Dual Fuel CONFUSION: 3 nest 3rd gen tstats, heat pump w/heat strips, 2-zone baseboard heat

[rny1nestcom]

folks,

trying to remedy an installation on the house we are retiring to AND trying to learn nest at the same time.

ranch house:

1. 2-zone baseboard, each zone has its' own nest tstat set for heat

2. a/c has heat pump and 10kw electric strips for emergency heat, with its' own tstat set for cool

right now, the contractor gave up with nest and dual fuel, and i figured i might as well try to solve this on my own. i have read Houptee post to 'dual duel system' [314112], which helped my understanding a great deal, but i think i come up short. - do i really need 3 tstats? is this 'efficient' for heat pump and baseboard control?

- if set dual fuel on a/c, how do i keep the heat pump from not staying on at the same time as the baseboard is on

- i am a little confused on exactly what wiring is needed to control the baseboard tstats if the a/c tstat is the master programmer?

ok, i am not sure what else is important to provide? the a/c heat pump and electric heat strips are Goodman, the boiler is a natural gas Bosch combi-boiler, and i have FIOS for internet access. if i can get this setup more simply, then i think i might figure out the heat pump balance stuff, lockout temps and how to manually switch on the electric heat strips as emergency heat  if ever needed.

note that the wiring between the a/c nest tstat and the Goodman air handler looks like it was patched somewhere up in the attic, so i think i may need to do a wiring checkout at some point.

thanks, ron

[and thanks to Houptee who got me up the learning curve with an excellent post [314112]]

[GabrielaG]

Hi rny1nestcom,

Thanks for reaching out to the community. I'm sorry to hear that you are having problems connecting your Nest Learning thermostats to your heat pump with strips and 2-zone baseboard heat. I appreciate the information you sent me. It's my pleasure to assist you right now.

 I'd like to ask you a few questions in order to gather more information to fix it:

•  When did the issue first occur?
• When was your Nest thermostat installed?
• Do you have three different systems, or is it just one with a dual fuel system?
• Is there a preheating message on the display?
• Can you please provide me with a picture of your three Nest thermostats wiring?

 I'll be waiting for your response; please let me know if you have any other details that could be useful.

Regards,

Gabriela

[rny1nestcom]

Gabriela,

ok, good questions. let me answer and then also try to simplify my original post:

1 & 2. when: original install about 3yrs ago, contractor threw up hands in frustration with nest & dual fuel, and left

3. i have 3 nest learning tstas: 1 each for the 2 zones of the baseboard heating, and 1 for the hvac heat pump. note: the heat pump includes 10kw heat strip in the air handler for auxiliary/emergency heat once i figure out the definitions and proper use

i set up the 3 tstats as follows just to get some heat: (for the baseboard) only heat, (for the hvac) only cool, not even the heat pump setup, since i was getting both baseboard and heat pump running at the same time. DUMB, YES, but i got tired of installers saying use ECOBEE, why not a simple HONEYWELL, etc etc. AND if i mentioned DUAL-FUEL, i sensed great panic in their eyes. I would like to resolve and make this work, so I want to learn how in my lifetime if possible.

It seems the dual fuel setup in the NEST PRO manual's diagram set should work, but it is the 2 zones that i couldn't figure out how to manage. Some site, using Honeywell, said their solution was to use a relay to be the over-all control for the zones in the baseboard, but they didn't show a wiring diagram.

now, if i had just 1zone baseboard, i should be able to have 1 tstat, setup as dual fuel:

- heat pump runs when temp above 40deg

- baseboard is in Nest terms the Aux Heat (yes?), and runs when temp is below 40deg

- the heat strips turn on (automatically? or manually?) if the temp goes below 20deg

and, for this to work with 2zones, i need some kind of relay lockout that then allows the baseboard zone tsats to be enabled when temp goes below 40deg, but allows their tsats to allow their program schedules to be independent of the hvac tstat schedule, yes?

i will get the wiring diagrams tomorrow morning. Bear in mind that the hvac tstat is i think wired for heat pump and Aux heat, but is set for COOL only, because i never got that part correct.

and thanks for listening,'

Ron

[GabrielaG]

Hi rny1nestcom,

 Thank you for your reply. I appreciate the time you took to answer my questions. I have seen all the pictures you provided me with the wiring. I will be happy to continue assisting you right now.

Based on the information you sent me, I recommend checking the thermostat settings, specifically the safety temperatures. Please follow the steps below:

• Press the thermostat's display to bring up the Quick View menu.
• Select Settings.
• Choose Safety Temp.
• Turn the ring to select the heating or cooling safety temperature you'd like to change and press the ring to choose it. Turn the ring to change the temperature and then press the ring to confirm the change.
• Note: You can disable a safety temperature by turning the dial to off when choosing a temperature, but I don't recommend this since setting a safety temperature helps protect your home.

You can refer to the thermostat safety temperatures article to see other options. Also regarding the two-zone systems, you can refer to zoned system compatibility with Nest thermostats.

 Feel free to keep us posted if you have more questions.

Regards,

Gabriela

[rny1nestcom]

Gabriela,

ok, here are the wiring diagrams

- the 2 baseboard heat setups [both work fine]

- and the hvac heat pump setup [set for 'cool' only, but the wiring is set for my last attempt at trying to use/not use dual duel - this i think was set up for heat pump with auxiliary heat and emergency heat (perhaps wrong? where aux heat was supposed to be the baseboard system)]

thanks for helping, 

ron

[rny1nestcom]

gabriela,

thanks for the help, let me see if i got this right and then advise on the next steps, ok?

1. first my house:  

My house is ranch-style and the diagram mirrors the physical locations of the Nest 3E tstats [looking left-to-right][move the lower image up to the right of the upper image]

By Nest Definition: this is a ‘zoned system’
[it is unclear if a ‘zoned system’ is mutually exclusive with ‘dual fuel system’? can a single zone be configured as ‘dual fuel system’? in my example, could the heat pump and electric heat strips be considered a ‘dual fuel system’ with the strips as AUXILIARY HEAT instead of EMERGENCY HEAT? (probably waste electricity?)]

[left-most tstat] [zone-1] kitchen/living rm/mud room
– heat only
– [set a ‘lockout temperature’ here? Turn off zone-1 hydronic baseboard when outside temp is greater than 40deg?]
– [set a ‘safety temperature’ here? Turn on zone-1 hydronic baseboard when outside temp is lower than 20deg? Even if the tstat is set to ‘off’?]

[middle tstat] [zone-2] hallway between kit/lv rm/bedrooms/bathrooms
– hvac: heat pump w/electric heat strips for EMERGENCY HEAT
– heat & cool
– [set the ‘safety temperature’ for heat and cool here? 20deg for heat/95deg for cool? Even if the tstat id set to ‘off’]
– [set the ‘lockout temperature’ for the heat pump here? Turn off the heat pump when outside temp is less than 40deg?]
– [set the EMERGENCY HEAT here? Turn on the electric heat strips ‘manually’? This is different than the ‘safety temperature’ setting which would automatically turn on the heat pump? Yes?]

[right-most tstat] [zoe-3] bedroom tstat
– heat only
– [set a ‘lockout temperature’ here? Turn off zone-3 baseboard when outside temp is greater than 40deg?]
– [set a ‘safety temperature’ here? Turn on zone-3 hydronic baseboard when outside temp is lower than 20deg? Even if the tstat is ‘off’?]

Question-1: ‘safety temp’ and ‘lockout temp’ are separate, distinct and independent parameters? Yes? OR are the terms interchangeable?

Question-2: since the hvac system has electric heat strips in the air handler, are the heat strips ‘loosely considered’ a ‘dual-fuel system’? Yes? No? (Should they be set up as AUXILIARY HEAT or EMERGENCY HEAT depending on how Question-2 was answered?)

thanks for your patience,

Ron

[GabrielaG]

Hi rny1nestcom,

Thank you so much for keeping me updated. I appreciate the time to perform the steps. I understand that you want to know about the differences between safety and lockout temperatures to work with AUX heat. I will be so happy to assist you right now.

Safety temperatures can keep your home warm or cool in extreme weather conditions. When your home reaches a predetermined temperature limit, Safety Temperatures activates heating or cooling, even if the thermostat is turned off. This can help keep your pipes from freezing and your home from overheating.

Nest thermostats with AUX heat will automatically use Heat Pump Balance to determine lockout or break point temperatures. As a result, your Nest thermostat will automatically set a lockout temperature for you.

Feel free to keep us posted if you have more questions.

Regards,

Gabriela