|I had been thinking about doing an email on the Honeywell Smart Valves for a long time now. And since I recently had a discussion with a fellow service technician about his trouble diagnosing one, it made me think of the 2 most common issues I experienced with those valves. So, today is the day.
While there is nothing simple about a Smart Valve, it’s not complicated. Honeywell designed this valve to be a universal valve. The valve has a circuit board that can control a pilot valve, it energizes an HSI, it has flame rectification, it energizes the main valve, it does it’s own diagnostics, and can be used to energize another 24 or 120v circuit. And some models don’t even use a pilot burner to light the main burners. In essence, the manufacturer doesn’t need an S8610U / S8910U ignition control board nor a few other controls to do what they want to do.
This valve is used in many heating applications like forced air, boiler, domestic water, and oil. Some manufacturers run their limit circuit and / or a pressure switch circuit through it. Others energize their inducer motor, and still others energize a simple Electronic Fan Timer Board to control an ‘on/off’ fan cycle.
The different manufacturers that use the Smart Valve don’t always use the same color wiring and they designate some terminals differently. The 4 pin plug on the SV9520 series valve is dedicated to 120v usage, but on the 9501 series it’s used for 24v communication. That means this will not be an exhaustive email about Smart Valves as there is lots to learn so you will have to read the wiring diagram on your specific unit to know which terminals do what.
Now, there are a couple models of Smart Valves. The SV9400, the SV9500, and the 9600 series cover single and 2 stage, slow and fast opening applications. The BTU rating on the 9400 series is the lowest and the 9600 is the highest with 3/4″ inlet and outlets.