Better Dual Fuel Control

[Mindslip]

I recently installed a 2 stage heat pump inline with my Trane propane furnace. I was able to set the system working correctly with my 3rd gen nest thermostat using the pro setup and setting the system for dual fuel.

My gripe is this is they way Next handles dual fuel is very simplistic. The only way to bring on the propane furnace is if the outside temperature drops below the break over temperature set by the thermostat. My 15 year old Honeywell thermostat lets me specify time to temperature letting the system kick on the gas furnace if the house hasn’t hit temperature in a user defined interval (I set mine for 60 minutes). Only using the break over temperature doesn’t work a lot of the time. If the requested temperature rise and/or the outside temperature is too low, the heat pump will never hit the requested temperature without turning off and turning on the gas furnace. 

As a feature request I would ask that as a minimum, Nest dual fuel has a time to temp setting. Better yet the Nest should do something similar to heat pump balance available with electric aux heat and use AI to learn which combinations of temp rise and outside temp will need gas heat to achieve.

Sorry, just my rant. I really like the Nest with it’s combination of features, Ui and integration with other Google products but if this dual fuel issue isn’t’ resolved I’ll have to switch to an Ecobee.

Cheers, Gordon

[Keyvoon]

I have the same issue, I know there is a heat pump efficiency settings but only appears if you set it at single fuel. I had a 40 Years old thermostat which was able to correctly handle this issue. It seems they don't have any answer as after 8 month, no one answered your post.

[Mindslip]

I gave up and switched to an Ecobee. I prefer the Nest UI but the Ecobee has much more advanced setup options for dual fuel. If you leave the advanced settings to “auto” then it will decide when and for how long to run the furnace as it gains experience with your system and home. Or you can go to manual settings and adjust things like time to temp and differential temp manually.

[Jhonleanmel]

Hi everyone,

Thanks for posting and sorry for the delay.

Mindslip, we're sad to see you go. We hope we can make it up to you in the future. Send us a message if you change your mind.

Keyvoon, A few questions: what Nest Thermostat do you have? Check this link to know what thermostat you have. Since when has this been happening? Also, what troubleshooting steps have you done so far?

Best,
Mel

[Jhonleanmel]

Hey there,

Checking back in should you still have some questions here. Let us know by replying to this thread. 

Best, 
Mel

[Jhonleanmel]

Hi everyone,

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 thread after 24 hours.

Thanks,
Mel

[Keyvoon]

Ok before you lock this post, I am using the 3rd gen nest learning thermostat, to use heat pump balance, I should set my aux heat to electric furnace, and it will run simultaneously with the heatpump wich is really inappropriate. 

The heatpump balance should be available for all system with aux, alt heat. Also never ever heat pump and another source of heat should run together.

[Keyvoon]

This is a manual of a thermostat from 1995, it has more setting and better flexibility than nest, it's in french but i am sure your product support team can understand the details. https://www.modes-d-emploi.com/manuals/715597/viconics-cbe118-cbe117.html

[MrChips]

• Hi Mindslip, If my comments look much like your well written message to Nest, I've used parts of yours for consistency purposes, which I hope Nest will see a trend and try harder in providing solutions faster if they hope to maintain a market share.

Lets start, I recently installed a 2 stage heat pump in Jan, 23 inline with my Mar,21 Tempstar NG furnace. I was able to set the system working correctly with my 3rd gen nest thermostat using the pro setup and setting the system for dual fuel.

My gripe is lose of heat pump efficiency the way Next handles dual fuel is not very accommodating for todays high efficiency heat pumps. The only way to bring on the NG furnace is if the outside temperature drops below the break over temperature set by the Nest Dual fuel at -12/10.4f. Break over temperature on the heat pump is -17c/1.4f.  If the requested temperature rise and/or the outside temperature is too low, the heat pump will never hit the requested temperature without turning off below -12c/10.4f and turning on the gas furnace. 

As a feature request I would ask that as a minimum, Nest dual fuel AI sets itself to the break over temperature of the heat pump. Better yet the Nest should do something similar to heat pump balance available with electric aux heat and use AI to learn which combinations of temp rise and outside temp will need gas heat to achieve.

I too really like the Nest with it’s combination of features, Ui and integration with other Google products but if this dual fuel issue is not resolved I’ll have to switch to an Ecobee or other smart thermostat my service provider has requested I do if I want to gain heating/cooling efficiency that Nest is currently falling behind with.

Additional setup details 

Nest equipment settings

Dual fuel -12c

Heat source 1 Electric 

Alt. heat source 1 Gas

Heat type 1 Forced air

Alt. Heat Type 1 Forced air

Heat pump Orientation 0

Equipment wiring/detection

Y1 heat/cooling, G fan, OB heat pump, W2 alt heat, C 24V common,

* humidifier, RH power

Nest Learning Thermostat model 3.4 Gen 3, SW version 6.2-27

Heat pump 

Tempstar TVH8 2.0 Ton DLCSRBH24AAK modulating 19 SEER  Communicating Heat Pump 

NG Furnace 

Tempstar model F96VTN01714A2

Looking for a Nest solution ASAP

Sincerely, Andy

[Jenelyn_O]

Hi there,

I saw your post and wanted to chime in — I'm sorry for the delay. I just want to follow up if you're still encountering the issue. Please let me know as I'll be willing to assist you from here. 

Thanks for assisting this thread, Mel. 

Best,

Jenelyn

[MrChips]

Hi Jenelyn,

Thanks for responding. Issues not changed.