Question:
I have a 3” Watts Model 007DCDA that needs to be serviced. I want to replace the check valve discs. Can you go over the repair procedures for this assembly?
Mark:
The 3” Watts Model 007DCDA is a double check detector assembly. Production of the original unit began in 1995 and is still manufactured. Early versions utilized a ¾” 007M1 for the bypass assembly. It currently utilizes a ½” 007 for the bypass assembly. There are no special tools needed to make this repair. This unit has a single access cover that is o-ring sealed and secured by hex head bolts. There is no spring load on the cover.
Doug:
Once the cover has been removed, the check valves can be serviced. The check valve modules are sealed by an o-ring and secured by a retainer. The stainless steel retainer should slide straight up and out of the body. To remove the first check module, simply grasp the spring retainer (cage) and pull toward the center and straight out of the body. To remove the second check module, use a flat head screwdriver to help pry it toward the center and straight out of the body.
Mark:
To disassemble the check modules, the plastic retainer (cage) must be removed. Note: The check spring is retained, so there should be no spring load to deal with during disassembly or disc replacement. The retainer cage is attached to the seat with a bayonet locking system. Hold the cage firmly in one hand, push the seat inward with the other hand, and rotate counterclockwise approximately ¼ turn. Once it is unlocked, then the poppet assembly and seat are free.
Doug:
To replace the check disc, simply remove the stainless steel retaining nut and washer from the poppet assembly. Now the checks can be reassembled in reverse order. It is important to note that the retainer cages can become brittle and break during service. When replacing the rubber disc, we would advise that the cage be replaced as well. Once the check assembly has been assembled, simply push each check module back into the body until it is fully seated. When replacing the stainless steel retainer, make sure that it slides into place easily. If it does not, then the check modules are not fully seated into the body.
