Question about Honeywell RTH230B 5-2 Day Programmable Thermostat Large

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I just replaced a t87 with a 7 day digital honeywell tstat but it will not light up, I have a 3 zone system so I bought more then one of these tstats but none light up, the t87 only had 2 wires, black

Only not the 5-2, its 7 day but same unit

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Try replacing or installing two AA batteries. or call 1-800-468-1502 for help, that number is from the manual you read.

Posted on Nov 26, 2014


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Posted on Jan 02, 2017

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SOURCE: got a honeywell t8400c thermostat

R--- rc or rh y--yellow g---green w--white red is power yellow is cool g--fan white is heat

Posted on Sep 03, 2008

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SOURCE: i have a honeywell focus

W== heat which we'll call this w-1! w2== second stage!

Posted on Sep 04, 2008

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SOURCE: installing thermastat

any wire can go to any terminal. unfortunately you now have to hand trace each onre to the device it powers and hook it up accordingly. a daunting task even for a pro. having said that the installer could have used the normal colrs for the usual wiring if you were real lucky. as a general rule the red goes to the r terminal. the yellow goes to the y terminal. the white on a heat pump usually goes to w2. the green powers the fan and goes to g. usually the changeover valve is powered by the o terminal and that is usually wired with an orange wire. that only leaves two more wires. one is the auxilliary or emergency heat terminal and any color wire can be used for that. it will go back to the airhandler and tie on to the w terminal along with the white wire from the stat on most units. or they may have jumped the w and emergency terminal together and hooked the white wire to both. it will work either way. that only leaves one wire and that is the common wire to the stat taht allows it to light up and think and have power. . most stats need the red and a common to work. you may have bought a stat that works off battery power only but since you are blowing fuses it seems you have a common pulled on one wire that you have hooked up wrong and it is creating a dead short , aka a blown fuse. if you go to airhandler and finf low voltage terminal board look for terminal labeled comm . observe what color wire is connected to it and if that is the wire that goes off to the stat. if it is hooked to common and goes with the others to the stat then thats your common and should be hooked to your stat common terminal as outlined in your install sheet. you can keep replacing those fuses till you get it right or take a chance and use an amp probe and a jumper wire . only run an instant and if amps are 4, 5, 6, amps at trans your wrong. only test an instant or you will ruin transformer.probably best if you get a box of fuses.label stuff make notes and good luck. i have gotten in the habit of using a sharpie pen to make copius notes right on the service panel for me and the next guy.

Posted on Oct 30, 2008

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SOURCE: Hi, I'm fitting a replacement Honeywell

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Posted on Oct 31, 2008

SOURCE: Replaced Bryant T-stat model TSTATBBNB001 with Honeywell t-stat

Hello,You forgot to wire the O terminal w1 witch is the reversing valve.It is important to check if old stat is using O or B in witch case B terminal=w1 leaving O unused.

Posted on Apr 21, 2010

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