Honeywell RTH3100C compatibility question


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Old 04-03-15, 03:00 PM
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Question Honeywell RTH3100C compatibility question

I am looking to install a new Honeywell RTH3100C to replace an old mercury Honeywell Q674F.

The wires coming out of the wall go to O, G, W2, E, R, Y1, W1, X

The new thermostat has E, Aux, Y, G, O, L, R, B, C

It is for a water source heat pump (Model WPH 044-1J) with an electric heat back up (Dell Corporatin HXOB-443/027-15-240-1PH)

The manual for the RTH3100C says to contact a contractor if you have W1, W2, and Y wires.

Any help is greatly appreciated! Thanks!
 
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Old 04-03-15, 03:53 PM
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Welcome to the forums.

I moved your thread to the thermostat forum.

The Honeywell stat you have picked out is not the correct one for your application.
Houston, the forum pro, will be able to help you pick out a good replacement for your application.
 
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Old 04-03-15, 05:06 PM
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That stat may work...

What are the 4 numbers after Q674F on your old thermostat subbase?

Did you have a jumper wire between W1 and Y1?
Are you sure that X wasn't actually X1?


 
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Old 04-04-15, 06:50 AM
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Thanks PJ!

Houston,

The old thermostat is Q674F 1345. W1 and Y1 have two different color wires. All wires appear to come out of the wall.


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Any recommendations on a stat if that one won't work? Or even if they would work better?

Thanks again!
 
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Old 04-04-15, 09:29 AM
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The Honeywell Prestige IAQ would work better.
In my opinion it is the best thermostat available at this time. It will support more stages of heat than the TH3100 but it is on the opposite end of Honeywell's price range.


I would still like to identify these wires.
How many white wires are coming out of the wall?
 
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Old 04-04-15, 11:19 AM
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There are three white wires...one each to W1, W2, E
 
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Old 04-04-15, 09:40 PM
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It looks like that model was a little different than most...

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Old = new
C = C
R = R
W1 = Y
W2 = Aux
G = G
Y1 = O ( this would be O/B on most new Honeywell stats and then you would need to configure for O, but the RTH3100 has an O)
X = L
E = E

I would label those 3 white wires and turn off power to the unit before replacing the stat.





I recommend upgrading to at least the 5000 series model.
The Honeywell TH5220D1029 would be a better choice for your application than the Honeywell RTH3100C.

http://www.amazon.com/Honeywell-TH52...eywords=TH5220

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Last edited by Houston204; 04-04-15 at 10:04 PM.
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Old 04-05-15, 07:05 AM
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Sounds good, I will switch it out for the Honeywell TH5220D1029, thanks for the recommendation.

When doing the installer set up am I setting it to a 2 heat / 1 cool heat pump?

Set Up Function = Setting
1 = 5
2 = 0
3 = 1
5 = 9
6 = 9
8 = 8
9 = 3
10 = 3
12 = 0
14 = 0
15 = 5
26 = 0
27 = 90
28 = 50
 
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Old 04-05-15, 07:39 AM
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I don't think function 5 will show up when you configure for heat pump but set it for 3 if it does.

I would set function 8 to 3 (cycles per hour) for increased comfort. I get callbacks with the short cycles you get when setting it much higher.

10 shouldn't appear.

If you are unhappy with your new electric bill, changing 26 to 1 would lower it.

The rest of your settings look fine.
 
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Old 04-05-15, 08:04 AM
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Thanks a lot...definitely greatly appreciated!
 
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Old 05-11-15, 03:17 PM
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Houston,

One more question, I have finally had an opportunity to install the thermostat and you had previously said that:

Old = new
W2 = Aux
E = E

However the Honeywell TH5220D1029 only has one spot for Aux & E, should I put the two wires in the same spot?
 
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Old 05-11-15, 04:05 PM
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It looks like two separate terminals to me......

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Old 05-11-15, 04:06 PM
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You can connect both Aux and E to the Aux/E terminal.

Do you have a wiring diagram for the heat strip?

I usually only like 10KW for the Aux terminal.
I would tape off the old E wire to save money, but both wires connected would be warmer if it gets very cold in your neck of the woods.
 
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Old 05-11-15, 04:10 PM
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The new models often combine Aux and E.
Some new 8000 series thermostats also have this change.
 
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Old 05-11-15, 05:05 PM
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Looking at the furnace, the other end of the wires connect to a strip labeled with W2, W1, C, R, G1, G.

Going by the colors of the wires:

Old Thermostat = New Thermostat = Furnace
X = L = G1
Y1 = O = Not used
R = R = R
G = G = G
C = C = C

These have white wires so it's hard to be sure...W1, E, W2
 
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Old 05-11-15, 07:37 PM
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W1, W2 and E might control different elements or the same one(s).
The diagram would help prove this.

If you do not have a diagram, connecting both wires to AUX/E would be the better option in New York.

I would only connect Aux down here.
 
 

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