Question about Honeywell Programmable Thermostat Heater

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Changing Thermostats I have an American Standard furnace with Heat Pump. The present thermostat is a ASYSTAT655 (American Standard). I want to replace with a Honeywell RTH7400 But the wiring is confusing. I went through Honeywells "Wizard" but the only options were for systems with 7 wires Mine has 8. I don't want to blow something up it is cold and gonna get colder

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This is one where you will need a good control man or woman. The American Standard ASYST system is not intended for the homeowner to change out. It has a room sensor wire that others do not account for.

Posted on Jan 16, 2008


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Posted on Jan 02, 2017


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Stage 2 is on the screen but no heat will come on. American standard thermostat. A/c comes right on but when heat is turned on "stage2" comes up on the screen but the heat won't Not a touch screen.

You should look at your furnace and see if any safety lights are flashing. Make sure your thermostat is set to heat.Check system your using for updates.

Nov 19, 2016 | American Standard Heating & Cooling


How to change a thermostat yourself

Choosing your new thermostat:
Firstly you have to ask yourself why you are changing your thermostat. Is your old thermostat simply broken? Are you wanting a simple upgrade from analog to digital? Are you looking to save on energy costs using a programmable? Are you attempting to integrate your central system into a smart home network? Whatever the reason your choice of thermostat should not be simply the cheapest on the shelf. Different system types may require different thermostat types.
Before purchasing your new thermostat you need to figure out what kind of system you have. The general idea is *H/*C, denoting the number of heating/cooling stages and options, and fuel type (heat pump, gas furnace, electric furnace, etc.). An example would be a typical heat pump- it has a single cooling stage and a dual heating stage (heat strips, compressor) making it a 2H/1C heat pump thermostat. I usually install the Honeywell FocusPro 5000/6000 series for non-programmable/programmable applications for it's ease of use and general reliability.

Before beginning the swap always make sure power is off to both the indoor and outdoor sections!

Determining which wires go where:
First off, you may not ever rely on wire colors to guide you to the proper terminal. We have standard practices for wire color to function, but this varies from region to region and sometimes if a wire shorts out a substitute in the bundle may be used. When removing the old thermostat physically writing down or labeling the wires is not an exercise in tedium- it is almost necessary and something which I do every single time. You will usually have these terminals on the new device:
Rc- Cooling Power (usually jumpered to R/Rh)
R/Rh- Heating Power (usually jumpered to Rc)
Y- Primary Compressor
C- Common
O/B- Reversing valve (activated in cooling/heating)(Heat pump)
W- Primary heat (Furnace or Electric heat)
G- Indoor Blower
E/Aux/W2/X2- Emergency/Secondary heat stage
Y2- Secondary Compressor (2 stage cooling)
L- Communicator for E-Heat (Heat pump)
If you do not have all of the terminals on the old as you have on the new it may not be the end of the world. Required terminals are an R, a Y (if AC is present), a W/W2/E/Aux/X2 (if heat is present), an O/B (if heat pump), and usually a G. Common is optional most of the time as it is used to power the thermostat only and batteries may be substituted. L is not commonly used. If you have any doubts as to which wires go where, stop now. Miswiring can destroy a system's low-voltage and potentially start a fire.

After labeling the old wires and removing the old thermostat, you must attach the new baseplate. Leveling the baseplate is not as important as it was with older mercury thermostats, but still applicable at least within +-5 degrees of rotation. If you are attaching the baseplate to drywall with no backing wood installing wall anchors (usually supplied) is key. Make sure you have a proper length of bare wire (not too long, not too short) before attaching to the terminals. Do not overtorque the screw lugs. Pull back on the wires after attaching them to ensure the connection is proper. It is a good idea to plug the hole through which the wires come with something (I use plumbers putty) to keep a draft from effecting the thermostats temperature. Many thermostats will require some pre-programming before hooking up (refer to installers guide)- I find this much easier to do via batteries before attaching the face to the baseplate. Once the face is on and the power returned to equipment, test the system. Keep in mind modern thermostats include a 3-5 minute delay for compressors as a protective layer.

Common Pitfalls:
Zone system wiring can be confusing and is not as standardized as it should be. If you have a zone system and plan to purchase new thermostats it is highly recommended to call in an experienced service technician.
High SEER and IQ drive systems use very different types of thermostats than conventional systems. For now the newer technology has yet to be perfected in the public market and these changeouts are best left to an experienced professional.
Some older thermostats use B as common (Trane Weathertron for example) This is not to be confused with B as a heating changeover valve and if it is can blow out a fuse,transformer, and/or your brand new thermostat upon startup.
Most face to baseplate interfaces are pin based- if one is not quite careful bending one of these pins during attachment can be irreparable.
Common is the least standard color across installers. Most use either brown or blue, but I've seen some use green and black, usually used for blower and secondary heat respectively. Never assume wire color as a standard.
Most of the service calls regarding thermostats I receive come from homeowners who have purchased and self installed incompatible thermostats. This is something I do everyday for a living, not so for the average homeowner. Take your time and do your research.
Save your manuals- all of them. Many cheap offbrands can be next to impossible to find manuals for online.
When in doubt, call in a pro. Most of us charge around $70-100 to install a thermostat (plus cost). This is almost always much cheaper than a service call to diagnose and repair a low voltage problem.

on Sep 25, 2011 | Heating & Cooling

4 Answers

My gas furnace and heat pump runs at the same time???

its likely the outside control unit board its supposed to only kick on gas only when the temp is at freezing..
the inside thermostat is not selected for heat pump, open it an look at the jumper / switch.
or just replace the thermostat , then return it saying you couldnt figure it out. :P
there are a lot more variables here after that you cant know how to check.

Nov 05, 2014 | Honeywell VisionPRO 8000 Programmable...

1 Answer

Can't get the gas furnace to heat.

All York/JCI thermostats made by Venstar

The setup is probably incomplete. Did you configure the thermostat for a 2 stage heat pump? The heat pump should have a thermostat wire connected to R, C, Y1, Y2, and O, that makes 5 wires. I suspect you are only using first stage compression and or first stage blower speed.

Nov 23, 2013 | Source1 CTS Series Model S1-THPU32P7S...

1 Answer

Wiring a thermostat

Are you changing out thermostat? If so you must turn off power to your furnace or air handler. You should mark or write down each color and what terminal it was removed from. example= red from term r=green from term.=g yellow from y... Be careful, some thermostats are wired different according to type of system you have. Heat pumps are different than straight cools and the thermostats sometimes have setting or little switches. Honeywells have installer set up guides in package. Read it carefully

Sep 16, 2012 | Honeywell RTH3100C - Digital Heat Pump...

1 Answer

I am trying to install a thermostat and I am not sure where to put all the wires... it is for american standard freedom 90 two stage - furnace and air conditioning

Should be like this:

Y from furnace goes to Y on thermostat (yellow)
C from furnace goes to C on thermostat (usually blue)
G from furnace goes to G on thermostat (green)
W1 (first stage heat) to w1 on thermostat(white)
w2 (second stage heat) to w2 on thermostat (black)

Doesn't sound like you have a heat pump but if you do "o" will also have to be connected which is the reversing valve.

Jun 21, 2011 | Heating & Cooling

1 Answer

I installed a Honeywell TH5220d 1029 thermostat on a American Standard AC/Heat pump and the install and setup went fine. It cooles for about and hour and quit. I found the 5 amp fuse at the furnace...

Red wire to R on thermostat red on furnace and red on heat pump Same with white except w1 on thermostat. Blue to common on thermostat common of furnace (probably brown but will be marked) and blue to common on heat pump. yellow to Y on thermostat and straight to heat pump. Orange to O on thermostat and straight to heat pump. If wired correctly with no shorts fuse problem should be solved. commonly people leave enough wire exposed inside the t-stat for wires to short together. This will blow the fuse. Hope this helps. I understand the frustration.

Jun 27, 2010 | Heating & Cooling

1 Answer

Furnace blowers continues to run after reaching temp

It actually sounds like you may have answered the question yourself. If the mercury isn't breaking contact, then obviously it's still calling for more heat. This is a common problem with the old mercury thermostats and are usually replaced with digital ones that are way more accurate. The are fairly cheap at Wal-Mart and such, and replacing one is basically all color coded.

Jan 27, 2010 | Electric York / Paragon A-111-20 Heat...

1 Answer

Wc wiring on thermostat

sounds like you have a heat pump the w2 on old thermostat is for a second stage heat. If you can give me a little more information on type of system you have (forced air furnace with heat/cool, Heat pump or boiler)? How many wires are on old thermostat? Is it a no programmable or programmable? How old is the furnace?

Jan 17, 2009 | Honeywell Programmable Thermostat Heater

1 Answer

Furnace not running along with heat pump

Someone did not program your thermostat to operate according to your heat and air requirements.
Have it programmed correctly.

Apr 21, 2008 | Honeywell Programmable Thermostat Heater

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