Help installing a thermostat that needs a c wire to a Taco sr 501 controller.

[harryhood]

I'm trying to install a Wi-Fi thermostat to the radiant heat in my garage. The heater itself is a rinnai tankless water heater. The wires from the thermostat go to a Taco sr501 controller. I guess it is. I haven't been able to find anything on the internet to tell me exactly where on that controller I can tap in for AC wire. Anyone any HVAC people out there who could help?

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[massxj]

I assume your looking for a C wire.  How many wires did you run for the t stat

 

[harryhood]

Just 2, R and W.

Yes, a c wire.

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[mudpit]

if you pop the cover off your 501, there should be a third terminal next to the W and R labeled C for the wire.  You can also do an 'add a c wire' with a 24v AC transformer, which depending on the thermostat may or may not work. all you need to do is get a doorbell transformer and run it to C and RC.  Make sure the RH and RC aren't bridged. Some thermostats have the ability to steal power from the r/w terminals.  Somewhere I have a pic of the setup

 

[mudpit]

 

[MattG]

Do you have pictures?

Also if it’s a thermostat in your garage I would just get a plug in C wire, it just needs 24v constant to keep the battery in the stat charged and active. If you only have 2 wires in your cables your gonna have to run a new line anyways

 

[harryhood]

But yeah I should have added pics from the jump. Is this helpful?

If not, buying the c wire adapter would definitely work.

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[mudpit]

At the top is where you would put the C wire.  If you're down to run a new tstat wire, that's where it would go.  Everything at the bottom is high voltage and will make magic black smoke if you put stuff on it.

 

[harryhood]

Thanks. Got it. C wire = 24 vac

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[massxj]

that easy, oh and never run the minimum requirement.

 

[massxj]

Thanks. Got it. C wire = 24 vac

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yes, "C"    common    for a lack of a better term ground.  the 24 volt on that side is AC

 

[JeepinMaxx]

As other's mentioned - you need 24V AC.  I used a cheap 24V doorbell transformer when I adapted a smart thermostat to my 1940's farmhouse furnace... 

https://www.amazon.com/LIANSUM-Thermostat-Transformer-Compatible-Honeywell/dp/B08TWDT4J2/ref=sr_1_2?crid=22WSPUGPT6VT1&dib=eyJ2IjoiMSJ9.Db3ksSrPTKd00UrFEzn4oXFhT7DcJql0uSXBBHSESDaF5oGQZHW47QlJV2S9lxQDPZGKhxwXz27VmfUNOx_vpGaawsbEnLjEmNFor7SmWmu-tT9iFCOUObHhLAg0Q94zjOELmzSAIxMk5CpUdbe6b1b84ICL8-frHzIZfOHP_Uhxn4H-va9JbQ_zUFtehbIfFCgsjiuA2pmjaviQuUUF4Orjf5gHZJNz6-aSD1Fbvbnm5S9ciiXlDbsa0F0bMWUepseRi5RpqnT_CfGvD5Ol84Fm3jceREymA_CfCK11HoHQGErxZ7BLdriES2GKdV7-6d45zxFX-jorCsx9m83-KaTTm-bDBBRTK1yG1mw_aE1RokVfCrWErsK22pTwn9a3pKdHwZvZMk_-i-gsQIdMpip2TA4hFKm36yZB2P7sGNpzByX8CbY2bk4QSdwNtrme.4HoFbKP6EPtkHs89HdMKcACKaTMYlSmayhE7LAO5Bow&dib_tag=se&keywords=24v+c+wire+adapter+for+smart+thermostat&qid=1743389626&sprefix=24V+C+%2Caps%2C109&sr=8-2

 

[A new level]

Any relation to a C hair?

 

[JohnyPro]

I'm doing this to my 1941 boiler with a Carlin burner/controller, adding a Nest. Have all the pieces, just haven't installed it yet. Watching to learn more opcorn:

 

[harryhood]

that easy, oh and never run the minimum requirement.

Yes, very simple now that I know.

 

[massxj]

Now you can add HVAC tech to your resume

 

[harryhood]

Not. And hopefully I never have to update my resume again in this lifetime

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[JohnyPro]

Think I did it right… no c wire, added 24v plug from wall. Connected on plug wire to “c wire” pigtail from adapter, other 24v wire to Red wire to T-stat. Connected all the other common W to W and R to R from boiler to adapter to wires to T-stat.

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[JohnyPro]

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[JohnyPro]

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