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Honeywell VisionPRO 8000 with RedLINK thermostat in RV 12vdc installation

Honeywell VisionPRO 8000 with RedLINK thermostat in RV 12vdc installation


  #1  
Old 07-23-15, 04:43 PM
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Honeywell VisionPRO 8000 with RedLINK thermostat in RV 12vdc installation

I have a Honeywell model TH8320R1003 thermostat which is working fine in my 12vdc RV system to control heat/cooling/fan. My understanding about why this 24vac thermostat works fine in this scenario is because it operates on 4 alkaline batteries, and is working only as a relay in this situation. My problem is the RedLINK usage. RedLINK requires 24vac common, which of course I don't have. Nor is switching G (fan) with C (common) an option in this scenario since again I don't have 24vac.

I know I can add an additional 24vac transformer (300ma) to enable RedLINK, per a number of contractor's videos on youtube.com. Bogen PRS2403 Power Supply 24v 300ma

I'm not actually using R (heat/hot) on this system (this is a gas heat system and we're not using gas, since in winter we use efficient electric space heaters instead), only Rc (cool/hot) and in fact i don't currently have R wired to the thermostat (nor jumped). So could I safely use the additional 24vac transformer and wire it to R (heat/hot) and C (common) with no jumper between R/Rc - so the 24vac wiring is not actually in contact with the 12vdc circuits/wires?

My concern is for the Honeywell thermostat.
 
  #2  
Old 07-23-15, 05:10 PM
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Welcome to the forums.

So could I safely use the additional 24vac transformer and wire it to R (heat/hot) and C (common) with no jumper between R/Rc
No.... the 24vac must be connected to Rc and C (no R jumper) for the WiFi to work.

I'm not quite following what you are actually using the stat for..... how it's wired to your electric heaters ?

Energy efficient electric heaters over gas ?
 
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Old 07-23-15, 05:51 PM
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We don't use the gas heat system because this is a 10 year old 5th Wheel and the gas(propane) system leaks like a sieve. Several professionals have quoted outrageous prices to repair/replace it, so instead we're using electric heat which works just fine in our Texas winters. If RedLINK requires Rc and C instead of R and C, that will be an additional problem. Rc connector on the thermostat panel to the 12vdc (RV) system is required to activate the cooling system. Could I use some type of inverter to connect both the 24vac transformer to Rc and the also connect the 12vdc cool/hot line to Rc but use the inverter between to stepdown the 24vac coming off the Rc connector going to the hot line wire to the 12vdc (RV) system? This RV system has only one hot line not two (and the idiots used the green colored wire no less, LOL). So normally you'd jumper R/Rc, but as I said, since we're not using heat we only need Rc and the thermostat system setup is set only for Cool. I used a good volt-ohm meter to test all the circuits first, then once identified, just crossed the wires to test fan/cool/heat (though without gas heat only clicks to light the pilot). This system does have either a 2 stage fan or 2 stage cooling system. When I do the "Installer Options" test, there's a noticeable difference between stage 1 cooling and stage 2.
 
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Old 07-23-15, 10:43 PM
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Ok....just so I'm sure what you're doing. You're using the stat for cooling only. You are switching the 12+ lead which means you're using the Rc and Y connections.

The only way I can see doing what you want safely is to use a relay. The relay is a SPST 24vac coil relay. The relay will keep the 24vac isolated from the 12vdc.

The type and model of the relay is completely unimportant.

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  #5  
Old 07-24-15, 02:54 PM
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Pete,
If I'm understanding your wiring diagram, you're saying the 12vdc hot wire and the 24vac common wire will share the same terminal block post on the Honeywell board, with the 12vdc hot circuit passing through a coil relay first?

I was actually dreaming about this problem last night when a simple idea dawned on me, LOL. HVAC (other than the simplest of issues) is mostly new to me, but basic electrical issues are not. If the 12vdc hot and the 24vac hot wire share the Rc connector on the board, but the 24vac common connector has only the 24vac common wire coming in - doesn't that mean that the 12vdc RV heating/cooling transformer and 24vac external transformer aren't completing a circuit (crossing power) since they don't have a common neutral connector or common ground connector? Or is the Honeywell thermostat itself, in this scenario, acting as the common neutral/common ground between the two transformers? If that's true, then that would potentially endanger both the 12vdc RV transformer and the Honeywell thermostat (perhaps).

In that case your diagram would be the only solution, if you're correct, which I assume you are. My problem with your diagram is the wiring of the coil relay. Is the 12vdc IN using the existing 12vdc hot wire (currently on the Rc terminal), and if so, where is the 12vdc OUT wire going? And what do I do with my existing 12vdc cooling system wire (Y/Yellow) currently connected to the Y terminal, since your diagram shows replacing it on the terminal with a yellow wire coming from the OUT side of the coil relay? Or are you implying that the 12vdc OUT (red/hot) from the coil relay is then paired with the 12vdc Y/Yellow wire going back to the RV 12vdc transformer/cooling system?

By the way, thank you for your help!
P.S. Is this the type of 24vac coil relay you're speaking of?
http://www.amazon.com/PACKARD-PR360-.../dp/B003ZZIK9K
P.S.S. If I ever became independently wealthy and was able to repair the RV gas system would I simply need an additional 24vac coil relay to do the same thing for the R & W wires (to the R & W terminals) as you've shown for the Rc and Y in order to enable the thermostat heating options?
 
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Old 07-24-15, 07:08 PM
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I added labeling to diagram.

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P.S. ------- Yes.
P.P.S. ----- The R and W terminals do not share a connection to Rc therefor no relay required.
 
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Old 07-28-15, 07:03 AM
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Thanks again, Pete. Love the updated diagram! Sorry for the delay in getting back. Things have been hectic at work lately. I purchased the following at Amazon to complete this project:
PACKARD PR360 Fan Relay 24 VAC Coil Voltage SPST (Coil Relay)
Southwire 64169622 5 Conductor 18/5 Thermostat Wire, 18-Gauge Solid Copper (50ft, overkill but cheap)
LockState Connect LS-24VAC 24 Vac Adaptor for LS-90i (AC/AC Adaptor/Transformer 120v to 24v 300mA, 20ft)

I watched several videos on youtube.com again, with a number of guys giving differing opinions on how to hook up a secondary power adapter/transformer to a wifi/redlink thermostat. About half said the 24v transformer was connected to Rc and C, and the other half said Rh and C (or R and C). LOL, I found it funny that the 'experts' don't seem to agree on the wiring.
https://www.youtube.com/watch?v=cZdIGOyLPZE says Rc and C but later says Rh and C
https://www.youtube.com/watch?v=BgDseEF-4OY connects to R and C (says doesn't matter if it's 24vac or 24vdc...) confusing...
https://www.youtube.com/watch?v=8a_f2_iAW1U shows Rh and C with Rh shared
 

Last edited by DanCallaghan; 07-28-15 at 07:22 AM.
  #8  
Old 07-28-15, 08:29 AM
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In your case, since you aren't using heat, you can leave the Rc/Rh jumper in place.

As a rule..... the thermostat gets it's power from the cooling side which is Rc and C. Some thermostats like the nest it doesn't make a difference. I have no idea what others.
 
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Old 08-13-15, 12:42 PM
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Pete,
If I do end up repairing the gas heating system and connecting it to the thermostat, how will this affect the wiring diagram you've described?
 
 

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