Thank you for the video. I installed 2 add a C wire kits in our Church. They did not change anything. They are still working off batteries. Any help would greatly be appreciated.
When you say "C-wire kit" are you talking about the old Honeywell product by that specific name?Or are you referring to the Venstar Add-A-Wire kit as shown in this video? Or one of the many other similar products out there (ecobee PEK, FAST-STAT Common Maker, etc).
@@TECTubefilms We installed 2 Sensi Smart Thermostats . There was not a C wire. Sensi sold us Common Wire Maker Kits. Looks just like the one in your video. We installed them just like your video showed. They work the same after we added the C wire maker kits as they did before. They are working off the batteries so they go off line often to save the batteries. Once Sensi called me to tell me that the C wire maker kits were working. But a few hours later they stopped working. Thank you very much for replying to me.
I am trying to instal a Sensi wifi thermostat. I have no C wire at thermostat. I purchased an sensi add a wire kit. They have a install Video on web site. Basically converting G wire to common. It shows to remove yellow wire and wing nut it to yellow wire from add a wire kit.. i am stuck here cause I have two yellow wires at my furnace control panel. Which yellow wire do I remove?
We believe the Sensi Add-A-Wire kit is manufactured by Venstar and hence the same one show in this video. So everything Ryan did in the video would likely apply.
In regards to the wire color, it does not really matter what the wire color is. You can use any color you want so long as what you do at the stat matches at the other end at the equipment. If you have two yellow wires at your furnace, it is unlikely both go to the stat. You will need to trace out each wire and know where it goes before you re-wire something.
Question ? I just install a Honeywell wifi I have the 5 wires already connected heat is working perfect but When I turn the AC the thermostat goes off and comes right back on but is not turning the AC and on the screen shows a massage WAITING FOR EQUIPMENT please Advice thanks
Sir, thank you for this great video. One question. Can add-a-wire kit be used for replacing R (power wire) or it can be used only for common, cooling and fan only?
It can be used on any pair of signal terminals (Y1, Y2, W1, W2, G) which means it cannot be wired to R or to C. But once you combine two signal terminals on one wire in your wall (say G and Y), it then frees up a dedicated wire that can be used for either C or R.
We are not sure what you mean by "two slot." Are you saying that between your furnace and your thermostat there are only 2 wires total? If that is the case, we also assume you do not have a cooling system. The PEK cannot be used on a 2-wire heating-only system. Either pull more wires or take a look at a product called Fast-stat Common Maker www.fast-stat.com
Excellent video for the add a wire, however it would be much more helpful to show the condenser wires hooked up because this obviously just shows the t stat connections, for us pros is ok, but for DIY people they can easily get stuck seeing the extra two wires from the condenser.
Our channel is intended for use by our customers, who are HVAC service professionals. If a DIY homeowner finds our channel on accident, we cannot stop that, but assisting them directly is not our mission.
Hi I have a question about the cor. my old stat has a wire going to the RC with a jumper from the RC to the RH. when I install the COR do i put the wire back on the RH or do i put the wire back on the RC and chose RC and RH from the set up menu ?
Michael, it depends on whether the application has a single or dual transformer setup and what the "R" wires are connected to. In regards to your Carrier Cor thermostat, we have a 3 part video series on that topic and here is the link to the part of the video that addresses your specific question - ruclips.net/video/JvDsy_X-jNk/видео.htmlm9s
once complete with "add a wire kit" I should be able to just run my fan by itself. Reason being is that I have a april air cleaner and run it to keep the air clean if the temperature in the house is already comfortable.
If the AC is 2 stage and the furnace is single stage, would there be a problem with installing the common wire? The Nest that I have seems to be working just fine, but unsure if it is using the 2 stages without the common wire.
The common wire (C) is used in conjunction with the hot wire (R) to power up a thermostat. The common wire has no affect on the staging control of the thermostat.
Thanks for the video. For the add a wire, on my current 4 wire system the R G and W seem to be normal, but there is no Y wire at the air handler. There is a wire seemingly going to the outside condenser from C, and a return wire going up to Y on the thermostat. Should I bring down the return from the condenser and hook to Y on the handler, then bring down the wire that ran up to Y to use for the add a wire?
We are not completely clear on your question and can't visualize what you are describing. And it sounds like you are not confident where some of the wires are connected/routed... for example you said "seemingly going to the outside condenser," with lack a of certainty. You should draw a wiring diagram showing how all 3 devices (stat, furnace, and A/C) are currently wired to each other. If you are unsure where a wire goes, use your electrical meter to trace it out. If you're a homeowner and not familiar with electrical wiring you may want to hire a HVAC contractor to do this work.
Tec Tube Sorry. I was as sure as I could be without using a wire tester, but if I'm not 100% sure I tend to use seemingly, etc. They basically had y on the stat going to the a/c unit, and the other a/c wire going to c on the furnace. I split that y wire, bringing the compresser side to y, and the y from the thermostat to the venstar. So I ended up with c and y wires from the furnace to the a/c unit, and everything else like the add a wire diagrams. Not sure if there was an easier way, but everything is working now.
Does it have to be Y and G? Say I have 2 wire heat only and want to add the fan (G) can I then use the W and G? Or is there something about Y and G that allows them to communicate in the 1 wire?
John, it does not have to be Y & G. You can use Add-a-Wire to combine any two "signal wires" that you want. So this could be G, Y, W, Y2, W2, etc.). However, you must have dedicated wires (both R & C) for 24v power. You can only share signal wires, not power wires. Therefore, you cannot use Add-a-Wire in your example because you only have 2-wires and once you consumer them for power (R & C), you are out of wires.
There are numerous variables that could cause the blower to run without a request from the thermostat. This could range anywhere from a simple mis-wiring by the installer to a more concerning safety lockout on the furnace combustion. Certified service technicians should contact their local distributor's technical assistance department for troubleshooting tips. Consumers should contact a factory authorized dealer for their brand of furnace.
@@matthewnowak3222 I ended up having to run a plug in transformer in order to get my power to the thermostat. I can't remember off the top of my head which terminals went to which letter but I have a very old system so it was easier to but the transformer, plug it in and run the wire up for C.
That symptom can be caused by any number of root causes. Did this blower motor issue exist prior to your new thermostat installation or did it begin because of the new stat? The answer to that will help you determine if perhaps you wired and programmed something on the new stat to cause it to run all the time or if perhaps you have a larger issue. Either the thermostat or the furnace circuit board can engage the fan and for different reasons. One of these reasons may include combustion safety. There are also many areas of the country that have residential ventilation codes that require a fresh air intake on the home and the furnace blower is often setup to run continuously to meet those codes. If you in the Midwest, we can likely refer you to a trusted residential service provider who can troubleshoot and repair the issue.
For most climates, the past 7 months have been the heating season and the cooling season just began in the past couple of weeks. Perhaps your problem is related to the air conditioning side only and it did not manifest itself until you turned the A/C side on recently. What brand and model of stat did you have installed? Which professional dealer installed it? If the dealer is local to the area that we serve and if they purchased the thermostat from us, then we would be able to assist them (and hence you) with troubleshooting and solving the issue.
I bought a Honeywell WiFi thermostat. There is no C wire. There are 5 wires going to thermostat. However, there is a black and red wire from the furnace's R terminal going to the R and RC of the old thermostat. Could I simply move the black wire from the furnace's R and put it to the C terminal and same on the thermostat? Then put a jumper on R and RC on the thermostat?
No. The wire colors are not as important as what they are wired to. You need to figure out why you have a R and a RC. If you are not the original installer of the old thermostat, you need to trace the wires out. It is highly probable that you have two transformers and hence to 24 hot "R wires."
You may also want to check out the Honeywell WireSaver. It works similar to Venstar's Add-a-Wire kit, except instead of working with all 24vac stats, WireSaver only works with Honeywell.
Thanks. I was able to figure the C wire and got the thermostat working. The issue now is: 2-3 minutes into the heat call (burners firing up and blower running) the burners shut off and thermostat shuts off and comes back 30 seconds later. What do you think it is? Do you think the Wi-Fi thermostat is robbing power from the furnace? Do you think it needs a dedicated transformer? Existing transformer is 24V 40VA.
The Add-a-Wire kit can combine any two "signal" wires such as fan (G), cool (Y), cool2 (Y2), heat (W), heat2 (W2), reversing valve (O/B), etc. It cannot combine the power wires of 24vac hot (R) or common (C). So the answer to your question will depend on whether your new stat has a LCD and needs a common wire and if your equipment needs a fan (G) signal every time you energize cooling (Y) or if you want independent fan control. Your HVAC installer should know what is needed for your specific application.
I finally upgraded to a WiFi Thermostat. This guide was EXACTLY what I needed. I only had 4 wires to my old battery thermostat, so I bought the Add-a-Wire Kit. It took a little bit of time to make sure the wires were correct, but if this un-manly guy can do it, anyone can! Thanks for the tutorial!
@@aurvaroy6670 interesting that out of that entire comment, the only thing you picked up on was the use of one particular word, completely unrelated to the subject at hand. What did you find remarkable about that word?
@@aurvaroy6670 then what else did you pick up on, and if there WERE other things, why was "the one thing" the ONLY thing you wrote about? Obviously, it was the most important thing, or the only thing important enough to mention.
We have never tested it on nest but there is no reason to suspect it would work any differently on their stat. A nest stat uses the traditional old school wiring of most stats (R, G, Y, W, etc.).
Tec Tube you probably don’t need a add a wire with a nest. Nest stat will work with just 4 wires. You don’t have to connect anything to C terminal. It has internal battery that charges when your AC is on.
I use this add a wire kit with every nest install, although nest says you just need a 4 wire hookup, I’ve had issues in the past, and the add a wire kit saves much money and time, so yes this will work on nest t stats.
@@matthewnowak3222 Was that a Version 3 Nest. I have used an external 24v transformer to power the thermostat. Problem is the air tech warned me about having two 24v transformers on the red loop. What do you think?
Are you asking if a Venstar Add-a-Wire accessory can be added to a system that only has 2 wires total? No, it cannot. It cannot be used to split R or split C. Those needed to be dedicated wires.
@@antoniosantiago2770 If you already have 3 wires in the wall, then yes you can put one each on R, C, and W. You do not need an Add-a-Wire kit in that application. However, if you only have 2 wires in the wall and you are trying to use the Add-a-Wire to get a 3rd wire, then no you cannot. That is why below we said that R and C must be dedicated wires. If you only have 2 wires, and you dedicate them to R and C, then you have nothing left.
This doesn't make any sense. If you are able to access to the board, you just get a 5 wire connect from board to new thermostat directly. There is not need to your device at all
Correct! If you have the ability to easily pull an additional wire, then you should. An Add-a-Wire device is used for applications where pulling new wires is not an option. We believe Ryan stated that in this video.
Am I missing something here?!?! Why would you spend a dime on this rediculous, unnecessary adapter? If you went to the trouble of running a blue wire from t-stat to heater why wouldn't you just run a new 8 wire cable and be done with it?? Please, if I'm missing something clue me in.
Running new or additionally wires is impractical or cost prohibitive in some applications. This device allows you to make 4 wires in the wall behave like 5... or make 7 behave like 8, or whatever.
What trouble of running a blue wire? We are not sure what you mean. You would only use Add-a-Wire instead of running new wires. If you are in a situation where you can easily and quickly run new wire, that is the preferred method.
I'd rather buy the adapter than try to fish a new wire or cable (only for C-wire capability) through my existing 70 year old walls. This is the perfect solution.
Excellent video! Thank you! Now I can add 2 more devices (smart thermostats) to my home wifi networks! Just what the wife will want to hear! :-)
This is fantastic sir! You demystified Add-A-Wire circuit to me! 👌👌
Awesome! Great video.
Ha new to the channel was watching this video and I was paying attention to the blue wire Ryan lol good stuff man learn a lot keep up the good work!
Thank you for the video. I installed 2 add a C wire kits in our Church. They did not change anything. They are still working off batteries. Any help would greatly be appreciated.
When you say "C-wire kit" are you talking about the old Honeywell product by that specific name?Or are you referring to the Venstar Add-A-Wire kit as shown in this video? Or one of the many other similar products out there (ecobee PEK, FAST-STAT Common Maker, etc).
@@TECTubefilms We installed 2 Sensi Smart Thermostats . There was not a C wire. Sensi sold us Common Wire Maker Kits. Looks just like the one in your video. We installed them just like your video showed. They work the same after we added the C wire maker kits as they did before. They are working off the batteries so they go off line often to save the batteries. Once Sensi called me to tell me that the C wire maker kits were working. But a few hours later they stopped working. Thank you very much for replying to me.
I am trying to instal a Sensi wifi thermostat. I have no C wire at thermostat. I purchased an sensi add a wire kit. They have a install Video on web site. Basically converting G wire to common. It shows to remove yellow wire and wing nut it to yellow wire from add a wire kit.. i am stuck here cause I have two yellow wires at my furnace control panel. Which yellow wire do I remove?
We believe the Sensi Add-A-Wire kit is manufactured by Venstar and hence the same one show in this video. So everything Ryan did in the video would likely apply.
In regards to the wire color, it does not really matter what the wire color is. You can use any color you want so long as what you do at the stat matches at the other end at the equipment. If you have two yellow wires at your furnace, it is unlikely both go to the stat. You will need to trace out each wire and know where it goes before you re-wire something.
Question ? I just install a Honeywell wifi I have the 5 wires already connected heat is working perfect but When I turn the AC the thermostat goes off and comes right back on but is not turning the AC and on the screen shows a massage WAITING FOR EQUIPMENT please Advice thanks
www.honeywellhome.com/en/questions/my-thermostat-display-shows-wait-or-waiting-for-equipment-or-has-a-flashing-cool-on-in-display
Sir, thank you for this great video. One question. Can add-a-wire kit be used for replacing R (power wire) or it can be used only for common, cooling and fan only?
It can be used on any pair of signal terminals (Y1, Y2, W1, W2, G) which means it cannot be wired to R or to C. But once you combine two signal terminals on one wire in your wall (say G and Y), it then frees up a dedicated wire that can be used for either C or R.
Great info! Thanks.
How can i install power kit in my furnace. In my furnace have only two slot for wire. Black and white.
Please advise
We are not sure what you mean by "two slot." Are you saying that between your furnace and your thermostat there are only 2 wires total? If that is the case, we also assume you do not have a cooling system. The PEK cannot be used on a 2-wire heating-only system. Either pull more wires or take a look at a product called Fast-stat Common Maker www.fast-stat.com
I have 6 wires with a jumper from rh to rc.... will this work for me with 6 wires. No C
Very helpful and clearly stated. Thank you, this is going to save me some cashola!
Excellent video for the add a wire, however it would be much more helpful to show the condenser wires hooked up because this obviously just shows the t stat connections, for us pros is ok, but for DIY people they can easily get stuck seeing the extra two wires from the condenser.
Our channel is intended for use by our customers, who are HVAC service professionals. If a DIY homeowner finds our channel on accident, we cannot stop that, but assisting them directly is not our mission.
The wiring to the condensing unit will be the same with or without a Venstar Add-a-Wire kit.
Hi I have a question about the cor. my old stat has a wire going to the RC with a jumper from the RC to the RH. when I install the COR do i put the wire back on the RH or do i put the wire back on the RC and chose RC and RH from the set up menu ?
Michael, it depends on whether the application has a single or dual transformer setup and what the "R" wires are connected to. In regards to your Carrier Cor thermostat, we have a 3 part video series on that topic and here is the link to the part of the video that addresses your specific question - ruclips.net/video/JvDsy_X-jNk/видео.htmlm9s
once complete with "add a wire kit" I should be able to just run my fan by itself. Reason being is that I have a april air cleaner and run it to keep the air clean if the temperature in the house is already comfortable.
As long as your customer has a "G" wire, then the thermostat can be used to control the fan independent of heating and cooling.
If the AC is 2 stage and the furnace is single stage, would there be a problem with installing the common wire? The Nest that I have seems to be working just fine, but unsure if it is using the 2 stages without the common wire.
The common wire (C) is used in conjunction with the hot wire (R) to power up a thermostat. The common wire has no affect on the staging control of the thermostat.
And nest is by far our least favorite smart stat. Check out ecobee... Cor... Housewise... Honeywell... Venstar... Sensi... just about anything else.
Thanks for the video. For the add a wire, on my current 4 wire system the R G and W seem to be normal, but there is no Y wire at the air handler. There is a wire seemingly going to the outside condenser from C, and a return wire going up to Y on the thermostat. Should I bring down the return from the condenser and hook to Y on the handler, then bring down the wire that ran up to Y to use for the add a wire?
We are not completely clear on your question and can't visualize what you are describing. And it sounds like you are not confident where some of the wires are connected/routed... for example you said "seemingly going to the outside condenser," with lack a of certainty. You should draw a wiring diagram showing how all 3 devices (stat, furnace, and A/C) are currently wired to each other. If you are unsure where a wire goes, use your electrical meter to trace it out. If you're a homeowner and not familiar with electrical wiring you may want to hire a HVAC contractor to do this work.
Tec Tube Sorry. I was as sure as I could be without using a wire tester, but if I'm not 100% sure I tend to use seemingly, etc. They basically had y on the stat going to the a/c unit, and the other a/c wire going to c on the furnace. I split that y wire, bringing the compresser side to y, and the y from the thermostat to the venstar. So I ended up with c and y wires from the furnace to the a/c unit, and everything else like the add a wire diagrams. Not sure if there was an easier way, but everything is working now.
Does it have to be Y and G? Say I have 2 wire heat only and want to add the fan (G) can I then use the W and G? Or is there something about Y and G that allows them to communicate in the 1 wire?
John, it does not have to be Y & G. You can use Add-a-Wire to combine any two "signal wires" that you want. So this could be G, Y, W, Y2, W2, etc.).
However, you must have dedicated wires (both R & C) for 24v power. You can only share signal wires, not power wires. Therefore, you cannot use Add-a-Wire in your example because you only have 2-wires and once you consumer them for power (R & C), you are out of wires.
what is the problem when the fan blower won't turn off even if the thermostat is on off
There are numerous variables that could cause the blower to run without a request from the thermostat. This could range anywhere from a simple mis-wiring by the installer to a more concerning safety lockout on the furnace combustion.
Certified service technicians should contact their local distributor's technical assistance department for troubleshooting tips. Consumers should contact a factory authorized dealer for their brand of furnace.
My board at my HVAC Doesn't have a C terminal. Then what?
EGGINFOOLS what terminals does it have corresponding to what letters?
@@matthewnowak3222 I ended up having to run a plug in transformer in order to get my power to the thermostat. I can't remember off the top of my head which terminals went to which letter but I have a very old system so it was easier to but the transformer, plug it in and run the wire up for C.
EGGINFOOLS the plug in transformer I use a lot for the ring doorbell and in some instances to power up the smart stat. Main thing is you got it going.
Hi, my blower motor won't turn off even though I installed a new thermostat any suggestions
That symptom can be caused by any number of root causes. Did this blower motor issue exist prior to your new thermostat installation or did it begin because of the new stat? The answer to that will help you determine if perhaps you wired and programmed something on the new stat to cause it to run all the time or if perhaps you have a larger issue. Either the thermostat or the furnace circuit board can engage the fan and for different reasons. One of these reasons may include combustion safety. There are also many areas of the country that have residential ventilation codes that require a fresh air intake on the home and the furnace blower is often setup to run continuously to meet those codes.
If you in the Midwest, we can likely refer you to a trusted residential service provider who can troubleshoot and repair the issue.
I had this thermostat put in professionally about seven months ago and I didn't have any problems until a week ago
For most climates, the past 7 months have been the heating season and the cooling season just began in the past couple of weeks. Perhaps your problem is related to the air conditioning side only and it did not manifest itself until you turned the A/C side on recently.
What brand and model of stat did you have installed? Which professional dealer installed it? If the dealer is local to the area that we serve and if they purchased the thermostat from us, then we would be able to assist them (and hence you) with troubleshooting and solving the issue.
I bought a Honeywell WiFi thermostat. There is no C wire. There are 5 wires going to thermostat. However, there is a black and red wire from the furnace's R terminal going to the R and RC of the old thermostat. Could I simply move the black wire from the furnace's R and put it to the C terminal and same on the thermostat? Then put a jumper on R and RC on the thermostat?
No. The wire colors are not as important as what they are wired to. You need to figure out why you have a R and a RC. If you are not the original installer of the old thermostat, you need to trace the wires out. It is highly probable that you have two transformers and hence to 24 hot "R wires."
You may also want to check out the Honeywell WireSaver. It works similar to Venstar's Add-a-Wire kit, except instead of working with all 24vac stats, WireSaver only works with Honeywell.
Thanks. I was able to figure the C wire and got the thermostat working. The issue now is: 2-3 minutes into the heat call (burners firing up and blower running) the burners shut off and thermostat shuts off and comes back 30 seconds later. What do you think it is? Do you think the Wi-Fi thermostat is robbing power from the furnace? Do you think it needs a dedicated transformer? Existing transformer is 24V 40VA.
Have you yet determined if it is a thermostat issue or furnace issue?
Not sure yet. When i put back my non-WiFi thermostat back on, no issues.
Does it work if I only have 3 wires currently, namely heat, cold and power (y w r)? Can I combine the heat and cold?
The Add-a-Wire kit can combine any two "signal" wires such as fan (G), cool (Y), cool2 (Y2), heat (W), heat2 (W2), reversing valve (O/B), etc. It cannot combine the power wires of 24vac hot (R) or common (C). So the answer to your question will depend on whether your new stat has a LCD and needs a common wire and if your equipment needs a fan (G) signal every time you energize cooling (Y) or if you want independent fan control. Your HVAC installer should know what is needed for your specific application.
Perfect. Thank you
Tec Tube ií
I finally upgraded to a WiFi Thermostat. This guide was EXACTLY what I needed. I only had 4 wires to my old battery thermostat, so I bought the Add-a-Wire Kit. It took a little bit of time to make sure the wires were correct, but if this un-manly guy can do it, anyone can! Thanks for the tutorial!
"un-manly" you say. Interesting choice of words...
@@aurvaroy6670 interesting that out of that entire comment, the only thing you picked up on was the use of one particular word, completely unrelated to the subject at hand. What did you find remarkable about that word?
@@realSamAndrew "the only thing you picked up on was the use of one particular word'
That's not the only thing I "picked up" on that comment...
@@aurvaroy6670 then what else did you pick up on, and if there WERE other things, why was "the one thing" the ONLY thing you wrote about? Obviously, it was the most important thing, or the only thing important enough to mention.
@@realSamAndrew Why do you care so much about what I commented? If my comment bother you this much, why don't you report it?
Can you use the fan by itself?
Yes, certainly.
The add a wire segment was kind of confusing.
Is there a specific question we can help answer to make it less confusing?
Can I use this Add-a-Wire kit with Nest Thermostat?
We have never tested it on nest but there is no reason to suspect it would work any differently on their stat. A nest stat uses the traditional old school wiring of most stats (R, G, Y, W, etc.).
Tec Tube you probably don’t need a add a wire with a nest. Nest stat will work with just 4 wires. You don’t have to connect anything to C terminal. It has internal battery that charges when your AC is on.
I use this add a wire kit with every nest install, although nest says you just need a 4 wire hookup, I’ve had issues in the past, and the add a wire kit saves much money and time, so yes this will work on nest t stats.
@@matthewnowak3222 Was that a Version 3 Nest. I have used an external 24v transformer to power the thermostat. Problem is the air tech warned me about having two 24v transformers on the red loop. What do you think?
Can it be done with r and w to add a common
Are you asking if a Venstar Add-a-Wire accessory can be added to a system that only has 2 wires total? No, it cannot. It cannot be used to split R or split C. Those needed to be dedicated wires.
I’m asking if I have a stat with r and w can designate c and use the other two for r and w
@@antoniosantiago2770 If you already have 3 wires in the wall, then yes you can put one each on R, C, and W. You do not need an Add-a-Wire kit in that application. However, if you only have 2 wires in the wall and you are trying to use the Add-a-Wire to get a 3rd wire, then no you cannot. That is why below we said that R and C must be dedicated wires. If you only have 2 wires, and you dedicate them to R and C, then you have nothing left.
Tec Tube got it now thanks
I’ll have to use the fast stat
This doesn't make any sense. If you are able to access to the board, you just get a 5 wire connect from board to new thermostat directly. There is not need to your device at all
Correct! If you have the ability to easily pull an additional wire, then you should. An Add-a-Wire device is used for applications where pulling new wires is not an option. We believe Ryan stated that in this video.
Am I missing something here?!?! Why would you spend a dime on this rediculous, unnecessary adapter? If you went to the trouble of running a blue wire from t-stat to heater why wouldn't you just run a new 8 wire cable and be done with it??
Please, if I'm missing something clue me in.
Running new or additionally wires is impractical or cost prohibitive in some applications. This device allows you to make 4 wires in the wall behave like 5... or make 7 behave like 8, or whatever.
What trouble of running a blue wire? We are not sure what you mean. You would only use Add-a-Wire instead of running new wires. If you are in a situation where you can easily and quickly run new wire, that is the preferred method.
I'd rather buy the adapter than try to fish a new wire or cable (only for C-wire capability) through my existing 70 year old walls. This is the perfect solution.
I assume you are supposet to turn of the power from the thermostat, before you begin?
Yes, we disconnected power and we do state that in the video