Humidifiers and Dehumidifiers - Wiring Carrier Thermidistat to Truesteam humidifier

Another Truesteam wiring question, appreciate any help on this issue. I have a Carrier furnace model #58mxa100-16 series 111 approximately 15 years old that was recently updated to a hybrid system with a Carrier outdoor unit and coil, model #25hpa5 along with a Carrier Thermidistat. I am using the Carrier Thermidistat instead of the manual humidistat included with the Truesteam.

The Thermidistat has two separate connectors. The connection at the bottom of the unit is as follows: S2-Brown wire, S1-Black wire, B-not used, HUM-not used, DHUM-not used, C-blue wire. The connections at the top right of the Themidistat are: W/W1-White wire, Y/Y2-Yellow wire, G-Green wire, R-Red wire, Y1/W2-not used, O/W2-Orange wire.

The furnace board connections are: HUM-not used, COM-2 Blue wires, W-2 White wires, Y-2 Yellow wires, R-2 Red wires, G-1 Green wire. There are also three leads, Orange, Brown and Black wiretied to matching color leads that must be for the thermidistats outdoor sensor.

It seems as though I may have to run an extra wire to the Thermidistat as the current wire has only eight leads and all of them are used.

I understand the basic wiring diagram provided in the Truesteam manual; G from Thermidistat to GT on Truesteam, GF from Truesteam to G on furnace board. What is a little confusing is the two terminals shown on the mechanical humidistat running directly to the two HUM terminals on the Truesteam. The Carrier Thermidistat has only one terminal marked HUM so I cannot figure out how to finish the wiring to complete the circuit without the fear of damaging one unit or the other.

A little more information on this system, it does not have an air flow switch nor obviously an equipment interface module. I am also taking for granted that wiring the system as above will activate the humidifier only when there is a call for heat and not independently for humidification.

Any help on wiring this humidifier would be appreciated. Thanks

Stat Hum to humidifier to furnace Com.

Don't wire anything yet!

What is the full model # on the Thermidistat?

Thanks Jay, I have not wired anything yet. The Thermidistat model# is TSTATCCPRH01-B. The Thermidistat has a warning label stating not to wire the HUM terminal directly to the furnace HUM terminal as it could bypass the furnace safety features and potentially cause a fire risk. This definitely put a hold on my progressing any further until I got solid information about how to wire the Truesteam to this stat. Thanks for the help, it is greatly appreciated.

Ok, the HUM on that stat will be "HOT", and the TrueSTEAM HUM is "HOT" as well, so you can NOT wire these two together.

You must use a relay between the two to make it work.

Thanks again Jay,

Could you provide some specifics concerning the type of relay, manufacturer, model# etc... and how it should be wired. I am taking for granted that I will use a two lead thermostat wire from the Thermidistat and run that to the relay and then link that to the Truesteam. Am I also correct to think that the other wiring stays the same in the original post.

Your help is appreciated. Thank you again.

Any SPST (Single pole/single throw), or DPST (Double pole/double throw) can be used.

Maybe look at the Honeywell R4222D1013 relay.

On the coil side, you run H wire from t-stat to coil, and other end of coil to C on furnace.

Them HUM to #1, and other HUM on to #3 on the contacts.