[Half-Inch Stud]

Originally Posted by Shiny

Please forgive me but I can't resist...
You sure nobody swapped that ID plate? Those rivets don't look factory to me...

And yes, that thermostat looks like it was built like a tank. Why do you think it would lose 40 degrees calibration? Is the bimetallic coil corroded or was solder used as a mechanical connection and then creeped/relaxed or ??? If the calibration changed because the coil relaxed I'm not sure I'd be calling it a good design, but hey..

There's some serious nostalgia in that thing but geeeshhhh.. I'd say you are lucky the contacts in that switch are still working.

I figure there was friction for where the swingarm pivoted on the centershaft, maybe dug a groove. Also the switch might have increased in Click pressure, just a wee. No corrosion but i could figure some fatigue or bimetal strain relief occured.

The system is holding Temp as usual 70 inside, 29 Outside. Temps to 180 then shuts the gas.
Cleaned-up the gauges; Temp gauge needle seems flakey, so would enjoy a replacement.

Here's a photo of the Furnaces: Coal (water and exhaust disabled) on left, Auger all there but not shown in photo. Natural gas on right..

[bluebandit]

In your last photos there is a relief valve right after the feed regulator on the supply line. If you have a temp gun shoot the outlet pipes to compare to the gauge

[Half-Inch Stud]

Originally Posted by bluebandit

In your last photos there is a relief valve right after the feed regulator on the supply line. If you have a temp gun shoot the outlet pipes to compare to the gauge

Oh thaaaat! Yea there is a relief valve on the water feed side which goes into the return. Never a drop seen.

I never had the expansion tank drained. However the radiators seems restored because none of them show any leak or rust stains. So i figure the tank was done at that time...whenever that was.

[Shiny]

Originally Posted by Half-Inch Stud

I figure there was friction for where the swingarm pivoted on the centershaft, maybe dug a groove. Also the switch might have increased in Click pressure, just a wee. No corrosion but i could figure some fatigue or bimetal strain relief occured.

Thanks for the insight. The coiled strip seems an opportunity for residual stress that could relax over time but gotta admire the old-school mechanical approach. I'm still amazed the switch still works and overall, that the entire system still works.

My son texted me yesterday, fuming because his cell-phone battery won't hold a charge right when he paid it off. Device failure is a marketing conspiracy in his mind. I should tell him two cans and a string would last longer.