Dual Fuel system (LP) no fan start

[johnschmidty]

I have a dual fuel system but the primary system doesn't work. In setting "Dual fuel breakpoint" I changed the alternate heat to "Always use alt." 

In the Heat Configuration I have set the Alternate heat to Propane (LP) > Forced air.

When I turn on the heat, I hear the Furnace start and begin to blow but the main fan doesn't start to circulate the air throughout the whole house. To test the main fan I tried to turn on the fan manually and it worked. Is there way to run the Furnace (alternate heat) and fan at the same time? Currently the fan only turns on with the prior heat.

The wiring on the old thermostat was setup as R - C - OB - W2 - Y - G therefore I connected R-R | C-C | OB-OB* | W2-W | Y-Y | G-G.

Any thoughts?

[johnschmidty]

I also just tried "emergency heating"... and both the Furnace (alternate heat) and fan started correctly.

[Houptee]

Is this a heat pump and a LP furnace system?

[johnschmidty · Accepted solution]

Yes… but I think I figured it out. I disconnected the heat pump and it appears to be working. This is the change… R-R | C-C | OB- disconnected | W2-W | Y disconnected | G-G. Now the system is running as a heat only and it appears that everything is working. (It’s an old system)

[Jhonleanmel]

Hey folks, 

Thanks again for helping here, @Houptee. 
@johnschmidty, awesome — glad to hear that your issue is fixed. It looks like we can consider this one complete, so I will lock the thread shortly unless I can help out with anything else.

Best, 
Mel

[EdwardT]

Hi folks,

I wanted to follow up and see if you are still in need of any help. Please let me know if you are still having any trouble from here, as I would be happy to take a closer look and assist you further.

Thanks,

Edward

[EdwardT]

Hi folks,

I'm just checking in to make sure that you've seen our response. Please let us know if you have any other questions or concerns as I will be locking this in 24 hours.

Thanks,

Edward

[DBrad]

Greetings!

I have a dual fuel system.  My original Lennox thermostat had 7 wires connected:  Black to W, White to W2, Blue to C, Yellow to Y, Green to G, Orange to O, and Red to R. 

I installed the Nest 3rd generation thermostat and connected the wires as follows.. Black to W, White to W2, Blue to C, Yellow to Y1, Green to G, Orange to O, and Red to RH.  After completing the install and configuration settings, I am not getting any heat.  The system turns on but the temp does not reach the desired setting.  I have watched countless videos and searched for information online to no avail.  My question is, should the black wire connect to the star * terminal or W?  My system configuration on the thermostat shows system... Heat pump heating, Alt heat, Alt heat stage 2, Heat pump cooling, and Fan.  Also, should dual fuel setting be Gas or LP?  I have propane, but saw something online which said, set it to Gas, and set fan to "don't activate."  Need help sorting this out.  

[EdwardT]

Hi DBrad,

Thanks for the response. Since you have a dual fuel system, we would suggest to get a trained professional set up your thermostat. It’s important for a professional to assess the requirements for your specific dual fuel configuration since choosing incorrect options for a dual fuel system can result in damage to your system. You can click on this link to learn about our Nest Pro services.

Thanks,

Edward

[Houptee]

Try Red to Rc 

[EdwardT]

Hi folks,

@Houptee, thanks for the help!

@DBrad, It's me again. I wanted to check back in to see if you have other questions and concerns. Feel free to let me know if you do. 

Thanks,

Edward

[DBrad]

Thanks for the follow  up.  I took your advice and had your recommended Onsite Tech professional come out a few days ago.  The tech checked my thermostat wiring / settings and didn't find any problems.  He recommended I have an HVAC tech come out and check the system to see why it isn't heating properly.  It cost me $139 to get that info.  Guess, I should've just called an HVAC tech to begin with.   It would have saved some of my money.

[EdwardT]

Hi DBrad,

Thanks for the update. I'm sorry to hear about your experience. Keep us posted once you get a tech to check your system.

Thanks,

Edward

[Markjosephp]

Hi DBrad,

I wanted to follow up and see if you are still in need of any help. How's it? Were you able to get hold of an HVAC technician?

Best regards,

Mark

[Markjosephp]

Hello DBrad,

It has been a few days since the last reply, and I am going to lock the thread in 24 hours. If you have any questions, please feel free to create a new post.

Best regards,

Mark

[DBrad]

Yes.  So it turns out that the upstairs unit isn't dual fuel.  It has a heat pump with a secondary heat pump for alt heating.   That being said, my original Lennox thermostat had 7 wires connected (Black, White, Red, Yellow, Blue, Green, and Orange).  I need to confirm if the Nest thermostat is properly configured?  Right now my system shows the following on the Nest Thermostat:

Heat pump heating, Alternate heating, Alt. heat stage 2, Heat pump cooling, and Fan

The wiring connections are as follow:

W1 = Black, W2 = White, C=Blue, Y1 = Yellow, G = Green, O/B = Orange, Rc = Red.

Can you confirm if this is correct?

[Markjosephp]

HI there,

Thanks for getting back to us and letting me know your systems configuration.

I can tell that the way you label the wires is correct, but to be sure, do you still have the wiring diagram of your previous thermostat? If possible, please send us a picture so I can determine it.

I'll look forward for your response.

Best regards,

Mark

[Markjosephp]

Hi DBrad,

I wanted to follow up and see if you are still in need of any help. Please let me know if you are still having any trouble from here, as I would be happy to take a closer look and assist you further.

Best regards,

Mark

[DBrad]

My original Lennox thermostat had 7 wires connected: Black to W, White to W2, Blue to C, Yellow to Y, Green to G, Orange to O, and Red to R. 

Unfortunately , I do not see an option to attach a photo to this reply.

[aatienza]

Hey DBrad,

Understood. Could you fill out this form and let us know once you're done?

Thanks,

Archie

[DBrad]

Why is my personal information necessary to help me ?  Please advise.

[EdwardT]

Hi DBrad,

Thanks for the response. When you fill out the form, we will create a case for you and our team would reach out to you to investigate further.

Thanks,

Edward

[aatienza]

Hey there,

It's us again. How's it going? Do you still need our help?

Thanks,

Archie

[aatienza]

Hi there,

Just checking in to make sure that you've seen our responses. Please let me know if you have other questions or concerns as I will be locking this in 24 hours if I won't hear back from you again. Feel free to start a new thread and we'll be happy to help.

Thanks,

Archie

[DBrad]

You can close this thread. Thanks.

[EdwardT]

Hi folks,

@Houptee, thanks for the help!

@DBrad,thanks for the response. I will be locking this thread now. Please feel free to create a new thread should you have some more questions or concerns in the near future and we'll be more than glad to help.

Thanks,

Edward

[Houptee]

Only way to know if it is correct is to go to the Furnace end and look at what the wires are connected to on the actual equipment you are trying to control.

Post a pic of the wires on the equipment end. In the chat box see the camera icon across the top as you are typing that is how to attach pics.

Also if you are not sure what kind of equipment you have look for the Make and Model number decal on the equipment and Google it to find out if it is a heat pump or gas furnace etc.