Welcome! Here are the website rules, as well as some tips for using this forum.
Need to contact us? Visit https://heatinghelp.com/contact-us/.
Click here to Find a Contractor in your area.

Honeywell ML7421A1032

I have this valve. 24 volt supply 
0-10volts dc control to open and close the valve
I found space over heating when I got here. Checked valve and found in mid open position. With no call from control system. I cycled valve a couple times , but always goes back to mid position. I checked the jumpers on the W3 and W4  spaces. They seem to be set correctly. 
Am I missing something ?  Or is the valve no good
thank you 


    EBEBRATT-Ed Member Posts: 15,624
    Make sure the selector plugs are in the right spot. Did you check the signal? if it is in mid position you should have a 5 volt signal.

    Selector has to be set up right for 0-10vdc, 2-10vdc, or 4-20ma

    I would unhook the signal wires to it and hook up a signal generator if you have one and see if that drives it back and forth