RA832A which 24v is positive?


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Old 03-29-14, 09:27 PM
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RA832A which 24v is positive?

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I am installing a 1F95-1277 White Rogers thermostat, using a WR remote sensor, and connecting to a RA832A 1066 relay, which will then run my circulation pump on my hot water heating system. The pump ran fine before with the antique mechanical t'stat. I changed it out and trying to set this up.
As I read it, in the WR thermostat manual, the connections for this would be:
24 vac 'hot' from the RA832A (T terminal) to RC/RH on the 1F95.
24 vac 'neutral' from the RA832A (other T terminal) to W/E on the 1F95.
24 vac ''neutral' from RA832A to C on 1F95. I think this one powers the t'stat so I don't need batteries.
Question is, which of the T posts on the relay board are 'hot' or 'neutral'? I checked with the voltmeter and get the same reading either way - isn't that what I would expect with AC? I understand for a mechanical t'stat the polarity doesn't matter, cuz you're just interrupting a circuit. But on this-here fancy digital things, it states the polarity so I wonder.
Which is 'hot', which is 'neutral'?
Thanks!
 
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Old 03-29-14, 10:21 PM
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Welcome to the forums.

As far as I know you can't run a thermostat that requires power off the RA832A since there is no required Common connection point. You can use a battery powered thermostat and connect one wire from T to W and the other T to R. No polarity.... no difference.

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Old 03-30-14, 02:53 PM
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Thanks for the quick comeback and the diagram. You're exactly right. Further reading in my T'stat manual indicates that the 24v C is also REQUIRED when using the remote sensor. I have to use a remote sensor in this application, so I'm currently stymied.

I'll be looking for a replacement for the RA832A that provides 3 t'stat wires. Any suggestions out there? I'm running a Wilo 1/12hp pump up 3/4 pex to second floor heat system. 2nd floor system is 10' of hot water baseboard and about 270 ft 1/2 pex in the floor.

For now I'll continue to run the pump manually with my extension cord.
 
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Old 03-30-14, 04:13 PM
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The older design relays typically don't have a Common connection point since they were designed 'back in the day' when electromechanical t'stats were the norm.

The new design SR501 from Taco will fix you up. It has a clearly marked Common for the 24VAC.

SR501-4 - Taco SR501-4 - 1 Zone Switching Relay
 
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Old 11-08-14, 11:49 AM
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okay, now trying to wire the t'stat

Got the SR501-4 as recommended, weather got warm, project on hold till now. Trying to understand the connections to my 1F95-1277 t'stat. One instruction sheet is item 37-6753D, there's another wiring diagram sheet item 37-6808D. Their terminolgy varies. The 3 connections to my remote sensor are fine {using a F145-1378 sensor in my floor joists for radiant heating}. I think I'll connect the C terminal to 24v common on the Taco. Do I jump the RC and RH? and what 2 wires to T and T on the Taco?
any assistance appreciated.
J
 
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Old 11-08-14, 01:15 PM
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Is your new control labeled R, W and 24 VAC Com?

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Old 11-08-14, 04:51 PM
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tried pic again to get it more clear
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Old 11-08-14, 04:55 PM
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photo of stat back, he said, as he typed over 25 characters
 
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Old 11-08-14, 04:58 PM
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instruction manual. Last of 3 pics posted relative to thermostat.
thanks for your help on this! The old mercury switches sure are easier to understand.
 
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Old 11-08-14, 05:10 PM
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oh, my controller. Like this...Name:  Tacoclose.png
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Old 11-08-14, 06:38 PM
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At your stat,
white = W/E
Red = Rc (keep the jumper installed)
Blue = C

At your new controller,
White = W
Red = R
Blue = 24vac com
 
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Old 11-08-14, 07:20 PM
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Another option that would have been under $20 would have been an external transformer and keeping the old boiler control.

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Old 11-12-14, 06:19 PM
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working great!

quoted
At your stat,
white = W/E
Red = Rc (keep the jumper installed)
Blue = C

At your new controller,
White = W
Red = R
Blue = 24vac com

Yep, that did it. Working great. I've been trying it with the underfloor temp set at 82. The system control is very nice and the floor feels good. Can't wait for some real cold weather...

Thanks for all the help!
 
 

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