Buzzing in control panel

[handyhomeowner]

We have a HE Oil furnace with an EWC ST-2E Ultra-Zone control system. We have been having an issue where the furnace will not kick on for Zone 2, but it will for Zone 1.

Example: If I set the Zone 1 thermostat to 60 degrees, and set the Zone 2 thermostat to 70 degrees, the furnace will not stay lit once the temperature drops below 70 degrees, and will not kick on again until Zone 1 hits 59 degrees. However, if I leave the Zone 1 thermostat at 70 degrees, then Zone 2 will continue to get heat. I was able to verify that I have independent control of Zone 2 (from Zone 1). If I turn Zone 2 down to 55 degrees, the heat will cut off.

In the control panel, I was able to confirm that both zones are "OPEN". An interesting observation that I made was that there is a loud buzz coming from the Control panel. I can isolate it to K4 and K5 by pressing on the housing of the individual (relay?). This buzzing only occurs when the furnace is not lit. If/when the furnace kicks on, it goes away.

I can see that there has been some corrosion in the control panel. I am wondering if that is causing my issue, and if I need to just replace the entire panel, or if there is another issue that may be causing the problem?

Thanks in advance for your input.

[Paul Z.]

I would like to speak with, give the office a call. 1-800-446-3110X490