Thermostat wiring - need help

icer22x · 02-22-2009, 12:38 AM

Howdy guys,

Hopefully someone here knows about thermostats.
I moved into an apartment that has your typical everyday three-layered Mercury switch thermostat.

(Fan control set to auto)

I've done a little research on the wiring for this type thermostat, but some seem to vary.
Anyway, I was wondering how to completely disconnect the heat so when I switch the thermostat to heat, nothing happens. I know I can just turn it off, but I am running some diagnostics.

I have two red wires running out of the wall and connecting to the RH terminal on the circuit card. From the research I have done, this seems to be the power to the heat control. But nothing mentions TWO wires like I have. Anyways, I have disconnected these two wires from the RH terminal and reassembled the thermostat. I switch it to Cool and I can hear the AC come on. All good. But then I switch it to Heat and I can hear the darn thing fire up.

Is there something I am missing? Is what I am hearing just the fans coming on and the furnace is not getting power to heat up (like what I want to happen)?

Thanks in advance for any help!

bwire · 02-22-2009, 01:15 AM

It's a two wire doesn't matter you got it right even though you don't want to. Disconnect the thermostat wire that actuates the heat (:

icer22x · 02-22-2009, 01:04 PM

Quote:

Originally Posted by bwire

It's a two wire doesn't matter you got it right even though you don't want to. Disconnect the thermostat wire that actuates the heat (:

Cool man thanks.
So am I right about the fans coming on? If I turn the heat on with the wires disconnected from the terminal, do the fans still come on to circulate air? the only difference is - the air is not being heated?

**tinner105** · 03-01-2009, 04:45 PM

What are u trying to accomplish, are you trying to run a fan by its self?
Let me know what you want to do, and we can go from there.

Tony

**wrench97** · 03-01-2009, 05:00 PM

Is there more then 1 thermostat in the apartment?
The second wire may jump to the other thermostat.

Islandspud · 04-08-2009, 03:55 PM

Hey there Guys!......I am trying to find a way to disconnect the wires on my thermostat in my basement so that I will be able to hook back up again next fall...I can turn the switch on the furnace off but then i get no hot water or heat for the rest of the house.....just want to shut off the heat completely in the basement as the tenant in there now justs keeps jacking it to max when there is no need as there is windows that allow sun in to warm the room....it is more than comfortable without the heat!.....Please help me!.....:)
signed,
Keep me out of the poorhouse!

bwire · 04-08-2009, 08:03 PM

Have you ascertained if what you intend is legal?
You haven't given example of type furnace unit in use.

You may need a remote or wireless unit:

If you're handy or computer savvy this could work http://www.owfs.org/

or google wireless thermostat

02-22-2009, 12:38 AM	#1 (permalink)
icer22x Registered User Join Date: Feb 2009 Posts: 34 OS: Windows 7 32-bit	Thermostat wiring - need help Howdy guys, Hopefully someone here knows about thermostats. I moved into an apartment that has your typical everyday three-layered Mercury switch thermostat. (Fan control set to auto) I've done a little research on the wiring for this type thermostat, but some seem to vary. Anyway, I was wondering how to completely disconnect the heat so when I switch the thermostat to heat, nothing happens. I know I can just turn it off, but I am running some diagnostics. I have two red wires running out of the wall and connecting to the RH terminal on the circuit card. From the research I have done, this seems to be the power to the heat control. But nothing mentions TWO wires like I have. Anyways, I have disconnected these two wires from the RH terminal and reassembled the thermostat. I switch it to Cool and I can hear the AC come on. All good. But then I switch it to Heat and I can hear the darn thing fire up. Is there something I am missing? Is what I am hearing just the fans coming on and the furnace is not getting power to heat up (like what I want to happen)? Thanks in advance for any help! Last edited by icer22x; 02-22-2009 at 12:42 AM.

02-22-2009, 01:15 AM	#2 (permalink)
bwire Registered User Join Date: Nov 2007 Posts: 34 OS: XP / VISTA	Re: Thermostat wiring - need help It's a two wire doesn't matter you got it right even though you don't want to. Disconnect the thermostat wire that actuates the heat (:

03-01-2009, 04:45 PM	#4 (permalink)
tinner105 I helped the forums. Join Date: Jan 2008 Location: S Calif Posts: 174 OS: xp	Re: Thermostat wiring - need help What are u trying to accomplish, are you trying to run a fan by its self? Let me know what you want to do, and we can go from there. Tony

03-01-2009, 05:00 PM	#5 (permalink)
wrench97 Moderator, Hardware Team Join Date: May 2008 Location: S.E. Pennsylvania Posts: 18,339 OS: Win7	Re: Thermostat wiring - need help Is there more then 1 thermostat in the apartment? The second wire may jump to the other thermostat. __________________ Power Supply and Selection

04-08-2009, 03:55 PM	#6 (permalink)
Islandspud Registered User Join Date: Apr 2009 Posts: 1 OS: xp serv pak 3	Re: Thermostat wiring - need help Hey there Guys!......I am trying to find a way to disconnect the wires on my thermostat in my basement so that I will be able to hook back up again next fall...I can turn the switch on the furnace off but then i get no hot water or heat for the rest of the house.....just want to shut off the heat completely in the basement as the tenant in there now justs keeps jacking it to max when there is no need as there is windows that allow sun in to warm the room....it is more than comfortable without the heat!.....Please help me!.....:) signed, Keep me out of the poorhouse!

04-08-2009, 08:03 PM	#7 (permalink)
bwire Registered User Join Date: Nov 2007 Posts: 34 OS: XP / VISTA	Re: Thermostat wiring - need help Have you ascertained if what you intend is legal? You haven't given example of type furnace unit in use. You may need a remote or wireless unit: If you're handy or computer savvy this could work http://www.owfs.org/ or google wireless thermostat