gdgalla
11-25-2007, 02:59 PM
I'm trying to understand how the b-60 millivolt gas valve works.I've always been under the impression that when a sufficiant amount of millivolts was supplied to the valve that a magnetic field would pull up the diaphram inside and open the valve,very similar to how a contactor pulls in. After checking the millivolts supplied to the valve was correct and after checking all wire and valve connections for good contact,the valve still would not open,so I would use the term stuck gas valve.I'm installing a new replacement gas valve due to the b-60 being an obsolete valve.I took the valve out of the floor furnace and connected a new 750mv thermopile generator to it and put pressure on the inlet.It still wouln't open.With nothing to loose now I opened the valve up to try to understand how it works.now I'm more confussed-instead of just one coil I found two seperate coils.Each coil had only one wire going to it.these 2 wires connected to the top of the valve, that compleated the circuit through the thermostat and powerpile generator.There was a u shaped rod and each coil slipped over an end of this u bent rod.At the end of u bent rod was a thin metal plate that could only move back and forth a few thousands of an inch between two small orfices.One of the orfices goes out to the gas vent tube that goes close to the pilot to burn off the gas released from it.The other orfice could possibly go to the top or bottom of the internal diaphram.I'm assuming that closing off one of the orfices diverts the incoming gas pressure under the diaphram and the pressure under the diaphram opens the valve and when the circuit opens the plate moves to close the other orfice and the gas pressure under the diaphram is released out the vent tube allowing the diaphram to go in the closed position. When i checked for continuity at the top of the valve through the coil it showed open and it will because there are two coils inside with only one wire going to each coil. Very easy to diagnose an open coil.How is a magnetic field produced using a coil with only one wire going to it?What started all this was first I removed the thermostat & jumpered the thermostat-valve didn't open -used 1.5 flashlight battery across thermostat wires -valve opened-tested millivolts-350 -replaced powerpile generator-jumpered valve under house-valve opened. I thought problem was resolved-connected thermostat-unit took several seconds to come on-went back under house checked all connections ,tightened all connections-valve worked perfect-quick responce-left jobsite-got a call back-furnace not working-could not get it to do anything-condemed valve-will replace valve.what is the proper procedure for testing a b-60--thanks