Nest 2 Install with Heat Pump w/Aux Heat


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Old 11-25-12, 07:16 AM
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Nest 2 Install with Heat Pump w/Aux Heat

I am thinking about getting a NEST 2 for what I believe is my single stage cooling 2 stage heating unit (Heat Pump w/ Emergency Heat) and I wanted to verify I would be able to install it without needing a professional installation.

I have read I don't need any jumpers so the RH to RC wire can go away.
And I am guessing Y = Y1 so I think I have that covered as well.
What I am worried about is the W/E wire. Does this wire to W1 or Aux on the NEST?

 
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Old 11-25-12, 09:08 AM
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Nest states that it can be wired either way. None of us PRO's here are very experienced with the NEST, so you may need to call nest support and ask the difference of this wiring. In my mind the top one you have to manually call for your aux heat by switching to emergency heat mode; on the bottom one the thermostat automatically calls for aux heat as needed when the HP can't keep up. Unfortunately, NEST does not quite understand that aux can be the same as emergency heat. By losing the emergency heat function you can NOT switch to just aux heat if the HP ever has a problem. By losing the automatic switching to aux heat as needed you spend more money to heat your home when you switch to aux heat by itself using the Emergency heat function.
In MY OPINION, the NEST is not the correct thermostat for your system. Besides on a HP system with aux heat you do NOT want to use setback temperatures because you will lose all your energy saved trying to reheat the home after a setback.

There are other thermostats that are WIFI that are cheaper and will operate your system properly.
 
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Old 11-25-12, 09:15 AM
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My current Thermostat doesn't automatically switch to Aux when the HP can't keep up, I have to manually turn it on. Are you saying if I hook it up via Aux the Thermostat will automatically turn on Aux when the HP can't keep the thermostat high enough by itself?
 
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Old 11-25-12, 10:17 AM
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Yes. And your current thermostat may do that too if you jumpered w/e to w2. I would need to know your current thermostat model number to know for sure. Looks like the model number may be in your Lichtenstein I will look it up when I get home.
 
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Old 11-25-12, 11:21 AM
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http://www.emersonclimate.com/Docume.../0037-6994.pdf


It looks like an Emerson Brand Thermostat (1F95EZ-0671), I found the spec sheet above.

I'm kind of set on the Nest as I'm just another gadget freak, but I want to make sure it will at least match the functionality I have currently. Reading through some of the Heat Pump Balance settings I can see how it might interrupt energy savings depending on how I have the Nest configured as running the Heat Pump longer is still cheaper than running Aux heat.

I live in Ohio so currently at 30-40F the HP is doing great, but another month or so when its 0F or lower it would be nice to have the Nest be able to intelligently compensate without me having to check the Thermostat everyday before & after work.
 
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Old 11-25-12, 12:02 PM
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Your current thermostat is wired properly to control aux heat automatically as needed for the heat load sensed by the thermostat. It may not be setup to operate properly though in the settings. What about the NEST is what draws you to it? I'm asking because other thermostats would be much better to properly operate your system, if I can give you some options you may choose one of them over the NEST, but if you are set on the NEST then, YES, it will operate your system.
 
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Old 11-25-12, 06:45 PM
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I agree with Kevin, the nest may end up costing you more money to run your HP w/ Aux electric heat.

When it comes out of recovery, the Aux is going to come on and costing a lot of money.

HP are best to set it and forget it!
 
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Old 11-26-12, 05:42 AM
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Nest and Heat Pump

The Nest actually adjusts the setback temperature automatically so that the aux heat does not have to come on in the morning. It chooses a slightly higher temperature if that what is needed. It also starts heating early enough to reach the target temperature on time. (It uses internet-provided outdoor temperature data and perhaps even forecasts - I'm not sure - to make the best prediction about time-to-temperature.)

So, it seems like a very suitable t-stat for a heat pump!
 
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Old 11-26-12, 07:10 AM
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David, do you have something showing this??
 
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Old 11-26-12, 08:50 AM
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Is this what David was referring to?

Nest | What is Heat Pump Balance?

Even with my current Thermostat I have it lowering the Temp when I am at work, should I not be doing this with a Heat Pump system at all?

Home: 70 (I have bad windows so its set somewhat high.)
Away: 60 (System comes online about 30m before I get home from work.)
 
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Old 11-26-12, 09:17 AM
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Ok, guess Nest is ahead on this. Most Non-Pro stat and lower ends don't keep the Aux off.

On your current stat, you are using Aux on your recover so your savings been thrown out the window or costing you more than you should of been paying with that much of temp set back.
 
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Old 11-26-12, 11:22 AM
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My Aux heat does not come on by itself (at least I've never seen it automatically kick on), I always have to manually turn on Aux.
 
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Old 11-26-12, 12:41 PM
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The way I understand, it won't show it on the screen, and it will automatically turns it on as needed.(in your case, recovery mode)

Then you can turn it on manually(Emergency heat) and the Aux will show on the screen till you turn it off.
 
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Old 11-26-12, 02:48 PM
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jay, I think the aux operation depends on how it is wired. The NEST 2.0 has a terminal for aux and one for Emergency heat (*). Since the nest will NOT let you jumper the 2 you either have it as auto aux control or you have to switch it to emergency heat.
 
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Old 11-26-12, 02:59 PM
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Yes, I saw that for the nest, but I was talking about the WR that the OP has now.
 
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Old 11-26-12, 04:11 PM
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Yep, I read the manual for that stat and it is wired correctly to automatically pull on aux heat the way it is wired.
 
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Old 11-26-12, 09:40 PM
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I live in Ohio so currently at 30-40F the HP is doing great, but another month or so when its 0F or lower it would be nice to have the Nest be able to intelligently compensate without me having to check the Thermostat everyday before & after work.

liquid123, regarding this, the keyword on the Nest here is "lockout temperature". This, IIRC, is the maximum outside temperature at which it may turn on aux heat (resistance based heat). It gets this temperature from the internet - you enter your zip code. (It does not have its own outside temperature sensor.)

So the answer is, yes, it does exactly that.

In my experience with the Nest (and current central PA temperatures at around freezing), aux heat comes on more often than needed unless I switch heat pump balance to "more savings" (as opposed to "comfort" or "balanced").
 
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Old 11-27-12, 05:19 AM
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I bought the Nest 2 and got it installed last night, however I wired my White (W/E) wire to the * port on the Nest and selected Emergency Heat for the * wire option. This gives me the same functionality I had on my old TStat and which brings me to my next question.

I'm guessing since I selected E-Heat and not Aux Heat, there is no HP Balance option enabled and while I can manually turn on Emergency Heat, I'm not seeing an option for HP Balance to enable it to turn on the Strips while the compressor is running. Looking through my old options it looked like my old TStat had the compressor lockout enabled so if Aux was turned on it shut the compressor off. I would like the HP Balance options but I am afraid changing the settings from what the Professionals setup originally will damage my unit.

Is it possible to damage my unit if I wire & configure the Nest to run the Strips while the compressor is running in certain scenarios? I do understand there are problems with setting it up this way due to the extra costs of running the strips, I'm just wanting to see if the Nest can keep the Strips under control by itself without me having to manually turn them on or off.

As a side note everything else seems to be running correctly, AC is blowing cold, HP is blowing Hot and Emergency Heat works (Manual Only as far as I can tell) and shuts down the compressor when enabled. It was fairly easy and I'm somewhat surprised I didn't somehow blow up my condo.
 
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Old 11-27-12, 06:26 AM
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Liquid, wire that wire to Aux, and the set the setting "More Savings", then from what I am reading from Nest's web page, it will not turn on the Aux unless it really has to.

Why would you want the strip wired to come on?? NO, you can't do that, otherwise, the heat strip would be on when you are running your A/C.
 
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Old 11-27-12, 11:30 AM
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The * port on the Nest looks like it can be programmed to do either Aux or E-Heat in the settings on the Nest itself (I currently have it set to E-Heat). Should I try that first or will wiring it to W2/Aux allow the Nest to use the Strips while the Heat Pump is running without any extra programming since it a dedicated Aux wire?

I was just curious about this as the Professional Installers had it wired to W/E originally and I wasn't sure if they had set it this way for a reason. (Thinking maybe running the strips while the heat pump was running could damage something.)

EDIT: I apologize I did not mean to say the Strips would come on with the compressor on, I meant the Heat Pump.
 

Last edited by liquid123; 11-27-12 at 11:46 AM.
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Old 11-27-12, 11:56 AM
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If the * is Aux2, and your system has more than one banks of heat strips, then we'd stage them than rather than having all 2 banks on at once.

I'd move it to the W2/Aux...
 
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Old 11-30-12, 07:56 AM
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As I am also looking to buy a Nest (v1 or v2), I had this same question for the folks at Nest support. The representative said I'd have to choose AUX or Emergency heat, not both, unless I ran a separate wire down to the air handler for Emergency heat to be connected to *. I suppose if my outdoor unit went down, I could move the wire from W2/Aux to * and activate Emergency Heat in the settings. It's easy enough to do if I find myself without heat, but it seems ludicrous that Nest did not take this situation into consideration. I'd imagine that many heat pump thermostats use a jumper between E/W1 to W2/Aux and Nest dropped the ball on this one. Seems odd for a company that claims to be so innovative.

One other question if you don't mind me momentarily hijacking this thread... Should a typical 14 year old HP system activate the Heat Strips when in Defrost mode? It seems that there is >55F air coming out when in defrost mode and it pretty much un-does any warmth the heating mode had provided.
 
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Old 11-30-12, 05:38 PM
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Does the Nest have some type of low temp alarm? At the price for the Nest 2 I would hope so.
 
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Old 11-30-12, 08:05 PM
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Should a typical 14 year old HP system activate the Heat Strips when in Defrost mode? It seems that there is >55F air coming out when in defrost mode and it pretty much un-does any warmth the heating mode had provided.


Bill- Yes, it should kick in the Aux heat while it goes into defrost..

McHero, I am not aware of any low temp alarm.
 
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Old 11-30-12, 09:39 PM
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Honestly, for the money..... NEST is not the way to go, IMO.
 
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Old 12-11-12, 05:05 PM
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Thank you Jay11J. I picked up and installed the Nest v2. I'm happy with my purchase so far. I am interested to see what Heat Pump Balance at Max Savings does in the next few nights when it gets down to the upper 20's.
 
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Old 12-20-12, 11:45 AM
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I moved my wire from * to W2/Aux awhile back and it seemed to be working correctly, only turning on Aux when the jump in temperatures was very high. However last night I noticed while watching TV, it sounded as if it didn't turn on the outside Heat Pump until towards the end of the heating cycle. So when I get off work, I will probably be doing some more testing to see if I was just imagining things or not. I've currently got Heat Pump Balance set to 'Max Savings'.
 
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Old 01-21-14, 07:47 PM
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Wink W1 or W2

Hi
I opened a case with Nest because I have a similar system and I am considering buying a Nest 2. They stated I should install the white wire into W1 instead of W2.

Any feedback? liquid123
 
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Old 11-12-14, 12:07 PM
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Use ONLY AUX Heat with Nest? Possible?

My HP has died and I want to continue to use the Nest to operate the furnace. When in regular heat mode it just blows cool air. Once I turn it up four degrees the AUX kicks in and heats my house in no time. I would like to set the Nest to automatically use AUX every time with out having to manually crank it up until it comes on. Is this something that I can do? I can send a picture of the wires if that might help. Is there a way to bypass the blower all together by disconnecting something? Thank you in advance for any insight you can provide.
 
 

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