - you'll never need it unless you decide to add a/c later on.
 
 

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