lp13-30 wrote:
Hi CB. A few years back I ran into something wierd on three T87's.
Somethng happened to the mercury in the bulb-- instead of being a shiny
silver, it was a grey that looked more llike molten lead, and flowed
like lead. Normally, as soon as the bulb moves just past level the
mercury rolls freely to the lower side. In these cases, the mercury
wouldn't move either way until the bulb was at damn near a 45 deg angle.
For the amount of temperature control that gave, they were more of a
toggle switch than a thermostat. The first one I saw was on a wall
heater. I had installed the stat the fall before, so it was replaced
under warranty. The other 2 were on central a/c-- age unknown, probably
5- 10 y/o. Both of those calls were in a/c season as I recall. Funny,
never seen anything like that on any other mercury bulb stat, and never
seen another one since the last of those three, about 7 years ago more
or less. Larry

This is Turtle.

I do remember this problem but mine was on a White Rogers Rectangle
standard gas / Electic combo type WRXXXX444 thermostat. this was on a
new one out of the Box on about 3 of them about 15 years ago. they
would wait for ever to switch then when they did switch they would
bounce back and forth and short cycle the compressor with out a time
delay on the compressor. the reason they were doing this as persay the
Factory Rep. they had put too much mercury in the bulb which would make
it really fly over when it did switch. The Warehouse had about 2 Gross
of them they sent back to be replaced. This is the only time in my life
i ever seen this.

TURTLE