Question on home heating furnace

Sizing is approximately the same as AC, 12000 btu for every 500 sf. My house is 1900 sf and furnace is 40K btu on 2 burners.
Pierre
 
My adjustment for the Sensi thermostat is in firmware, programmable through a smart phone app. The Honeywell adjustment is on the rear of the thermostat, only accessible by removing the thermostat. Once temperature is reached, our L.P. furnace will probably run for around five minutes in each cycle. The off time depends upon the outside temperature.
 
I would suggest you look into a different "smart" thermostat that is more adjustable. You can set the temperature swing (heat differential setting) to decrease the on/off cycling as well as time (heat dissipation time) when the furnace shuts off after the burners turn off. If you had a variable speed furnace you could modulate the heat output and fan speed which saves energy and is more comfortable. In addition some thermostats have a remote battery operated wireless sensor so it can be controlled by the temperature in a different location vs. the main thermostat. I have the Ecobee 4, they now have the 5 with native voice control. Does a very good job of modulation the temperature and they have a motion detectors so if it does not sense motion it can turn down the heat. It has a fairly elaborate menu system of adjustments that can be done on screen, smart phone or computer. I tried Google Alexa to control things, but she got banished from my house. There are often rebates for these smart thermostats that make them more reasonable. I do not use any of the learning modes, I prefer to set all my own controls, but if you leave the house the Ecobee will go into vacation mode with no movement or you can use your smart phone. Well worth the investment. I recommend the Ecobee over the Nest, the latter I have had more people complain about the thermostat having a mind of its own.

Help Centre

support.ecobee.com support.ecobee.com
 
Older thermostats had a "heat anticipator". It was basically a way to appy some curent to the thermostat coil to heat it up, causing it to shut down the furnace before the room got up to full temperature, so it would not overshoot. Some of these are adjustable with a dial (rheostat). Newer electronic thermostats probably do something similar in firmware, check the settings.
 
Flyinfool said:
I have 3 of the 4 bedrooms with the heat shut off cuz I don't use them for anything other than storage. That means I have 80K BTU feeding about 2/3rd of the house.I wonder if it might be more efficient to open those rooms back up to have better use of the furnace.
Click to expand...

Closing off too many registers can definitely cause your problem. As I said in my earlier post, the unit could be cycling on the high temperature thermal safety switch. If you cut down too much air flow over the heat exchanger it gets too hot and shuts the unit off. When the thermal switch cools down and re-closes the unit will re-start (unless the thermal switch is a manual re-set type). May be worth checking.

Ted
 
The more research I do into this the more screwed up I think the whole system is.

I set up a temp probe right next to the thermostat to see what the actual temps are doing.
The thermostat is trying to hold temp on this old house to within 1/2 degree. the stat asks for heat when the temp drops by 1/2° and shuts off when it reaches set temp a half degree higher, the room then climbs a half degree more while the furnace is in cool down mode.
There are no adjustments of any kind on this stat, I even took it down to check the back.
I guess this means that I need a new stat.

It is not the furnace hitting over temp It is defiantly the stat that is doing it all, I have an indicator to tell me when the stat is asking for heat.

I was hoping to be able to do a new furnace next summer anyhow, it has to be a summer job cuz I want to move the furnace to a different location in my shop, more out of the way and with the rest of the appliances (washer, dryer, water heater, laundry tub). This means plumbing changes to make room and a lot of duct work and even some structural work on the house. but it will make a lot more room in the shop.
 
Our electric utility is Alliant Energy and every so often in partnership with a group called Focus on Energy, they send me offers for free or greatly reduced products related to energy saving. Several years ago, they offered a choice of one of two free smart thermostats; one the Nest thermostat and the other the Sensi thermostat. I chose the latter.

There may be similar programs with your utility company. Worth checking out.
 
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Mine did that at first then I found the thermostat was set for electric baseboard heat. changed it for a gas furnace and it fixed it
 
We had a lot of trouble with short cycling when we moved into our current house. It was more with the AC than with the heat. I tried different things, including a fancy new thermostat that had an adjustable range between the "on" and "off" temperatures. Nothing seemed to work. Then, one day I was fiddling with it and I just happened to have the thermostat pulled away from the wall. The AC came on, and I immediately felt a cool blast of air coming out of the hole in the wall for the thermostat wire. With the system running, a pressure differential existed between the basement and the upstairs, causing cool basement air to enter the stud cavity and exit through the thermostat wire hole in the wall. It caused premature cooling of the thermostat, which then shut the system off. I plugged the hole with a little caulk, and after that everything worked fine!

Again, we had more trouble with AC than with heat, but it's possible you could have a similar problem.
John
 
@Flyinfool give this a try: turn your fan switch to have the fan continuously run. I put in an 80K BTU 92% furnace inmy house years ago, and we don't have a short cycle problem. Our thermostat is located in the updtairs at the farthest point from all the vents, and we run the motor 124/7 365. This makes the heat even in the entire house winter and summer...
 
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