Astoria Straight Heat Exchanger cups-and-porcelain/cup-and-porcelain-capp Four holes for flow

Four holes for flow

Because it's held in place purely by the group gasket's compression

no special fitting required

and others with 57–58 mm baskets

then the nut — and reassemble in reverse

Astoria Straight Heat Exchanger cups-and-porcelain/cup-and-porcelain-capp Four holes for flowAstoria Straight Heat Exchanger The oldest version of this heat exchanger, no longer in production. This is limited old stock inventory that has been sitting for roughly two decades, so units show heavy surface oxidation. COMPATIBILITY Fits: older Astoria boiler assemblies using the straight style heat exchanger (discontinued, not interchangeable with later curved versions) INSTALLATION Moderate DIY to professional difficulty; recommend a qualified