Wiring a Thermostat, Furnace, and Heat Pump for Dual Fuel Hybrid Heat!

This HVAC Video is to show how to Wire a Thermostat to a Furnace and Heat Pump for Dual Fuel Hybrid Heat and Cooling. I go over the efficiency temperature settings, what to watch out for so the heat pump is not damaged, what the thermostat wire terminals colors and functions are, what happens during defrosting, and where the voltages are applied during the heating, cooling, defrosting cycles, as well as other tips! Supervision is needed by a licensed HVAC Tech before doing this 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: (Links In the Description Section)

[@ronaldswindell1525]

Have you had any issues with a bad outdoor sensor back feeding to the thermostat and making the thermostat screen go crazy? I unplugged the outdoor sensor and it stopped.

[@TheTastyMorsel]

It is abundantly clear to me that few techs are this well informed regarding dual fuel systems. I've actually had to argue with a couple techs that the gas furnace must come on during the defrost cycle to offset the cooling effect from the heatpump running in reverse. I've even had to argue that the air handler blower runs at a higher speed when in cooling mode and at a slower speed during the heating cycle. You clearly explain the why, how, and what behind everything, including what is in the best interests of the consumer with regards to efficiency and system longevity. You're a rare breed my friend. Would love to have you look at my Trane system if you're ever in Virginia!

[@acservicetechchannel]

Thanks and glad to help!

[@robertraynes3229]

thank you for these videos. i had to watch a few of your videos a bunch of times to understand the control wiring, but now successfully understand how to add a heat pump unit to my furnace.

[@aze216]

OUTSTANDING! Thanks for taking the time and posting this really well done presentation.

[@liberaltearsaredrowningme7049]

The best explanation of dual fuel wiring that I've seen or heard

[@acservicetechchannel]

Thank you very much!

[@oneswolf]

@@acservicetechchannel I agree with LiberalTears' comment. I finally understand why dual fuel is different than heat pump with emergency heat strips. Thank you!

[@johnhennan3604]

Getting ready to install my first duel fuel system and you made it crystal clear!!

[@acservicetechchannel]

Very Cool, Thanks John Hennan!

[@loromachaco1]

nicely done, well explained...put it on for my helpers and they were able to explained it back to me... I could not have made it more clear. thanks

[@Mowers11]

I really like how you explain things. 4 months in the field as service tech. I can wire standard heat cool system and this is the next step. Keep up the good work.

[@acservicetechchannel]

Thanks a lot Brian Mowers!

[@heatncool]

5 years later....how's it going now bud? 😁

[@JeffBNH]

This was very instructional and well done. Thank you.

[@jakethehvactech2018]

Young new tech here... thanks so much for your videos, these are so great!

[@acservicetechchannel]

Thanks Jake!

[@aircooledtx]

Great directions of wiring, keep up great videos. Helps young techs understand what is happening in heat/mode.

[@acservicetechchannel]

Thanks Michael Lee!

[@dcrickerson7611]

Great video, you explained everything very well.

[@acservicetechchannel]

Thanks you DC Rickerson!

[@EnjoyCalculus]

Excellent video. Thank you Craig

[@michaelcostello6991]

Really great video. The video was very clear also making it easy to watch. I have a very good understanding about how this whole system should work now. Thank you

[@acservicetechchannel]

Thanks

[@adammullins8390]

Thanks for the explanation. This really helped me with a mental image .

[@miked9104]

Great video. Very informative. Thank you 👍🏽

[@EhNothing]

Outstanding explanation. Thank you!

[@gilbertopatino2616]

Thank you again for another great video!!!!

[@acservicetechchannel]

Glad to help! Thanks for the Comment!

[@clinthartzler8216]

Explained like a boss, thanks bud.

[@acservicetechchannel]

Glad it helped

[@smborum]

You really are the man. Thank you for making me a better tech.

[@acservicetechchannel]

I appreciate your note Spencer! Have you checked out the full outline to our book at acservicetech.com ? Thanks!

[@RALPHD57]

NICE! Crystal clear! Thanks!

[@acservicetechchannel]

Thanks Ralph!

[@RussKatona]

Excellent video, thank you!

[@acservicetechchannel]

Thanks Russ!

[@jimbola77]

excellent video thank you for sharing!!!!

[@acservicetechchannel]

Thank you for your Comment!

[@robc2682]

Love the vid. You got me out of a pinch today thank you

[@acservicetechchannel]

Thanks Rob C!

[@knighthvac4876]

Great video ! thanks for posting

[@acservicetechchannel]

Thanks Paul, glad you liked it!

[@10bigjj]

Yup I’m subscribing. Great video, awesome explanation. Exactly what I was looking for in my google question

[@acservicetechchannel]

Awesome, thank you!

[@jimmyung3212]

great teaching thank you!!!

[@acservicetechchannel]

Thanks Jimmy!

[@cooltime3040]

Wow - great job!

[@acservicetechchannel]

Thank you! Cheers!

[@dereksorto1]

Thanks for the explanation. How would a heatpump with a gas boiler be wired?

[@minnesotasalamander5913]

Good explanation.

[@rocker8692]

Good vid, I'm learning alot

[@acservicetechchannel]

Thanks Chad!

[@whitesheatingairappliancer7101]

great video thanks again

[@acservicetechchannel]

Thanks Ron!

[@geojor]

valuable info, thanks ...

[@acservicetechchannel]

Thank you

[@dmeskill2]

Very helpful video. Thank you. I have a hvac, propane hybrid system that cannot have both running once or the heat in the copper line gets too hot and the pressure is too high. What thermostat would your recommend? The technician we had look at it said we needed a 3 heat thermostat. Not sure how to hook that up. I should add we don't have a C terminal. I was looking for something with a wireless outdoor sensor to know when to engage the furnace.

[@bcarter1430]

great video man

[@acservicetechchannel]

Thank you Justin!

[@tmangtricks]

Nice little carrier mvb board

[@khig2025]

Thanks for the great teaching video. I have a heatpump/gas furnace with a nordyne dual fuel kit. I installed a Honeywell TH6320WF2003/U and think I need to remove the dual fuel kit to let the thermostat control everything. Thermostat wiring. S1 S2 to sensor, Y to furn Y, G to furn G, C to furn C, O wirenut to O on heatpump. Aux/W2 to furn W, R/Rc jumped to furn R. Defrost control board wiring. C to furn C, Y to furn Y, O wire nuted from thermostat, W2 to furn W, R to furn R. My question is there is a wire at the defrost board E that was wired to dual fuel kit. Does it need this wire? Where does it need to be terminated? Thanks in advance. Ken

[@eliezerpaner6666]

thanks man.

[@garymartin2336]

Thank you for this helpful information! Are there dual fuel thermostats that have a lower programmable temp.? I expect my system to go much lower than 32 degrees F.

[@DC.402]

Need this

[@edbouhl3100]

Ah, finally an installation that shows the O/B wire from the thermostat directly to the heat pump control board. I was stuck for quite a while wondering why the furnace board needed to know about the reversing valve signal. So is the O/B terminal on some furnace boards just to simplify/standardize the wiring (without actually connecting to anything on the furnace board)?

[@mantolaman]

I replaced a dead central AC with a Trane heat pump, (without heat strip). I have a hot water boiler for heat. Can I use this Honeywell 8000 to control the heat pump and boiler separately when the outdoor temp is 35° or below?

[@papoloco34]

can you please make a video of a full pm in ac unit and another one in how to fill a job site sheet..thank you for your videos and thanks for think in the new guys in the trade.

[@acservicetechchannel]

I plan on incorporating the service ticket and proposal fill out in a book that will be publishing. Thanks!

[@xtremecomfort7799]

Is the outside temp sensor preset when you purchase with t-stat?Thanks!😃

[@papazurdo4199]

Thanks!

[@papazurdo4199]

You provided exactly the information i was looking for in a clear and concise manner! Thanks much "AC Service Tech"!

[@acservicetechchannel]

You're very welcome! I'm thrilled to hear that the information I shared was helpful to you. If you have any more questions or need further assistance, don't hesitate to reach out. Remember, learning and growing in the HVAC field is a continuous journey, and I'm here to support you every step of the way!

[@jayschmid2808]

Well done! Info I was looking for. Why are w1 and w2 jumper ? You mentioned it but didn’t explain.

[@questionable9210]

I have a dual fuel system heat pump with propane gas, with s1 and s2 wires coming to the thermostat. What would be newer thermostat models that would take s1 and s2 with wifi functionality? The model that you demonstrated with it in this video is fairly obsolete, and does not have wifi function. Hopefully you would get comment notification from your old post. Thanks!

[@556suppressor]

This is why I paid Best Buy to install mine for $129.

[@edbouhl3100]

If you trust the tech, money well spent.

[@scoobtoober2975]

I brought 7 extra wires and i'm about using them all now with a heat pump furnace setup

[@mackenziegray2090]

Part I'm confused on is where you mentioned about defrost. When the heat pump boards sends 24v on W in the indoor board. How is it preventing the gas furnace from coming on during defrost? Does the main Indoor board locks out the furnace while Y is energized?

[@nothankyou5524]

Depending on where the indoor coil is, of course... Which generally isn't very effective at that point, anyway... Just kibitzing.... Nicely done, as usual.

[@acservicetechchannel]

Thanks

[@jonwiersig5800]

AC Service Tech, great videos! I have an issue that two service companies can't figure out. I have a 2-year-old dual fuel 5 ton 16 SEER single stage American Standard system. Every month or so, in cooling, I notice my house is warm. I find the indoor unit is running but the outdoor unit is not running. To fix, I raise the set point until the indoor unit shuts down. Then I lower the setpoint and both the indoor and outdoor unit come on and all runs fine for another month or so. My thermostat has been replaced twice but the problem persists. What might cause my intermittent problem? Bad contactor? I can never duplicate the problem when the service tech is present. Next time it happens I need to check that I have 24 volts on Y1 at the compressor.

[@rivergate950]

My heatpump's reversing valve froze up and now only works in AC mode so I had a furnance added since it cost about the same as getting the reversing valve fixed. But I have to manually chage the wiring and thermostat settings each change in season. I need a zone control board that can run a duel fuel service . any recommendations appreciated!

[@neilwilson7345]

Question: what would happen if we from stat and outdoor were wired to w2 instead of w1 at the indoor board, In this scenario?

[@michaelcostello6991]

Is the DFT sensor on the liquid or in the middle of the evaporator ? Surely the liquid line would not reflect the temp of the cold outside coil which is the evaporator during heating mode ? 11:25 in video

[@Sptsmn700]

My heat pump has W and Wout wires. Where does the Wout wire get connected to with aux gas furnace and ecobee thermostat?

[@tyl8ter]

Can you do a thermostat- BPC-1 with ODS explanation....Thanks

[@abel4776]

Thanks for the explanation. Quick question. For these dual fuel HVACs, is it possible for the unit to run automatically in heat pump (heat mode) as soon as the unit detects a lack of natural gas? I ask this because of what happened in Texas on February 2021. If natural gas lines get shut, will the unit be smart enough to revert back to heat mode on the heat pump and attempt to heat the home? Even if say it's 20'F outside? Or does it have to be forced to heat pump on the control module? Also, do you know of any HVAC system with dual orifice natgas and propane lines and have the capability of switching automatically between them if say natgas gets shut, and the propane backup tank kicks in? Thanks.

[@logancook4790]

In this scenario your system(assuming the temp was below your setpoint) would try to light 3 times and then lock out due to flame failure. You would have to cycle power to reset the alarm and manually change your heat pump setting to force the heat pump to run.. however, in doing this when your outdoor units calls for defrost you will not have backup heat to counteract against the air conditioner meaning that when the unit goes in to defrost you would be cooling your home not heating it. Hope this makes sense.

[@pablopicaro7649]

@@logancook4790 Excellent point, the defrost cycle needs the dual fuel heat or either gas furnace or 240v Heat strips.

[@dinosaur_fuel1872]

help do you need the outdoor sensor if the heat pump has one already or is that for the defrost board only? my problem is that the heat pump and gas turn on together I'm using a Honeywell t6 pro stat

[@cf220610]

Question for you @acservicetechchannel - I just bought a dual fuel system with 2-stage gas furnace and 2-stage heat pump. I'm trying to figure out what thermostat I need. Is that considered 2 heat cycles/2 cooling cycles or is that technically 4 heat cycles and 2 cool cycles? Also, if you have any recommendations for thermostats or brands, that'd be great! Thanks in advance.

[@jims2012videostore]

How can I keep an undersized heat pump running all the time and the furnace coming on when it can't keep up? Could I put the coil in the return duct and use a separate thermostat?

[@kolaphillips4187]

Thanks for the reply. The electric furnace comes up when I go to the thermostat and call for emergency heat otherwise it does not go into the auxiliary heating with the heat pump on. The old thermostat works , by going into auxiliary heating with one degree drop in temperature. Can heat pump increase temperature by 3 degree with the reverse valve heating? The system is electric heat pump 2stage heat and cool and furnace. Is there reversing valve heating or is it simply just reversing valve cooling option on York Zye series?

[@kolaphillips4187]

You have orange wire looped up (for the defrost) , in mine it is two blue looped up that did not go into the furnace board. Then I have orange wire from the O on the board to the O on the thermostat- ?so this the reversing valve connection. It appears O powers in cooling mode on York zye series heatpump. I don’t have B terminal

[@rontucker2502]

Very good video, however there is one point I'm not clear on. My dual fuel system is programmed so that if the outside temp is too low for the heat pump alone (say 20F) the system will function as follows. When the thermostat calls for heat, the heat pump alone comes on for 6-7 minutes and shuts down because it can't meet demand. Then the gas furnace comes on for a few minutes until the heat demand is met. Is this the optimal logic? Seems like it would be better in this case (low outside temp) for only the gas furnace to operate.

[@acservicetechchannel]

Normally yes that is what is supposed to happen. Only gas furnace heat should turn on if the cut out temp you set it to is 20 degrees, thanks

[@joseluisalvarado3125]

Hi thanks for the info but I have 1 question if can help me with this for dual on the thermostat the wite wire always go in a/e Or on nest thermostat it's diference thanks for your time

[@9-5channel]

So can I use a heatpump thermostat on a non heatpump system?

[@DemLocus]

how do you make the defrost cycle and the heat pump to stop when the furnace is running?

[@acservicetechchannel]

During defrost the furnace would be running putting heat into the refrigerant to help with defrosting while keeping the customer comfortable. The heat pump should not be running in heat mode while the furnace is heating and this is set in the programming of the thermostat. You have to make sure that you have a dual fuel thermostat like this one. I believe that the model number is in the comments below. Thanks

[@rmwaseem]

Very good video about the duel fuel but my question is during the reverse changeover (satisfied heat ) in which the furnace is turning OFF does it get some time to cool the evap coils before the heat-pump fires up (at this stage the Freon in coil is very hot already and possibly go to trip on hi-pressure) ? Is there a provision in the programming of the thermostat to wait till 2~3 minutes before it is commanded to be on for the heat-pump ? Sorry for the long question. This question is bothering me for a long time?

[@acservicetechchannel]

Great question! Let me get in front of a system wired like this in order to answer that question. I know I have never had a problem with the unit going off on high limit and want to make sure I tell you the right thing. I know exactly what you mean. Thanks and I will get back with you!

[@dacoobob]

@@acservicetechchannel i know it's been 3 years now, but did you ever find out an answer to this guy's question? I have the same question : )

[@juliodiaz9077]

Thank you ser 😎Gob bless yuo&family☝🏻️

[@acservicetechchannel]

I Pray that God would Bless you and your Family too! Thanks for your Comments!

[@TheAndrewWScott]

Do you have a video laying out how to do this same thing, except the heat pump has 2 stages cooling and heat? Is it as simple as just adding the extra Y wire?

[@TheAndrewWScott]

Did you find an answer to this? I have the exact setup, but the hack that installed it only ran 2 wires to the outdoor unit, C and Y. So the HP isn't utilized at all for heating, just the gas furnace. I'd like to remedy that, So I need to pull new 18/8 to connect everything correctly. Currently, it's also not utilizing the 2 stage compressors, so the supposed energy efficiency is out the window, as it's only running 2nd stage (high speed) all the time. EDIT whoops, just realized I replied to myself from over a year ago...doh!

[@usahoangsatruongsa]

I've never installed and worked on Honeywell TH8000 but for the other heat pump thermostats when you turn on the HEAT and set the GOAL temperature let say 3-5 degree HIGHER than the ROOM temperature then the thermostat will automatically turn on the AUXILIARY HEAT to help the heat pump. So in the case of dual fuel heat pump will the Honeywell TH8000 will turn on the gas heat to help the heat pump ? Thanks for your reply.

[@dennismartin3110]

I have a heat pump and an oil furnace. I have chosen not to have the oil heat come on when the hp goes into defrost. I do not mind the cold air for a few minutes. Has anyone figured out how to trick the defrost cycle so that it will not operate when the temperature is above my 35 degrees set point?

[@aaronclark1599]

Wouldn't a reversing valve most likely break when it is powered? But you said it would most likely break when it is not being powered

[@SombraLocs]

Would you just have to redo the low voltage wiring, if you're going from a furncace with dual fuel to straight A.C.?

[@acservicetechchannel]

Hey nice to hear from you! If you were turning a heat pump into straight ac only then you would use a single speed furnace and ac thermostat and just connect y 24v through the pressure switches and then to the reversing valve and the contactor. Come out of the reversing valve and the contactor to common. This would be for manufacturers that power their reversing valve in cooling mode, thanks!

[@aort2823]

Hello, I installed a new gas furnace and kept the heat pump. I want to use the heat pump for AC only. how can I wire it with my new furnace to use it as ac? Thanks!

[@pablopicaro7649]

Economics of it: most place in N.America Electricty costs 3x as much as Nat Gas per unit energy, than means use gas if COP is below 3 on the heat pump . for an Air-Air heat pump that is at abut 40F outdoor.

[@kurtcasey38]

What would happen if everything was wired this way except w from heatpump to furnace was left off. Would it ever use outdoor for heat? I wired everything except w for outdoor because I wasn't sure if t stat was dual fuel capable.

[@acservicetechchannel]

W from the outdoor unit is powering 24v during defrost. You would want to hook that up so that you give the indoor coil's refrigerant heat to take outside and reject into the ice to melt it off the fins, thanks

[@filemontorres7635]

is this in any of your books? Also do you have a book on VRF systems for beginners?

[@gaetzwarren8146]

How do I add an o terminal for a gas furnace that dose not have heatpump capability? Do I use another board?

[@Matt-bd2or]

I have a bosch inverter heat pump 1st generation, a 97% efficiency modulating gas valve , varible speed Goodman furnace, and I'm using a emerson sensi thermastat, the heat pump does come on and does work, thermastat says "heat" because it's my primary heat source, but the furnace seems to kick on and does say " Auxiliary heat" which it should, it was 23 degrees out over night, I thought this bosch inverter was supposed to heat to -5 degrees before auxiliary heat or emergency should kick on , I'm just not sure if this thermastat is the right one, but it says hp 1 , hp 2, my bosch tech is new at these heat pumps, and old school with these types of thermostats, not sure what's going on, can you help?

[@michaelcostello6991]

Why does the 24vac come from the indoor furnace. Could the 24vac be supplied by the outdoor unit ??

[@acservicetechchannel]

The outdoor unit does not usually have a 24v transformer in it, thanks

[@luismontoya7230]

the new termostat that I bought it only haves w1 but the old one haves w1 and w2 and I don't know we're to connect the w2

[@acservicetechchannel]

So check on the board of your furnace. Most furnaces will actually control 1st and 2nd speed from the board and that seems to be more efficient than if you controlled it from the thermostat. This is usually done by wiring one wire to the w/w2 terminal on the board of the furnace. I say most but not every one. What is the model number of your furnace? Is this a dual fuel as well with a heat pump like in the video?

[@keithaction1326]

Great Content! I recently purchased a new thermostat and would like to configure it to run the heat pump for air conditioning purposes only. I live in the Northeast and have a dual fuel system. I want to convert to a conventional 2H / 1C system using the existing wiring. Is this possible with my current setup? Can I just wire the O and Y together on the new thermostat and program the thermostat to run as a conventional system? - Heat Pump Model: Lennox XP14-024-230-03 ( Heat Pump) - Furnace Model: Lennox G61MPV-36B-071-12 (2-stage Variable Speed) - New Thermostat Model: Honeywell RTH9585WF1004 Keep up the great work!!

[@dsprings8565]

Can u please hit this exact topic again. U can do better.. this 1 was a little harder to follow. And appreciate a bigger view of a system if that makes sense. This is still the best explanation of this but it is the ONLY 1.

[@scoobtoober2975]

This is already 7 years old. I discuss this with friends and their minds are blown. I just want to get all the action out of my system. If the outdoor unit can take 4 stages. The furnace has 2 gas stages. Can a t9 thermostat utilize all of them? Their website and support says, call a pro. I say hell no. Call Craig. I think it can do it. The furnace manual. Aciq calls out 4 stages of heat. The first 2 stages would be the heatpump, the next two would be low and high on the furnace it self. I just worry about how it chooses those various ones. Or should I go opensource.

[@Ray-wr2wr]

Hi I'm about to replace old r22 outdoor unit COOLING ONLY with Goodman heat pump + coil But owner wants to keep old gas furnace with the blower motor)) It's possible to connect to control board terminals C G Y W R if yes how many wires has to come from outdoor heat pump condenser? Many thanks!

[@samvernon7851]

I noticed that for some reason my heat pump and the furnace are running together when the temperature is in between 35 and 40 degree as the thermostat programmed. Please let me know what is wrong with my settings or wiring. Thank you.

[@acservicetechchannel]

Wow not good. It sounds like you have two overlapping temperature periods set for each of those for instance heat pump shuts off at 35 degrees and the furnace turns on at 37 degrees. It also could be that there are two components installed in the system instead of one to do this job of dual fuel. I would see about fixing that right away before damage is done to the compressor and high pressure relief valve due to high head pressure. Thanks

[@jackperlmutter5957]

Question, I am adding a 2 stage Goodman Heat Pump to an existing Goodman Furnace for Dual Fuel. Heat Pump has R, C, W1, Y1, Y2, L and O terminals. The Furnace has R, C, W, Y and G terminals. Should I connect wiring as follows from the heat pump to furnace to Nest, R to R to Rc, C to C to C, W1 to W to W1, Y1 to Y to Y1, Y2 to Nest Thermostat Y2, L do not connect, O to Nest Thermostat O. Thank you for any assistance you may be able to offer. Jack Perlmutter

[@kolaphillips4187]

I need help with my hvac. My unit suddenly gets cold in the middle of the night when the mode is in heat. I am not sure if it is the reversing valve connection problem. I have 7 wires coming out from thermostat (plus Grey and Brown unused) . connected Red R, Black(comon),Green(fan),Yellow (compressor),Y2(single Brown ) on the electric furnace board but not collected to the thermostat. Blue wire from Heat pump and thermostat looped up in the furnace but NOT connected to furnace board. Orange is On O on the board. White W1 and W2 looped/linked on furnace board. On the thermostat all are connected but not sure if orange wire should go to Y2( Y1 has yellow wire already) Or W1(o/b) or blue wire should go to Y2 or W1(o/b). W2(Aux) has white wire heat. W1 and W2 on the furnace box is linked. Now it is giving cooling instead of heat with orange wire on w1(o/b) and blue wire is on Y2 on the thermostat. The system is York Zye , thermostat is Zen thermostat Thanks

[@acservicetechchannel]

So that is a dual fuel system. Has the furnace ever turned on for heat since you installed that thermostat or is only the heat pump running? Did this start happening after you installed the tstat? It could be that you are in defrost mode or also the heat pump not producing much heat since it is a low ambient temp outside.

[@nothankyou5524]

These are the best troubleshooting exercises a tech can find. Two instructors I know and I currently go through them for personal honing and also to provide extra credit test questions not passed on from student to student over time.

[@raddadization]

how many wires needed at the stat?

[@heatncool]

If a lennox had a communication thermostat. 4 wires ( R, I+, I-, C) and customer changed thermostat to nest. What would happen then in the rewiring at the indoor/Furnace communication board?

[@zyzzyva303]

I'm working on that now with the Amazon smart thermostat which doesn't support dual fuel. My choices are to either use a Lennox C7500 thermostat (which I have) or write my own control firmware using a PI Zero/Arduino and use a relay board to handle this. The MCU will have to read and handle outdoor temp as well.

[@nimaalibabaei7109]

Regardless of the fact that Nest and ecobee support dual fuel systems, it seems they are not compatible with Mitsubishi and Dettson hybrid systems. Is there any way to match them up? Thanks.

[@acservicetechchannel]

I am not aware of any at this point. It may be that the manufacturers of say Mitsubishi are trying to keep that proprietary for the future, not sure, thanks Nima!

[@nimaalibabaei7109]

Thank you for your comment.

[@geoffrunge5969]

Ecobee does not support a communicative thermostat, which you need for a heat pump correct? I just tried to go down that road, and ecobee told me I need to bypass a solenoid in order for it to work.

[@TheHunterofshadow]

I have this now and it just stopped working. What can I replace it with???

[@bluebeastgamer3005]

What is the MODEL # of the dual fuel thermostat for a single furnace and single stage heat pump???????????? Thank you barry

[@acservicetechchannel]

This is the model number of the TSAT used TH8320U 1008 and here is a link from honeywell--customer.honeywell.com/resources/techlit/TechLitDocuments/68-0000s/68-0280.pdf

[@acservicetechchannel]

Hey Techman 143 For some reason I recieved your question in my email but it is not in the comment section. So I have a Rheem Prestige Heat Pump/AC matched up with a Luxaire 95.5% efficient LP gas furnace. My installer recommended the Honeywell TB8220U 1003 thermostat. I'm not seeing in the operators manual any way to separate the two systems by temperature. I have the external temp sensor for ambient. What was the model number of the TH PRO 8000? I was very pleased with your video...it exists nowhere but here. I've been chasing this since we installed the new gas system in January and have been manually changing over with the source option on the 8220U. You are a Godsend. This is the model number of the TSAT used TH8320U 1008 and here is a link from honeywell--customer.honeywell.com/resources/techlit/TechLitDocuments/68-0000s/68-0280.pdf Look at the upper left of the doc and it says this model number can be used for dual fuel. I looked up your number and it cannot be used for dual fuel customer.honeywell.com/resources/techlit/TechLitDocuments/63-0000s/63-2625.pdf

[@Lilmiket1000]

I wish I had someone like you that can help me. they installed a heat pump with electric furnace in my house for 10k dollars and it's 13 degrees out tonight and i'm freezing! My auxiliary heat has been running all day for the past few days. I already know my power bill is going to be 400+. My house is only 800 sqft. and my air handler is a combo type with ac and heater in one cabinet. I'm wondering can I keep the heat pump unit outside and just switch my air handler for the modular type with a gas furnace and ac in separate connected cabinets. I don't know what to do or who to ask for help because the company just basically took my money and disconnected themselves from me.

[@Lilmiket1000]

by the way that defrost mode is a bitch! there is a loud gascious noise outside of the valve switching over. and then blow the icy cold air! god I would rather it shut off or the blower slows down to defrost. but it just blast all the cold air out as hard as possible. omg I hate this system! and its top of the line! I wish I had went with the much cheaper option and a whole different company. it was GSM btw

[@acservicetechchannel]

If you have dual fuel then you likely have a gas furnace with an evaporator coil in front of it and not an air handler. If it is a gas furnace then you need 24v on the w terminal of the control board for gas heat, thanks

[@yardietraxx]

Can you show this setup with a Nest thermostat, instead?

[@dus10dnd]

I completely don't understand how this can even work. So, when the only new wire that is introduced from a gas furance and AC when switching to a gas furnance with a heat pump is the O/B wire... how on Earth does a signal work that tells heat pump on in heating or gas furnace on when heating? I only have one W wire... I have G and O/B. My furnance control board looks just like that one but I think it is a different model number. What is the actual signal being sent when it should call for the furnace versus the heat pump?

[@Pretzel114]

Hi Acservicetech, nice video! I am scaring myself I am actually understanding this stuff better and better lol! Could you do this with a oil furnace with lets say a beckett AFC burner?

[@acservicetechchannel]

Ha ha nice! Yes Absolutely!

[@Pretzel114]

acservicetech Thanks for the reply. That's good to know.

[@pogtuber5146]

I thought a gas furnace should NOT be running during defrost mode as this could raise the temperature to an unsafe level and reduce the lifespan of the compressor.

[@michaelcostello6991]

is this 24 V AC or DC ?? Is there a transformer ?

[@acservicetechchannel]

24v ac and the transformer feeds into the indoor control board on r and c is common, thanks