Honeywell L408J 1009 Vaporstat Failures

Gordo

I suspect that the diaphragm is not not being sealed around the edges properly and that is allowing pressure to leak away, drawing in non-compressible water into the diaphragm space.

neilc

how does it matter that water (or oil, or air) is under the diaphram, it still pushes up, right?
isn't this just like a pressure reducer diaphram doing its same thing?
or is this that the sensitivity of ounces isn't transmitted well thru the water?
without a gage there telling us otherwise I'm guessing we're just leaking and not building pressure at the trol.

Double D

I just installed a new Honeywell L408J1017, 0-4psi vaporstat today and it makes that popping sound. The last 2 did not make that noise. Should I exchange it or wait and see?

dean_20

Now I'm glad I listened to Steamhead years ago and put a mercury one on my boiler.