searched, didn't see much in the way of wiring.

here's the situation:

older heat pump. air handler model # TWV018B140A1 (trane/american standard). not sure about the compressor/outdoor coils, it's dark outside

old thermostat was a honeywell TH5220D1029. i'm replacing the thermostat with a programmable one (the lux tx9000ts).

old thermostat had E, Aux, G, O/B (assuming O), C, Y, and R hooked up to terminals, with R (assuming RH?) bridged to RC. there was also a white wire that was not hooked up at all.

new thermostat only has W, Y, G, B, O, RC, RH, and C terminals.

i hooked it up like this:

old	new
E	
Aux	
G	G
O/B	O
C	C
Y	Y (bridged with W)
R	RH (bridged with RC)

8/24/2009 3:00:03 AM

http://www.ronhazelton.com/archives/tips/Programmable_Thermostat.shtm

http://www.youtube.com/watch?v=owV0t_8zNpk

8/24/2009 3:29:25 AM

...because that sure helped a lot.

8/24/2009 3:32:29 AM

Quote :

"2. COMPATIBILITY The TX9000TS can be used with most 24 volt gas, oil or electric heating and air conditioning systems, single stage heat pumps or gas millivolt heating systems. It cannot be used with 3 wire zone valves, 120V systems, or multistage systems. Ask your dealer for other LUX thermostats to control those systems."

http://www.luxproducts.com/ART/support/TX9000TS_ENG_LARGE-SIZE.pdf

The fact that you have E and Aux wires before means that you have electric heating elements that turn on when it becomes too cold outside (somewhere below 40F usually) to effeciently draw heat (or generate heat from the compressor). This auxillary heat is second stage heating. The E forces the electric heating elements to run despite the temperature outside, usually in "emergency" situations such as it being too warm to trigger Aux heating but your compressor is broken.

So in effect the heat should work*, just not aux heat, so when it drops somewhere below 40F outside (exact temp depends on the system) you aren't going to keep the house warm soley by running the compressor. Running the compressor + running the electric heating element will keep the house warm though.

Quote :

"For use on: Up to 2 Stage Heat/1 Stage Cool: Heat Pump Systems Will Operate Aux. and Emerg. Heat"

http://www.luxproducts.com/thermostats/hp2110.htm

[Edited on August 24, 2009 at 11:34 AM. Reason : *could be wrong on that, not an HVAC person/wizard]

The extra wire is probably a hot wire to power the thermostat so no batteries are needed to run it. (Could be wrong on that too)

[Edited on August 24, 2009 at 11:37 AM. Reason : ]

8/24/2009 11:29:05 AM

^that's what i figured. thx2u sir.

(and i think the C wire is the 24v power)

8/24/2009 1:54:55 PM

I have an ~18 y/o Trane heat pump, and I tried to hook up new-fangled programmable thermostat and popped the breaker in my air handler so i'm still rocking the ~18 y/o thermostat

^^ think this would work with aold ass trane heat pump? http://www.trane.com/Residential/Products/Thermostats/XL900-Thermostats

8/24/2009 2:06:56 PM

^^just in case you didn't extract what I was getting at (it's confusing and I didn't come right out and say it for some reason): even if it works for now, that t-stat isn't really for you system. When the winter rolls around and temperatures drop into the 30s the house is gonna get cold (you aren't going to get the electric heating elements to cut on without the aux wire plugged into something, the HP2110 or TX9100E will operate that though as they specifically note Auxillary heat).

^I'd call/visit a trane place and talk to them about it. That seems like overkill for a 18 y/o system imo when you are probably going to need a new HP sooner than later. If you are in a position to buy a new HP it's a good time to buy with the tax credit (thru dec 2010) and next stage of the r-22 phase out happening Jan 2010 (no new r-22 equipment) with r-22 production stopping all together in 2020.

8/25/2009 10:18:20 AM

^ Got any details on the credit?

8/25/2009 10:23:19 AM

Can you rig the system to only let the electric strips run when you manually cut them on? Those things use a ton of energy and we do not need them much in this area.

8/25/2009 10:23:42 AM

Quote :

"If you are in a position to buy a new HP it's a good time to buy with the tax credit (thru dec 2010) and next stage of the r-22 phase out happening Jan 2010 (no new r-22 equipment) with r-22 production stopping all together in 2020."

how much would an entry-level Trane HP cost, for a 1350 square foot house. basically how much could i get back with that credit? at least I can wait until the end of next year to do it...I would just hate to throw out a unit thats working perfectly fine.

and as far as the phase out goes, i'm assuming i'd still be able to get equipment for my old ass HP, it would just be more expensive right? or are dealers etc not allowed to sell equipment? and i'm assuming my heat pump uses this r-22 stuff right?

thanks!

8/25/2009 10:40:30 AM

^^^http://www.energystar.gov/index.cfm?c=tax_credits.tx_index
30% of the installed cost up to $1500 for the higher effeciency models

^^Well the thing is the thermostat decides when to call for aux heating depending on the difference between the current temp and the set temp and it could be as low as a 2 degree difference. So if it is 70 and you set it to 72, the t-stat is going to call for aux heat until 71 is reached (therefore there is really little to no savings, and may actually cost you more money, to play with the settings on a regular t-stat to try and save money, ie turning the heat down when you leave work and back up when you get home, unless you do it in 1 degree increments). One of the benefits of the new fangled programmable t-stats is that it is possible to have more control over the aux heating. Some you can lock out using aux heat until you decide to use it. Some you can make it so its 72 until 9 am then its 65 until 3 pm and to reheat to 72 without using aux. Just have to research the t-stat and/or talk to a dealer.

^The thing about the credit is that it has to be the higher effeciency models so it cost more money, but the credit will help offset the cost along with energy savings. The only way to know the cost for sure is to get quotes. I just threw the idea out there to get a new one mainly because an 18 y/o HP in my mind is like a car with 180K miles on it that gets 15 mpg (if a new more fuel effecient car costs ~$2-7k). It's hard to say what the price of r-22 will do in the near future (comapny's will still be able to produce r-22 for existing equipment until 2020), but it the cost of servicing the system will go up well before 2020 as supplies of r-22 and replacement parts/equipment dwindle as manufacturing gears towards 410A or other replacement options.
http://www51.honeywell.com/sm/genetron/common/documents/r22-allocation.pdf

8/25/2009 11:10:11 AM