Looking For a New Thermostat


  #1  
Old 04-20-13, 06:47 AM
C
Member
Thread Starter
Join Date: Apr 2013
Location: USA
Posts: 7
Upvotes: 0
Received 0 Upvotes on 0 Posts
Looking For a New Thermostat

Hello All! I just moved into an apartment and I am looking to upgrade the thermostat to something more reliable and accurate. Particularly the Nest. Right now the thermostat is a LUX LHP750. Here are the instructions: http://www.luxproducts.com/support/L...ENG_Manual.pdf

The apartment has a heat pump and also an electric furnace inside (apartment is all electric). The apartment welcome packet said to use the heat pump put the thermostat on "NORM" and to use the furnace (below 30F outside) put the thermostat on "EMER HEAT".

The thermostat is wired:
E
G
Y
R
X (which I think is the same as C on the Nest)
O
W2

What I would like to know is is this a dual fuel system? The air path comes in the return, through the coils (heat pump/AC), through the heating elements and then out to the ducts and registers. In other words, the coils are downstream from the heating elements. I believe I can have the furnace and heat pump running at the same time using the furnace as an auxiliary.
 
  #2  
Old 04-20-13, 07:06 AM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 6,526
Received 95 Upvotes on 88 Posts
A dual fuel system has a gas furnace with an evaporator coil sitting above or below it (or next to it with horizontal applications) and a heat pump outside.








A standard heat pump application only has an air handler inside and a heat pump outside. It will not have PVC or metal exhaust piping. It will usually have the evaporator coil inside of the air handler, not above or below it.

Like the first and last image shown here...

 
  #3  
Old 04-20-13, 07:36 AM
C
Member
Thread Starter
Join Date: Apr 2013
Location: USA
Posts: 7
Upvotes: 0
Received 0 Upvotes on 0 Posts
So from what you are saying, I have a single fuel system that is wired in a way where only the heat pump or the furnace is activated?
 
  #4  
Old 04-20-13, 08:16 AM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 6,526
Received 95 Upvotes on 88 Posts
I am only trying to explain the difference between a heat pump system and a dual fuel system.

The word "furnace" is commonly used to describe a gas, oil, or propane furnace.
An "air handler" is more commonly used with heat pumps.

[QUOTE][The air path comes in the return, through the coils (heat pump/AC), through the heating elements and then out to the ducts and registers.][QUOTE]

This sounds like an air handler.
 
  #5  
Old 04-20-13, 08:53 AM
Gunguy45's Avatar
Super Moderator
Join Date: Dec 2007
Location: USA
Posts: 19,281
Received 7 Upvotes on 7 Posts
In laymens terms, you have a heat pump with electric heating strips...for use when the HP can't keep up or is broken for some reason. Imagine a giant electric heater bathroom heater placed after the HP coils.

They are very expensive to operate and their use should be avoided to maximize the benefit of the HPs efficiency.

With HPs the standard usage is to set it and forget it. Using setbacks (in winter) can cause the heat strips to kick in when they really aren't needed, but the system is trying to recover the house temp from the setback.

As I understand, newer systems can use the heat strips in stages, but that all depends on what system you have.

If the HP is working correctly, you should never have to place it in "EMER" mode. It will automatically kick in "AUX" heat when needed. You will see that happen by a light or display on the stat. I think the strips can also be "locked out" so they never come on.

Not a Pro...but thats how I understand them.
 
  #6  
Old 04-20-13, 08:53 AM
C
Member
Thread Starter
Join Date: Apr 2013
Location: USA
Posts: 7
Upvotes: 0
Received 0 Upvotes on 0 Posts
Got it. The furnace is electric and can be used to heat the apartment if heat pump fails or can not keep up due to the outside temperature being to cold for the set point. The unit inside contains the coil, blower, and heating elements for the furnace. But as of right now it is either the furnace OR the heat pump.
 
  #7  
Old 04-20-13, 08:57 AM
C
Member
Thread Starter
Join Date: Apr 2013
Location: USA
Posts: 7
Upvotes: 0
Received 0 Upvotes on 0 Posts
That was what I was thinking; the "heat strips" are the heating elements in the furnace since it is a forced air system.

Now I am wondering why the apartment complex wired it as an "either or" rather than using the furnace as a auxiliary (helping the HP heat the home). Hmm...

EDIT: I did see the AUX light come on this morning, but how can I actually tell if it is using the furnace in tandem with the HP?
 
  #8  
Old 04-20-13, 09:14 AM
Gunguy45's Avatar
Super Moderator
Join Date: Dec 2007
Location: USA
Posts: 19,281
Received 7 Upvotes on 7 Posts
Except for as I stated....the heat strips CAN be used at the same time as the HP...thats what I meant by AUX heat. In EMER, only the strips are used.

Your use of the electric furnace terminology is sort of confusing. You have an HP with electric aux heating strips, that's clear to anyone.

I'm not sure where that first started, but I've been hearing it used more often for some reason. Seems like in Europe they use those terms quite a bit...possibly they actually have some sort of electric furnaces over there with no HP at all?
 
  #9  
Old 04-20-13, 09:18 AM
Gunguy45's Avatar
Super Moderator
Join Date: Dec 2007
Location: USA
Posts: 19,281
Received 7 Upvotes on 7 Posts
Oops...we were typing at the same time. If the AUX light is on...the system is using the strips...thats the way it works. The system will automatically turn them on when needed (unless they are locked out). Unless it's extremely cold where you are right now...or you had just bumped up the set temp...it shouldn't be coming on. As I said...it greatly increases your electric usage and thus your bill. HPs are very efficient....but not when they use the electric heat.
 
  #10  
Old 04-20-13, 09:51 AM
C
Member
Thread Starter
Join Date: Apr 2013
Location: USA
Posts: 7
Upvotes: 0
Received 0 Upvotes on 0 Posts
Maybe a miscommunication or an assumption...but I do not have heating strips along the baseboards near the floor.

I only have a heat pump outside and an electric furnace inside; unless you are referring to the furnace's heating elements as the heat strips? Or I am thinking heat strips meaning strips along the baseboards?

Hopefully we can make sense of each other now. Lol.
 
  #11  
Old 04-20-13, 10:20 AM
Gunguy45's Avatar
Super Moderator
Join Date: Dec 2007
Location: USA
Posts: 19,281
Received 7 Upvotes on 7 Posts
Yes....the heating strips are up in the air handler area...just as you described in your first post. I said strips...you said elements...same thing. (btw...per your description the heating elements are DOWNSTREAM from everything else...since they are the last thing before the registers.) Normal configuration is intake (or "return" in HVAC talk), air handler (squirrel cage fan), gas or propane furnace heat exchanger (which you don't have), HP coils (or A/C coils if you had the gas or propane), then the electric heat elements/strips for a straight HP system.

With a little looking..I found that "electric furnaces" do exist....but basically they are add-ons to houses that may already have ductwork for A/C which may have been retro-fitted to an old house or newer homes built in areas that did not originally have central heat due to the climate.


A little off topic...but a friend bought a VERY nice home on an island in WA state. It had no central heat or A/C. In each room there were these electric heaters with small fans behind grilles in the wall. I'd never seen anything like it.....and the house was quite uncomfortable (to me) in colder weather.
 
  #12  
Old 04-20-13, 11:39 AM
C
Member
Thread Starter
Join Date: Apr 2013
Location: USA
Posts: 7
Upvotes: 0
Received 0 Upvotes on 0 Posts
Now that we are on the same page! I thought heat strips meant baseboard heaters...whoops! Now I know!

My configuration is intake (return), HP coil, air handler, heat strips, plenum to the registers. I guess in my configuration the air handler is between the HP coil and the heat strips.

Thanks for everyones help!
 
  #13  
Old 04-20-13, 12:35 PM
Gunguy45's Avatar
Super Moderator
Join Date: Dec 2007
Location: USA
Posts: 19,281
Received 7 Upvotes on 7 Posts
Like I said...no Pro...I've always had a gas furnace and A/C. It was always as I described...fan blew through the furnace and then the A/C coil.

About the AUX heat coming on earlier....had you just bumped the stat up or was it recovering from a programmed setback? How cold is it there?
 
  #14  
Old 04-20-13, 12:49 PM
C
Member
Thread Starter
Join Date: Apr 2013
Location: USA
Posts: 7
Upvotes: 0
Received 0 Upvotes on 0 Posts
A combination of both. It was a little chilly in the house so I bumped it up a degree or 2 (mechanical t-stat so it is hard to tell) and it was about 35F outside.
 
  #15  
Old 04-20-13, 02:36 PM
hvactechfw's Avatar
Member
Join Date: Jan 2011
Posts: 5,491
Upvotes: 0
Received 4 Upvotes on 4 Posts
DO NOT use the NEST..... They are known for problems especially on Heat pump systems. Do a lot of research on Nest problems/with heat pumps. Buy a time tested thermostat from a manufacturer like Honeywell.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: