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Honeywell Wifi Thermostat, I have two changeover valve wires it has one input

Honeywell Wifi Thermostat, I have two changeover valve wires it has one input


  #1  
Old 12-24-14, 08:31 AM
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Honeywell Wifi Thermostat, I have two changeover valve wires it has one input

Hello everyone,

First time poster. Happy holidays. I'm trying to install a new Honeywell 9000 WiFi thermostat (TH9320WF5003). This new thermostat has one input for a changeover valve and in the setup you specify if it's a heating or cooling changeover. My existing thermostat (Braeburn 5000) has two separate wires for that. One heating and one cooling. The technical details of my setup are below:

Forced hot air oil burning unit and a single AC compressor. I have 3 zones that are managed with a Ultra Zone control panel (model EWC-ST-3D) and the three existing Braeburn 5000 thermostats are single stage each and the zone control panel actually controls everything. the primary zone which i'm trying to replace with the Honeywell has the following wires:

W = Heating Control
Y = Cooling Control
G = Fan Control
R = Heating Transformer (power)
O = Reversing Valve Cooling
B = Reversing Valve Heating

The other two thermostats use simple 3 wire for cooling control, heating control and heating transformer. The primary zone has to be engaged for the other two zones to work.

The crux of my issue is the two reversing valve wires (the new honeywell unit calls them changeover valves). One for heat and one for cool. As mentioned the Honeywell unit only has one input and you specify in the digital setup interface whether it's for heat or cool. Does this mean the unit will not work? Each input specifically says it will only take one wire input. I'd be happy to provide pictures if that will help.
 
  #2  
Old 12-24-14, 09:03 AM
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I found an alternate set of installation instructions for the residential version (the one I have is the pro install version) and it specifies for heat pump installation if you have separate O and B wires attach the O to the O/B terminal and the B to the C wire terminal. However, I don't have the heat pump AC, I have conventional...and the conventional installation instructions mention nothing of separate O and B wires. So i'm still stuck but thought maybe that would be a helpful clue. But even if I did do it that way i'd still have a W heat relay wire that would have normally gone into the W or O/B input that would now be leftover instead. I'm starting to think this unit won't work.
 
  #3  
Old 12-24-14, 10:18 AM
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Can you determine where the O,B wires are connected now? If you don't have a heat pump I don't see the need.
Geo
 
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Old 12-24-14, 10:33 AM
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Yes on the old thermostat it is wired to the reversing valve - cooling and the reversing valve - heating inputs. The other ends wire into identical inputs on the sub-base on the zone control panel. So they are definitely connected somehow.
 
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Old 12-24-14, 10:54 AM
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So just to clarify.... you do have a heat pump or you do not ?
 
  #6  
Old 12-24-14, 11:41 AM
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Do you have a wiring Dia of the EWC ST-3D?
Geo
 
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Old 12-24-14, 12:10 PM
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No heat pump. It's a forced hot air furnace and a conventional A/C unit. The only reason I mentioned the alternate heat pump installation wiring is because it's the only other alternate wiring diagram that included both a heat and cold changeover valve wire
 
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Old 12-24-14, 12:10 PM
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I might suggest that before you remove the old stat,remove the O and B wires from it and see how the system functions.
Just a thought
Geo
 
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Old 12-24-14, 12:34 PM
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You can add a relay to address the need for separate O and B terminal at the zone 1 thermostat.

 
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Old 12-24-14, 01:55 PM
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So with the relay...assuming I would wire the cooking for example to the primary input and then after wiring the relay to the thermostat I would program the thermostat for the cooling changeover to be the default and when it called for heat it would switch the relay over to the heating changeover wire? I have limited knowledge of relays so I wanted to double check. If correct is there a specific type of relay you would recommend? Thank you!
 
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Old 12-24-14, 02:53 PM
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Just curious,would that require 2 relays?
Geo
 
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Old 12-24-14, 04:39 PM
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Connect the stat (or EIM) "O/B" terminal to the coil of a 24 vac DPDT 90-340 relay.

Connect the other side of the relay coil to "C" 24VAC common.

Connect "R" to a common terminal on the new relay.

Connect the normally closed terminal on the relay to the EWC "B" terminal.

Connect the normally open terminal on the relay to the EWC "O" terminal.

Configure the stat "O/B" terminal to be "O" (energize for cooling).


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Last edited by Houston204; 12-24-14 at 05:08 PM.
  #13  
Old 12-24-14, 05:08 PM
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Great thank you. So just to clarify the c and r wire previously went directly to the thermostat but in this setup it should go through the relay instead and those inputs in the thermostat will now be empty?

Also after wiring can I tuck it inside the wall or does it need to be mounted? Or would I wire it in the basement next to the zone panel?
 

Last edited by cmn135; 12-24-14 at 05:25 PM.
  #14  
Old 12-24-14, 06:11 PM
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C and R connect to the relay in addition to the stat.

The stat still requires power.
The relay also requires power.

Install the relay by your zone control board.

I prefer White Rodgers, Honeywell or Mars dpdt (double pole double throw) relays when I buy them. A spdt relay would also work but I have had trouble getting more than a few years from the lighter duty spdt (single pole double throw) relays.
 
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Old 12-24-14, 07:02 PM
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Excellent thanks so much. One more question if you don't mind and I think I am set. I have one set of R and C coming from the zone control panel. Can I split/pigtail that one set to send one C and R to the thermostat and one to the relay? Thank you!
 
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Old 12-24-14, 08:21 PM
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I would grab zone 1 thermostat R and C.
 

Last edited by Houston204; 12-24-14 at 09:24 PM.
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Old 12-25-14, 04:49 AM
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Thank you Houston. And I can use that one zone 1 R and C for both the thermostat and the relay correct? Just want to be sure. Thank you for your help and happy holidays.
 
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Old 12-25-14, 10:23 AM
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Yes, that is the way that I would wire it.
 
  #19  
Old 12-25-14, 11:50 AM
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Have you considered this type of relay,should be able to mount in a knock out on the controller,makes a much neater install. http://s3.supplyhouse.com/product_fi...1C-product.pdf
Just a thought
Geo
 

Last edited by Geochurchi; 12-25-14 at 11:55 AM. Reason: Tried to change link
  #20  
Old 12-25-14, 01:50 PM
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I always dread running into those relays.
By the time that I identify the coil, normally closed and normally open set of contacts, I could have diagnosed the real problem. I hope the sticker manages to stay on for the life of the relay these days. It is never on them when I see them above ceilings in high rises.

I am charging 99 or 109 dollars ($109 for high rises) an hour when tracing these wires.

It is a good solution when working with high voltage, especially in "common return air" applications.
 
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Old 12-26-14, 04:47 AM
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Haven't had that problem yet,you can always look them up on the web.much neater than trying to mount an open relay in a box.I must admit that the stickers if there are hard to read.
MO
Geo
 
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Old 12-26-14, 05:09 AM
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Thank you again. I ordered the relay and will install early next week and let you know how it goes.
 
  #23  
Old 12-26-14, 05:45 AM
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I would verify that the furnace has a low voltage fuse.


If you buy the relay that Geo recommends it might be a good idea to draw the diagram on the side of it near the relay. It might save you $100 one day.


A disadvantage to using a multistage heat pump stat for zone 1 is the difference between stage 1 and stage 2 heat.
You will need to set the zone 1 stat a degree higher than desired temperature in heat mode.
 
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Old 12-26-14, 05:55 AM
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I got the white rodgers relay toy recommended. The zone control panel has its own fuse and I will also verify the furnace has one. I am away visiting family at the moment which is why I won't be able to install till early next week.

With the low voltage is there any risk of shorting the thermostat if it is somehow wired wrong? I will wire exactly as you recommended.
 
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Old 01-01-15, 10:40 AM
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Houston we have a problem....sorry you probably get that a lot.

I wired up the relay as you suggested and was ready to wire in the new thermostat and noticed a problem I somehow missed before. The O/B input is also the W input. the W is the heating control. So now that i've wired in the relay and will be connecting the cooling changeover valve from the relay into the O/B input I now have the W heating control wire leftover.... Any ideas? Shown below is the wire input for the new thermostat as well as the wiring instructions. Not getting the warm fuzzies on this one.... Thanks again for your help I should have double checked this before rewiring the relay downstairs. Also can't figure out how to get my pictures in the right orientation they were fine on my pc.

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Old 01-01-15, 02:54 PM
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Also, just to provide a full picture...when I went to install the relay I noticed there is a similar relay already installed. So aside from the zone control panel I have the transformer on the top for the furnace and below it a relay that has an extra set of inputs versus the one you told me to purchase. The one you told me to get is to the right of it. The central air unit wires directly to the transformer on the top picture, the relay below wires to the furnace burner and gets its R wire from the transformer above as well. I'm hoping this helps and doesn't further cloud the issue. I've never seen so many wires on a residential 3 zone setup before.

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  #27  
Old 01-01-15, 05:22 PM
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Connect the old W to Aux on your new stat.
The drawback to replacing a single stage heat pump stat with a multistage stat is a 1 degree difference between heating setpoint and the heating signal output from your stat. Latching is an option that we may be able to enable.

It looks like the additional relay is controlled by the heating signal. You might trace the wires from this relay to a humidifier.
 
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Old 01-01-15, 05:53 PM
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Thanks Houston. I was hoping it would be something simple. I'm not too worried about the 1 degree differential. Can you tell me what latching is and the benefits? It seems like my HVAC install is a bit of a hack job. I have a really beautiful home and the inspector noted (I only moved in 18 months ago) that the builder really overbuilt almost all aspects of the house and then really cheaped out on the HVAC install. Thanks again for your help.

So just to be sure. Here is my understanding of the new wiring assuming the relay was wired as you mentioned below.

O - Reversing Valve Cooling will go into O/B with cooling set as default
W - Heat control will go into Aux
Y - cooling control will go into Y compressor contactor
G - Fan control will go into G fan relay
R - Heating Transformer will go into R power input
C (actually brown)- Common will go into C input.
 
  #29  
Old 01-01-15, 06:12 PM
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Your wiring is correct.

If you set your heat for 70 degrees, the Aux demand for heat wouldn't get 24 volts until it is 69 degrees. If you configure the stat for heat latching, the heating 24 volt signal from Aux would remain on until the desire temperature is reached.

So it would be more like a 1 degree heating temperature differential than off by 1 degree.

I know the pro version of that stat has this option. I am not certain that the retail version has the option.
 
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Old 01-02-15, 07:39 AM
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Hi Houston,

one more question. I wired it up but have no power.

I used my trusty multi meter and figured some things out but want to confirm before changing anything. If I test the wires coming into the thermostat, set my multimeter to 200 vac and test the R and C wires I get no voltage. If I go into the basement and check the power right at the transformer (shown below) for R and C I get 26 volts. I also get the same 26 volts on the relay because those are wired directly to the same transformer.

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Here is where I lose the power. For the set of wires going directly to the thermostat, the C is wired directly to the furnace, but the R comes from the R on the zone control panel. (shown below) If I test those paired together I get no voltage. Do I need to disconnect that R from the zone control panel and go right to the transformer R on the furnace? It's the T1 set of inputs on the zone control not the system input so I believe the answer is yes but would like to verify. Thanks again for your help.

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  #31  
Old 01-02-15, 08:37 AM
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Do you get 24 vac between R1 on the control board and either 1 or 2 at the transformer on the control board? It would seem that C wire to the stat should connect to one side of that transformer.is that other transformer on the furnace a fan relay?
Geo
 
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Old 01-02-15, 09:18 AM
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I get 26 vac between R1 on the control board and the 1 at the transformer on the control board, but not if I connect R1 and the 2.

The C wire currently connects directly to the furnace transformer. Best I can tell the furnace transformer has the furnace wiring and air conditioner unit wiring...not sure if it's a fan relay but it could be since the fan needs to run for both the heat and air conditioning. There are actually 3 transformers on my furnace. 1 on the furnace itself which is what the C is currently wired to for both the tstat and the relay. The second wires from the transformer to the 24 vac transformer on the zone control board. The third transformer wires to an old humidifier that is no longer connected and whomever connected it did it on the return side anyway and i'm assuming it never worked well and is covered in rust...but that's another story.

If the R only supplies power does it matter if it's directly to the furnace transformer and not the zone control panel?
 
  #33  
Old 01-02-15, 09:25 AM
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Do you get 24 vac between R and C at the zone control Zone 1 thermostat terminals?
 
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Old 01-02-15, 09:40 AM
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Well now I feel stupid. I somehow missed the C directly on the zone 1 tstat on the zone control board. Guess I don't need to wire C directly to the furnace transformer. Should I move the R and C wires from the relay to the zone control board as well or leave them on the furnace?

The R wire is currently in the R1 input and not the R, that's how the previous thermostat was wired. Also I only get 24 vac if I go C and R1 on the panel, if I go C and R I don't get anything. Pic below of closeup.

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  #35  
Old 01-02-15, 10:11 AM
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Then R1 and 2 Are the same side of the transformer,1 is the other side of the transformer or C.I would use 1 that way you know where your supply is coming from.
Geo
 
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Old 01-02-15, 10:16 AM
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I would also move the relay wires to C and R1.

You are saving a good chunk of change installing this yourself. You should enjoy the feeling of accomplishment when this is installed.
 
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Old 01-02-15, 10:16 AM
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Ok thanks. So that settles the t stat wire. But what about the relay R and C. Should those be pigtailed into the same input as the t stat R and C or leave it wired as is to the transformer directly on the furnace? Thanks so much.

Just came back and saw Houston replied while I was typing. I will rewire as specified and report back.
 
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Old 01-02-15, 10:51 AM
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Ok on and powered but not quite working 100% yet. I set it up for 1 stage cool and 1 stage heat, forced hot air, standard efficiency heating. It's calling for heat but the furnace doesn't turn on. I read through the instructions and it said you can only set the default for the heat/cool changeover valve if you selected heat pump for system type. I thought I had a forced hot air system. Do I need to change it to heat pump due to how I wired it?

I tried changing it to heat pump, single stage, cooling changeover as default and it also asked me if I connected backup heat into auxilary. I selected yes as Houston mentioned wiring the white heat relay to aux input. Now instead of saying it's calling for heat it says 'waiting for equipment' in status.

ok one more update...I left it set up as mentioned above and was trying to review my wiring to see if i did anything wrong...I also hit the red restart button on the burner as sometimes when I remove the thermostat (the old one) I would have to hit the restart button to get it going. But nothing happens when I do that. The burner doesn't fire. So the furnace magically turns on within ten minutes as mentioned and after a minute or two the thermostat reboots itself. But it appears it's doing a software update. I'm hoping it will work fine after and actually get to blowing heat this time.
 
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Old 01-02-15, 11:34 AM
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Ok one more update. It appears to be working. I went through the directions. Apparently after restarting the thermostat it has a compressor protection mode where it doesn't actually fire the compressor for several minutes to prevent equipment damage.

I'll give it a few days to see how it does. I tested moving from heat to cool. It does work through the relay which is great. The only thing slightly unnerving preventing me from declaring victory is when in heat mode the heat coming out of the registers feels lukewarm and not as hot as it should. When I go to the basement it doesn't seem that the burner is going, just the fan circulator. And as mentioned before if I hit the burner reset switch it doesn't engage the burner and it always has before. I'll know for sure overnight when my wood burning insert can't keep up through the entire night and the furnace takes over. I'll report back tomorrow. In the meantime thanks again for all of your help Houston and Geo as well. You guys have been great.
 

Last edited by cmn135; 01-02-15 at 11:52 AM.
  #40  
Old 01-02-15, 12:21 PM
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Set the new stat for heat pump with Aux heat.
 
 

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