glitch
Veteran Member
I picked up a new-to-me heater for the workshop, manufactured sometime in the 1960's. It's a gas heater, but they didn't have combination gas valves back then, so it's got a separate pilot valve, regulator and electronic gas valve. Everything is pretty normal, except the gas valve.
The first oddity I noticed is that the nameplate said it was a 21V AC or DC valve. Its control transformer was also 21V. The transformer tested as good, so I connected it to the gas valve and...nothing. I removed the top of the valve to find what I thought was a standard solenoid gas valve, which lifts a plunger and opens what amounts to a poppet valve in the valve body. It showed a low resistance with my multimeter, but nothing moved when powered up. After taking a closer look, I realized that what I thought to be a solenoid coil was really a slide gasket, and that what I thought was the return spring and lever of the solenoid was a metal plate with a zig-zag of wire sandwiched between two pieces of mica!
After applying 21 VAC for around 45-60 seconds, the valve starts to move a little, and then snaps open. The supposed return lever is apparently bimetallic, and flexes up when heated, opening the gas valve. Just as it takes a while to open up when power is applied, it takes around 30-45 seconds to close when power is removed, as the bimetal spring cools down.
Has anyone ever seen a control valve like this? It's a new one to me!
The first oddity I noticed is that the nameplate said it was a 21V AC or DC valve. Its control transformer was also 21V. The transformer tested as good, so I connected it to the gas valve and...nothing. I removed the top of the valve to find what I thought was a standard solenoid gas valve, which lifts a plunger and opens what amounts to a poppet valve in the valve body. It showed a low resistance with my multimeter, but nothing moved when powered up. After taking a closer look, I realized that what I thought to be a solenoid coil was really a slide gasket, and that what I thought was the return spring and lever of the solenoid was a metal plate with a zig-zag of wire sandwiched between two pieces of mica!
After applying 21 VAC for around 45-60 seconds, the valve starts to move a little, and then snaps open. The supposed return lever is apparently bimetallic, and flexes up when heated, opening the gas valve. Just as it takes a while to open up when power is applied, it takes around 30-45 seconds to close when power is removed, as the bimetal spring cools down.
Has anyone ever seen a control valve like this? It's a new one to me!