In fairness to all, we don't discuss pricing on the Wall. Thanks for your cooperation.
Vaporstat sticking / biasing after vacuum
Have a L608A 1046 2 Vaporstat picked up used.
Generally works well, though I can gripe that the faceplates are only approximate indicators, requiring one to rely mostly on the low-pressure gauge, and that this particular Vaporstat cannot diff less than 3 ounces.
But today I nailed down a problem that has been most vexing. Due to a lack of pipe insulation (coming this summer) the furthest radiator hammers when the system exceeds 8 ounces. I've set the Vaporstat to 4.5 cut-in 7.5 cut-out and most of the time it works fine.
Yet every now and then that radiator starts hammering away. I run down to the boiler and, there it is 9 ounces on the gauge!
Was observing the system just now and finally saw that what's happening. After long cycles all the vents close and the system pulls a decent one-inch vacuum as it cools. I was watching the needle on the expensive low pressure gauge reversing half way around the dial worried it would wreck the gauge when the Vaporstats makes a loud WHACK sound and gives me a start.
Seems when the vacuum pulls hard the mechanism jumps from a neutral balanced state to a negative stop of some kind, overcoming a good deal of friction.
Then on the next cycle the Vaporstat biases a full ounce-and-a-half, possibly two ounces higher than the nominal setting of 7.5 ounces and then WHACK again and it's back to normal.
After detaching the Vaporstat at the union, I was able to reproduce this behavior by simply sucking and blowing on pressure inlet.
Has anyone see and/or dealt with this sort of glitch? I'm quite pleased the system is tight enough after 90 years that it may be possible to experiment with vapor-vacuum, but for the moment I'd just like to get that Vaporstat behaving properly after cycles ending with vacuum.