infinity 58MVB060-14

[Inert air]

Trying to get a humidifier to work on call for heat.
I don't have 24 volts from humidifier tab and com when blower is running in heat mode
thinking the board needs replaced?

[Admin]

Humidifier (HUM)
Connect an accessory 24 VAC, 0.5 amp maximum humidifier (if used) to the 1/4-in. (6 mm) male quick-connect HUM terminal and COM-24V screw terminal on the control board thermostat strip. The HUM terminal is energized when blower is energized in heating. (See Fig. 37.)

You could always wire the humidifier solenoid and humidistat in series with the W and C terminals on the furnace control board.  It's the same 24V source as the HUM terminal.  The only difference is the humidistat will get power on a call for heat instead of when the fan is energized on a call for heat.

I have never seen a faulty HUM terminal when everything else is working.

What type of thermostat control is being used? 

DO NOT connect furnace control HUM terminal to HUM (humidifier) terminal on Thermidistatt, Zone Controller or similar device. See Thermidistatt, Zone Controller, thermostat, or controller manufacturer's instructions for proper connection.

Also, if you're using a bypass humidifer make sure to make the following adjustment,

NOTE: If a bypass humidifier is used, setup switch SW1-3 (Low HEAT Rise Adjust) should be in ON position. This compensates for the increased temperature in return air resulting from bypass.

[Inert air]

Im also not getting voltage from the w and c terminal while the system is heating as i would have done that.
the t/stat is wired into an a,b,c,d block on furnace and infinity t/stat.
Even with this type of hookup i think i should still have low voltage readings on those terminals...hum ,c, or w, c

[Admin]

Are you using a seperate humidistat with the humidifier?

The Infinity control should be setup to control the humidifier.  When those settings are enabled, the Infinity control will energize the HUM terminal.

Humidifier Connection
A 24VAC bypass or fan powered humidifier may be installed. NOTE: Do Not Use a traditional humidistat to control humidifier operation. If a humidifier is installed, let the Infinity Control operate humidifier.

Bypass Humidifiers
A bypass humidifier should be wired directly to the furnace or fan coil HUM and 24VAC COM terminals. The Infinity Control will automatically energize the HUM output during a call for humidification.

Fan Powered Humidifiers
Most fan powered humidifiers produce internal 24VAC in order to energize upon a switch or contact closure. For this application, a 24VAC N.O. Isolation Relay (DPST) MUST be used to prevent mixing the internal humidifier power with the indoor equipment transformer. Applying 24VAC isolation relay coil to furnace or fan coil HUM and COM terminals will allow the Infinity Control to automatically energize the HUM output during a call for humidification. The N.O. relay contacts will be used to energize the humidifier. See fan powered humidifier installation instructions for more details.