The sight glass assembly is a fragile part that is prone to cracks if disturbed. It's critical that one over the compression nuts is loose before removing frozen side. twisting of compression nut will stress glass causing leak or cracking glass. In this review, it was only necessary to run a cleaning brush in tube to clear.
Thoughts on Site Glass removal. The assembly is held in place by the back frame (no ID# which is not available) See page 9-86 Tab G-2. It's only supported by the tabs at both ends. I don't believe the backing frame was intended to support the site glass but really an "After Thought" to highlight the water level against the boiler (it's copper in Italy and silver in USA) There are times when there is a Glass blanket with silver backing wrapping boiler. The backing frame was not needed if the ball (green or red) indicator float was in place. But with the frame in place, there is an assumption that it's a support. But inspection shows it's only supported by the pipes attached to the boiler.
Reasons to remove glass assembly:
- Site glass already Cracked. Remove assembly completely and clean/clear clogs. Replace all gaskets. Assemble site glass Loosely without tightening down. Assemble glass, gaskets, lock nuts prior to installation. Apply Teflon paste to pipe expansion collar. Attach pipes and finger tighten. Insert class assembly. Start tightening pipe nuts to boiler while watching boiler fittings to prevent twisting. Monitor glass side for twisting. Continue to tighten till pipe nuts are secured. Note, do not over tighten as the nut will crack. Snug down Glass upper and lower nuts. Only light tightening is needed as the new gaskets will easily seal against pipe. Use Teflon past or High temperature Engine gasket sealant if your still using old gaskets. Note, when using gasket sealant. Don't tighten nuts. Very loose, just enough to grab threads. let sit 24 hours to cure. Additional locking only if leakage occurs.
- Lower or upper pipes not allowing water levels to show tank levels. BUT only AFTER boiler drained and cleared. Ports to Site Glass checked and probed to clear any clogs from the Boiler side. Use wire probes and air gun to clear rubbish in site glass pipes.
- Cosmetic cleaning. Not recommended as pipes are assessable directly with wire brush or steel wool,