Weil McLain 590-317-629 Gasket
The Weil McLain 590-317-629 Starter Tee Gasket seals the starter tee connection on the Weil-McLain GV gas boiler. The GV Series 3 and GV Series 4 parts lists both show it as a "Starter Tee Gasket," in the section assembly figures (Figs. 11/12) and again in the later assembly figures (Figs. 18/19), marked for all boilers on the list. It is a flat red gasket with four mounting holes and a large round center opening, shown in the photo against a ruler so you can check the size against the gasket you are replacing.
On a condensing boiler the vent connection is not just a pipe joint. The starter tee is where the flue gas leaves the boiler, so the gasket has to hold a gas-tight seal against the boiler while it sees heat and condensate. A hardened, cracked or shifted gasket can leak flue gas into the boiler room, drip condensate onto the jacket, or draw room air into the vent. The Weil-McLain parts list notes that the 699-999-025 GV starter tee itself comes from the vent manufacturer, so the gasket is the one part you order here when you are resealing that joint.
Replace the gasket every time the starter tee is removed. Clean both mating surfaces, line the four holes up with the fasteners, and tighten evenly in a cross pattern so the gasket seats without crushing. After the boiler is running, check the joint with a combustion analyzer for carbon monoxide and look for any sign of leakage. The companion inspection port gasket is the 590-317-628, and the 560-907-629 is the inspection port cover. Inspect the joint at every annual service for staining, soot or crust, which are usually the first signs of a failing seal. This gasket is not listed on the GV Series 1 and 2 parts list, so confirm your series before you order.
Key Benefits
- Gas-Tight Vent Joint: Seals the starter tee flange so flue gas and condensate stay in the venting.
- Listed by Weil-McLain: Shown on the GV Series 3 and GV Series 4 parts lists.
- Four-Hole Pattern: The four mounting holes and round center opening are visible in the photo, so you can compare against your old gasket.
- Inexpensive Insurance: A fresh gasket every time the tee comes off prevents leaks and a repeat visit.
Common Questions
- Which boilers list the 590-317-629? The Weil-McLain GV Series 3 and GV Series 4 parts lists.
- Does it come with the starter tee? No. The 699-999-025 GV starter tee is available through the vent manufacturer. The 590-317-629 is the gasket only.
- When should it be replaced? Every time the starter tee is removed, and whenever you see staining, soot or leakage at the joint.