Ecobee and dual fuel system

Hi guys,

I'm loving this forum. Last week I had the quickest and most detailed response in no time. So a friend just bought an ecobee3 to replace a Honeywell thermostat. His setup is a dual fuel system and has the following installed:

Old thermostat: Honeywell (model TH8320U1008)
Furnace: Trane XV80 (model TUD080R9V3K4)
Outdoor unit: Trane XL14i Heat Pump (model number 2TWX4024B1000AA)

The wiring diagram of the current setup is attached.
Thanks so much.

p.s when I checked the ecobee compatibility website, it said 'not all features' will be available. I am not sure what that means, and if we're better off with our current setup.

 

You sound happy so I guess the nest install was a success.

So you use the gas furnace as backup and emergency heat..... no electric reheat ?
I don't see a diagram. Maybe this will help... How-to-insert-pictures
A picture of the old stat base with the wiring would be helpful too.

 

Oh I'm so sorry about that, I forgot to attach it. Here it is.


The nest was a success, thanks!! Although I'm thinking of switching to the ecobee as well. Any thoughts???

 

I am sorry I don't know the answer to that. How can I figure that out? I tried looking up setup details not the Honeywell, but I can only get the basic settings.

 

I haven't forgotten you. There are several considerations here. With a dual fuel setup..... the furnace cannot run when the heat pump is running. The Honeywell stat will supply that if an outdoor sensor is used. You don't have one. The S1 and S2 terminals are empty. That means we need to see how your system currently locks out the furnace/heat pump.

honeywell/resources/TechLitDocuments/68-0000s/68-0280.pdf
Using installer setup on page 15. Get me these current settings.

170 - system type
200 - aux heat
210 - ext fuel setting
350 - compressor lockout

The Ecobee 3 does not list dual fuel and I don't think you can activate emergency heat manually. The E4 says dual fuel compatible but I haven't seen anything about activating emergency heat manually from that stat either.

 

Hi Pete,

Thanks for your help. Here are the settings you asked for:
170 - system type: 7—2 heat/1 cool heat pump (with auxiliary heat)
200 - aux heat: 0—heat pump backup heat source is electric (factory setting)
210 - ext fuel setting: not shown on the thermostat (I guess because the backup heat source is electric)
350 - compressor lockout: also not shown on the thermostat

Thanks so much

 

Ecobee's documentation is not the best though I do see that both the Ecobee3 and Ecobee3 lite are showing dual fuel support. You need to set the heat pump "Min outdoor" temp as well as setting "Aux Heat Simultaneous Operation" to disabled.

The issue with any Ecobee is that they don't believe in emergency heat. Their documentation says just to cap off any E wire.

 

Thank you so much

Is that a big issue in your opinion, or at least something that should deter us from using the ecobee? Really, the only reason we went for it is because it's a multilevel house and the option of having remote sensors is appealing.

 

The big issue is that Ecobee's installation directions say to not hook up the emergency heat wire if you already have aux heat. In your case that means never using the furnace. There are work-arounds (cap the aux heat wire instead) but are not as clean.

The other issue with not having the option for emergency heat is that you lose control. For some people they don't want emergency heat except in rare instances because of cost and are willing to flick a switch. Others find it annoying and don't want the switch, they want it to be automatic.

 

The ability to manually activate emergency heat is good if the heat pump malfunctions. The furnace can be used as the AUX heat source. Since there is no electric heat strips.... the furnace must be the AUX heat.

That's why I was trying to see if there's a dual fuel kit in place. Based on the Honeywell programming..... there seems to be one installed.

To the Op..... the typical way a thermostat works is that when the room temperature is 3 or more degrees below the set point..... the AUX is turned on. Then both the heat pump and the AUX heat run at the same time until the system catches up. The problem is that the furnace can't be heating when the heat pump is running.

This type of system can be difficult to set up without a tech on location.

 

Thank you so much for going into that much detail. I am definitely re-considering this.

 

hi again Pete,
so we returned the ecobee and were wondering if a nest would be easier to install. based on the system we have do you still think we need tech to install properly?

I've been reading a bit on a prior answer you gave for a similar setup to ours, although with slightly different wiring (https://www.doityourself.com/forum/t...v-80-nest.html). would love to read your input.

thanks for the help

 

Hi guys, please ignore the last post. There is a little bit of a mix-up in the system and I will need to figure that out first. I will re-post with new images