Thank you for this! I popped off my existing thermostat (has to be at least as old as our 20 yr old home and sure enough had a C wire tucked in there as well as the C wire coiled up in furnace fuse box! You saved me so much $ with this video!
@mrskatiana9852 I’m glad to hear you had all the wires ready to go and the video was helpful to you! It feels good when it all works out like that! Use the money you saved to get a nice fancy thermostat! You’ll love it!
Perfect! I couldn’t figure out why the thermostat wouldn’t run. Forgot to put the cover of the furnace back on. It’s the little details! Thank you so much
@Ktimson Rose Designs Yep, that would do it! I’ve even had some furnaces that wouldn’t run if the cover was o but wasn’t fit perfectly. Glad you found the video helpful!
Thanks for the video... I did not fall asleep :). I have one thermostat with only 2 wires going in on the thermostat end, but there's a third common wire hanging out on the furnace end. I'm still trying to figure out that mystery. Thanks for adding to my bag of tricks on this one
@O_ Carltop Thank you for checking out the video! I'm glad you found it useful. And you made it all the way to my 'falling asleep' comment! MUCH appreciated! lol On your wires it sounds like maybe someone cutoff the unused wire on the thermostat end but left it for future use on the furnace end?. It would be interesting to see if the wire is there at the thermostat end if you stripped the insulation back a bit....
thank you for the video...very informative for beginners like me..so now i know i can independently supply c-wire if there is none using AC transformer...that is a great solution for old houses...thanks again.
@Halim Jaffar I’m glad you found the video useful. The AC option is a great way to update older homes as you note. I really like the modern thermostats, so easy to use. Thanks for the note! 😀
Thank you so much for the video I too had the blue wire that was wrapped up around the wire casing made life a lot easier once again thanks for the video
@Jim Baker Glad to hear the video was helpful! I think some HVAC tech kept that wire in place knowing it would be useful down the line. They were right! 😀
Great explanation! Now I know where to get my C wire power from. I have an extra wire like you mentioned and all I need to do is connect it at the control block and bring power to my thermostat. Should work well with my new Honeywell Home thermostat.
Oh man thank you I purchased the same thermostat cause it's real nice and works well but I don't have access to the power. I was gonna DIY a plug to make a C-wire but thankfully you showed us the C-wire power adapter I'm gonna remove the listing on Mercari of the thermostat cause I really don't want the other version of the same thermostat that doesn't require a C-wire.
Thanks for your excellent video. I found a few other videos but your video explained why the extra wire (c wire) was needed. A long time ago I had had a heat pump but now have gas furnace & central air. The heat pump required more wires to the thermostat So I have an extra wire to accommodate the new WiFi Thermostat in my current setup.
@Lawrence Schall I’m glad to hear the video was useful to you! Having extra wires is always super handy! I had one wire go bad for some reason but luckily I had a spare wire. Better to be lucky!
Your video showed a cable with 5 wires from the controls board to thermostat. I have a cable to the thermostat with 4 wires. It's not easy to replace the cable or add an additional wire. I think to use Y wire for bringing Common to the thermostat and use single W wire to bring both Heating and Cooling from the thermostat through diodes to extra 2 relays or simple circuit with thyristors.
@Tim Kishelov That might work but it might be easier to just use an external AC power supply near the thermostat. Use the 4 wires you have for control and use the new wire for power from nearest outlet. Something to consider….
I have a new Sensi WiFi thermostat made specifically for systems like mine that does NOT require a C-wire. The thermostat has 2 AA batteries instead. My gas furnace/AC system was replaced in 2019 and the house built in 1995, so never had a C-wire.
@Steve_in_NJ Yes, I have a Sensi battery powered thermostat that does not require a C wire as well. It works very well, especially with lithium batteries. It’s another useful option to upgrade older systems. Thanks!
@@DougForceMy current thermostat was installed by the HVAC people and I cannot remove it so they will swap it out when they come to my house this week to do the annual AC service visit. 🙂
Ok, after pulling off the cover to my old thermostat I have 4 wires (W1, G, Y1 & RH) I've already purchased the Transformer, which would now give me 6 wires. How should the thermostat be wired now? I know one of the wires should go into the C terminal where should the other wire go? I also purchased the Sensi Touch thermostat.
@Jas1n9b78 Usually most modern thermostats look for power between RH and C, but look at your thermostat documentation and the transformer documentation for specifics. You might find this link helpful: roboauthority.com/thermostat-c-wire/
@Tim K. - thanks for checking it out! There is no battery on this particular thermostat but it does not lose the program when power is cut. It still remembers the settings to match your HVAC, etc. I’m not sure if it stores the data locally or in the cloud, but it does not lose anything.
@djkavish lal It’s usually better to use a traditional c wire or use a c wire replacement transformer. You might be able to kludge something at the thermostat but then you run into issues like the red wire loses power between heat and cool, or the thermostat doesn’t sense when unit is running correctly, etc. I’d use a c wire replacement transformer if no good c wire option was available.
@MrAjd1982 Some older furnaces don’t have a C wire. There are several things you can do in this case. Check out this article for more info. www.aztilac.com/i-want-a-smart-thermostat-but-dont-have-a-c-wire-what-are-my-options/
@ddemier I’ve been very happy with them. I have three and no issues until recently when the oldest one quit connecting to wifi. Still worked fine otherwise. It was at least 5 years old. Replaced it with same model.
If the red wire was already connected to the C-terminal at the furnace, why not simply put a jumper between the RC and the C terminal in the thermostat???
@FlyingDutchmanWA I think systems with RC connected to 24v full time are for AC only, is that what you have? In that case I believe you are right about the jumper. The issue would be when there is an RH and an RC. Then the C wire would have to be independent of the reds.
@@DougForce actually, I have neither. I only have 2 wires going to thermostat and don’t have option to run an external 24v power supply. Am going to install a power supply at furnace and rewire existing set up. Found a video on how to do that for heat only systems.
@Seeking Truth I’m very glad to hear that the video was helpful in figuring out your setup! I’m not familiar with a two stage furnace - what did you have to do to get it going?
@@DougForce have not done yet but after watching ur video and several others I’m being told that I can use the green fan wire for the W2 (second stage) terminal & then I can run jumper from yellow wire (cooling terminal) to g terminal to control fan.
@Seeking Truth interesting - I’ll be interested to hear how it works for you when complete. Jumpers seem to be the key to lots of variations in hookup.
@@DougForce Yeah, it was a rather long one. Just because I wanted to add extra to better help. Extra as in mod #s info etc. So I posted and it took. Few later and was gone. I'll try a short one sorta. Got a Goodman older furnace. No Ac to it just heat. To help, here is the mod # to that board. B18099-13. Now on that board left to right is TW IN prong. That has no wire. Meter check shows 15vac. Next, is a screw saying 24v hum ( ? ). No wire and meter shows no voltage. Next, is W,G,R. Them wires are there. The wire is 3 only. Going into Hunter non touch screen is G- green. RC- red jumper to 3. 3. Red plus red jumper to that rc. Y/o no wire. WB white. Y1 no wire. I want to get that thermostat in your vid. What do I need to do or understand being I have only 3 wires?- red white green and that red jumper. I guess I am confused here because my board does not have "C". That and do I place that red jumper same on new touch thermostat.
@ForcedOnline- Doug Force little info above on my 3 wire and no C on board ( listed mod # of board for you to run and view ). I think I'm gonna run that Ac adapter. I just brought it. So on this 24vac adapter exactly where do them wires clip in at on that thermostat you have? What letter markings? Is it RH and C for your thermostat from the wall ac adapter.
I'm pulling my hair out trying to figure this out. let me explain as quick as i can. the c wire adapter seems to require a 4 wire ran through the house, other videos point to this as well. however, you can run a wifi amazon honeywell on a 3 wire system, r, w, c. i've got one working currently. it appears c is just grounded to the chassis though, so is one leg of the 24v transformer on my garage heater. Also, with a second transformer installed on my old boiler, i can run theses thermostats with 4 wires. orginal system is just 2 wire t (R), t (W). simple. it also has x(aux) but not usefull. so i've got original t, t going to r, w on thermostat and from second transformer, i ran as a test with leads, to Rc, and C on thermostat for constant power. and it works fine. problem is, i only have 3 wire through the house. 3 wire works on my garage forced air heater fine. i cannot figure out how to duplicate a three wire set up on my boiler to work. thermostat will not power up with just R, W, C connected. i've tried jumping R , Rc together, no luck. i have the voltage but nothing happens. I know it can be done but i'm missing something. my thoughts are on the garage heater logic board even though both the transformer and the c wire are grounded to chassis, something is different with the R lead. on my boiler the R lead reads 25.6v while off, when calling for heat, it drops to about 5volts. so i don't know. i thought the whole point of the c wire adapter was for people with old systems and few wires. thanks for any help possible. and yes i've read not to ground the c wire. but its like that from the factory on this mr. heater. i think people are refereing to using the ground system in your house as the c wire. thats not my issue, i need to find a way to use my 3rd green wire as my c wire. while still completing the circuit. i would think i could find a way to pull from the original transformer but if it drops to 5v that wouldnt keep the thermostat on.
@Justin Paone Sounds like you have quite a setup puzzle! The benefit of the external adapter is that you don’t have to use any of the existing wires to power the thermostat. It will come with its own cable and you run that from the nearest electrical outlet to your thermostat to power it. Then use the furnace wires to control the system as you listed. I agree with you that your existing transformer won’t work for you since it drops to 5 volts in use. But with the external thermostat power adapter, you won’t need to use your existing power. Does that help or did I miss the point entirely?
@@DougForce UPDATE: I ended up running a new 5 wire cable to the thermostat simply because my 3 wire had a short or break somewhere. that was terrible crawling around in the attic of a 130 year old house with wires running everywhere. be that as it may that doesn't solve my issue. but with the new wires hooked up i no longer had the voltage drop during operation. now i had the extra wires to use the second transformer with but still didn't want to if i didnt have to. with further research i found i could attach a c wire to the exsisting transformer if i did so at the leg, prior to it going through the relay. its a surface mount transformer on the control board. the board has no logic, its just there to save wiring i guess. one leg of the transformer goes directly to a T terminal, (r) wire,the other has no terminal but terminates at the relay, also surface mounted. i simply soldered the C wire to the board at that termination, hooked up the red and white, and all is good on a three wire setup. now i have to figure out why i don't have enough draught. with manifold pressure at 3.5 inwc, and primary air wide open i still have too high co. currently i have the manifold pressure dialed back so eliminate co from the room but now i'm not as efficient. my next step is to pull the stack and clean the fire chamber or tubes or whatever. thanks for the reply and wish me luck.
Links to the items mentioned in the video: Sensi Thermostat amzn.to/3m4dmfe Nest Thermostat amzn.to/3tbi5zI C Wire Power Adapter amzn.to/3t3QSyP Thermostat wire amzn.to/3x3j2Lx
Thank you for this! I popped off my existing thermostat (has to be at least as old as our 20 yr old home and sure enough had a C wire tucked in there as well as the C wire coiled up in furnace fuse box! You saved me so much $ with this video!
@mrskatiana9852 I’m glad to hear you had all the wires ready to go and the video was helpful to you! It feels good when it all works out like that! Use the money you saved to get a nice fancy thermostat! You’ll love it!
Perfect! I couldn’t figure out why the thermostat wouldn’t run. Forgot to put the cover of the furnace back on. It’s the little details! Thank you so much
@Ktimson Rose Designs Yep, that would do it! I’ve even had some furnaces that wouldn’t run if the cover was o but wasn’t fit perfectly. Glad you found the video helpful!
Thanks for the video... I did not fall asleep :). I have one thermostat with only 2 wires going in on the thermostat end, but there's a third common wire hanging out on the furnace end. I'm still trying to figure out that mystery. Thanks for adding to my bag of tricks on this one
@O_ Carltop Thank you for checking out the video! I'm glad you found it useful. And you made it all the way to my 'falling asleep' comment! MUCH appreciated! lol On your wires it sounds like maybe someone cutoff the unused wire on the thermostat end but left it for future use on the furnace end?. It would be interesting to see if the wire is there at the thermostat end if you stripped the insulation back a bit....
thank you for the video...very informative for beginners like me..so now i know i can independently supply c-wire if there is none using AC transformer...that is a great solution for old houses...thanks again.
@Halim Jaffar I’m glad you found the video useful. The AC option is a great way to update older homes as you note. I really like the modern thermostats, so easy to use. Thanks for the note! 😀
Thank you so much for the video I too had the blue wire that was wrapped up around the wire casing made life a lot easier once again thanks for the video
@Jim Baker Glad to hear the video was helpful! I think some HVAC tech kept that wire in place knowing it would be useful down the line. They were right! 😀
Great explanation! Now I know where to get my C wire power from. I have an extra wire like you mentioned and all I need to do is connect it at the control block and bring power to my thermostat. Should work well with my new Honeywell Home thermostat.
&TheCrowdPhoto That’s the best case when you have the existing wire. The Honeywell thermostat is great!
Oh man thank you I purchased the same thermostat cause it's real nice and works well but I don't have access to the power. I was gonna DIY a plug to make a C-wire but thankfully you showed us the C-wire power adapter I'm gonna remove the listing on Mercari of the thermostat cause I really don't want the other version of the same thermostat that doesn't require a C-wire.
@Lou Glad you found the video helpful! I agree this is a great thermostat and much better than the battery powered model.
Thanks for your excellent video. I found a few other videos but your video explained why the extra wire (c wire) was needed. A long time ago I had had a heat pump but now have gas furnace & central air. The heat pump required more wires to the thermostat So I have an extra wire to accommodate the new WiFi Thermostat in my current setup.
@Lawrence Schall I’m glad to hear the video was useful to you! Having extra wires is always super handy! I had one wire go bad for some reason but luckily I had a spare wire. Better to be lucky!
Excellent video that confirmed what I was thinking. Should have my Amazon t stat up and running soon.
@Lee R I’m glad you found it helpful!
Your video showed a cable with 5 wires from the controls board to thermostat. I have a cable to the thermostat with 4 wires. It's not easy to replace the cable or add an additional wire. I think to use Y wire for bringing Common to the thermostat and use single W wire to bring both Heating and Cooling from the thermostat through diodes to extra 2 relays or simple circuit with thyristors.
@Tim Kishelov That might work but it might be easier to just use an external AC power supply near the thermostat. Use the 4 wires you have for control and use the new wire for power from nearest outlet. Something to consider….
Great video sir!!!!!!! Thank you very much!!!! In my case, I’ll have to use a transformer.
@fernandodelpuerto1021 Glad it helped! The transformer is an easy and cheap option!
I have a new Sensi WiFi thermostat made specifically for systems like mine that does NOT require a C-wire. The thermostat has 2 AA batteries instead. My gas furnace/AC system was replaced in 2019 and the house built in 1995, so never had a C-wire.
@Steve_in_NJ Yes, I have a Sensi battery powered thermostat that does not require a C wire as well. It works very well, especially with lithium batteries. It’s another useful option to upgrade older systems. Thanks!
@@DougForceMy current thermostat was installed by the HVAC people and I cannot remove it so they will swap it out when they come to my house this week to do the annual AC service visit. 🙂
Ok, after pulling off the cover to my old thermostat I have 4 wires (W1, G, Y1 & RH) I've already purchased the Transformer, which would now give me 6 wires. How should the thermostat be wired now? I know one of the wires should go into the C terminal where should the other wire go? I also purchased the Sensi Touch thermostat.
@Jas1n9b78 Usually most modern thermostats look for power between RH and C, but look at your thermostat documentation and the transformer documentation for specifics. You might find this link helpful: roboauthority.com/thermostat-c-wire/
@@DougForce Thanks for the information.
Great video, If no c wire and you use a transformer does the sensi have battery backup if power is lost?
@Tim K. - thanks for checking it out! There is no battery on this particular thermostat but it does not lose the program when power is cut. It still remembers the settings to match your HVAC, etc. I’m not sure if it stores the data locally or in the cloud, but it does not lose anything.
Can you bridge the red and “C” wire in the thermostat without going to the furnace?
@djkavish lal It’s usually better to use a traditional c wire or use a c wire replacement transformer. You might be able to kludge something at the thermostat but then you run into issues like the red wire loses power between heat and cool, or the thermostat doesn’t sense when unit is running correctly, etc. I’d use a c wire replacement transformer if no good c wire option was available.
My furnace wire panel doesnt have a C labeled terminal to connect the wire to, what do you do then?
@MrAjd1982 Some older furnaces don’t have a C wire. There are several things you can do in this case. Check out this article for more info. www.aztilac.com/i-want-a-smart-thermostat-but-dont-have-a-c-wire-what-are-my-options/
Thank you! Very informative!!
@Street Stories Thanks for checking it out, Anthony!
How do you like the Sensi? Any issues with it?
@ddemier I’ve been very happy with them. I have three and no issues until recently when the oldest one quit connecting to wifi. Still worked fine otherwise. It was at least 5 years old. Replaced it with same model.
If the red wire was already connected to the C-terminal at the furnace, why not simply put a jumper between the RC and the C terminal in the thermostat???
@FlyingDutchmanWA I think systems with RC connected to 24v full time are for AC only, is that what you have? In that case I believe you are right about the jumper. The issue would be when there is an RH and an RC. Then the C wire would have to be independent of the reds.
@@DougForce actually, I have neither. I only have 2 wires going to thermostat and don’t have option to run an external 24v power supply. Am going to install a power supply at furnace and rewire existing set up. Found a video on how to do that for heat only systems.
@FlyingDutchmanWA Sounds like a good plan! Good luck with the upgrade!
great info thanks
@Daniel Vega My pleasure! Glad it was useful to you!
This was a Awesome video thx so much. Also my scenario is a little different my furnace has 2 stages.
Figured things out with your help
@Seeking Truth I’m very glad to hear that the video was helpful in figuring out your setup! I’m not familiar with a two stage furnace - what did you have to do to get it going?
@@DougForce have not done yet but after watching ur video and several others I’m being told that I can use the green fan wire for the W2 (second stage) terminal & then I can run jumper from yellow wire (cooling terminal) to g terminal to control fan.
@Seeking Truth interesting - I’ll be interested to hear how it works for you when complete. Jumpers seem to be the key to lots of variations in hookup.
Where did all my time go to help in my asking reply. The reply is gone.... So, Use G wire or fan wire as the C wire
@Joseph Baumgardner I’m not sure what happened- seems like a number of comments have disappeared!
@@DougForce Yeah, it was a rather long one. Just because I wanted to add extra to better help. Extra as in mod #s info etc. So I posted and it took. Few later and was gone. I'll try a short one sorta. Got a Goodman older furnace. No Ac to it just heat. To help, here is the mod # to that board. B18099-13. Now on that board left to right is TW IN prong. That has no wire. Meter check shows 15vac. Next, is a screw saying 24v hum ( ? ). No wire and meter shows no voltage. Next, is W,G,R. Them wires are there. The wire is 3 only. Going into Hunter non touch screen is G- green. RC- red jumper to 3. 3. Red plus red jumper to that rc. Y/o no wire. WB white. Y1 no wire. I want to get that thermostat in your vid. What do I need to do or understand being I have only 3 wires?- red white green and that red jumper. I guess I am confused here because my board does not have "C". That and do I place that red jumper same on new touch thermostat.
@ForcedOnline- Doug Force little info above on my 3 wire and no C on board ( listed mod # of board for you to run and view ). I think I'm gonna run that Ac adapter. I just brought it. So on this 24vac adapter exactly where do them wires clip in at on that thermostat you have? What letter markings? Is it RH and C for your thermostat from the wall ac adapter.
Hi man, I installed 3 of this and none of the
Worked. It was blowing hot air and one of the units and other units it never get to desired temperature.
@Jefferson Silva Sorry to hear about the issue! You mean three Sensi thermostats?
I'm pulling my hair out trying to figure this out. let me explain as quick as i can. the c wire adapter seems to require a 4 wire ran through the house, other videos point to this as well. however, you can run a wifi amazon honeywell on a 3 wire system, r, w, c. i've got one working currently. it appears c is just grounded to the chassis though, so is one leg of the 24v transformer on my garage heater. Also, with a second transformer installed on my old boiler, i can run theses thermostats with 4 wires. orginal system is just 2 wire t (R), t (W). simple. it also has x(aux) but not usefull. so i've got original t, t going to r, w on thermostat and from second transformer, i ran as a test with leads, to Rc, and C on thermostat for constant power. and it works fine. problem is, i only have 3 wire through the house. 3 wire works on my garage forced air heater fine. i cannot figure out how to duplicate a three wire set up on my boiler to work. thermostat will not power up with just R, W, C connected. i've tried jumping R , Rc together, no luck. i have the voltage but nothing happens. I know it can be done but i'm missing something. my thoughts are on the garage heater logic board even though both the transformer and the c wire are grounded to chassis, something is different with the R lead. on my boiler the R lead reads 25.6v while off, when calling for heat, it drops to about 5volts. so i don't know. i thought the whole point of the c wire adapter was for people with old systems and few wires. thanks for any help possible. and yes i've read not to ground the c wire. but its like that from the factory on this mr. heater. i think people are refereing to using the ground system in your house as the c wire. thats not my issue, i need to find a way to use my 3rd green wire as my c wire. while still completing the circuit. i would think i could find a way to pull from the original transformer but if it drops to 5v that wouldnt keep the thermostat on.
@Justin Paone Sounds like you have quite a setup puzzle! The benefit of the external adapter is that you don’t have to use any of the existing wires to power the thermostat. It will come with its own cable and you run that from the nearest electrical outlet to your thermostat to power it. Then use the furnace wires to control the system as you listed.
I agree with you that your existing transformer won’t work for you since it drops to 5 volts in use. But with the external thermostat power adapter, you won’t need to use your existing power.
Does that help or did I miss the point entirely?
@@DougForce UPDATE: I ended up running a new 5 wire cable to the thermostat simply because my 3 wire had a short or break somewhere. that was terrible crawling around in the attic of a 130 year old house with wires running everywhere. be that as it may that doesn't solve my issue. but with the new wires hooked up i no longer had the voltage drop during operation. now i had the extra wires to use the second transformer with but still didn't want to if i didnt have to. with further research i found i could attach a c wire to the exsisting transformer if i did so at the leg, prior to it going through the relay. its a surface mount transformer on the control board. the board has no logic, its just there to save wiring i guess. one leg of the transformer goes directly to a T terminal, (r) wire,the other has no terminal but terminates at the relay, also surface mounted. i simply soldered the C wire to the board at that termination, hooked up the red and white, and all is good on a three wire setup. now i have to figure out why i don't have enough draught. with manifold pressure at 3.5 inwc, and primary air wide open i still have too high co. currently i have the manifold pressure dialed back so eliminate co from the room but now i'm not as efficient. my next step is to pull the stack and clean the fire chamber or tubes or whatever. thanks for the reply and wish me luck.
Links to the items mentioned in the video:
Sensi Thermostat amzn.to/3m4dmfe
Nest Thermostat amzn.to/3tbi5zI
C Wire Power Adapter amzn.to/3t3QSyP
Thermostat wire amzn.to/3x3j2Lx