Connecting Nest thermostat to Genisys 7505 oil burner


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Old 02-09-19, 03:24 PM
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Connecting Nest thermostat to Genisys 7505 oil burner

Hello!

I currently have an oil furnace that uses a GeniSys 7505 120v burn control that is connected to a Honeywell round basic thermostat with 2 wires (Red and White). I wanted to upgrade to a Nest Thermostat E, so, I turned off the furnace and swapped out the thermostats. When I powered the furnace back up, the Nest began booting, but, I could hear the furnace "pulsing". After doing some research, I came to the conclusion that I need to add a C wire to provide more power. After looking a bit more into the furnace, I see there is a White Rodgers 90-113 fan controller in it, which has a C wire on it. Can I just run a wire from that C terminal on the fan controller to my thermostat and get power for the Nest? Or is there more involved?

GeniSys 7505 top view
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GeniSys 7505 side view: Tw and Tr wires go to the Honeywell Thermostat
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Honeywell Thermostat: red wire is connect to R + Rc and the white wire is connected to W
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White Rodgers 90-113 fan controller
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White Rodgers Wiring
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I noticed while posting this, the white and red wires are in my mind "swapped" on the furnace: the White wire is connected to Tr post, while the Red wire is connected to the Tw post. This is the way the wires have been for a long time: does it not matter which is connected to which, I take it?

Thanks for your help!!
Bruce
 

Last edited by PJmax; 12-16-19 at 05:13 PM. Reason: resized pictures
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Old 02-09-19, 05:15 PM
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Welcome to the forums.

In my opinion..... a nest E is not directly compatible with your TT system.
You need a thermostat with an Rh and Rc like the regular nest.
That fan center has nothing to do with the burner control. That C on it is not a C for the two TT terminals.
You could use a full size nest and four wires or a 24vAC power supply at the nest itself.

Actually if you have three wires from the furnace to the stat..... you could use a 24vAC relay or the fan center relay to directly control the burner. If you'd like to use the fan center..... turn the power off, take the plate off and post a few pictures of the wiring.

That doesn't look like a three wire thermostat cable.
 
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Old 02-10-19, 08:19 PM
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Hello Pete. Thank you for your reply!

So much for things being easy! When you say I can use a 24vAC relay or the fan center relay: do you mean with this Nest E thermostat, or, would I have to get the Nest 3? I was hoping to use this one, as I only paid a little over $100 for it vs $249 for the Nest 3, but, if I have to get a Nest 3, I will.

Here's some pictures of the Fan Center wiring:

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I have some 18/5 thermostat wire that I'm going to replace the 2 wire with, so, that wiring shouldn't be an issue.

Thanks Again!
Bruce
 

Last edited by PJmax; 12-16-19 at 05:19 PM. Reason: resized pictures
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Old 02-10-19, 08:40 PM
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Your pictures are excellent. We can do what we need. I'll be back later to explain it.

This is so weird. Working with two members at the same time with similar equipment. In the other thread the member has the same seemingly unused fan center.

Aprilaire 500 american standard freedom 80
 
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Old 02-10-19, 09:06 PM
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Wow! That's crazy: the furnace pictured in post #10 of that thread looks almost exactly like mine! I have a Trane XP80, although it appears the insides are shared between companies.
 
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Old 02-25-19, 09:58 PM
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Thumbs up Solved! Nest Thermostat installed!

As an update: after doing some more research, I found that Beckett makes an add-on kit for the GeniSys 7505: the A/C Ready Kit (Part #51950U).
https://www.beckettcorp.com/product/ac-ready-kit/
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I was able to attach the kit to my system, ran 120v power to it, and then connect the Nest with the new R, W and C wires.

Thanks for pointing me in the right direction, Pete! I appreciate the help!
Bruce
 
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Old 02-25-19, 10:38 PM
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You're welcome and thank you for the additional information.
 
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Old 12-16-19, 04:42 PM
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Beckett 51950U A/C Ready Kit

Hi Ber1983,

Do you have a pic of the before and after ready kit install? I have the same setup and just purchased the kit. Going to try over the weekend!

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Last edited by PJmax; 12-16-19 at 05:21 PM. Reason: added wiring diagram
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Old 12-16-19, 04:53 PM
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Welcome to the forums.

A very easy kit to install. The guide they give you is basically before and after.
I added an easy to follow wiring diagram for you.

Beckett install (pdf)
 

Last edited by PJmax; 12-16-19 at 05:23 PM.
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Old 03-25-20, 08:21 PM
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beckett 7505 trying to hook up a ecobee 4 WiFi thermostat

I also have a beckett 7505 trying to hook up a ecobee 4 WiFi thermostat would this setup also work for me . I donít have a/c or fan, just a oil burning furnace . Only have two wires W and R missing C
 
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Old 03-26-20, 01:13 PM
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Welcome to the forums.


You either need to add a 24vac transformer and a relay OR a fan center OR the Beckett kit.
The PEK kit that comes with the Ecobee should allow it to run in two wires but I don't recommend it.
I highly recommend running a new cable.

 
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Old 09-26-21, 08:28 AM
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Not one for raising the dead but this covered 95% of my issues, only problem is my Ecobee SmartThermostat isnít coming on. I have the same burner with what I believe is a fan center that has a G wire running to the t stat. The burner just has the tt wiring direct to t stat. I connected everything in the same manner and ran a previously unused wire from C on the fan center terminal to C on the t stat. Unfortunately, no joy. Iíve been doing as much research as I can about how all of this functions but itís definitely not my area of expertise. As I understand the tt wiring completes a circuit to say furnace on, and the g wire controls the fan. Any help is appreciated.
 
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Old 09-26-21, 11:36 AM
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The C is not referenced to the TT terminals.

The only way I would connect that system is to use a basic single pole 24vac relay.
Any single pole 24vac relay would work. Choose one from below or pick your own.
Once you've committed to a relay I'll draw the easy to follow wiring.


24v relay
24v relay
24v relay
 
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Old 09-27-21, 10:24 AM
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Thanks PJ, itís ordered and should be here later this week.
 
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Old 09-27-21, 10:33 AM
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Let me know which one you ordered and I'll leave a diagram.
 
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Old 10-01-21, 12:42 PM
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Relay in hand and ready to go.


 

Last edited by jms5580; 10-01-21 at 03:23 PM.
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Old 10-02-21, 06:25 PM
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The way I have this laid out now is T/T wires to 2 and 4. W1 to 1 and C to 3. G stays as is. Does that sound correct?
 
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Old 10-03-21, 09:28 AM
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C = black and G = green

Something doesn't look right there.
Typically the blower (G) needs to get switched to R not C.
Can you tell me how the wiring is/was connected to the existing (old) stat ?

This would be standard wiring..........
Red to R
Black to C
Green to G
Yellow to relay terminal #1
Relay terminal #3 to C.

 

Last edited by PJmax; 10-03-21 at 10:54 AM. Reason: white changed to yellow wire
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Old 10-03-21, 10:23 AM
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Hereís how it is wired now. The black isnít currently connected to anything.

Yellow: Tw to W
Red: Tr to R

Green: G to G




 
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Old 10-03-21, 10:53 AM
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Your original setup was using four wires. Two to the fan center and two to the TT terminals.
What was black doing ?

Your confusing the issue. I don't see the relay in the new setup.

 
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Old 10-03-21, 11:01 AM
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This is a stand alone post. This is the way it should technically be wired.

stat ------> color ------> furnace
R --------> Red ----------> R
C --------> Black --------> C
G -------> Green --------> G
W1 -----> Yellow --------- to relay terminal #1
Relay terminal #3 to C.
Relay 2 and 4 to TT terminals.


 
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Old 10-03-21, 01:54 PM
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Success, thank you!
 
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Old 10-04-21, 08:13 AM
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Good job. Thanks for letting us know how you made out.

This thread is pushing the limit of viewable threads. It will be closed but it will remain in our searchable archives for viewing. If this thread doesn't answer your questions.... start a new one and reference this one.
 
 

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