Rebuild when we can,
replace when we must.

The 11 kits we stock

Eleven models cover 84% of the installed base on our books. The kits live in the cabinet. Each kit contains the diaphragms, seats, springs, O-rings, and gaskets needed for a full top-of-stem rebuild on one assembly. We do not stock body parts (housings, end caps, cover bolts) — those are not consumed in a routine rebuild and are special-ordered if a tester's inspection finds a body crack or pitting.

Model	Kit P/N	Parts cost	Avg rebuild duration
Watts 909 (1/2″–2″)	RK-909-RT	$78	25 min
Watts 957 (2.5″–10″)	RK-957-RT	$240	45–90 min
Watts 919 (DC, 1/2″–2″)	RK-919-RT	$68	20 min
Wilkins 350 (DC)	34-RTKL	$72	22 min
Wilkins 375 (RP)	36-RTKL	$92	30 min
Apollo 4ALF-500	RK-4ALF	$84	28 min
Conbraco 40-200	RK-40-200	$72	25 min
Febco 825Y	905-356	$76	26 min
Febco 860	905-360	$210	55 min
Febco 805Y	905-352	$54	18 min
Hersey FRP-II	HF-RK	$120	45 min

The rebuild procedure

The procedure for a small (1/2″ to 1″) RP rebuild, which is the most common job:

1. Isolate the assembly: close SOV-1 and SOV-2, then open TC#3 (relief test) to verify there's no upstream pressure leak.
2. Drain the assembly through TC#2 and TC#4 into a bucket.
3. Loosen the cover bolts in a star pattern. Lift the cover. Photograph the internals before removing them — diaphragm orientation matters and is the single most common rebuild mistake.
4. Remove old diaphragm, seat ring, spring, and lower poppet. Inspect the body interior for pitting, scaling, or solder flakes; clean with a soft nylon brush.
5. Install the new diaphragm with the printed orientation arrow pointing upstream. Install the new seat. Install the new spring. Install the new lower poppet.
6. Lightly grease the cover O-ring with the silicone supplied in the kit. Replace the cover. Re-torque the cover bolts in the manufacturer's specified sequence (always star pattern, never sequential).
7. Repeat for CK-2 and for the relief vent diaphragm.
8. Slowly open SOV-1, then SOV-2. Verify no continuous discharge from the relief vent. Re-test full sequence.

ASSE 5130

The American Society of Sanitary Engineering Series 5000 Standard for Professional Qualifications defines, in §5130, the qualifications and procedures for a backflow-prevention assembly repair technician. The credential requires 40 hours of bench training, a written exam, and a hands-on rebuild of at least four assembly families. Two of our crew hold this credential: Ferraro (since 2014) and Stoltzfus (since 2019). Okafor holds the testing credential but not the repair credential — she will isolate and re-test an assembly after a 5130 has rebuilt it, but she does not open one herself.

When not to rebuild

Four conditions take rebuild off the table:

• Body crack.

  A hairline crack on the bronze body, usually from a freeze, is not repairable. Replace.

• Obsolete model.

  Some older models — Hersey FRP-I, Beeco 6 — no longer have rebuild kits in production. Replace with a current USC-listed model.

• Hazard upgrade.

  A DC found protecting a high-hazard cross-connection cannot be rebuilt into compliance — only replaced with an RP.

• Repeated rebuild within 24 months.

  If we've rebuilt the same assembly twice in two years, the body has fatigued. Replace.

Freezes

Milwaukee runs 40–60 cycles per winter where the freeze line crosses 28 °F overnight. An RP in an unheated mechanical room — common in 1920s commercial blocks on Mitchell Street, common in foundry buildings in the Menomonee Valley, common on outdoor irrigation laterals — will freeze-crack if not protected. We charge $185 to install a heat tape and insulation jacket on a 1″ RP; $240 on a 1.5″–2″; $420 on a 4″+. The jacket pays for itself in a single avoided replacement.

References