Thermostat and Its Hysteresis

Everyone knows what a thermostat is, but some may think hysteresis is part of the female anatomy.

But still, I have an observation to share about my thermostat, to learn from and generate some discussion.

I have my t-stat about halfway across the house from my stoker. Stove is in basement, t-stat is on next floor up. House is warm and all, but it seems that my digital t-stat calls for heat for about 5 minutes, then senses the temp is met and shuts the stove off. It waits about 5 or 10 minutes, and starts the process over. I certainly don't get the overshoot and udershoot that others on the forum experience. And it's not because my t-stat is close to the stove, it's quite a ways away.

But I think it's pretty inefficient this way. I was thinking maybe I shoud try a good old-fashioned mercury t-stat, or similar, since their hysteresis is either somewhat adjustable by spring tension, or just naturally have that feature due to the weight of the mercury. I'm sure some digital t-stats have are adjustable as well, just don't know much about them.

Any thoughts, or experiences others have had on this?

Actually, some have an Anticipator Circuit

Inside the thermostat just behind the outer cover of these types of thermostats you will see a heat anticipator. It looks something similar to one of these two:
**Broken Link(s) Removed**These adjustments are the heat anticipator. They are for the length of the cycle of the heating, but sometimes there is one for the cooling. But almost always, the cooling anticipator is a fixed resistor on the subbase. It's a very critical measurement with special instruments for the professional. Don't worry, you can set a replacement thermostat heat anticipator just like the old one or you can make adjustments in very small increments as instructed here.

1. HEAT CYCLE TOO LONG--Set adjustable heater to a slightly lower dial setting. (1/2 division)
2. HEAT CYCLE TOO SHORT--Set adjustable heater to a slightly higher dial setting (1/2) division)

Another good article

http://inspectapedia.com/heat/Thermostats6.htm

My digital LUX, there are some settings in the setup of the digital for Heat Loss Factor or something, etc...that you can change to make it respond quicker. On the dial type, you can vary the resistance.

Coal Trol works way better controlling my Hyfire. it only lags/overshoots about 1 degree at times.

WNY - Yes I've seen these anticipator inside some t-stats. But my cheap digital t-stat is sealed up, not ajustments to be made except just the hold temp with a button. Guess I'll need to get a different t-stat to be able to ajust this setting.

Steinke

Which Digital, some have a Heat Loss Factor or something, mine you have to hold the "HOLD & RESET" buttons to get to it. I think it a 1-5 scale. I usually just leave mine on HOLD around 65 or so.

It's a Honeywell t8400. Page 5 in the following manual seems to explain how to change the setting. Any suggestion as to what I should try for coal?

**Broken Link(s) Removed**

It looks like you can set the cycles per hour, on the old thermostats you set the anticipator based on the amperage draw of the circulator pump if I remember correctly. On yours, I would start with 2 cycles per hour, then if that's not enough go up to 3, then 4, until you get the lowest # of cycles that does the job.