peter lena 8,072 #1 Posted January 30 was having erratic furnace , quick cycling , start / stop , burner is relatively new , 5 years , traced it back to internal mercury , glass shell tracking, not an absolute stop / start , bulb was horizontal , and had a very slight side to side rocking action , causing problem . replaced it with a new digital switch , that was it ! amazing that this was the original thermostat switch installed in the house over 50 YEARS AGO ! furnace is very happy now , I am too , Pete 5 2 Share this post Link to post Share on other sites
JCM 8,656 #2 Posted January 30 Was that an old T 87 T STAT Pete ? Share this post Link to post Share on other sites
peter lena 8,072 #3 Posted January 30 @JCM don't know that ,but he took it mentioned that they were not safe to handle , made by HONEYWELL . also said that now , thats a regular replacement on any newer burner replacement , similar problem to mine , he said they are outlawed today , dangerous possible collective related issues . 1 Share this post Link to post Share on other sites
JCM 8,656 #4 Posted January 30 The T 87 was the old round thermostat made by Honeywell with mercury switch. They lasted for many years used on hot air furnaces and hydronic systems. He is correct and they are no longer in use. 1 Share this post Link to post Share on other sites
rmaynard 14,909 #5 Posted January 30 My father was in the heating business. When he would replace an old mercury thermostat, he would throw them in the trash. That was the 50's and 60's. I'd pull the mercury tubes out and put them in an old coffee can. I left home in 1968. When dad died in 2004, we cleaned out his garage/shop and I found my coffee can. I still have a good collection of old mercury tubes. 1 Share this post Link to post Share on other sites
c-series don 7,843 #6 Posted January 30 @JCM Do you mean like this one? Set on 65, but it’s 72 because of my wood stove! 1 Share this post Link to post Share on other sites
JCM 8,656 #7 Posted January 31 I have 5 zones here at home that have Honeywell T stats with a Burnham cast iron boiler with cast iron baseboard heat. I still prefer the mercury ones. The new ones that replaced those are a bit of a PITA. Tough to beat old school stuff. Love the patina on that old Stat @c-series don . Share this post Link to post Share on other sites
c-series don 7,843 #8 Posted January 31 (edited) @JCM Ha! I have three of those hooked to a Burnham and baseboard also!! Since my kids grew up and moved out, the second floor is basically shut down to 50 degrees. My wife and I live on the first floor and I can heat that with the wood stove. I try my best not to burn oil, but I still need hot water! My daughter said I should replace the thermostat with an electronic one, I said NOPE this thing needs nothing, is not broken and I’m not changing it! Edited January 31 by c-series don 1 1 Share this post Link to post Share on other sites
Blasterdad 2,564 #9 Posted January 31 Had a good friend call me at 10:00 at night panicking, her 70 something year old Dad was home alone during the cold spell we had a couple of weeks ago. He had called her & said the furnace wasn't working & the thermostat was blinking "Low Battery" & he didn't know how to change it. 30 minutes later I changed the battery & had the heat back on, I told him if it was me I'd get rid of it for a simple one. He said he told his daughter on the phone he was going to smash it with a hammer & twist the wires together knowing she would flip out & call me. 2 2 Share this post Link to post Share on other sites
lynnmor 6,796 #10 Posted January 31 You guys would love my new Honeywell T6 Pro thermostat, it has a list of settings as long as your arm. Scroll thru the list Share this post Link to post Share on other sites
