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Posted: 12/4/2016 7:40:55 PM EDT
Guys I need some help. My objective is to replace a dual thermostat setup with 1 Nest thermostat.
My system uses an outdoor wood boiler for primary heat, controlled by the top thermostat. The bottom tstat controls the propane furnace for backup heat, and also the central AC. A few of the wires are self explanatory, but I'm stumped by the fact that I see 3 red wires for the R and 2 wires going into G. First person to tell me the correct wiring gets a Pmag on me. If you give incorrect instructions you owe me a Pmag (jk). Here's the current setup, including pics of the wiring.  Attached File Attached File Attached FileHere's the available connections on the Nest.  Attached File |
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Posted: 12/4/2016 7:42:51 PM EDT
[#1]
The arfcom HVAC guys have come through for me multiple times.
Best of luck OP. |
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Posted: 12/4/2016 7:46:49 PM EDT
[#2]
Quote HistoryQuoted:
The arfcom HVAC guys have come through for me multiple times. Best of luck OP. Thank you. I'm sure this is child's play for a pro. |
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Posted: 12/4/2016 7:49:08 PM EDT
[#3]
I can't help you on this one but you're gonna love that T-stat
when you get it working. |
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Posted: 12/4/2016 8:02:07 PM EDT
[#4]
Are you running a heat pump or straight AC?
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Posted: 12/4/2016 8:07:08 PM EDT
[#5]
Quote HistoryQuoted:
Are you running a heat pump or straight AC? No heat pump. Have a normal AC system. |
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Posted: 12/4/2016 8:07:23 PM EDT
[#6]
This is a little different, do you know if the same transformer powers both stats?
So your wood burner is 1st stage heat. Heat pump is second stage back up, and propane furnace is third stage backup? |
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Posted: 12/4/2016 8:14:04 PM EDT
[#7]
Quote HistoryQuoted:
This is a little different, do you know if the same transformer powers both stats? So your wood burner is 1st stage heat. Heat pump is second stage back up, and propane furnace is third stage backup? I don't know about that the transformer. How could I find out? Wood is 1st stage if I have the top thermostat on. Propane is backup. I don't have a heat pump. |
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Posted: 12/4/2016 8:17:46 PM EDT
[#8]
Quote HistoryQuoted:
I don't know about that the transformer. How could I find out? Wood is 1st stage if I have the top thermostat on. Propane is backup. I don't have a heat pump. This may not be possible with one thermostat without quite a bit of wiring outside in the units. The thermostat wire from the top stat, does the red wire come from the "R" thermal all on the bottom stat? |
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Posted: 12/4/2016 8:20:14 PM EDT
[#9]
Looks like a shit show OP, hire a local professional.
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Posted: 12/4/2016 8:25:04 PM EDT
[#10]
Can we get a picture of the wires somewhat untangled and pulled out from the wall a bit? G is for fan output, seems maybe you have some wires from each piece of equipment to turn on your indoor fan motor.
Edit: the wood boiler has a coil for hot water at the furnace or are you using hydronic floor heat? |
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Posted: 12/4/2016 8:28:25 PM EDT
[#11]
If all three "R"s are fed by the same transformer, no problem. If the wood burner has a separate transformer from the one controlling the gas heat, then you may have to do some reworking. I wouldn't be too worried about the two wires on "G", the second one is probably just something to do with the wood burner.
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Posted: 12/4/2016 8:35:00 PM EDT
[#12]
Quote HistoryQuoted:
Can we get a picture of the wires somewhat untangled and pulled out from the wall a bit? G is for fan output, seems maybe you have some wires from each piece of equipment to turn on your indoor fan motor. Edit: the wood boiler has a coil for hot water at the furnace or are you using hydronic floor heat? Small update. The red and white wires on the top thermostat are simply jumped to the bottom thermostat. I believe the white wire goes from G straight to the top tstat. No using floor heat. The hot water/antifreeze circulates from the burner to the hot water tank to the furnace. I'll try to get a pic of the wires pulled out soon. |
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Posted: 12/4/2016 8:36:22 PM EDT
[#13]
Quote HistoryQuoted:
If all three "R"s are fed by the same transformer, no problem. If the wood burner has a separate transformer from the one controlling the gas heat, then you may have to do some reworking. I wouldn't be too worried about the two wires on "G", the second one is probably just something to do with the wood burner. |
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Posted: 12/4/2016 8:41:01 PM EDT
[#14]
So all the top t'stat is doing is controlling the indoor fan while the wood burner is running. Just to clarify, how does the wood burner turn on?
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Posted: 12/4/2016 8:43:07 PM EDT
[#15]
Ok then get rid of the top stat and wiring. Wire the same as bottom stat is laid out. Add jumper from w1 to g for the wood burner. So when stage 1 heat calls fan only turns on. Have the other wire from W on the bottom stat to w2. Everything else stays the same, remember you black wire goes to C.
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Posted: 12/4/2016 8:44:41 PM EDT
[#16]
Doesn't the nest walk you through with a "wizard" where it tells you what wires go where, or if it is even possible? When I installed mine I remember going through their website step by step to see if it would work with my system.
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Posted: 12/4/2016 8:47:52 PM EDT
[#17]
Quote HistoryQuoted:
So all the top t'stat is doing is controlling the indoor fan while the wood burner is running. Just to clarify, how does the wood burner turn on? It's one of these: 
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Posted: 12/4/2016 8:50:26 PM EDT
[#18]
Quote HistoryQuoted:
Ok then get rid of the top stat and wiring. Wire the same as bottom stat is laid out. Add jumper from w1 to g for the wood burner. So when stage 1 heat calls fan only turns on. Have the other wire from W on the bottom stat to w2. Everything else stays the same, remember you black wire goes to C. This right here, don't really understand the second tstat unless the original ones were cheap and did. It have enough programmable days and segments to allow the single stat to control everything. |
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Posted: 12/4/2016 8:52:56 PM EDT
[#19]
Quote HistoryQuoted:
So all the top t'stat is doing is controlling the indoor fan while the wood burner is running. Just to clarify, how does the wood burner turn on? That would be my guess also. The top tstat is using the red and white wires to run the fan on the unit only. It would be set at the temperature you want the house to be normally. The bottom tstat is wired normally, and would be set at a somewhat lower temperature to be used as a backup, so that the heat doesn't go to low in case the wood burner runs out of fuel. Not quite sure how you are going to run that same setup on the nest. ETA: From looking at the nest documentation, the white wire from your propane backup would go on the W2/Aux terminal, much like a heat pump installation. The Green wire would have to be jumpered from W1 to G. that way when your tstat calls for heat, the fan would run. You would also have to go into the Pro setup to select the options for backup heat. Pro Setup |
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Posted: 12/4/2016 8:53:15 PM EDT
[#20]
Quote HistoryQuoted:
Ok then get rid of the top stat and wiring. Wire the same as bottom stat is laid out. Add jumper from w1 to g for the wood burner. So when stage 1 heat calls fan only turns on. Have the other wire from W on the bottom stat to w2. Everything else stays the same, remember you black wire goes to C. I don't think I can use a jumper with the Nest though can I? |
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Posted: 12/4/2016 8:53:20 PM EDT
[#21]
I told my dad about that thermostat. He went off about how Google owns nest and who knows what data they're collecting from it and tracking.
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Posted: 12/4/2016 8:55:54 PM EDT
[#22]
Quote HistoryQuoted:
I don't think I can use a jumper with the Nest though can I? If you can't fit both the g wire and your jumper from w1 in the hole you will have to pigtail with a wire nut. I'm sure you can get them both in. |
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Posted: 12/4/2016 8:55:58 PM EDT
[#23]
I sent a picture of the wires to my old thermostat to NEST. They gave me step by step directions through and email with pictures.
If you take a picture and send it to them they will give you the correct wiring. Does the PMAG I get come loaded or what? |
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Posted: 12/4/2016 8:56:21 PM EDT
[#24]
Quote HistoryQuoted:
Turns out the R on the top tstat is just a jumper form the bottom. Same goes for that white wire, it goes from G on bottom tstat to W on top stat. The boiler probably just maintains temperature, constantly pumping water through the hot water coil in your furnace. The second thermostat just turns the fan on when heat is needed. Even with the fan off, you would still get some heat probably out of the return vents. Does your house ever overheat? |
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Posted: 12/4/2016 8:56:25 PM EDT
[#25]
Quote HistoryQuoted:
That would be my guess also. The top tstat is using the red and white wires to run the fan on the unit only. It would be set at the temperature you want the house to be normally. The bottom tstat is wired normally, and would be set at a somewhat lower temperature to be used as a backup, so that the heat doesn't go to low in case the wood burner runs out of fuel. Not quite sure how you are going to run that same setup on the nest. |
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Posted: 12/4/2016 8:57:53 PM EDT
[#26]
Quote HistoryQuoted:
I sent a picture of the wires to my old thermostat to NEST. They gave me step by step directions through and email with pictures. If you take a picture and send it to them they will give you the correct wiring. Does the PMAG I get come loaded or what? |
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Posted: 12/4/2016 8:58:09 PM EDT
[#27]
Okay, this is not standard wiring, but I think you can get what you already have with the two t'stats by: 1. Get rid of the 2 conductor wire going into the top t'stat, it is no longer needed. 2. Take the one red wire remaining and hook it to Rc, and you need to hook a jumper between Rc and Rh, check the instruction manual, the Nest may have one built in. 3. Hook the green to "G", and run a jumper wire between "G" and "W1". W1 will now turn on the fan when the 1st stage of heat is calling.
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Posted: 12/4/2016 9:03:44 PM EDT
[#28]
Quote HistoryQuoted:
You described the system exactly, but in reverse. The top tstat is set to the emergency temp of 59*. If the house hits that temp the propane furnace kicks on. When using wood, the bottom tstat is used for all temp settings and controls when the fan kicks on. Now this confuses me. If the top t'stat is truly hooked to "R" and "G" in the bottom t'stat, all it could do is turn on the fan when the temperature drops. |
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Posted: 12/4/2016 9:10:15 PM EDT
[#29]
Quote HistoryQuoted:
Now this confuses me. If the top t'stat is truly hooked to "R" and "G" in the bottom t'stat, all it could do is turn on the fan when the temperature drops.  Attached File |
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Posted: 12/4/2016 9:15:13 PM EDT
[#30]
Quote HistoryQuoted:
Here's a pic showing the current settings. http://AR15.Com/media/mediaFiles/50102/File-000--1--100033.JPG In this instance OP you would be using propane and the hot water loop each time you called for heat. You would need to set the bottom stat to your emergency setting of 59 and the top stat to 70 to run the heat off the loop. |
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Posted: 12/4/2016 9:26:10 PM EDT
[#31]
So u have three stages of heat.
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Posted: 12/4/2016 9:27:13 PM EDT
[#32]
Okay, I think I see now what's going on. The white wire from the top t'stat is hooked to "W", not "G", in the bottom t'stat. I need to rethink this this.
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Posted: 12/4/2016 9:33:29 PM EDT
[#33]
Hook the nest up to the t stat with the most wire and just hook the white wire from the 2 wire t stat to w2
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Posted: 12/4/2016 9:39:09 PM EDT
[#34]
...Take it back to the store and exchange it for something else.
Nest is owned by Google and Google is fucking evil. Don't invite Google into your house. |
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Posted: 12/4/2016 9:40:34 PM EDT
[#35]
Quote HistoryQuoted:
In this instance OP you would be using propane and the hot water loop each time you called for heat. You would need to set the bottom stat to your emergency setting of 59 and the top stat to 70 to run the heat off the loop. |
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Posted: 12/4/2016 9:41:19 PM EDT
[#36]
Quote HistoryQuoted:
Hook the nest up to the t stat with the most wire and just hook the white wire from the 2 wire t stat to w2 Quote HistoryQuoted:
Hook the nest up to the t stat with the most wire and just hook the white wire from the 2 wire t stat to w2 The 2nd and 3rd generation Nest Learning Thermostats support up to three stages of heating and two stages of cooling for conventional systems, and two stages of heating and cooling with auxiliary heat for heat pumps. The Nest Thermostat uses its algorithms to estimate how long it will take to reach the target temperature with its Time-to-Temperature feature. It uses Time-to-Temperature to help decide when to use stages two and three of your heating and cooling system. If your first stage of heating or cooling won’t reach your desired temperature in a reasonable amount of time, the Nest Thermostat will activate additional stages of heating or cooling to ensure that you’re kept comfortable. Taken from this link Nest support article |
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Posted: 12/4/2016 9:44:31 PM EDT
[#37]
You have been given the correct answer already.
Hook up the wires like they are on the bottom thermostat and eliminate the two going to the upper thermostat with these two changes; W on the existing thermostat goes to W2 on the nest. Add a jumper on the nest from W1 to G, there will be two wires on G and one on W1. When programming the the Nest do it as two stage heat and one stage cool. And the one guy is right, you had your thermostats set wrong. You were turning the heat on with propane and blowing thru the hot water coil using both sources of heat. Should have had the "normal" set point on top and the emergency set point on the bottom. I have done Nests and hot water boilers on forced air furnaces before. Edit due to more bad info being given; W1 must be jumped to G to use the boiler heat as first stage, do not put the wire from the upper stat on W2!! |
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Posted: 12/4/2016 9:48:56 PM EDT
[#38]
If you are sure about the top t'stat controlling the fan, the following will probably will work for you, although I don't know if you can adjust the temperature differential between W1 and W2 on the Nest.
Quote HistoryQuoted:
Okay, this is not standard wiring, but I think you can get what you already have with the two t'stats by: 1. Get rid of the 2 conductor wire going into the top t'stat, it is no longer needed. 2. Take the one red wire remaining and hook it to Rc, and you need to hook a jumper between Rc and Rh, check the instruction manual, the Nest may have one built in. 3. Hook the green to "G", and run a jumper wire between "G" and "W1". W1 will now turn on the fan when the 1st stage of heat is calling. eta:the white wire on "W" on the old bottom t'stat goes to "W2" on the Nest. |
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Posted: 12/4/2016 9:57:23 PM EDT
[#39]
Quote HistoryQuoted:
OMFG! You're absolutely correct, I just tested it. The top tstat is controlling the fan, the bottom one is controlling the propane. Wow you just saved my ass. Quote HistoryQuoted:
Quoted:
In this instance OP you would be using propane and the hot water loop each time you called for heat. You would need to set the bottom stat to your emergency setting of 59 and the top stat to 70 to run the heat off the loop. Glad to help OP  . Remember when programming the Nest to select two stages of heat. The only time your propane should fire is if the thermostat is having a hard time ( too long) to get to temp. You may be able to set a temp deferential between both stages of heat to help with the thermostat calling for second stage. I would set it between 4-6 degrees. Just following my original post on wiring and you shouldn't have a issue. No need to ship a pmag FHRC stocked me up for life. Thanks for your service.
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Posted: 12/4/2016 10:00:34 PM EDT
[#40]
Quote HistoryQuoted:
Glad to help OP . Remember when programming the Nest to select two stages of heat. The only time your propane should fire is if the thermostat is having a hard time ( too long) to get to temp. You may be able to set a temp deferential between both stages of heat to help with the thermostat calling for second stage. I would set it between 4-6 degrees. Just following my original post on wiring and you shouldn't have a issue. No need to ship a pmag FHRC stocked me up for life. Thanks for your service.
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Posted: 12/4/2016 11:28:12 PM EDT
[#41]
RESULTS
I was unable to put in a jumper from G to W1 because only 1 wire fits in each hole. What I did instead was install the green wire directly into W1. Everything works perfectly, primary uses the fan/wood and secondary uses propane. Now - I assume this will not be ideal when it's time to use the AC? Do I need a pro to correct my bubba fix? |
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Posted: 12/5/2016 12:28:57 AM EDT
[#42]
It will not work for air conditioning like that. If you have to, wire nut the G wires together. Did you put w1 and w2 as I said? You were wasting a shitload of money.
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Posted: 12/5/2016 11:59:37 AM EDT
[#43]
A short pigtail hooked to G, another short pigtail hooked to W1, the free ends of these two wirenutted to the green wire. I like the Ideal orange wirenuts for control wiring, whatever works for you.
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Posted: 12/5/2016 12:09:01 PM EDT
[#44]
You wouldn't need the jumper if you set the thermostat up as heat pump with gas backup with nothing hooked up to the reversing valve terminal. In that setup first stage heat would energize only the fan. Second would energize the gas backup. Just kick the breaker on the ac in wintertime.
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Posted: 12/5/2016 12:12:26 PM EDT
[#45]
Have you considered labeling that? For heat and what temp to set if you're not home when something happens?
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Posted: 12/5/2016 3:36:27 PM EDT
[#46]
Discard 2wires from top thermostat. Red wire goes to R. Yellow goes to Y, Black goes to C, Green goes to G, White goes to *. Set system to electric heat this will cause fan to
cycle on with a call for heat. White wire is heating wire for propane heat and this will be your emergency/auxiliary heat set to 59 degrees. Not programmable. Etc. Follow all other set up procedures per nest. Test system. |
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Posted: 12/5/2016 5:37:20 PM EDT
[#47]
Quote HistoryQuoted:
Discard 2wires from top thermostat. Red wire goes to R. Yellow goes to Y, Black goes to C, Green goes to G, White goes to *. Set system to electric heat this will cause fan to cycle on with a call for heat. White wire is heating wire for propane heat and this will be your emergency/auxiliary heat set to 59 degrees. Not programmable. Etc. Follow all other set up procedures per nest. Test system. |
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Posted: 12/5/2016 6:46:15 PM EDT
[#48]
Tag, this is relevant to my interests
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Posted: 12/9/2016 3:02:52 PM EDT
[#49]
Quote HistoryQuoted:
Discard 2wires from top thermostat. Red wire goes to R. Yellow goes to Y, Black goes to C, Green goes to G, White goes to *. Set system to electric heat this will cause fan to cycle on with a call for heat. White wire is heating wire for propane heat and this will be your emergency/auxiliary heat set to 59 degrees. Not programmable. Etc. Follow all other set up procedures per nest. Test system. The configuration previously mentioned of green to W1 and propane to W2 works like a charm. Before cooling season arrives I'll figure out how to put a jumper from W1 to G. |
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Posted: 12/9/2016 3:05:30 PM EDT
[#50]
Quote HistoryQuoted:
Looks like a shit show OP, hire a local professional. This. I tried myself once. Even make each wire with the code from the old thermostat. Messed with it for 2 days. Hired a local company for $90. Had it done in less than an hour |
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