Sensitive thermostat

[bigtiller]

How sensitive should the thermostat in the house be? We hired a guy to replace it a few months ago and noticed the temperature never changes. We have a propane fired forced air furnace with central air. The furnace/air-conditioner runs for a very short period of time but it runs many more times per day. It has less than one degree difference from demand to satisfied. Every thermostat I have seen would demand at say, 69 and was satisfied as soon as it reached 71. That's one full degree difference.

The new one has (guessing) half a degree from demand to satisfied.

Is this the best economical way to run a furnace and central air conditioner? Does it cause more wear & tare this way?

 

[CobyRupert]

How sensitive should the thermostat in the house be? Don't know.
Is this the best economical way to run a furnace and central air conditioner? No.
Does it cause more wear & tear this way: Yes.

This range is also referred to as "deadband" and/or "hysteresis". In some thermostats it can be adjustable.
It is probably a little more economical for your furnace to run at operating temp longer than short cycling, and definitely a lot less wear and tear if it's only starting and stopping, heating (expanding) and cooling (contracting) fewer cycles.

 

[JimRB]

What does the thermostat owners manual say about differntial settings? Thermostats With Adjustable Cycle Rate Differential – HVAC How To

 

[ultrarunner]

I generally go no more than 2 degrees in commercial buildings between heat and cool... generally have to make major adjustment twice... going into heating season and going into cooling season.

The reality is many buildings have heat loads and the hospital is no different in the office/administration areas... heat may not be called for all summer and fall...

Neighbor had a new system and it was always on/off... made a change to the blower and heating stages and now it cycles less... biggest change was keeping the blower on low setting to keep air moving which helps to keep it more even temp wise and filtered.

 

[bigtiller]

What does the thermostat owners manual say about differntial settings? Thermostats With Adjustable Cycle Rate Differential – HVAC How To

It doesn't have any differential settings. This is the one we have
Honeywell Thermostat, Stages 2 Heat/2 Cool TH522D13 | Zoro.com

And this is the owners manual.
Table Of Contents - Honeywell FOCUSPRO TH5 Operating Manual [Page 3]

 

[bigtiller]

Update;

Our HVAC guy came out today and changed thermostats. The first new one's deviation was not programmable. It was factory set at .4 degrees. The new one is set at 1 degree. It should be much more economical to run.