Hi all, first question here! I've spent an hour searching, learned a lot, but not a specific answer so I hope this isn't too common a question!

One family ranch home with gas furnace, hot water baseboards, 40 year old Honeywell thermostats in main floor hall and basement main room. When working properly, the 'stats control the floors separately but this seldom happens. The symptoms when not working are inconsistent varying from one floor okay but the other cold, to furnace cycling every 15 seconds, to lukewarm silent pipes.
The thermostats need to be replaced regardless, both full of crud, sticky contacts, it's time! Question being are they the problem, and should I blindly buy the Honeywell models that fit the same profile and wiring? I noticed the specs mention "not for two stage systems" and from researching here, I get the idea that doesn't pertain here. We have no need for timers or electronics, just the basic model that can be super-glued to 65 degrees :p

Thanks for your reading time!

Is this a boiler system?

You can just replace the honeywell stats with like same units. T-87 is the current round one number.

Thanks hvac1000. That's what I'm assuming, I unscrewed one from the wall and there are only two wires connected, red and white. Gave them both a good scrubbing with an old soft toothbrush and emery on the contacts, last night was warm & cozy! Also fiddled with the adjustment plates (forgot the proper term.)

Can I assume that all specific zoning controls take place in the wiring at the furnace end and there is nothing special where the thermostats are concerned?

By the way, yes, hot water boiler. Thanks!

The thermostat just activates the zone valve or water pump depending upon the system you have. Thermostats are sensitive so do not scrub too much or you might put them out of calibration.

As far as heating goes, most thermostats are just simple on/off switches. If you read the sticky, you should have seen the trick of connecting thread and white wires to diagnose a bad thermostat. You would have also seen the sequence operations which follows the simple switching power from the red to the white at the thermostat.

Some furnaces such as mine have 2 firing stages that I could control with a more complicated thermostat. I have a simple thermostat and let the furnace use its internal program to select the firing rate. 2 stage is different from 2 zone.

It the cleaning proves to be a lasting fix, I would stick with what you have. Otherwise, I agree a new round Honeywell maybe as good as anything.

Thanks, I'm going to replace them just because of the age of these two, no reason not to!