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Saturday, December 8th 2018, 9:44am

Control valve on one zone does not open properly (without help)

I have a 6 zone system and all use Richdel 205S. About a month ago one zone stopped opening. Disassembled and everything looked ok. Diaphragm looked good and control solenoid worked OK. Carefully reassembled and rechecked. Only way I can get valve to come on is to temporarily open "bleeder" valve on top and then the main valve opens. Once the main valve opens I shut the bleeder and it continues to work OK and when the small control solenoid turns off the main valve shuts down OK. I disassembled the valve again and checked all of the ports that relieves the pressure from the top of the main valve diaphragm when the control solenoid opens and there are no obstructions. Reassembled carefully so as to not obstruct the control ports with the diaphragm gasket. I am at a loss. There appears to be just slightly to much pressure on the diaphragm top to allow the main valve to open even though the control solenoid is open and should relieve this pressure. I must temporarily open the manual bleeder valve and then close it and then the main valve will open OK. What would be keeping the pressure on the valve diaphragm to high to allow the main valve to open even though the control solenoid is opening OK and should be relieving the pressure on the main valve diaphragm?



Posts: 2,315

Location: USA


Saturday, December 8th 2018, 2:47pm

It's almost always the diaphragm on the 205. ON the old Richdel there's a white plastic piece holding the diaphragm together. It breaks off and the valve does exactly what you've described. I'm thinking you would have noticed that if that's the case. The white thing and the stainless steel washer would be missing.

That valve is an easy rebuild. You've already done it twice. Just buy new parts and swap them out. Maybe since the valve's so old, just buy a new 205 and swap out the diaphragm and the bonnet with the new solenoid.

As long as the valve's getting the proper output from the controller, the rebuild will fix you up.205

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