Is there such a thing as a combo Thremostat & Humidistat?
 

A couple of years ago someone mentioned to me that there was such an animal. I've never found it.

I'm looking for a controller that will work like the normal Thermostat (Digital/programmable) to control heat and A/C BUT will also actuate the A/C based on Humidity...not just temp.

Does this exist?

I think so Rick. Look at Home Depot or something. I know we have one in our lab at work. Its made by Honeywell.
Troy

Not at HD, at least not here in NJ. I also checked the net and came up dry.

Can you get a model #?

Thanks

I'll have to walk across the plant. I'll get back to you ASAP.
Troy

try Page 554 at McMaster Carr (www.mcmastercarr.com)

hi Rick,
The Honeywell RH controller is designated H775. The output from the controller goes to an Industrial Control Transformer that then triggers the HVAC heater unit. Another output goes to the humidifier power. In this way you can control both RH and temp. Its obviously not what you want. Sorry.

Some more information:

http://www.mcmaster.com/catalog/110/...e/4733kp1l.gif

Modular Thermostats and Humidity Controls
You'll get the accuracy of an electronic unit in an easy-to-install design. Modules mount to surfaces or DIN-rails and plug together to reduce wiring. Each module is 5" Ht. x 2 3/8" Wd. x 2 3/8" Dp. and has four mounting slots for #6 screws (not included). Modules operate on 24 VAC, 50/60 Hz and control 120-240 VAC loads. UL listed. On/off thermostat modules can be used for heating and cooling and include a temperature sensor with two 9 3/4" leads. Switch is 10 amp SPDT (single pole, double throw). Units have screw terminal connections and a 7/8" dia. opening for conduit. You can add up to nine stage adder modules. Humidity control modules adjust humidity within a 10% to 90% relative humidity range. They have a 10-amp SPDT (single pole, double throw) switch and a sensor. Units have screw terminal connections and a 7/8" dia. opening for conduit. You can add up to five stage adder modules.
On/Off Thermostat Modules
Setpoint Range Each

On/Off Control -30° to +130° F 4733K71 $68.74

On/Off Control +90° to +250° F 4733K62 68.74


Humidity Control Modules
Each

Control Module with Room Sensor 4733K87 $273.08

Control Module with Duct Sensor 4733K89 288.63


Accessories and Replacement Parts

Stage adder modules provide the switching for each additional stage you add. They have a 10-amp SPDT (single pole, double throw) switch.
Digital display modules show the actual room temperature or humidity (from 0% to 100% humidity levels). Setpoint is displayed at the press of a button.
Remote cables let you mount displays further from controls.
Power supply produces 24 VDC power from 120/240 VAC input. Use to run controls and other modules. Has screw terminals and a 7/8" dia. opening for conduit.
Each

Thermostat Sensor Housing for Wall Mounting 4733K75 $38.27

Thermostat Sensor Housing for Submersion 4733K76 33.06

Stage Adder Module for Thermostat Modules 4733K73 44.29

Stage Adder Module for Humidity Control Modules 4733K82 64.17

Digital Display Module for Thermostats 4733K74 91.36

Digital Display Module for Humidity Controls 4733K83 98.64

3-ft. Remote Cable for Digital Display Modules 4733K92 33.93

50-ft. Remote Cable for Digital Display Modules 4733K93 69.10

120/240 VAC Input/24 VDC Output Power Supply 4733K91 40.02

Thermostat Repl. Sensor with 9 3/4" leads 4733K39 25.83

Thermostat Repl. Sensor with 9'9" leads 4733K41 47.43

I just visited the Honeywell web site. Try this link:

http://customer.honeywell.com/catalog/pages/datasheet.asp?PN=PC8900A1007&FAM=Therm_Prog&P=3568 ,3569

Harry, I think this may be it! Thanks! (I have to see if it just controls a humidifier during furnace operation or AC during cool operation)

Troy, Thanks for going out of your way to check for me.

BTW, I could swear that the person who mentioned this device to me called it a Thermidistat...am I hallucinating?

Harry,

Honeywell responded to my inquiry.

Quote:

"Rick,

Thank you for contacting Honeywell.

The PC8900 can be configured to control humidity in heating and
cooling. The PC8900 is available through heating and cooling contractor. For more information on this thermostat, visit the website
http://content.honeywell.com/yourhome/ac-automated_control/hc.htm
<http://content.honeywell.com/yourhome/ac-automated_control/hc.htm> . "

Thanks for the tip. Now to find two of these puppies for a discount. Bet they're not cheap as they're the top-of-the-line units.

glad to help. When you talk to the vendor, ask about alternatives. I just grabbed that one but they may have others.