# wiring aprilaire 700 with carrier infinity



## bigMikeB (May 31, 2007)

The power from the thermostat would power the coil on the isolation relay (ie Honeywell R8222D1014) and the relay "NO" contacts would make the humidifier power circuit, or you can use a current sensing relay installed on the heat speed power leg of the blower motor.


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## chburdette (Nov 26, 2007)

I assume that either solution will be straight forward to wire, or is there anything special I should know?


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## chburdette (Nov 26, 2007)

One other note, which is the easiest, prefered, and most commonly used solution. So far it looks like the current sensing relay is easier to install. Thanks again.


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## bigMikeB (May 31, 2007)

The current sensing relay is cheapest and the easiest to wire.


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## chburdette (Nov 26, 2007)

Thanks for the reply. I have been doing a little more digging on the current sensing relay and looking at the wiring instructions. This had lead to additional questions. My new t-stat has four wires that go to the board of the furnace. The relay shows that a wire should be connected to the t-stat. The control board on the furnace has a HUM and COM connection. How should this be wired?


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## bigMikeB (May 31, 2007)

The "HUM" and "COM" terminals should be used to power a single outlet on the side of the furnace that the humdifier will plug into. The controls on the 700 work best in the auto mode. If you wire the outlet from the board as stated you don't need any other relays, the unit will only be powered when the furnace is running in the heat mode.


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## chburdette (Nov 26, 2007)

Theortically, I think I understand everything, but I do have another question. However, berfore I get to the question, let me give a little more information. Wires come from the breaker panel to a switch on the furnace which shuts power on and off to the furnace if necessary. From that switch, run wires to an outlet that the humidifier is plugged into, I assume to power the humidifier fan. I now have 2-24V brown wires coming from the humidifier that are connected to nothing. What should they connect to?


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## bigMikeB (May 31, 2007)

They would hook up to the Aprilaire controller that came with the unit. You should also have an outdoor temp. sensor with that unit.


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## chburdette (Nov 26, 2007)

I think that is where my confusion is coming into play. My T-stat will control the humididty and I don't have to use the control with that came with the humidifier. Here is a link to the instructions for the thermostat I have. http://www.favret.com/pdf_files/thermostats/SYSTXCCUID01_Infinity_Control_Installation_Startup.pdf
Sorry for the many questions, but I do appreciate the help.


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## bigMikeB (May 31, 2007)

The "HUM" and "COM" in your case are only 24v. These terminals will go to the coil on an isolation relay (Honeywell R8222D1014). The two wires from the humidifier will go to the common and normally open terminals on top of the relay. And your done.


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## chburdette (Nov 26, 2007)

Got it. Thanks again. Have a good weekend.


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## dantakayama (Jan 10, 2013)

*infinity Control on humidifier with isolation relay*

The manual "SYSTXCCUID01-B" states on page 5, "24 VAC N.O. Isolation Relay (DPST) must be used ......." but this applies only to the humidifiers with internal power supply. Otherwise I read that humidifiers can be directly connected to "HUM" and "COM/24V" terminals. Question I have is how can you tell if a humidifier has its own internal 24V power supply. 

I have a 2 years old Carrier Model 58MVC heater and the same people who installed the heater also installed the Carrie Model HUMCCSFP1016 Humidifier with an isolation relay. After 2 mild winters, both the fan motor and the solenoid on the humidifier went dead. And I put in a new exact replacements but the humidifier is not working due to the dead relay(?) 

This humidifier does not seem to have its own internal 24 V power supply. So why the need for an isolation relay? The CPU board in the furnace has "HUM" and "COM/24V" terminals which only get activated (or called for) after the heater kicks in anyway?

So many questions... Maybe I should sign up for Carrier Service Training... only if I can afford it.

Thanks for reading.
Daniel Takayama


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## truite (Jan 13, 2013)

*Carrier to Aprilaire*

I'm having a similar problem but mine is a tad more elusive. Your problem however is fairly straightforward and the little that I've figured out I'm glad to offer in the hopes that it'll help. The humidifier unit (eg like a aprilaire 700) itself probably has transfomer power onboard (to power a relay that will turn on the fan) and you can verify this by simply looking on the label affixed to the side of the unit. There will be info disclosing that there is a fan (with power consumption info) and a transformer (24V etc). The two free wires coming from the housing will be merely shorted together (done for you by the connector on the housing when you close it up) and thereby connect power to the relay inside which in turn powers the fan. The relay here in question has nothing to do with the isolation relay that's needed to couple this humidifier to the heating system. The iso relay (a 24V one which you'll supply) would be actuated by the heating system control board (24V via the "HUM" & 'COMMON' connectors) and in turn short the two wires spoken of earlier (via its switch contacts) when the heater blower turns on. Hope this helps.


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## dantakayama (Jan 10, 2013)

truite said:


> I'm having a similar problem but mine is a tad more elusive. Your problem however is fairly straightforward and the little that I've figured out I'm glad to offer in the hopes that it'll help. The humidifier unit (eg like a aprilaire 700) itself probably has transfomer power onboard (to power a relay that will turn on the fan) and you can verify this by simply looking on the label affixed to the side of the unit. There will be info disclosing that there is a fan (with power consumption info) and a transformer (24V etc). The two free wires coming from the housing will be merely shorted together (done for you by the connector on the housing when you close it up) and thereby connect power to the relay inside which in turn powers the fan. The relay here in question has nothing to do with the isolation relay that's needed to couple this humidifier to the heating system. The iso relay (a 24V one which you'll supply) would be actuated by the heating system control board (24V via the "HUM" & 'COMMON' connectors) and in turn short the two wires spoken of earlier (via its switch contacts) when the heater blower turns on. Hope this helps.


Hi,
Thanks for your input. I did figure out by shorting the blue and red wire that there is not an internal power supply. 120V AC only powers the fan and the humidifier needs the on signal as well as 24VAC from the heater unit. Thus eliminating the need for the isolation relay. I still don't know why the people who installed it originally (2 years ago) put the isolation relay.
Anyway, all is OK now.
Daniel


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