I have a heat pump and an electric heat system and I am trying to replace my old
thermostat (Robertshaw 300-208) with a Honeywell RTH8500D.
The original wiring setup on the Robertshaw 300-208 was the following:
terminal - color
W1 - white
Y1 - yellow
G - green
R - red
24V - jumper to R
24V(c) - black
O - orange
B - not connected
I have made the following connections on the Honeywell RTH8500D:
terminal - color
RC - jumper to R
R - red
O/B - orange
Y - yellow
G - green
C - black
E - jumper to AUX
AUX - white
This wiring scenario seems to be working ok for a while, but after some time the
circuit breaker turns off and I have to reset it. I have tried other wiring
scenarios as per the manual without success, but I have to admit that it's
pretty difficult for me to understand.
I would welcome any help to resolve this issue and the Honeywell site and their
client service is of no use.
The "classic"/legacy labeling is:
W1 commands heat
Y1 commands cooling
Rh & Rc are the 24V "hot" supplies for heat and cool, respectively.
C is the 24V "common" (I hesitate to say "ground")
G commands the fan/blower
O & B change the "direction" of a heat pump (cooling & heating, respectively)
The colors *typically* used are rather intuitive: White, Yellow, Red, Common
is brown/black/blue -- depends on "what's left over" in the cable, Green or
Grey, Orange and Brown (!!) There's no guarantee that the original installer
followed this convention, though... In your original case, it does *appear*
to be the case -- assuming the other ends of the wires are connected
appropriately (just because he used the right colors doesn't mean he
wired them to the right actuators!)
The Homelywell appears to be rational in its labeling. But I wonder why white
(heat) is relegated to E/AUX??
I suspect your tstat is wired more or less correctly and the breaker
tripping is an unrelated issue. Presumably, the circuit breaker
that you are referencing is the (large) breaker that supplies
"heating power" to your system (?). Are you sure the loads aren't
wonked?? I.e., that the breaker isn't actually doing what it is
supposed to do -- protecting you from something that's not as it
Are you sure the breaker isn't fatigued and tripping at a lower
than expected point?
Without an ammeter, the only practical way of determining the actual
load placed on the electrics is to monitor your KWHr meter with
everything OFF except the heat. You can then determine the rate
of power consumption which translates into amperage -- which you can
then compare to the marking on the breaker.
[For most folks, this is too tedious an exercise to "get right"]
Can you isolate portions of the heater "load" to determine if one
section is possibly failing? (this assumes the breaker is not
On Wednesday, November 25, 2015 at 1:07:48 AM UTC-5, Don Y wrote:
I don't have experience with heat pump based systems. But from what
I can see, I agree with most of your analysis. The only way I can
see that miswiring a thermostat could cause an AC supply breaker to trip
would be if it somehow resulted in the heat pump stopping, then
restarting immediately without a 5 min rest period, putting a higher
starting current on, or similar. On systems with aux heat, I assume
there are probably at least two breakers? One for the heat pump,
one for the aux heat/air handler? Which breaker is tripping and
what size is it?
Don't solely depend on wire colors. Have to understand the nomenclature
of terminal markings. Some thermostats are not compatible with heap
pump. Please start with reading the manual and from the typical wiring
diagram there try to match your system.
And you have to go into service mode to set the options like you have
one stage heat pump. Also you can test the system there. All in the
manual. Also Honeywell support is very good if need help from them.
On Thursday, November 26, 2015 at 9:28:09 AM UTC-5, Tony Hwang wrote:
Unless you buy one of their better there better thermostats, eg VisionPro.
Then they tell you that they won't answer questions about how to change
the system settings and you have to call one of those guys with saggy pants
and a butt crack for $150.
RTH8500D is Vision Pro 8000 series. I never had problem with Honeywell
tech support. Always prompt and gives correct answer to my questions.
BTW, with that thermostat, if you run one more wire battery is only back
up for power failure which means battery lasts LONG time. All in the
manual. I have two Vision Pro 8000 series, one out at our 4 season
cabin, one at downtown rental condo with split A/C and hot water heating
system. At home I have wireless one with Redlink for Internet connection
so I can control the system remotely from any where in the world as well
as in/outdoor video surveillance cameras using DDNS.
Thank you all for your responses.
I'm tempted to think that the wiring is fine and that it may be a breaker issue.
The breaker that trips from time to time is the aux heat / electric furnace.
Now, I have to find what's causing it to trip. Since I wrote the first note, it
tripped twice at different intervals and times (one while asleep and once during
the day) but I can't connect the dots yet.
OP, did you set what kind of system you have in the service mode like
heat pump or force air furnace, single stage or multi stage, and few
other stuffs. If you have heat strip and old thermostat worked fine
I don't think it is breaker issue. Go thru set up procedure and see if
you missed any thing. You can also test the system basic operation in
About 15 years ago when my mother was still alive, she would call me a few times
a week to tell me that the central A/C in her condo was out. I would go over
there, and sure enough, the 30 amp breaker was tripped. I would reset it and a
few days later it would trip again. I went nuts looking for a cause, and then I
said "Screw it", and replaced the breaker. Never had a problem after that. I
guess the breaker fatigued over the years and was tripping at a much lower
current than it was supposed to. REPLACE THAT BREAKER !!!
=======================================================Remove the ZZZ from my E-mail address to send me E-mail.
On Thursday, November 26, 2015 at 11:09:52 AM UTC-5, Tony Hwang wrote:
Baloney. It's not branded, marketed or sold as VisionPro. The "Pro"
means something, ie that it's not meant to be sold retail, to
consumers. The RTH8500D looks like a VP and has some of the
features, but it's sold in retail channels. So, Honeywell will answer
homeowner install questions on the RTH, but not on VP series.
Depends on what you consider a problem. If you
buy an actual VisionPro thermostat and call up to
ask how to change the setup settings, they will
tell you to call an HVAC company and will refuse
to answer your questions. Been there, done that.
8000 series has many varieties. Even basic one is quite robust in
features. And it comes with a manual, quite thick booklet in English and
Spanish. Or you can download it in PDF form which will need a small
binder to keep it in order. Of course if you ask dumb question you'll
get dumb answer or just stare in the eye or totally ignored. If you ask
good intelligent question you get more than you asked for usually.
Honeywell makes good stuffs in Mexico, vs. cheap ones are from China. I
worked for Honeywell all my life after coming home from years overseas
work with DOD. More than 40 years.
My store which is in a LEAD building has Vision Pro 8000 under Lennox
badge. Their manual hid some important thing like how to go into service
mode. Most manuals trouble-shooting section always says call service
tech. Our Genie screw drive DC motor GDO manual does the same but I can
work on any problem. I had to find out a fuse on a control board which
was hidden in the schematics in the manual. Some people may have problem
setting up the Intellicode remote or synchronizing new car remote to
GDO. Now I am working on ways to take over new car PTS remote starter.
Looks like firmware needs tweaks.
On Sunday, November 29, 2015 at 10:21:46 AM UTC-5, Tony Hwang wrote:
Of course non of that has any relevance to the fact that Honeywell will
not provide phone support, answer questions for homeowners about how
to install the VisionPro series. Words have meaning and "Pro" means that
product series is not intended to be sold through retail channels to
consumers. It's intended to be sold through pro HVAC channels and they
are the ones that are supposed to install it. I've been there, done that.
I called up Honeywell on a VisionPro thermostat question (Not the RTH8500, which isn't a VP), and they would not answer my install setup question.
They told me to call one of those guys with loose pants and a butt crack
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