Replacement of 2 Thermostats with 1 New One!- Detailed Heat and AC Tstat Wiring Installation!

In This HVAC Installation Video, I go over how to Replace 2 HVAC Thermostats with 1 Thermostat that will Control Both Heating and Cooling System Operations. I show how to determine which thermostat is for which unit, how to verify wire destinations, how to fish the wire from one Tstat hole to the other Tstat hole, How the new connections are made in the new Thermostat, and many other tips! Supervision is needed by a licensed HVACR Tech while performing tasks as Experience and Apprenticeship garners Wisdom and Safety.
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⚠️ Disclaimer:
Information in this video is intended for educational purposes only. Any work related to the topics in this video should be performed by licensed technicians or by apprentices under the supervision of licensed technicians. AC Service Tech LLC is not responsible for any possible damages or injuries caused by the use or misuse of any information provided.
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[@acservicetechchannel]

Tool List- www.amazon.com/shop/acservicetech Support- www.patreon.com/acservicetech For those that are looking for the tools used in the videos: (Linked Below) Here is a link to the self drilling white wall anchors- amzn.to/2xRvoJh Here is a link to the Pro 3000 24v Thermostat used in the video- amzn.to/2keuUbs Here is a link to the Heat Pump 24v Thermostat with Aux and E Controls- amzn.to/2x8ISBE Here is the link for the Irwin Wire Stripper/Cutter/Crimper amzn.to/2dGTj2V Here is the link to the 3amp fuse 10 pack- amzn.to/2x8PATt Here is a link to the thermostat 3/32 screwdriver -- amzn.to/2hxt7uK Here is a link to the Fieldpiece SC640 Multimeter- amzn.to/2x8k4Kb Here is a link to the Stanley 6 in 1 screwdriver- amzn.to/2x7NuaZ Other tool links can be found in the video description section. ACSERVICETECH is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon. All of the ACSERVICETECH Playlists- kzbin.info/door/OZR-1IqsAer9wzlvFgb4mAplaylists?view_as=public If you want to support the ACSERVICETECH Channel and receive more HVAC content, check out www.Patreon.com/acservicetech

[@Termonder]

Moving into a new house on Thursday, this is exactly what I needed. Thanks!

[@geojor]

good information for DIYers ...

[@rdigity1]

My dude, that was a very informative and helpful video! Very well done.

[@acservicetechchannel]

Thanks a lot!

[@mrharlemike28]

This video was epic! So much detail! Things I didnt know and never thought about. Thanks for being so thorough! Happy new follower! 😎

[@acservicetechchannel]

Glad it was helpful!

[@Angel-bs1hm]

Espectacular as usual, Ty!

[@acrepairnearme]

Thank you! Cool video. Very helpful!)

[@acservicetechchannel]

Tapch MC thank you very much for choosing to support the channel through Patreon.com/acservicetech Let me know what you think of the article and if you have any hvacr questions feel free to post it through patreon comments or through email at [e-mail]

[@jimbola77]

thank you acservicetech for sharing another outstanding video!!!! keep em rollin'' God Bless.

[@acservicetechchannel]

Thanks Jimbolla77!

[@jimbola77]

acservicetech you welcome I'm glad you have the patience to show your expertise! I really want to get into the trade, I am tired of driving over the road dead end .

[@acservicetechchannel]

Jimbola77 did you get your 608 universal cert yet? Let me know your status to date such as if you have been applying at companies or what has been going on. You could also always email me if you didn't want to comment on that here- [e-mail]

[@acservicetechchannel]

All of the ACSERVICETECH Playlists- kzbin.info/door/OZR-1IqsAer9wzlvFgb4mAplaylists?view_as=public If you want to support the ACSERVICETECH Channel and receive more HVAC content, check out www.Patreon.com/acservicetech

[@johncote2776]

Great video. Not sure if you posted a video like this before, but a video showing how to set the heat anticipator on the analog thermostat. Also how to wire in a delay on make for an outdoor condenser for cooling when an analog thermostat is installed.

[@acservicetechchannel]

Just this so far- kzbin.info/www/bejne/e3bXm6iqrdp5mdE

[@ausjom]

Thanks for the video. I also have one thermostat for cooling and one for heating, but the heating thermostat is for radiant heat with an in-floor sensor. Do you know if I can safely replace these with a Nest? Nest has this "True Radiant" feature, but I am not sure if it supports an in-floor sensor (or I can just not use the floor sensor). The current thermostat is a little Watts Radiant. Thanks!

[@RHD_327]

Hi, I could use a little advice. I have followed your instructions on a 3 TSTAT system going to a ZonePro. Heating and blower work fine (for all TSTATS). A switch to Cool on any TSTAT trips fuse even when breaker is Off on compressor. I tested Yellow lead from ZonePro to HVAC for Ohm and continuity and it properly went to OL and continuity went on/off dependent on any TSTAT Cooling or not. I thus ruled out Zonepro or wires from ZonePro to HVAC as shorted. Error code on HVAC board indicated a "ground short" by its flashes. For fun I disconnected the compressor Red and White (Compressor) at HVAC board and ran Cool. No trip occurred and HVAC ran normally. Thus, I assumed the short to be from HVAC board to compressor. I opened compressor panel and found the four lead cable to be fairly short and tight. I clipped the red and white and inserted Blue and Green in place assuming the short was either on red or white. Wired it up and TSTAT Cool tripped it again. My thinking is to replace entire HVAC to compressor run assuming a significant short? I would like a professionals opinion on this in case I am missing something? Thank you very much. -R

[@vitalloz]

Hi, and how to connect two thermostats in parallel?

[@throttlebottle5906]

I like to seal the thermostat wire hole with "electric/duct seal putty", just be careful it does stain. I prefer to power the thermostats from the heating system, but it freezes here in winter and happens fast!

[@acservicetechchannel]

I use GE silicone1 to seal the hole but you don't need to if the hole in the attic and or crawlspace are sealed though, thanks!

[@dr.seanstelting5575]

I have a thermostat for AC/Fresh air return unit, 4 wires, R, Y, G, and C. I also have a thermostat for radiant in-floor heating, 2 wires, R and W. I would like to install a Nest thermostat that would control both. I spoke with their support and was told I need to have a Nest Pro come out and install a relay. First off do I really need that and second could you specify where you connected all the wires. In the video you only mention a couple of them. (ie: common, Rc)

[@johnmiller102]

So here is a question for you. Im installing a heat pump with AH in the attic and existing gas furnace in the basement. The homeowner wants to run the hp until it gets below 40 degrees outside using one thermostat. I have an od temp sensor. The heat pump has a heat strip to temper during defrost. Any suggestions on the wiring?

[@catdaddy7582]

I have a somewhat unique situation I'm trying to figure out. In one unit of my quadplex- currently being renovated- is a heat pump with gas over AND a coil for a hot water boiler system, which I haven't used yet, but heats all the water heaters via heat exchangers, and, I believe one other heretofore unused HVAC system in the Flea Market. It has two thermostats, both non-digital. I want to go to one digital, but I believe I will have to add in a DPDT switch to change heat sources. For ALL heat sources, I need the fan signal. For boiler heat, I need NO compressor, NO signal to gas, only the fan signal. For gas I need to add the gas valve. For heat pump, I need to add the compressor contactor. I was thinking of running the compressor contactor and heat request wires to the DPDT center terminals. In center position, no contactor, no gas. This is boiler heat. In one position the contactor is on- now I have heat pump. (Also A/C) In the other, the contactor is off, but heat request is sent to the gas valve. Does this make sense to you, or is there a better way?

[@angeljr8282]

Hi I have to separate units as well I have Y,G,RC for cooling and W,RH for heat but no common wire can I add a 24v adapter to the thermostat if so where would I plug them into

[@gracelarosa2071]

Is there a combination thermostat to control my new radiant heat and my existing AC.

[@waynemiles7027]

A few questions. What type of heat was this system? You have two separate transformers correct? So both reds, R and Rc are 24v hot? To check Heating transformer you should have 24v from red to white is that correct? Thanks and great video.

[@acservicetechchannel]

After r connects to w in the thermostat face, you can check for 24v at the furnace from w to c. At the tstat, the only way to check with the face off is from r to c for 24v. You would need the c terminal. This was a boiler and ac system, thanks

[@sal8575]

I was hoping to get your help regarding a question I have, one of the tenants at a commercial shopping center I manage has 2 package units, both Gas Electric, the suite does have a open floor plan, they do not have any walls, rooms or office. Each package unit has its own thermostat and the Tenant is curious if it's possible to run both of them off of one thermostat. What would be the procedure if possible? Thank you

[@acservicetechchannel]

You could run a tstat wire from one packaged unit to the other packaged unit, keep the voltages separate but use three 8 amp fan relays to call for heat, cooling, and fan when the first one calls, thanks

[@goobot1]

My thermostats aren’t far from each other but they definitely aren’t on top of each other, upstairs is probably 5 or 6 feet from the other and the downstairs maybe 7 feet or so from the other. Is it realistic that I could move it without a stud getting in the way or even have enough wire?

[@kennyw7453]

Very good video, I would just add two things related to this that I have seen over the years that cause problems. 1) Improper stripping of the thermostat cable jacket. Some brands include a thin string or rip cord that can be used to safely strip the brown jacket. I have seen many bad t-stat wires that were damaged because someone used a wire stripper to cut the jacket and it went to deep and cut the conductors and with 18 gauge solid it does not take much to damage it, sometimes this problem does not show itself for years. 2) Though this video was only about thermostats one thing I do not understand is why more people in the trade do not add a small whip (piece of liquidtite) for the low voltage to a condensing unit or outdoor unit. It only cost a few dollars and would eliminate many of the outside thermostat wires that I have seen which were damaged by pets, rodents, falling ice of a roof, grass trimmers etc. Any jobs I do I include a low voltage whip to prevent these issues. You make really good videos! Thank you

[@ashalasha56]

Helpful video, thank you! I am rewiring two thermostats into one with the same wiring configuration (Y, G, and RC, and W and RH) with the difference that it is into a Nest learning thermostat and I don't seem to have a common wire. Any tips as to what I can do in this case? Without the common wire and when everything is plugged in, it seems the RH is forced off. (N72 message says "Power wire Rh detected. Not connected to equipment.") Any advice appreciated! Thanks! Ashley

[@acservicetechchannel]

You would need to run another wire from the air conditioner air handler to the tstat. If one is not being used then connect at the air handler to c and c to the tstat, thanks

[@angeljr8282]

I have the same setup no common wire did you fix your issue

[@ashalasha56]

I did! But I ended up swapping the wiring on my air handler. I don’t remember the specifics now but it basically made it that I can’t run the air handler on “fan” but I can run the AC. I know that’s not super helpful but I did get it to work.

[@kingstonhernandez6930]

Is there a way to combine two digital thermostats to one when they're on different floors?

[@acservicetechchannel]

If one is heat and one is ac then yes but you would need to run the thermostat wire all the way from one unit to the other thermostat and make sure that the tstat will still read the temp correctly, thanks

[@hamidbahrami6620]

In a 2-story house, I have a 4ton unit for downstairs and a 3-ton unit upstairs. I would like to bring the control of both ACs to the thermostat downstairs. Is this possible? Currently, I have both thermostats sitting side by side but they are not perfectly syncronized. The problem I have is the ist floor unit will not cycle without the aid of the 2nd floor. (2nd floor is not occupied cuurently.

[@acservicetechchannel]

Thermostats will typically only be able to control one heat and one cool from different units. They don't typically controll 2 heats and 2 cool of different units that are not run together. A savvy tech could wire up 3 isolation relays, one for fan, one for cooling, and one for heating to control the second one at the same time, thanks

[@gatoortega78]

I have an air conditioner on my roof and I have a gas heater inside the house each one with a thermostat I can connect the two in one? Thanks

[@acservicetechchannel]

If they are both controlled by 24v AC voltage then yes, thanks

[@ddcws1]

I noticed you didn’t use a common for the heating. Are the two systems tied together? I did hear you mention you wanted to remove the jumper because you didn’t wanted connect the two transformers. Thanks

[@acservicetechchannel]

The two systems are not together and are separate but you can only hard wire a thermostat with one common and in this case it is common for the cooling, thanks David!

[@VeryPersian]

acservicetech everyone is use to that Rc rh jumper. I feel old...

[@acservicetechchannel]

I am covering it for the new techs. I always want to have a mix of videos, some in depth for those in the field for a long time and those that are new, thanks na na!

[@cinstan]

Excellent! I think my situation is covered by this video but I want to confirm. I have an A/C system in the attic and a gas-fired heat/hot water system in the basement, completely independent. The heat is controlled by an old-school Honeywell Round 2- wire with just red and white connected. The A/C is controlled by a programable Tstat with a display, it is connected (totally separate run of wire) with Blue "C", Green "G", Yellow "Y1" and red "Rc" with a jumper to "Rh". I want to install a single wifi tstat to control both systems. Can I do exactly what you did in this video? Thanks!

[@acservicetechchannel]

Yes just don't jumper Rc and RH. They are separate with a single thermostat. Make sure the settings are correct for what kind of system you are connecting as well, thanks!

[@cinstan]

@@acservicetechchannel Great, thanks! So there's no connection between the heat and A/C circuits inside the thermostat, it doesn't care where the +24 comes from.

[@cannarris]

How do I power two different independent units? One AC with it's own fan and an Electric furnace with with its own fan... I want to use one thermostat... how do I set it up so when I click the thermostat 'cooling' the fan of the AC comes on and when I click 'heating' the fan of the AC stops and the heat furnaces fan goes one?

[@acservicetechchannel]

You would not want 24v from one unit to get connected with the 24v from another unit. You would have to use an isolation relay to power the other units blower such as a 12 amp fan relay, thanks!

[@cannarris]

@@acservicetechchannel thanks!

[@bland9876]

No we just need to know why there is a thermostat in every room in my house im use to my perants house where there is just one

[@acservicetechchannel]

That may be for heating for the hot water baseboard or electric baseboard. It could possibly be for a forced air heating and cooling system that has zones, thanks

[@Chilllybob]

It's for electric heat. I had this situation. The house is all electric heat. Thermostat in every room

[@throttlebottle5906]

lol, why have one thermostat when you can have two! why only run heat or a/c when you can run both at once :)) I shouldn't laugh, I've seen it happen multiple times, including older homes with additions and multiple systems, half house on heat @ 80F, the other side A/C at 60F. Alzheimers and Dementia are very bad things.

[@acservicetechchannel]

Oh no, yes I get called on service calls where after I ask all the relevant questions like is the breaker and switch on and are all the windows closed, I get there and it is one of them and I have to charge them for the call, thanks!

[@Anthony-du3he]

Too vague. I can hardly see what your doing. Dont explain what wires power or tell what unit to do what. No good👎

[@themaximusone]

Dude you need to remind folks that they this is the furnace wire and just to much BS in this video I think I had 4 kids during this sheesh