Question:
I have a 3” Flomatic model RPZ that needs repair. Can you give me some basic information about this assembly? Are there any repair tips I should know?
Doug:
Production for the Danfoss/ Flomatic model RPZ was from 1993 to 2013. The 3” size uses a ductile iron body that is fused epoxy coated. These units have a single access cover that is sealed by the relief valve diaphragm. The check valves are modular in design and the springs are contained. No special tools are needed to repair this assembly. Now that we know some of the basics about the device, we can start the disassembly process.
Mark:
The access cover is secured by hex head bolts and sealed by the diaphragm. The access cover is also the guide for the relief valve stem. There is slight spring tension on the lid, so be sure to hold the cover firmly. Once the cover has been removed, the relief valve stem and spring are free. At this point, you can inspect the relief valve for any damage or wear. The relief valve assembly is made up of a brass stem, plastic disc holder, and plastic upper and lower guides. The diaphragm is held in place on the stem between two large stainless washers. When replacing the RV disc, the bottom fin guide must be unscrewed. Take care not to break the plastic guide fins during the repair.
Doug:
Now we can turn our attention to removing the check valve modules. The #1 check module must be removed before the #2 check can be removed. Each check valve is held into place by a stainless steel retaining ring and sealed by an o-ring. The retaining ring is one piece and fits between a groove in the body and the seat of the check valve. You will notice two small pins at the top of the check valve. You can use your fingers or channel lock pliers to squeeze the pins together so that the retainer wire can be removed. Once removed, the check valve module will pull straight out of the body. Use the same procedure to remove the second check valve assembly.
Mark:
Once the check valve modules are out of the body, the disc holder must be removed to service the seat and disc. Be aware that the spring tension must be released for the 3” model RPZ. You will notice that the brass disc holder has a raised hex area and the brass spring retainer is hex shaped as well. This will allow you to use adjustable wrenches to unscrew the check valve stem from the disc holder. NOTE: Be careful of the spring tension, especially as you unscrew the first check valve. Now you can examine the check seat and check disc. If the seat has been damaged, the complete check module must be replaced. When you reassemble the check valves, it may be helpful to have an extra set of hands to help compress the spring.
Now that the checks have been reassembled, they can simply be placed back into the valve body. It is important to note that as you reinstall the RV stem, be sure to align the holes so that the #3 test cock port in the body is not blocked. You can use the lid bolts to help align the diaphragm correctly.
