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Watts
Plumbing

Model # 1788 Official Watts 1/2" water pressure reducing valve

Here are the diagrams and repair parts for Official Watts 1788 1/2" water pressure reducing valve, as well as links to manuals and error code tables, if available.

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  • In the search box below, enter all or part of the part number or the part’s name.

Not all parts are shown on the diagrams—those parts are labeled NI, for “not illustrated”.

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Error Codes

Model diagram and schematic

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Showing 10 of 45 parts  |
Service Kit 5B

#NI

All parts diagram

Service kit

Part #5B

The manufacturer no longer makes this part, and there's no substitute part

Disc Holder 50C47
#15B

Replacement parts diagram

Disc holder

Part #50C47

The manufacturer no longer makes this part, and there's no substitute part

Disc Holder 50B47
#15A

Replacement parts diagram

Disc holder

Part #50B47

The manufacturer no longer makes this part, and there's no substitute part

Union Tailpc 135C139
#23C

Replacement parts diagram

Union tailpc

Part #135C139

The manufacturer no longer makes this part, and there's no substitute part

Seat 50C16
#12B

Replacement parts diagram

Seat

Part #50C16

The manufacturer no longer makes this part, and there's no substitute part

Union Nut 35C140
#21C

Replacement parts diagram

Union nut

Part #35C140

The manufacturer no longer makes this part, and there's no substitute part

Spring 124
#5A

Replacement parts diagram

Spring

Part #124

The manufacturer no longer makes this part, and there's no substitute part

Lock Washer 174C46
#8

Replacement parts diagram

Lock washer

Part #174C46

The manufacturer no longer makes this part, and there's no substitute part

Disc 50C37
#14B

Replacement parts diagram

Disc

Part #50C37

The manufacturer no longer makes this part, and there's no substitute part

Gasket 1-1/2X1-3/4
#16A

Replacement parts diagram

Gasket

Part #1-1/2X1-3/4

The manufacturer no longer makes this part, and there's no substitute part

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