Outdoor Wood Furnace Info

All-Purpose OWF Discussions => General Outdoor Furnace Discussion => Topic started by: sumptersmoker on October 26, 2012, 01:24:52 PM

Title: My central air is coming on ?
Post by: sumptersmoker on October 26, 2012, 01:24:52 PM
I used the wiring diagram from Central boiler for the wiring of the second thermostat.. I have a forced air furnace with central air. The compressor fan keeps coming on ... what did I do wrong ?
Title: Re: My central air is coming on ?
Post by: RSI on October 26, 2012, 01:30:08 PM
You need to take the wire off the G terminal on the original thermostat, not just add the new wire. Just splice it to the wire going to the new thermostat.
Title: Re: My central air is coming on ?
Post by: netwerx-r-us on October 26, 2012, 02:14:24 PM
would you be kind enough to share that diagram? , that actually was going to be one of my next posts to ask for that  , thank you sir
Title: Re: My central air is coming on ?
Post by: jbc on October 26, 2012, 02:37:38 PM
Lets call your old thermostat "thermostat A"...New one added to your system "thermostat B"

On thermostat A look for the G marked terminal, it should have your A/C wire hooked to it....REMOVE the wire going to the G terminal on Thermostat A.....

Next take the wire that is running from thermostat B (W marked one) and attach that to the "now" empty terminal G on thermostat A....wa'la your done---you will have the reverse the 2 wires in the spring for the A/c to work....there's other ways you can do this--but this is the easiest way.

Basically, the G terminal on a thermostat is the fan activation wire----when you do not unhook the A/C wire from thermostat A when you hook up thermostat B to it---the thermostat B wire backfeeds the A/C system and turns it on.

I'm a picture dunce on this forum..sorry
Title: Re: My central air is coming on ?
Post by: sumptersmoker on October 26, 2012, 02:38:16 PM
I just took the orginal thermostat off the wall and the compressor just stopped. Im not sure I understand what is going on but im not a HVAC guy ...
Title: Re: My central air is coming on ?
Post by: sumptersmoker on October 26, 2012, 02:41:18 PM
So did I just trash my compressor for the last 2 weeks my boiler was running ?
Title: Re: My central air is coming on ?
Post by: jbc on October 26, 2012, 02:46:40 PM
ok here is a nice posting also...still dont have a pictures for ya' but the internet should be your friend.

http://outdoorwoodfurnaceinfo.com/forum/index.php?topic=1348.0 (http://outdoorwoodfurnaceinfo.com/forum/index.php?topic=1348.0)
Title: Re: My central air is coming on ?
Post by: RSI on October 26, 2012, 04:44:44 PM
the G wire is for the fan. (Y is the compressor)
You need to remove the wire on thermostat A and leave it empty. Run the wire you took off the G terminal on thermostat A and run it to the W on thermostat B Then add a wire onto RH (leave original wire on this terminal too) of thermostat A and run it to RH on thermostat B.

Or you can just disconnect the wire from the Y terminal but then your AC won't work anymore.
Title: Re: My central air is coming on ?
Post by: sumptersmoker on October 26, 2012, 04:56:32 PM
the G wire is for the fan. (Y is the compressor)
You need to remove the wire on thermostat A and leave it empty. Run the wire you took off the G terminal on thermostat A and run it to the W on thermostat B Then add a wire onto RH (leave original wire on this terminal too) of thermostat A and run it to RH on thermostat B.

Or you can just disconnect the wire from the Y terminal but then your AC won't work anymore.

I just took the wire from G on the old stat and ran  it into the w on the new one.. do I still need to disconnect the yellow on the old one... ?
Title: Re: My central air is coming on ?
Post by: tanner on October 26, 2012, 07:39:44 PM
This is kinda what i had a ? about but im wona just use my old thermosat it has a off and cold and heat switch and when i turn the heat on my gas furnace kicks on i would like to un hook the gas furnace and make the fan come on with out my gas furnace trying to come on any ideas?
Title: Re: My central air is coming on ?
Post by: RSI on October 26, 2012, 08:12:13 PM
the G wire is for the fan. (Y is the compressor)
You need to remove the wire on thermostat A and leave it empty. Run the wire you took off the G terminal on thermostat A and run it to the W on thermostat B Then add a wire onto RH (leave original wire on this terminal too) of thermostat A and run it to RH on thermostat B.

Or you can just disconnect the wire from the Y terminal but then your AC won't work anymore.

I just took the wire from G on the old stat and ran  it into the w on the new one.. do I still need to disconnect the yellow on the old one... ?
You don't have any wires on the G terminal on the original thermostat and the compressor is still coming on?
Title: Re: My central air is coming on ?
Post by: RSI on October 26, 2012, 08:13:31 PM
This is kinda what i had a ? about but im wona just use my old thermosat it has a off and cold and heat switch and when i turn the heat on my gas furnace kicks on i would like to un hook the gas furnace and make the fan come on with out my gas furnace trying to come on any ideas?
If you want to just completely disable the gas and use the existing thermostat, all you have to do is take the W wire off and move the wire from the G terminal to the W.
Title: Re: My central air is coming on ?
Post by: sumptersmoker on October 27, 2012, 04:15:39 AM
I think I got it ... I just have to switch the wires back for cool air... Now do you think I did any harm to my compressor ?
Title: Re: My central air is coming on ?
Post by: Jack72 on October 27, 2012, 05:16:44 AM
You need to take the wire off the G terminal on the original thermostat, not just add the new wire. Just splice it to the wire going to the new thermostat.

Hello RSI.   
I've been wondering about this      This may be a stupid question.  But I've always just shut the breaker off to the ac   And just turn back on in the summer is this a bad thing or just a easy way out      I haven't ran mine OWB in the summer yet so it's not a issue for me right now     Thanks for any input you can give


Thanks Jack. 
Title: Re: My central air is coming on ?
Post by: lasor1 on October 27, 2012, 06:36:31 AM
You can put a diode on wire going to tstat to keep power from back feeding old tstat that would work too! Without changing anything but I like the relay deal it will keep them isolated from each other and I will probably change mine to relay in future but no problems here with diode inline
Title: Re: My central air is coming on ?
Post by: sumptersmoker on October 27, 2012, 07:08:49 AM
do you think I did any harm to my compressor
Title: Re: My central air is coming on ?
Post by: RSI on October 27, 2012, 08:17:36 AM
I think I got it ... I just have to switch the wires back for cool air... Now do you think I did any harm to my compressor ?
I am still confused here what is exactly happening. If you leave the G terminal empty on the main thermostat you should be able to leave the Y connected and the compressor should not run.

I don't know if it would have damaged the compressor. I don't see why it would have though, was probably just wasting a lot of power and wood.
Title: Re: My central air is coming on ?
Post by: yoderheating on October 27, 2012, 09:08:54 AM
If you are using a two thermostat system the only way for the compressor to come on is if its back feeding power to the old thermostat. A simple relay will fix that and you will not have to change wires around.
Title: Re: My central air is coming on ?
Post by: sumptersmoker on October 29, 2012, 06:03:03 AM
If someone has a diagram on the simple relay set up Im sure I could get the job done...lol Im just not a elect.

thanks for everyones help
Title: Re: My central air is coming on ?
Post by: SperleFarms on October 29, 2012, 08:57:37 AM
Lets call your old thermostat "thermostat A"...New one added to your system "thermostat B"

On thermostat A look for the G marked terminal, it should have your A/C wire hooked to it....REMOVE the wire going to the G terminal on Thermostat A.....

Next take the wire that is running from thermostat B (W marked one) and attach that to the "now" empty terminal G on thermostat A....wa'la your done---you will have the reverse the 2 wires in the spring for the A/c to work....there's other ways you can do this--but this is the easiest way.

Basically, the G terminal on a thermostat is the fan activation wire----when you do not unhook the A/C wire from thermostat A when you hook up thermostat B to it---the thermostat B wire backfeeds the A/C system and turns it on.

I'm a picture dunce on this forum..sorry

Why not just trip the main A/C breaker for the winter months and leave the thermostat wiring alone?  This way the system operates as it should, and there’s no need to flip flop thermostat wires every spring and fall.   :o
Title: Re: My central air is coming on ?
Post by: RSI on October 29, 2012, 09:13:55 AM
If someone has a diagram on the simple relay set up Im sure I could get the job done...lol Im just not a elect.

thanks for everyones help
I just drew up a really crude diagram. Did you try is like this?
Title: Re: My central air is coming on ?
Post by: RSI on October 29, 2012, 09:23:59 AM
Lets call your old thermostat "thermostat A"...New one added to your system "thermostat B"

On thermostat A look for the G marked terminal, it should have your A/C wire hooked to it....REMOVE the wire going to the G terminal on Thermostat A.....

Next take the wire that is running from thermostat B (W marked one) and attach that to the "now" empty terminal G on thermostat A....wa'la your done---you will have the reverse the 2 wires in the spring for the A/c to work....there's other ways you can do this--but this is the easiest way.

Basically, the G terminal on a thermostat is the fan activation wire----when you do not unhook the A/C wire from thermostat A when you hook up thermostat B to it---the thermostat B wire backfeeds the A/C system and turns it on.

I'm a picture dunce on this forum..sorry

Why not just trip the main A/C breaker for the winter months and leave the thermostat wiring alone?  This way the system operates as it should, and there’s no need to flip flop thermostat wires every spring and fall.   :o
If you just leave the G terminal on the original thermostat empty then you don't need to do anything, not even turn off breaker. If you do want to run the fan manually you can just turn up the temp on the second thermostat.
Title: Re: My central air is coming on ?
Post by: Scott7m on October 29, 2012, 10:07:00 AM
Can't we just place a diode in the yellow wire going to the outdoor unit? 

I always flip breakers on ones that backrest but have one now where customer has breakers all under his home
Title: Re: My central air is coming on ?
Post by: RSI on October 29, 2012, 10:22:10 AM
If you use a diode it will convert the power to DC and may or may not damage something on the furnace controls.

Anyway, if you do the diode, it would need to be on the G terminal of the original thermostat and go to the two spliced together wires. All that would do is allow you to keep the fan switch operational.
Title: Re: My central air is coming on ?
Post by: Scott7m on October 29, 2012, 10:36:51 AM
If you use a diode it will convert the power to DC and may or may not damage something on the furnace controls.

Anyway, if you do the diode, it would need to be on the G terminal of the original thermostat and go to the two spliced together wires. All that would do is allow you to keep the fan switch operational.


 your the electrical Guru, that stuff confuses me.  Like for example right now this customer can't turn his breaker off, wants his exsisting stat to work as it always has.  But the outdoor unit comes on with the blower, where would I put this relay?  What wire? 

I have seen this happen before but it was always convieinet for the customer to simply turn off the outside unit.  That's not the case this time
Title: Re: My central air is coming on ?
Post by: RSI on October 29, 2012, 10:51:34 AM
If you use a diode it will convert the power to DC and may or may not damage something on the furnace controls.

Anyway, if you do the diode, it would need to be on the G terminal of the original thermostat and go to the two spliced together wires. All that would do is allow you to keep the fan switch operational.


 your the electrical Guru, that stuff confuses me.  Like for example right now this customer can't turn his breaker off, wants his exsisting stat to work as it always has.  But the outdoor unit comes on with the blower, where would I put this relay?  What wire? 

I have seen this happen before but it was always convieinet for the customer to simply turn off the outside unit.  That's not the case this time

Did you wire it like the above pic?
Title: Re: My central air is coming on ?
Post by: RSI on October 29, 2012, 11:29:13 AM
If someone has a diagram on the simple relay set up Im sure I could get the job done...lol Im just not a elect.

thanks for everyones help
I just drew up a really crude diagram. Did you try is like this?

I forgot to mention before that the C wire to the new thermostat is only needed if the new thermostat doesn't use batteries.
Title: Re: My central air is coming on ?
Post by: Scott7m on October 29, 2012, 02:51:30 PM
No, w went to the g screw, didn't splice em together
Title: Re: My central air is coming on ?
Post by: RSI on October 29, 2012, 03:34:50 PM
If you just remove them and splice together the compressor shouldn't run when it isn't supposed to.
Title: Re: My central air is coming on ?
Post by: Scott7m on October 29, 2012, 03:45:27 PM
If you just remove them and splice together the compressor shouldn't run when it isn't supposed to.

What's the downside of doing this?

Does old stat still work the same as always
Title: Re: My central air is coming on ?
Post by: RSI on October 29, 2012, 04:01:44 PM
The fan switch on the old thermostat won't work. (I consider this a good thing because if it gets turned on it will overheat the house) There are a few furnaces and heat pumps that do require the G connection so I would turn on the heat and make sure the fan kicks on before leaving it that way. I have never seen one that did require it though but heatpumps are very rare around here.
Title: Re: My central air is coming on ?
Post by: Scott7m on October 29, 2012, 05:05:05 PM
The fan switch on the old thermostat won't work. (I consider this a good thing because if it gets turned on it will overheat the house) There are a few furnaces and heat pumps that do require the G connection so I would turn on the heat and make sure the fan kicks on before leaving it that way. I have never seen one that did require it though but heatpumps are very rare around here.

This place is full of heat pumps, I'm gonna have to do a relay to cover myself I'd think
Title: Re: My central air is coming on ?
Post by: RSI on October 29, 2012, 05:24:16 PM
Just disconnect the g terminal an turn the heat on and if the blower starts like normal then you are fine.
Title: Re: My central air is coming on ?
Post by: Scott7m on October 29, 2012, 05:30:27 PM
Just disconnect the g terminal an turn the heat on and if the blower starts like normal then you are fine.

So if the customer wants to use the heat pump, will his old stat still turn the fan on as normal
Title: Re: My central air is coming on ?
Post by: RSI on October 29, 2012, 05:33:32 PM
that is what you need to test. First thing is just remove the g wire and then turn on the heat pump and see if it works properly and the blower runs. Most will but some may require the G hooked up.
Title: Re: My central air is coming on ?
Post by: jerkash on October 29, 2012, 05:40:23 PM
Hey SumpterSmoker - Are you confused yet??
Don't worry, these guys will get you straightened out.  They have helped me a lot!
Title: Re: My central air is coming on ?
Post by: Scott7m on October 29, 2012, 05:51:12 PM
that is what you need to test. First thing is just remove the g wire and then turn on the heat pump and see if it works properly and the blower runs. Most will but some may require the G hooked up.

Ok makes sense, but if I'm 90 minutes from home and that don't work.  Then what?  I'll need to install a relay somewhere

I wasn't aware the diodes changed the current
Title: Re: My central air is coming on ?
Post by: RSI on October 29, 2012, 06:48:03 PM
Well,if I was going to use a relay, I would get a SPDT with 24v ac coil.
I would cut the wire going to the G on the original thermostat and run the furnace end to the common contact connection and the thermostat end to the NC connection. Then run a wire from the NO connection to the RH.

Then run one side of the coil to the C on the thermostat.

Now for the new thermostat run a wire from the W to the other side of the coil. You will also need a jumper wire between the two thermostats on the RH terminals (and the C terminals if it is a digital thermostat that doesn't use batteries)
Title: Re: My central air is coming on ?
Post by: Scott7m on October 29, 2012, 07:01:53 PM
Good grief lol

The ones I use do have batteries..

I thought it would be as simple as splicing into the yellow wire so the signal couldn't back feed and outdoor unit wouldn't come on
Title: Re: My central air is coming on ?
Post by: RSI on October 29, 2012, 07:09:15 PM
Lol it isnt really that complicated. You cant have the relay cut the connection to the y if it is a heat pump. If you do the heatpump wont work unless you shut off the owb thermostat.

If i get time i will try drawing up a diagram.
Title: Re: My central air is coming on ?
Post by: yoderheating on October 29, 2012, 07:38:10 PM
 I use relays on all my jobs, its the only way to be certain you make heat pumps do exactly what you want them to do. The other day I used 4 relays, a zone valve and a 24v ranco to make a unit work properly. As a wise man once told me, you can run the world off 24v if you have enough relays.
 SumpterSmoker, hopefully I can explain how to hook your system up with a relay. I use http://www.google.com/imgres?q=white+rodgers+90-293q+wiring+diagram&hl=en&sa=X&biw=1024&bih=613&tbm=isch&prmd=imvns&tbnid=r2DzaH9wuEWaPM:&imgrefurl=http://www.johnstonesupply.com/storefront/hvacr-parts/controls/electrical-controls/hvacr-parts/controls/electrical-controls/relays/switching-relays//prodL36-905.html&docid=PkH2qVJr1spNSM&imgurl=http://www.johnstonesupply.com/storefront/renderImage.image%253FimageName%253DWEB/10010/L36-905cl.jpg%2526width%253D407%2526height%253D268%2526padding%253D0&w=407&h=268&ei=Ni6PULGHE4zC0AHfmoHwCw&zoom=1&iact=hc&vpx=101&vpy=166&dur=550&hovh=140&hovw=184&tx=125&ty=101&sig=112355657484556333735&page=1&tbnh=139&tbnw=182&start=0&ndsp=18&ved=1t:429,i:71 (http://www.google.com/imgres?q=white+rodgers+90-293q+wiring+diagram&hl=en&sa=X&biw=1024&bih=613&tbm=isch&prmd=imvns&tbnid=r2DzaH9wuEWaPM:&imgrefurl=http://www.johnstonesupply.com/storefront/hvacr-parts/controls/electrical-controls/hvacr-parts/controls/electrical-controls/relays/switching-relays//prodL36-905.html&docid=PkH2qVJr1spNSM&imgurl=http://www.johnstonesupply.com/storefront/renderImage.image%253FimageName%253DWEB/10010/L36-905cl.jpg%2526width%253D407%2526height%253D268%2526padding%253D0&w=407&h=268&ei=Ni6PULGHE4zC0AHfmoHwCw&zoom=1&iact=hc&vpx=101&vpy=166&dur=550&hovh=140&hovw=184&tx=125&ty=101&sig=112355657484556333735&page=1&tbnh=139&tbnw=182&start=0&ndsp=18&ved=1t:429,i:71) a white rodgers 90-293q. Hopefully this link works.
 The new thermostat should be linked with the old c to c and r to r, this powers the new thermostat. I normally install the relay in the blower unit. Run c from the unit to the #3 on the relay. Run a wire from the w on the new thermostat to both the #1 and #2 on the relay. Splice the wire from g on the old thermostat and hook the thermostat side to #5 and the furnace side to #4.
 If you want to understand how it works I can explain further, it is very simple.
Title: Re: My central air is coming on ?
Post by: Scott7m on October 29, 2012, 07:44:45 PM
Yoder do you run a whole new line set down to the blower too?
Title: Re: My central air is coming on ?
Post by: yoderheating on October 29, 2012, 07:49:47 PM
If you are asking if I run a new thermostat wire then the answer is normally no. 95% of the time not all the wires are used in the existing wire and I just use one of those.
Title: Re: My central air is coming on ?
Post by: RSI on October 29, 2012, 09:14:01 PM
I use relays on all my jobs, its the only way to be certain you make heat pumps do exactly what you want them to do. The other day I used 4 relays, a zone valve and a 24v ranco to make a unit work properly. As a wise man once told me, you can run the world off 24v if you have enough relays.
 SumpterSmoker, hopefully I can explain how to hook your system up with a relay. I use http://www.google.com/imgres?q=white+rodgers+90-293q+wiring+diagram&hl=en&sa=X&biw=1024&bih=613&tbm=isch&prmd=imvns&tbnid=r2DzaH9wuEWaPM:&imgrefurl=http://www.johnstonesupply.com/storefront/hvacr-parts/controls/electrical-controls/hvacr-parts/controls/electrical-controls/relays/switching-relays//prodL36-905.html&docid=PkH2qVJr1spNSM&imgurl=http://www.johnstonesupply.com/storefront/renderImage.image%253FimageName%253DWEB/10010/L36-905cl.jpg%2526width%253D407%2526height%253D268%2526padding%253D0&w=407&h=268&ei=Ni6PULGHE4zC0AHfmoHwCw&zoom=1&iact=hc&vpx=101&vpy=166&dur=550&hovh=140&hovw=184&tx=125&ty=101&sig=112355657484556333735&page=1&tbnh=139&tbnw=182&start=0&ndsp=18&ved=1t:429,i:71 (http://www.google.com/imgres?q=white+rodgers+90-293q+wiring+diagram&hl=en&sa=X&biw=1024&bih=613&tbm=isch&prmd=imvns&tbnid=r2DzaH9wuEWaPM:&imgrefurl=http://www.johnstonesupply.com/storefront/hvacr-parts/controls/electrical-controls/hvacr-parts/controls/electrical-controls/relays/switching-relays//prodL36-905.html&docid=PkH2qVJr1spNSM&imgurl=http://www.johnstonesupply.com/storefront/renderImage.image%253FimageName%253DWEB/10010/L36-905cl.jpg%2526width%253D407%2526height%253D268%2526padding%253D0&w=407&h=268&ei=Ni6PULGHE4zC0AHfmoHwCw&zoom=1&iact=hc&vpx=101&vpy=166&dur=550&hovh=140&hovw=184&tx=125&ty=101&sig=112355657484556333735&page=1&tbnh=139&tbnw=182&start=0&ndsp=18&ved=1t:429,i:71) a white rodgers 90-293q. Hopefully this link works.
 The new thermostat should be linked with the old c to c and r to r, this powers the new thermostat. I normally install the relay in the blower unit. Run c from the unit to the #3 on the relay. Run a wire from the w on the new thermostat to both the #1 and #2 on the relay. Splice the wire from g on the old thermostat and hook the thermostat side to #5 and the furnace side to #4.
 If you want to understand how it works I can explain further, it is very simple.

Just curious, why do you run the W from the new thermostat to the #2 instead of the R? It will work the same, just wondering if there is a reason I am missing.
Title: Re: My central air is coming on ?
Post by: yoderheating on October 29, 2012, 09:50:21 PM
 You can do it either way, I just do it that way because its one less wire to hook up. The only time you need power on that terminal is when the relay is activated so I just run a jumper from #1 to #2 but you could get power for #2 from R. I have had a relay stick before and I guess the advantage there would be there would be no power on #2 if it did but you still wouldn't be able to activate the fan from the original thermostat if that happened.
Title: Re: My central air is coming on ?
Post by: RSI on October 29, 2012, 09:56:04 PM
That makes sense.

How often do you run into a system that does need the G wire to operate though? I bet most of the time just removing the wires from the G and splicing together would work fine.
Title: Re: My central air is coming on ?
Post by: yoderheating on October 29, 2012, 10:06:52 PM
95% of what I do is heat pumps so many do need a relay. When I do a gas or oil furnace I often do something different depending on the situation. I should mention doing this to a variable speed fan will only get you low speed.
Title: Re: My central air is coming on ?
Post by: RSI on October 29, 2012, 10:13:43 PM
Wow, never realized it was that much different in other parts of the country. Almost all LP or fuel oil forced air furnaces around here. Almost everything else is gas or oil boilers but they are way less common.
Title: Re: My central air is coming on ?
Post by: yoderheating on October 29, 2012, 10:20:58 PM
 I'm in Virginia where are you located?
Title: Re: My central air is coming on ?
Post by: RSI on October 29, 2012, 10:21:24 PM
Wisconsin
Title: Re: My central air is coming on ?
Post by: yoderheating on October 29, 2012, 10:26:21 PM
 Never mind, I see you are in Wisconsin. I'm sure you have much harsher winters. I most likely see about 95% heat pumps/electric furnaces, 2% gas furnaces, 2% oil furnaces and 1% oil or gas boilers. New homes around here are almost 100% heat pumps. I think this year I have only seen one boiler and one oil furnace so far, everything else has been heat pump.
Title: Re: My central air is coming on ?
Post by: Scott7m on October 29, 2012, 10:49:57 PM
Nearly the same in my area to, folks fail to realize it's to cold in this area for heat pumps and wind up paying out the wazoo